ensure view projections for extensions always point to extendee

Co-authored-by: Harmen Stoppels <harmenstoppels@gmail.com>

.github/workflows/audit.yaml

@@ -25,7 +25,7 @@ jobs:
         python-version: ${{inputs.python_version}}
     - name: Install Python packages
       run: |
-        pip install --upgrade pip six setuptools pytest codecov 'coverage[toml]<=6.2'
+        pip install --upgrade pip six setuptools pytest codecov coverage[toml]
     - name: Package audits (with coverage)
       if: ${{ inputs.with_coverage == 'true' }}
       run: |

.github/workflows/bootstrap-test.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -ex
 source share/spack/setup-env.sh
-$PYTHON bin/spack bootstrap untrust spack-install
+$PYTHON bin/spack bootstrap disable spack-install
 $PYTHON bin/spack -d solve zlib
 tree $BOOTSTRAP/store
 exit 0

.github/workflows/bootstrap.yml

@@ -42,7 +42,8 @@ jobs:
         shell: runuser -u spack-test -- bash {0}
         run: |
           source share/spack/setup-env.sh
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack external find cmake bison
           spack -d solve zlib
           tree ~/.spack/bootstrap/store/
@@ -79,7 +80,8 @@ jobs:
         shell: runuser -u spack-test -- bash {0}
         run: |
           source share/spack/setup-env.sh
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack external find cmake bison
           spack -d solve zlib
           tree ~/.spack/bootstrap/store/
@@ -143,7 +145,8 @@ jobs:
       - name: Bootstrap clingo
         run: |
           source share/spack/setup-env.sh
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack external find cmake bison
           spack -d solve zlib
           tree ~/.spack/bootstrap/store/
@@ -160,7 +163,8 @@ jobs:
         run: |
           source share/spack/setup-env.sh
           export PATH=/usr/local/opt/bison@2.7/bin:$PATH
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack external find --not-buildable cmake bison
           spack -d solve zlib
           tree ~/.spack/bootstrap/store/
@@ -261,7 +265,7 @@ jobs:
         shell: runuser -u spack-test -- bash {0}
         run: |
           source share/spack/setup-env.sh
-          spack bootstrap untrust spack-install
+          spack bootstrap disable spack-install
           spack -d gpg list
           tree ~/.spack/bootstrap/store/
 
@@ -298,7 +302,8 @@ jobs:
         run: |
           source share/spack/setup-env.sh
           spack solve zlib
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack -d gpg list
           tree ~/.spack/bootstrap/store/
 
@@ -315,7 +320,7 @@ jobs:
       - name: Bootstrap GnuPG
         run: |
           source share/spack/setup-env.sh
-          spack bootstrap untrust spack-install
+          spack bootstrap disable spack-install
           spack -d gpg list
           tree ~/.spack/bootstrap/store/
 
@@ -333,7 +338,8 @@ jobs:
         run: |
           source share/spack/setup-env.sh
           spack solve zlib
-          spack bootstrap untrust github-actions-v0.2
+          spack bootstrap disable github-actions-v0.4
+          spack bootstrap disable github-actions-v0.3
           spack -d gpg list
           tree ~/.spack/bootstrap/store/
 

.github/workflows/build-containers.yml

@@ -13,7 +13,7 @@ on:
     paths:
       - '.github/workflows/build-containers.yml'
       - 'share/spack/docker/*'
-      - 'share/templates/container/*'
+      - 'share/spack/templates/container/*'
       - 'lib/spack/spack/container/*'
   # Let's also build & tag Spack containers on releases.
   release:
@@ -80,16 +80,16 @@ jobs:
           fi
 
       - name: Upload Dockerfile
-        uses: actions/upload-artifact@3cea5372237819ed00197afe530f5a7ea3e805c8
+        uses: actions/upload-artifact@83fd05a356d7e2593de66fc9913b3002723633cb
         with:
           name: dockerfiles
           path: dockerfiles
 
       - name: Set up QEMU
-        uses: docker/setup-qemu-action@8b122486cedac8393e77aa9734c3528886e4a1a8 # @v1
+        uses: docker/setup-qemu-action@e81a89b1732b9c48d79cd809d8d81d79c4647a18 # @v1
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@c74574e6c82eeedc46366be1b0d287eff9085eb6 # @v1
+        uses: docker/setup-buildx-action@8c0edbc76e98fa90f69d9a2c020dcb50019dc325 # @v1
 
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@f4ef78c080cd8ba55a85445d5b36e214a81df20a # @v1
@@ -106,7 +106,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build & Deploy ${{ matrix.dockerfile[0] }}
-        uses: docker/build-push-action@c84f38281176d4c9cdb1626ffafcd6b3911b5d94 # @v2
+        uses: docker/build-push-action@c56af957549030174b10d6867f20e78cfd7debc5 # @v2
         with:
           context: dockerfiles/${{ matrix.dockerfile[0] }}
           platforms: ${{ matrix.dockerfile[1] }}

.github/workflows/ci.yaml

@@ -46,7 +46,7 @@ jobs:
         with:
           fetch-depth: 0
             # For pull requests it's not necessary to checkout the code
-      - uses: dorny/paths-filter@b2feaf19c27470162a626bd6fa8438ae5b263721
+      - uses: dorny/paths-filter@4512585405083f25c027a35db413c2b3b9006d50
         id: filter
         with:
           # See https://github.com/dorny/paths-filter/issues/56 for the syntax used below

.github/workflows/setup_git.ps1

@@ -6,6 +6,10 @@ git config --global user.email "spack@example.com"
 git config --global user.name "Test User"
 git config --global core.longpaths true
 
+# See https://github.com/git/git/security/advisories/GHSA-3wp6-j8xr-qw85 (CVE-2022-39253)
+# This is needed to let some fixture in our unit-test suite run
+git config --global protocol.file.allow always
+
 if ($(git branch --show-current) -ne "develop")
 {
     git branch develop origin/develop

.github/workflows/setup_git.sh

@@ -2,6 +2,10 @@
 git config --global user.email "spack@example.com"
 git config --global user.name "Test User"
 
+# See https://github.com/git/git/security/advisories/GHSA-3wp6-j8xr-qw85 (CVE-2022-39253)
+# This is needed to let some fixture in our unit-test suite run
+git config --global protocol.file.allow always
+
 # create a local pr base branch
 if [[ -n $GITHUB_BASE_REF ]]; then
     git fetch origin "${GITHUB_BASE_REF}:${GITHUB_BASE_REF}"

.github/workflows/unit_tests.yaml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['2.7', '3.6', '3.7', '3.8', '3.9', '3.10']
+        python-version: ['2.7', '3.6', '3.7', '3.8', '3.9', '3.10', '3.11']
         concretizer: ['clingo']
         on_develop:
         - ${{ github.ref == 'refs/heads/develop' }}
@@ -22,7 +22,7 @@ jobs:
         - python-version: 2.7
           concretizer: original
           on_develop: ${{ github.ref == 'refs/heads/develop' }}
-        - python-version: '3.10'
+        - python-version: '3.11'
           concretizer: original
           on_develop: ${{ github.ref == 'refs/heads/develop' }}
         exclude:
@@ -35,6 +35,9 @@ jobs:
         - python-version: '3.9'
           concretizer: 'clingo'
           on_develop: false
+        - python-version: '3.10'
+          concretizer: 'clingo'
+          on_develop: false
 
     steps:
     - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # @v2
@@ -52,7 +55,12 @@ jobs:
               patchelf cmake bison libbison-dev kcov
     - name: Install Python packages
       run: |
-          pip install --upgrade pip six setuptools pytest codecov[toml] pytest-cov pytest-xdist
+          pip install --upgrade pip six setuptools pytest codecov[toml] pytest-xdist 
+          # Install pytest-cov only on recent Python, to avoid stalling on Python 2.7 due
+          # to bugs on an unmaintained version of the package when used with xdist.
+          if [[ ${{ matrix.python-version }} != "2.7" ]]; then
+            pip install --upgrade pytest-cov
+          fi
           # ensure style checks are not skipped in unit tests for python >= 3.6
           # note that true/false (i.e., 1/0) are opposite in conditions in python and bash
           if python -c 'import sys; sys.exit(not sys.version_info >= (3, 6))'; then
@@ -61,7 +69,7 @@ jobs:
     - name: Pin pathlib for Python 2.7
       if: ${{ matrix.python-version == 2.7 }}
       run: |
-          pip install -U pathlib2==2.3.6
+          pip install -U pathlib2==2.3.6 toml
     - name: Setup git configuration
       run: |
           # Need this for the git tests to succeed.
@@ -73,7 +81,7 @@ jobs:
           SPACK_PYTHON: python
       run: |
           . share/spack/setup-env.sh
-          spack bootstrap untrust spack-install
+          spack bootstrap disable spack-install
           spack -v solve zlib
     - name: Run unit tests
       env:
@@ -81,11 +89,9 @@ jobs:
           SPACK_TEST_SOLVER: ${{ matrix.concretizer }}
           SPACK_TEST_PARALLEL: 2
           COVERAGE: true
-          UNIT_TEST_COVERAGE: ${{ (matrix.concretizer == 'original' && matrix.python-version == '2.7') || (matrix.python-version == '3.10') }}
+          UNIT_TEST_COVERAGE: ${{ (matrix.python-version == '3.11') }}
       run: |
           share/spack/qa/run-unit-tests
-          coverage combine -a
-          coverage xml
     - uses: codecov/codecov-action@d9f34f8cd5cb3b3eb79b3e4b5dae3a16df499a70
       with:
         flags: unittests,linux,${{ matrix.concretizer }}
@@ -98,7 +104,7 @@ jobs:
         fetch-depth: 0
     - uses: actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984 # @v2
       with:
-        python-version: '3.10'
+        python-version: '3.11'
     - name: Install System packages
       run: |
           sudo apt-get -y update
@@ -106,7 +112,7 @@ jobs:
           sudo apt-get install -y coreutils kcov csh zsh tcsh fish dash bash
     - name: Install Python packages
       run: |
-          pip install --upgrade pip six setuptools pytest codecov coverage[toml]==6.2 pytest-xdist
+          pip install --upgrade pip six setuptools pytest codecov coverage[toml] pytest-xdist
     - name: Setup git configuration
       run: |
           # Need this for the git tests to succeed.
@@ -155,7 +161,7 @@ jobs:
         fetch-depth: 0
     - uses: actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984 # @v2
       with:
-        python-version: '3.10'
+        python-version: '3.11'
     - name: Install System packages
       run: |
           sudo apt-get -y update
@@ -177,8 +183,6 @@ jobs:
           SPACK_TEST_SOLVER: clingo
       run: |
           share/spack/qa/run-unit-tests
-          coverage combine -a
-          coverage xml
     - uses: codecov/codecov-action@d9f34f8cd5cb3b3eb79b3e4b5dae3a16df499a70 # @v2.1.0
       with:
         flags: unittests,linux,clingo
@@ -187,7 +191,7 @@ jobs:
     runs-on: macos-latest
     strategy:
       matrix:
-        python-version: [3.8]
+        python-version: ["3.10"]
     steps:
     - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # @v2
       with:
@@ -210,15 +214,10 @@ jobs:
         git --version
         . .github/workflows/setup_git.sh
         . share/spack/setup-env.sh
-        $(which spack) bootstrap untrust spack-install
+        $(which spack) bootstrap disable spack-install
         $(which spack) solve zlib
         common_args=(--dist loadfile --tx '4*popen//python=./bin/spack-tmpconfig python -u ./bin/spack python' -x)
-        $(which spack) unit-test --cov --cov-config=pyproject.toml "${common_args[@]}"
-        coverage combine -a
-        coverage xml
-        # Delete the symlink going from ./lib/spack/docs/_spack_root back to
-        # the initial directory, since it causes ELOOP errors with codecov/actions@2
-        rm lib/spack/docs/_spack_root
+        $(which spack) unit-test --cov --cov-config=pyproject.toml --cov-report=xml:coverage.xml "${common_args[@]}"
     - uses: codecov/codecov-action@d9f34f8cd5cb3b3eb79b3e4b5dae3a16df499a70
       with:
         flags: unittests,macos

.github/workflows/valid-style.yml

@@ -21,7 +21,7 @@ jobs:
     - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # @v2
     - uses: actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984 # @v2
       with:
-        python-version: '3.10'
+        python-version: '3.11'
         cache: 'pip'
     - name: Install Python Packages
       run: |
@@ -40,7 +40,7 @@ jobs:
         fetch-depth: 0
     - uses: actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984 # @v2
       with:
-        python-version: '3.10'
+        python-version: '3.11'
         cache: 'pip'
     - name: Install Python packages
       run: |
@@ -57,4 +57,4 @@ jobs:
     uses: ./.github/workflows/audit.yaml
     with:
       with_coverage: ${{ inputs.with_coverage }}
-      python_version: '3.10'
+      python_version: '3.11'

.github/workflows/windows_python.yml

@@ -23,7 +23,7 @@ jobs:
         python-version: 3.9
     - name: Install Python packages
       run: |
-          python -m pip install --upgrade pip six pywin32 setuptools codecov pytest-cov
+          python -m pip install --upgrade pip six pywin32 setuptools codecov pytest-cov clingo
     - name: Create local develop
       run: |
         .\spack\.github\workflows\setup_git.ps1
@@ -32,8 +32,7 @@ jobs:
         echo F|xcopy .\spack\share\spack\qa\configuration\windows_config.yaml $env:USERPROFILE\.spack\windows\config.yaml
         cd spack
         dir
-        (Get-Item '.\lib\spack\docs\_spack_root').Delete()
-        spack unit-test --verbose --cov --cov-config=pyproject.toml --ignore=lib/spack/spack/test/cmd
+        spack unit-test -x --verbose --cov --cov-config=pyproject.toml --ignore=lib/spack/spack/test/cmd
         coverage combine -a
         coverage xml
     - uses: codecov/codecov-action@d9f34f8cd5cb3b3eb79b3e4b5dae3a16df499a70
@@ -50,7 +49,7 @@ jobs:
         python-version: 3.9
     - name: Install Python packages
       run: |
-          python -m pip install --upgrade pip six pywin32 setuptools codecov coverage pytest-cov
+          python -m pip install --upgrade pip six pywin32 setuptools codecov coverage pytest-cov clingo
     - name: Create local develop
       run: |
         .\spack\.github\workflows\setup_git.ps1
@@ -58,8 +57,7 @@ jobs:
       run: |
         echo F|xcopy .\spack\share\spack\qa\configuration\windows_config.yaml $env:USERPROFILE\.spack\windows\config.yaml
         cd spack
-        (Get-Item '.\lib\spack\docs\_spack_root').Delete()
-        spack unit-test --verbose --cov --cov-config=pyproject.toml lib/spack/spack/test/cmd
+        spack unit-test -x --verbose --cov --cov-config=pyproject.toml lib/spack/spack/test/cmd
         coverage combine -a
         coverage xml
     - uses: codecov/codecov-action@d9f34f8cd5cb3b3eb79b3e4b5dae3a16df499a70
@@ -83,7 +81,7 @@ jobs:
         echo F|xcopy .\spack\share\spack\qa\configuration\windows_config.yaml $env:USERPROFILE\.spack\windows\config.yaml
         spack external find cmake
         spack external find ninja
-        spack install abseil-cpp
+        spack -d install abseil-cpp
   make-installer:
     runs-on: windows-latest
     steps:
@@ -111,11 +109,11 @@ jobs:
         echo "installer_root=$((pwd).Path)" | Out-File -FilePath $Env:GITHUB_ENV -Encoding utf8 -Append
       env:
         ProgressPreference: SilentlyContinue
-    - uses: actions/upload-artifact@3cea5372237819ed00197afe530f5a7ea3e805c8
+    - uses: actions/upload-artifact@83fd05a356d7e2593de66fc9913b3002723633cb
       with:
         name: Windows Spack Installer Bundle
         path: ${{ env.installer_root }}\pkg\Spack.exe
-    - uses: actions/upload-artifact@3cea5372237819ed00197afe530f5a7ea3e805c8
+    - uses: actions/upload-artifact@83fd05a356d7e2593de66fc9913b3002723633cb
       with:
         name: Windows Spack Installer
         path: ${{ env.installer_root}}\pkg\Spack.msi

CHANGELOG.md

@@ -1,16 +1,284 @@
+# v0.19.0 (2022-11-11)
+
+`v0.19.0` is a major feature release.
+
+## Major features in this release
+
+1. **Package requirements**
+
+   Spack's traditional [package preferences](
+     https://spack.readthedocs.io/en/latest/build_settings.html#package-preferences)
+   are soft, but we've added hard requriements to `packages.yaml` and `spack.yaml`
+   (#32528, #32369). Package requirements use the same syntax as specs:
+
+   ```yaml
+   packages:
+     libfabric:
+       require: "@1.13.2"
+     mpich:
+       require:
+       - one_of: ["+cuda", "+rocm"]
+   ```
+
+   More details in [the docs](
+     https://spack.readthedocs.io/en/latest/build_settings.html#package-requirements).
+
+2. **Environment UI Improvements**
+
+   * Fewer surprising modifications to `spack.yaml` (#33711):
+
+     * `spack install` in an environment will no longer add to the `specs:` list; you'll
+       need to either use `spack add <spec>` or `spack install --add <spec>`.
+
+     * Similarly, `spack uninstall` will not remove from your environment's `specs:`
+       list; you'll need to use `spack remove` or `spack uninstall --remove`.
+
+     This will make it easier to manage an environment, as there is clear separation
+     between the stack to be installed (`spack.yaml`/`spack.lock`) and which parts of
+     it should be installed (`spack install` / `spack uninstall`).
+
+   * `concretizer:unify:true` is now the default mode for new environments (#31787)
+
+     We see more users creating `unify:true` environments now. Users who need
+     `unify:false` can add it to their environment to get the old behavior. This will
+     concretize every spec in the environment independently.
+
+   * Include environment configuration from URLs (#29026, [docs](
+       https://spack.readthedocs.io/en/latest/environments.html#included-configurations))
+
+     You can now include configuration in your environment directly from a URL:
+
+     ```yaml
+     spack:
+       include:
+       - https://github.com/path/to/raw/config/compilers.yaml
+     ```
+
+4. **Multiple Build Systems**
+
+   An increasing number of packages in the ecosystem need the ability to support
+   multiple build systems (#30738, [docs](
+     https://spack.readthedocs.io/en/latest/packaging_guide.html#multiple-build-systems)),
+   either across versions, across platforms, or within the same version of the software.
+   This has been hard to support through multiple inheritance, as methods from different
+   build system superclasses would conflict. `package.py` files can now define separate
+   builder classes with installation logic for different build systems, e.g.:
+
+   ```python
+   class ArpackNg(CMakePackage, AutotoolsPackage):
+
+       build_system(
+           conditional("cmake", when="@0.64:"),
+           conditional("autotools", when="@:0.63"),
+           default="cmake",
+       )
+
+   class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
+       def cmake_args(self):
+           pass
+
+   class Autotoolsbuilder(spack.build_systems.autotools.AutotoolsBuilder):
+       def configure_args(self):
+           pass
+   ```
+
+5. **Compiler and variant propagation**
+
+   Currently, compiler flags and variants are inconsistent: compiler flags set for a
+   package are inherited by its dependencies, while variants are not. We should have
+   these be consistent by allowing for inheritance to be enabled or disabled for both
+   variants and compiler flags.
+
+   Example syntax:
+   - `package ++variant`:
+         enabled variant that will be propagated to dependencies
+   - `package +variant`:
+         enabled variant that will NOT be propagated to dependencies
+   - `package ~~variant`:
+         disabled variant that will be propagated to dependencies
+   - `package ~variant`:
+         disabled variant that will NOT be propagated to dependencies
+   - `package cflags==-g`:
+         `cflags` will be propagated to dependencies
+   - `package cflags=-g`:
+         `cflags` will NOT be propagated to dependencies
+
+   Syntax for non-boolan variants is similar to compiler flags. More in the docs for
+   [variants](
+     https://spack.readthedocs.io/en/latest/basic_usage.html#variants) and [compiler flags](
+     https://spack.readthedocs.io/en/latest/basic_usage.html#compiler-flags).
+
+6. **Enhancements to git version specifiers**
+
+   * `v0.18.0` added the ability to use git commits as versions. You can now use the
+     `git.` prefix to specify git tags or branches as versions. All of these are valid git
+     versions in `v0.19` (#31200):
+
+     ```console
+     foo@abcdef1234abcdef1234abcdef1234abcdef1234      # raw commit
+     foo@git.abcdef1234abcdef1234abcdef1234abcdef1234  # commit with git prefix
+     foo@git.develop                                   # the develop branch
+     foo@git.0.19                                      # use the 0.19 tag
+     ```
+
+   * `v0.19` also gives you more control over how Spack interprets git versions, in case
+     Spack cannot detect the version from the git repository. You can suffix a git
+     version with `=<version>` to force Spack to concretize it as a particular version
+     (#30998, #31914, #32257):
+
+     ```console
+     # use mybranch, but treat it as version 3.2 for version comparison
+     foo@git.mybranch=3.2
+
+     # use the given commit, but treat it as develop for version comparison
+     foo@git.abcdef1234abcdef1234abcdef1234abcdef1234=develop
+     ```
+
+     More in [the docs](
+       https://spack.readthedocs.io/en/latest/basic_usage.html#version-specifier)
+
+7. **Changes to Cray EX Support**
+
+   Cray machines have historically had their own "platform" within Spack, because we
+   needed to go through the module system to leverage compilers and MPI installations on
+   these machines. The Cray EX programming environment now provides standalone `craycc`
+   executables and proper `mpicc` wrappers, so Spack can treat EX machines like Linux
+   with extra packages (#29392).
+
+   We expect this to greatly reduce bugs, as external packages and compilers can now be
+   used by prefix instead of through modules. We will also no longer be subject to
+   reproducibility issues when modules change from Cray PE release to release and from
+   site to site. This also simplifies dealing with the underlying Linux OS on cray
+   systems, as Spack will properly model the machine's OS as either SuSE or RHEL.
+
+8. **Improvements to tests and testing in CI**
+
+   * `spack ci generate --tests` will generate a `.gitlab-ci.yml` file that not only does
+     builds but also runs tests for built packages (#27877). Public GitHub pipelines now
+     also run tests in CI.
+
+   * `spack test run --explicit` will only run tests for packages that are explicitly
+     installed, instead of all packages.
+
+9. **Experimental binding link model**
+
+   You can add a new option to `config.yaml` to make Spack embed absolute paths to
+   needed shared libraries in ELF executables and shared libraries on Linux (#31948, [docs](
+     https://spack.readthedocs.io/en/latest/config_yaml.html#shared-linking-bind)):
+
+   ```yaml
+   config:
+     shared_linking:
+       type: rpath
+       bind: true
+   ```
+
+   This can improve launch time at scale for parallel applications, and it can make
+   installations less susceptible to environment variables like `LD_LIBRARY_PATH`, even
+   especially when dealing with external libraries that use `RUNPATH`. You can think of
+   this as a faster, even higher-precedence version of `RPATH`.
+
+## Other new features of note
+
+* `spack spec` prints dependencies more legibly. Dependencies in the output now appear
+  at the *earliest* level of indentation possible (#33406)
+* You can override `package.py` attributes like `url`, directly in `packages.yaml`
+  (#33275, [docs](
+    https://spack.readthedocs.io/en/latest/build_settings.html#assigning-package-attributes))
+* There are a number of new architecture-related format strings you can use in Spack
+  configuration files to specify paths (#29810, [docs](
+    https://spack.readthedocs.io/en/latest/configuration.html#config-file-variables))
+* Spack now supports bootstrapping Clingo on Windows (#33400)
+* There is now support for an `RPATH`-like library model on Windows (#31930)
+
+## Performance Improvements
+
+* Major performance improvements for installation from binary caches (#27610, #33628,
+  #33636, #33608, #33590, #33496)
+* Test suite can now be parallelized using `xdist` (used in GitHub Actions) (#32361)
+* Reduce lock contention for parallel builds in environments (#31643)
+
+## New binary caches and stacks
+
+* We now build nearly all of E4S with `oneapi` in our buildcache (#31781, #31804,
+  #31804, #31803, #31840, #31991, #32117, #32107, #32239)
+* Added 3 new machine learning-centric stacks to binary cache: `x86_64_v3`, CUDA, ROCm
+  (#31592, #33463)
+
+## Removals and Deprecations
+
+* Support for Python 3.5 is dropped (#31908). Only Python 2.7 and 3.6+ are officially
+  supported.
+
+* This is the last Spack release that will support Python 2 (#32615). Spack `v0.19`
+  will emit a deprecation warning if you run it with Python 2, and Python 2 support will
+  soon be removed from the `develop` branch.
+
+* `LD_LIBRARY_PATH` is no longer set by default by `spack load` or module loads.
+
+  Setting `LD_LIBRARY_PATH` in Spack environments/modules can cause binaries from
+  outside of Spack to crash, and Spack's own builds use `RPATH` and do not need
+  `LD_LIBRARY_PATH` set in order to run. If you still want the old behavior, you
+  can run these commands to configure Spack to set `LD_LIBRARY_PATH`:
+
+  ```console
+  spack config add modules:prefix_inspections:lib64:[LD_LIBRARY_PATH]
+  spack config add modules:prefix_inspections:lib:[LD_LIBRARY_PATH]
+  ```
+
+* The `spack:concretization:[together|separately]` has been removed after being
+  deprecated in `v0.18`. Use `concretizer:unify:[true|false]`.
+* `config:module_roots` is no longer supported after being deprecated in `v0.18`. Use
+  configuration in module sets instead (#28659, [docs](
+    https://spack.readthedocs.io/en/latest/module_file_support.html)).
+* `spack activate` and `spack deactivate` are no longer supported, having been
+  deprecated in `v0.18`. Use an environment with a view instead of
+  activating/deactivating ([docs](
+    https://spack.readthedocs.io/en/latest/environments.html#configuration-in-spack-yaml)).
+* The old YAML format for buildcaches is now deprecated (#33707). If you are using an
+  old buildcache with YAML metadata you will need to regenerate it with JSON metadata.
+* `spack bootstrap trust` and `spack bootstrap untrust` are deprecated in favor of
+  `spack bootstrap enable` and `spack bootstrap disable` and will be removed in `v0.20`.
+  (#33600)
+* The `graviton2` architecture has been renamed to `neoverse_n1`, and `graviton3`
+  is now `neoverse_v1`. Buildcaches using the old architecture names will need to be rebuilt.
+* The terms `blacklist` and `whitelist` have been replaced with `include` and `exclude`
+  in all configuration files (#31569). You can use `spack config update` to
+  automatically fix your configuration files.
+
+## Notable Bugfixes
+
+* Permission setting on installation now handles effective uid properly (#19980)
+* `buildable:true` for an MPI implementation now overrides `buildable:false` for `mpi` (#18269)
+* Improved error messages when attempting to use an unconfigured compiler (#32084)
+* Do not punish explicitly requested compiler mismatches in the solver (#30074)
+* `spack stage`: add missing --fresh and --reuse (#31626)
+* Fixes for adding build system executables like `cmake` to package scope (#31739)
+* Bugfix for binary relocation with aliased strings produced by newer `binutils` (#32253)
+
+## Spack community stats
+
+* 6,751 total packages, 335 new since `v0.18.0`
+    * 141 new Python packages
+    * 89 new R packages
+* 303 people contributed to this release
+    * 287 committers to packages
+    * 57 committers to core
+
+
 # v0.18.1 (2022-07-19)
 
 ### Spack Bugfixes
 * Fix several bugs related to bootstrapping (#30834,#31042,#31180)
-* Fix a regression that was causing spec hashes to differ between 
+* Fix a regression that was causing spec hashes to differ between
   Python 2 and Python 3 (#31092)
 * Fixed compiler flags for oneAPI and DPC++ (#30856)
 * Fixed several issues related to concretization (#31142,#31153,#31170,#31226)
 * Improved support for Cray manifest file and `spack external find` (#31144,#31201,#31173,#31186)
 * Assign a version to openSUSE Tumbleweed according to the GLIBC version
-  in the system (#19895) 
+  in the system (#19895)
 * Improved Dockerfile generation for `spack containerize` (#29741,#31321)
-* Fixed a few bugs related to concurrent execution of commands (#31509,#31493,#31477)  
+* Fixed a few bugs related to concurrent execution of commands (#31509,#31493,#31477)
 
 ### Package updates
 * WarpX: add v22.06, fixed libs property (#30866,#31102)

SECURITY.md

@@ -10,8 +10,8 @@ For more on Spack's release structure, see
 | Version | Supported          |
 | ------- | ------------------ |
 | develop | :white_check_mark: |
-| 0.17.x  | :white_check_mark: |
-| 0.16.x  | :white_check_mark: |
+| 0.19.x  | :white_check_mark: |
+| 0.18.x  | :white_check_mark: |
 
 ## Reporting a Vulnerability
 

bin/spack

@@ -49,52 +49,8 @@ spack_prefix = os.path.dirname(os.path.dirname(spack_file))
 spack_lib_path = os.path.join(spack_prefix, "lib", "spack")
 sys.path.insert(0, spack_lib_path)
 
-# Add external libs
-spack_external_libs = os.path.join(spack_lib_path, "external")
-
-if sys.version_info[:2] <= (2, 7):
-    sys.path.insert(0, os.path.join(spack_external_libs, "py2"))
-
-sys.path.insert(0, spack_external_libs)
-
-# Here we delete ruamel.yaml in case it has been already imported from site
-# (see #9206 for a broader description of the issue).
-#
-# Briefly: ruamel.yaml produces a .pth file when installed with pip that
-# makes the site installed package the preferred one, even though sys.path
-# is modified to point to another version of ruamel.yaml.
-if "ruamel.yaml" in sys.modules:
-    del sys.modules["ruamel.yaml"]
-
-if "ruamel" in sys.modules:
-    del sys.modules["ruamel"]
-
-# The following code is here to avoid failures when updating
-# the develop version, due to spurious argparse.pyc files remaining
-# in the libs/spack/external directory, see:
-# https://github.com/spack/spack/pull/25376
-# TODO: Remove in v0.18.0 or later
-try:
-    import argparse
-except ImportError:
-    argparse_pyc = os.path.join(spack_external_libs, "argparse.pyc")
-    if not os.path.exists(argparse_pyc):
-        raise
-    try:
-        os.remove(argparse_pyc)
-        import argparse  # noqa: F401
-    except Exception:
-        msg = (
-            "The file\n\n\t{0}\n\nis corrupted and cannot be deleted by Spack. "
-            "Either delete it manually or ask some administrator to "
-            "delete it for you."
-        )
-        print(msg.format(argparse_pyc))
-        sys.exit(1)
-
-
-import spack.main  # noqa: E402
+from spack_installable.main import main  # noqa: E402
 
 # Once we've set up the system path, run the spack main method
 if __name__ == "__main__":
-    sys.exit(spack.main.main())
+    sys.exit(main())

etc/spack/defaults/bootstrap.yaml

@@ -9,16 +9,15 @@ bootstrap:
   # may not be able to bootstrap all the software that Spack needs,
   # depending on its type.
   sources:
+  - name: 'github-actions-v0.4'
+    metadata: $spack/share/spack/bootstrap/github-actions-v0.4
   - name: 'github-actions-v0.3'
     metadata: $spack/share/spack/bootstrap/github-actions-v0.3
-  - name: 'github-actions-v0.2'
-    metadata: $spack/share/spack/bootstrap/github-actions-v0.2
-  - name: 'github-actions-v0.1'
-    metadata: $spack/share/spack/bootstrap/github-actions-v0.1
   - name: 'spack-install'
     metadata: $spack/share/spack/bootstrap/spack-install
   trusted:
     # By default we trust bootstrapping from sources and from binaries
     # produced on Github via the workflow
+    github-actions-v0.4: true
     github-actions-v0.3: true
     spack-install: true

etc/spack/defaults/concretizer.yaml

@@ -33,4 +33,4 @@ concretizer:
   # environments can always be activated. When "false" perform concretization separately
   # on each root spec, allowing different versions and variants of the same package in
   # an environment.
-  unify: false
+  unify: true

etc/spack/defaults/config.yaml

@@ -187,10 +187,20 @@ config:
   package_lock_timeout: null
 
 
-  # Control whether Spack embeds RPATH or RUNPATH attributes in ELF binaries.
-  # Has no effect on macOS. DO NOT MIX these within the same install tree.
-  # See the Spack documentation for details.
-  shared_linking: 'rpath'
+  # Control how shared libraries are located at runtime on Linux. See the
+  # the Spack documentation for details.
+  shared_linking:
+    # Spack automatically embeds runtime search paths in ELF binaries for their
+    # dependencies. Their type can either be "rpath" or "runpath". For glibc, rpath is
+    # inherited and has precedence over LD_LIBRARY_PATH; runpath is not inherited
+    # and of lower precedence. DO NOT MIX these within the same install tree.
+    type: rpath
+
+
+    # (Experimental) Embed absolute paths of dependent libraries directly in ELF
+    # binaries to avoid runtime search. This can improve startup time of
+    # executables with many dependencies, in particular on slow filesystems.
+    bind: false
 
 
   # Set to 'false' to allow installation on filesystems that doesn't allow setgid bit
@@ -201,3 +211,7 @@ config:
   # building and installing packages. This gives information about Spack's
   # current progress as well as the current and total number of packages.
   terminal_title: false
+
+  # Number of seconds a buildcache's index.json is cached locally before probing
+  # for updates, within a single Spack invocation. Defaults to 10 minutes.
+  binary_index_ttl: 600

etc/spack/defaults/packages.yaml

@@ -27,7 +27,8 @@ packages:
       fuse: [libfuse]
       gl: [glx, osmesa]
       glu: [mesa-glu, openglu]
-      golang: [gcc]
+      golang: [go, gcc]
+      go-external-or-gccgo-bootstrap: [go-bootstrap, gcc]
       iconv: [libiconv]
       ipp: [intel-ipp]
       java: [openjdk, jdk, ibm-java]

etc/spack/defaults/windows/config.yaml

@@ -1,5 +1,5 @@
 config:
   locks: false
-  concretizer: original
+  concretizer: clingo
   build_stage::
     - '$spack/.staging'

lib/spack/docs/_spack_root

@@ -1 +0,0 @@
-../../..

lib/spack/docs/basic_usage.rst

@@ -85,7 +85,7 @@ All packages whose names or descriptions contain documentation:
 To get more information on a particular package from `spack list`, use
 `spack info`.  Just supply the name of a package:
 
-.. command-output:: spack info mpich
+.. command-output:: spack info --all mpich
 
 Most of the information is self-explanatory.  The *safe versions* are
 versions that Spack knows the checksum for, and it will use the
@@ -998,11 +998,15 @@ More formally, a spec consists of the following pieces:
 * ``%`` Optional compiler specifier, with an optional compiler version
   (``gcc`` or ``gcc@4.7.3``)
 * ``+`` or ``-`` or ``~`` Optional variant specifiers (``+debug``,
-  ``-qt``, or ``~qt``) for boolean variants
+  ``-qt``, or ``~qt``) for boolean variants. Use ``++`` or ``--`` or
+  ``~~`` to propagate variants through the dependencies (``++debug``,
+  ``--qt``, or ``~~qt``).
 * ``name=<value>`` Optional variant specifiers that are not restricted to
-  boolean variants
+  boolean variants. Use ``name==<value>`` to propagate variant through the
+  dependencies.
 * ``name=<value>`` Optional compiler flag specifiers. Valid flag names are
   ``cflags``, ``cxxflags``, ``fflags``, ``cppflags``, ``ldflags``, and ``ldlibs``.
+  Use ``name==<value>`` to propagate compiler flags through the dependencies.
 * ``target=<value> os=<value>`` Optional architecture specifier
   (``target=haswell os=CNL10``)
 * ``^`` Dependency specs (``^callpath@1.1``)
@@ -1110,21 +1114,21 @@ set of arbitrary versions, such as ``@1.0,1.5,1.7`` (``1.0``, ``1.5``,
 or ``1.7``).  When you supply such a specifier to ``spack install``,
 it constrains the set of versions that Spack will install.
 
-For packages with a ``git`` attribute, ``git`` references 
-may be specified instead of a numerical version i.e. branches, tags 
-and commits. Spack will stage and build based off the ``git`` 
+For packages with a ``git`` attribute, ``git`` references
+may be specified instead of a numerical version i.e. branches, tags
+and commits. Spack will stage and build based off the ``git``
 reference provided.  Acceptable syntaxes for this are:
 
 .. code-block:: sh
-   
+
     # branches and tags
    foo@git.develop # use the develop branch
    foo@git.0.19 # use the 0.19 tag
-   
+
     # commit hashes
    foo@abcdef1234abcdef1234abcdef1234abcdef1234    # 40 character hashes are automatically treated as git commits
    foo@git.abcdef1234abcdef1234abcdef1234abcdef1234
-   
+
 Spack versions from git reference either have an associated version supplied by the user,
 or infer a relationship to known versions from the structure of the git repository. If an
 associated version is supplied by the user, Spack treats the git version as equivalent to that
@@ -1226,6 +1230,23 @@ variants using the backwards compatibility syntax and uses only ``~``
 for disabled boolean variants.  The ``-`` and spaces on the command
 line are provided for convenience and legibility.
 
+Spack allows variants to propagate their value to the package's
+dependency by using ``++``, ``--``, and ``~~`` for boolean variants.
+For example, for a ``debug`` variant:
+
+.. code-block:: sh
+
+    mpileaks ++debug   # enabled debug will be propagated to dependencies
+    mpileaks +debug    # only mpileaks will have debug enabled
+
+To propagate the value of non-boolean variants Spack uses ``name==value``.
+For example, for the ``stackstart`` variant:
+
+.. code-block:: sh
+
+    mpileaks stackstart=4    # variant will be propagated to dependencies
+    mpileaks stackstart==4   # only mpileaks will have this variant value
+
 ^^^^^^^^^^^^^^
 Compiler Flags
 ^^^^^^^^^^^^^^
@@ -1233,10 +1254,15 @@ Compiler Flags
 Compiler flags are specified using the same syntax as non-boolean variants,
 but fulfill a different purpose. While the function of a variant is set by
 the package, compiler flags are used by the compiler wrappers to inject
-flags into the compile line of the build. Additionally, compiler flags are
-inherited by dependencies. ``spack install libdwarf cppflags="-g"`` will
-install both libdwarf and libelf with the ``-g`` flag injected into their
-compile line.
+flags into the compile line of the build. Additionally, compiler flags can
+be inherited by dependencies by using ``==``.
+``spack install libdwarf cppflags=="-g"`` will install both libdwarf and
+libelf with the ``-g`` flag injected into their compile line.
+
+.. note::
+
+   versions of spack prior to 0.19.0 will propagate compiler flags using
+   the ``=`` syntax.
 
 Notice that the value of the compiler flags must be quoted if it
 contains any spaces. Any of ``cppflags=-O3``, ``cppflags="-O3"``,
@@ -1438,7 +1464,7 @@ built.
 You can see what virtual packages a particular package provides by
 getting info on it:
 
-.. command-output:: spack info mpich
+.. command-output:: spack info --virtuals mpich
 
 Spack is unique in that its virtual packages can be versioned, just
 like regular packages.  A particular version of a package may provide
@@ -1646,9 +1672,13 @@ own install prefix.  However, certain packages are typically installed
 `Python <https://www.python.org>`_ packages are typically installed in the
 ``$prefix/lib/python-2.7/site-packages`` directory.
 
-Spack has support for this type of installation as well.  In Spack,
-a package that can live inside the prefix of another package is called
-an *extension*.  Suppose you have Python installed like so:
+In Spack, installation prefixes are immutable, so this type of installation
+is not directly supported. However, it is possible to create views that
+allow you to merge install prefixes of multiple packages into a single new prefix.
+Views are a convenient way to get a more traditional filesystem structure.
+Using *extensions*, you can ensure that Python packages always share the
+same prefix in the view as Python itself. Suppose you have
+Python installed like so:
 
 .. code-block:: console
 
@@ -1686,8 +1716,6 @@ You can find extensions for your Python installation like this:
    py-ipython@2.3.1     py-pygments@2.0.1   py-setuptools@11.3.1
    py-matplotlib@1.4.2  py-pyparsing@2.0.3  py-six@1.9.0
 
-   ==> None activated.
-
 The extensions are a subset of what's returned by ``spack list``, and
 they are packages like any other.  They are installed into their own
 prefixes, and you can see this with ``spack find --paths``:
@@ -1715,32 +1743,72 @@ directly when you run ``python``:
    ImportError: No module named numpy
    >>>
 
-^^^^^^^^^^^^^^^^
-Using Extensions
-^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Using Extensions in Environments
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-There are four ways to get ``numpy`` working in Python.  The first is
-to use :ref:`shell-support`.  You can simply ``load`` the extension,
-and it will be added to the ``PYTHONPATH`` in your current shell:
+The recommended way of working with extensions such as ``py-numpy``
+above is through :ref:`Environments <environments>`. For example,
+the following creates an environment in the current working directory
+with a filesystem view in the ``./view`` directory:
 
 .. code-block:: console
 
-   $ spack load python
-   $ spack load py-numpy
+   $ spack env create --with-view view --dir .
+   $ spack -e . add py-numpy
+   $ spack -e . concretize
+   $ spack -e . install
+
+We recommend environments for two reasons. Firstly, environments
+can be activated (requires :ref:`shell-support`):
+
+.. code-block:: console
+
+   $ spack env activate .
+
+which sets all the right environment variables such as ``PATH`` and
+``PYTHONPATH``. This ensures that
+
+.. code-block:: console
+
+   $ python
+   >>> import numpy
+
+works. Secondly, even without shell support, the view ensures
+that Python can locate its extensions:
+
+.. code-block:: console
+
+   $ ./view/bin/python
+   >>> import numpy
+
+See :ref:`environments` for a more in-depth description of Spack
+environments and customizations to views.
+
+^^^^^^^^^^^^^^^^^^^^
+Using ``spack load``
+^^^^^^^^^^^^^^^^^^^^
+
+A more traditional way of using Spack and extensions is ``spack load``
+(requires :ref:`shell-support`). This will add the extension to ``PYTHONPATH``
+in your current shell, and Python itself will be available in the ``PATH``:
+
+.. code-block:: console
+
+   $ spack load py-numpy
+   $ python
+   >>> import numpy
 
-Now ``import numpy`` will succeed for as long as you keep your current
-session open.
 The loaded packages can be checked using ``spack find --loaded``
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Loading Extensions via Modules
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Instead of using Spack's environment modification capabilities through
-the ``spack load`` command, you can load numpy through your
-environment modules (using ``environment-modules`` or ``lmod``). This
-will also add the extension to the ``PYTHONPATH`` in your current
-shell.
+Apart from ``spack env activate`` and ``spack load``, you can load numpy
+through your environment modules (using ``environment-modules`` or
+``lmod``). This will also add the extension to the ``PYTHONPATH`` in
+your current shell.
 
 .. code-block:: console
 
@@ -1750,130 +1818,6 @@ If you do not know the name of the specific numpy module you wish to
 load, you can use the ``spack module tcl|lmod loads`` command to get
 the name of the module from the Spack spec.
 
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Activating Extensions in a View
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Another way to use extensions is to create a view, which merges the
-python installation along with the extensions into a single prefix.
-See :ref:`configuring_environment_views` for a more in-depth description
-of views.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Activating Extensions Globally
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-As an alternative to creating a merged prefix with Python and its extensions,
-and prior to support for views, Spack has provided a means to install the
-extension into the Spack installation prefix for the extendee. This has
-typically been useful since extendable packages typically search their own
-installation path for addons by default.
-
-Global activations are performed with the ``spack activate`` command:
-
-.. _cmd-spack-activate:
-
-^^^^^^^^^^^^^^^^^^
-``spack activate``
-^^^^^^^^^^^^^^^^^^
-
-.. code-block:: console
-
-   $ spack activate py-numpy
-   ==> Activated extension py-setuptools@11.3.1%gcc@4.4.7 arch=linux-debian7-x86_64-3c74eb69 for python@2.7.8%gcc@4.4.7.
-   ==> Activated extension py-nose@1.3.4%gcc@4.4.7 arch=linux-debian7-x86_64-5f70f816 for python@2.7.8%gcc@4.4.7.
-   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7 arch=linux-debian7-x86_64-66733244 for python@2.7.8%gcc@4.4.7.
-
-Several things have happened here.  The user requested that
-``py-numpy`` be activated in the ``python`` installation it was built
-with.  Spack knows that ``py-numpy`` depends on ``py-nose`` and
-``py-setuptools``, so it activated those packages first.  Finally,
-once all dependencies were activated in the ``python`` installation,
-``py-numpy`` was activated as well.
-
-If we run ``spack extensions`` again, we now see the three new
-packages listed as activated:
-
-.. code-block:: console
-
-   $ spack extensions python
-   ==> python@2.7.8%gcc@4.4.7  arch=linux-debian7-x86_64-703c7a96
-   ==> 36 extensions:
-   geos          py-ipython     py-pexpect    py-pyside            py-sip
-   py-basemap    py-libxml2     py-pil        py-pytz              py-six
-   py-biopython  py-mako        py-pmw        py-rpy2              py-sympy
-   py-cython     py-matplotlib  py-pychecker  py-scientificpython  py-virtualenv
-   py-dateutil   py-mpi4py      py-pygments   py-scikit-learn
-   py-epydoc     py-mx          py-pylint     py-scipy
-   py-gnuplot    py-nose        py-pyparsing  py-setuptools
-   py-h5py       py-numpy       py-pyqt       py-shiboken
-
-   ==> 12 installed:
-   -- linux-debian7-x86_64 / gcc@4.4.7 --------------------------------
-   py-dateutil@2.4.0    py-nose@1.3.4       py-pyside@1.2.2
-   py-dateutil@2.4.0    py-numpy@1.9.1      py-pytz@2014.10
-   py-ipython@2.3.1     py-pygments@2.0.1   py-setuptools@11.3.1
-   py-matplotlib@1.4.2  py-pyparsing@2.0.3  py-six@1.9.0
-
-   ==> 3 currently activated:
-   -- linux-debian7-x86_64 / gcc@4.4.7 --------------------------------
-   py-nose@1.3.4  py-numpy@1.9.1  py-setuptools@11.3.1
-
-Now, when a user runs python, ``numpy`` will be available for import
-*without* the user having to explicitly load it.  ``python@2.7.8`` now
-acts like a system Python installation with ``numpy`` installed inside
-of it.
-
-Spack accomplishes this by symbolically linking the *entire* prefix of
-the ``py-numpy`` package into the prefix of the ``python`` package.  To the
-python interpreter, it looks like ``numpy`` is installed in the
-``site-packages`` directory.
-
-The only limitation of global activation is that you can only have a *single*
-version of an extension activated at a time.  This is because multiple
-versions of the same extension would conflict if symbolically linked
-into the same prefix.  Users who want a different version of a package
-can still get it by using environment modules or views, but they will have to
-explicitly load their preferred version.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-``spack activate --force``
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-If, for some reason, you want to activate a package *without* its
-dependencies, you can use ``spack activate --force``:
-
-.. code-block:: console
-
-   $ spack activate --force py-numpy
-   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7 arch=linux-debian7-x86_64-66733244 for python@2.7.8%gcc@4.4.7.
-
-.. _cmd-spack-deactivate:
-
-^^^^^^^^^^^^^^^^^^^^
-``spack deactivate``
-^^^^^^^^^^^^^^^^^^^^
-
-We've seen how activating an extension can be used to set up a default
-version of a Python module.  Obviously, you may want to change that at
-some point.  ``spack deactivate`` is the command for this.  There are
-several variants:
-
-* ``spack deactivate <extension>`` will deactivate a single
-  extension.  If another activated extension depends on this one,
-  Spack will warn you and exit with an error.
-* ``spack deactivate --force <extension>`` deactivates an extension
-  regardless of packages that depend on it.
-* ``spack deactivate --all <extension>`` deactivates an extension and
-  all of its dependencies.  Use ``--force`` to disregard dependents.
-* ``spack deactivate --all <extendee>`` deactivates *all* activated
-  extensions of a package.  For example, to deactivate *all* python
-  extensions, use:
-
-  .. code-block:: console
-
-     $ spack deactivate --all python
-
 -----------------------
 Filesystem requirements
 -----------------------

lib/spack/docs/bootstrapping.rst

@@ -15,15 +15,13 @@ is an entire command dedicated to the management of every aspect of bootstrappin
 
 .. command-output:: spack bootstrap --help
 
-The first thing to know to understand bootstrapping in Spack is that each of
-Spack's dependencies is bootstrapped lazily; i.e. the first time it is needed and
-can't be found. You can readily check if any prerequisite for using Spack
-is missing by running:
+Spack is configured to bootstrap its dependencies lazily by default; i.e. the first time they are needed and
+can't be found. You can readily check if any prerequisite for using Spack is missing by running:
 
 .. code-block:: console
 
    % spack bootstrap status
-   Spack v0.17.1 - python@3.8
+   Spack v0.19.0 - python@3.8
 
    [FAIL] Core Functionalities
      [B] MISSING "clingo": required to concretize specs
@@ -48,6 +46,21 @@ they can be bootstrapped. Running a command that concretize a spec, like:
 
 triggers the bootstrapping of clingo from pre-built binaries as expected.
 
+Users can also bootstrap all the dependencies needed by Spack in a single command, which
+might be useful to setup containers or other similar environments:
+
+.. code-block:: console
+
+   $ spack bootstrap now
+   ==> Bootstrapping clingo from pre-built binaries
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.3/build_cache/linux-centos7-x86_64-gcc-10.2.1-clingo-bootstrap-spack-shqedxgvjnhiwdcdrvjhbd73jaevv7wt.spec.json
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.3/build_cache/linux-centos7-x86_64/gcc-10.2.1/clingo-bootstrap-spack/linux-centos7-x86_64-gcc-10.2.1-clingo-bootstrap-spack-shqedxgvjnhiwdcdrvjhbd73jaevv7wt.spack
+   ==> Installing "clingo-bootstrap@spack%gcc@10.2.1~docs~ipo+python+static_libstdcpp build_type=Release arch=linux-centos7-x86_64" from a buildcache
+   ==> Bootstrapping patchelf from pre-built binaries
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.3/build_cache/linux-centos7-x86_64-gcc-10.2.1-patchelf-0.15.0-htk62k7efo2z22kh6kmhaselru7bfkuc.spec.json
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.3/build_cache/linux-centos7-x86_64/gcc-10.2.1/patchelf-0.15.0/linux-centos7-x86_64-gcc-10.2.1-patchelf-0.15.0-htk62k7efo2z22kh6kmhaselru7bfkuc.spack
+   ==> Installing "patchelf@0.15.0%gcc@10.2.1 ldflags="-static-libstdc++ -static-libgcc"  arch=linux-centos7-x86_64" from a buildcache
+
 -----------------------
 The Bootstrapping store
 -----------------------
@@ -107,19 +120,19 @@ If need be, you can disable bootstrapping altogether by running:
 
 in which case it's your responsibility to ensure Spack runs in an
 environment where all its prerequisites are installed. You can
-also configure Spack to skip certain bootstrapping methods by *untrusting*
-them. For instance:
+also configure Spack to skip certain bootstrapping methods by disabling
+them specifically:
 
 .. code-block:: console
 
-   % spack bootstrap untrust github-actions
-   ==> "github-actions" is now untrusted and will not be used for bootstrapping
+   % spack bootstrap disable github-actions
+   ==> "github-actions" is now disabled and will not be used for bootstrapping
 
 tells Spack to skip trying to bootstrap from binaries. To add the "github-actions" method back you can:
 
 .. code-block:: console
 
-   % spack bootstrap trust github-actions
+   % spack bootstrap enable github-actions
 
 There is also an option to reset the bootstrapping configuration to Spack's defaults:
 

lib/spack/docs/build_settings.rst

@@ -302,88 +302,31 @@ microarchitectures considered during the solve are constrained to be compatible
 host Spack is currently running on. For instance, if this option is set to ``true``, a
 user cannot concretize for ``target=icelake`` while running on an Haswell node.
 
-.. _package-preferences:
-
--------------------
-Package Preferences
--------------------
-
-Spack can be configured to prefer certain compilers, package
-versions, dependencies, and variants during concretization.
-The preferred configuration can be controlled via the
-``~/.spack/packages.yaml`` file for user configurations, or the
-``etc/spack/packages.yaml`` site configuration.
-
-Here's an example ``packages.yaml`` file that sets preferred packages:
-
-.. code-block:: yaml
-
-   packages:
-     opencv:
-       compiler: [gcc@4.9]
-       variants: +debug
-     gperftools:
-       version: [2.2, 2.4, 2.3]
-     all:
-       compiler: [gcc@4.4.7, 'gcc@4.6:', intel, clang, pgi]
-       target: [sandybridge]
-       providers:
-         mpi: [mvapich2, mpich, openmpi]
-
-At a high level, this example is specifying how packages should be
-concretized.  The opencv package should prefer using GCC 4.9 and
-be built with debug options.  The gperftools package should prefer version
-2.2 over 2.4.  Every package on the system should prefer mvapich2 for
-its MPI and GCC 4.4.7 (except for opencv, which overrides this by preferring GCC 4.9).
-These options are used to fill in implicit defaults.  Any of them can be overwritten
-on the command line if explicitly requested.
-
-Each ``packages.yaml`` file begins with the string ``packages:`` and
-package names are specified on the next level. The special string ``all``
-applies settings to *all* packages. Underneath each package name is one
-or more components: ``compiler``, ``variants``, ``version``,
-``providers``, and ``target``.  Each component has an ordered list of
-spec ``constraints``, with earlier entries in the list being preferred
-over later entries.
-
-Sometimes a package installation may have constraints that forbid
-the first concretization rule, in which case Spack will use the first
-legal concretization rule.  Going back to the example, if a user
-requests gperftools 2.3 or later, then Spack will install version 2.4
-as the 2.4 version of gperftools is preferred over 2.3.
-
-An explicit concretization rule in the preferred section will always
-take preference over unlisted concretizations.  In the above example,
-xlc isn't listed in the compiler list.  Every listed compiler from
-gcc to pgi will thus be preferred over the xlc compiler.
-
-The syntax for the ``provider`` section differs slightly from other
-concretization rules.  A provider lists a value that packages may
-``depend_on`` (e.g, MPI) and a list of rules for fulfilling that
-dependency.
-
 .. _package-requirements:
 
 --------------------
 Package Requirements
 --------------------
 
-You can use the configuration to force the concretizer to choose
-specific properties for packages when building them. Like preferences,
-these are only applied when the package is required by some other
-request (e.g. if the package is needed as a dependency of a
-request to ``spack install``).
+Spack can be configured to always use certain compilers, package
+versions, and variants during concretization through package
+requirements.
 
-An example of where this is useful is if you have a package that
-is normally built as a dependency but only under certain circumstances
-(e.g. only when a variant on a dependent is active): you can make
-sure that it always builds the way you want it to; this distinguishes
-package configuration requirements from constraints that you add to
-``spack install`` or to environments (in those cases, the associated
-packages are always built).
+Package requirements are useful when you find yourself repeatedly
+specifying the same constraints on the command line, and wish that
+Spack respects these constraints whether you mention them explicitly
+or not. Another use case is specifying constraints that should apply
+to all root specs in an environment, without having to repeat the
+constraint everywhere.
 
-The following is an example of how to enforce package properties in
-``packages.yaml``:
+Apart from that, requirements config is more flexible than constraints
+on the command line, because it can specify constraints on packages
+*when they occur* as a dependency. In contrast, on the command line it
+is not possible to specify constraints on dependencies while also keeping
+those dependencies optional.
+
+The package requirements configuration is specified in ``packages.yaml``
+keyed by package name:
 
 .. code-block:: yaml
 
@@ -452,15 +395,15 @@ under ``all`` are disregarded. For example, with a configuration like this:
      cmake:
        require: '%gcc'
 
-Spack requires ``cmake`` to use ``gcc`` and all other nodes (including cmake dependencies)
-to use ``clang``.
+Spack requires ``cmake`` to use ``gcc`` and all other nodes (including ``cmake``
+dependencies) to use ``clang``.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Setting requirements on virtual specs
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-A requirement on a virtual spec applies whenever that virtual is present in the DAG. This
-can be useful for fixing which virtual provider you want to use:
+A requirement on a virtual spec applies whenever that virtual is present in the DAG.
+This can be useful for fixing which virtual provider you want to use:
 
 .. code-block:: yaml
 
@@ -470,8 +413,8 @@ can be useful for fixing which virtual provider you want to use:
 
 With the configuration above the only allowed ``mpi`` provider is ``mvapich2 %gcc``.
 
-Requirements on the virtual spec and on the specific provider are both applied, if present. For
-instance with a configuration like:
+Requirements on the virtual spec and on the specific provider are both applied, if
+present. For instance with a configuration like:
 
 .. code-block:: yaml
 
@@ -483,6 +426,66 @@ instance with a configuration like:
 
 you will use ``mvapich2~cuda %gcc`` as an ``mpi`` provider.
 
+.. _package-preferences:
+
+-------------------
+Package Preferences
+-------------------
+
+In some cases package requirements can be too strong, and package
+preferences are the better option. Package preferences do not impose
+constraints on packages for particular versions or variants values,
+they rather only set defaults -- the concretizer is free to change
+them if it must due to other constraints. Also note that package
+preferences are of lower priority than reuse of already installed
+packages.
+
+Here's an example ``packages.yaml`` file that sets preferred packages:
+
+.. code-block:: yaml
+
+   packages:
+     opencv:
+       compiler: [gcc@4.9]
+       variants: +debug
+     gperftools:
+       version: [2.2, 2.4, 2.3]
+     all:
+       compiler: [gcc@4.4.7, 'gcc@4.6:', intel, clang, pgi]
+       target: [sandybridge]
+       providers:
+         mpi: [mvapich2, mpich, openmpi]
+
+At a high level, this example is specifying how packages are preferably
+concretized.  The opencv package should prefer using GCC 4.9 and
+be built with debug options.  The gperftools package should prefer version
+2.2 over 2.4.  Every package on the system should prefer mvapich2 for
+its MPI and GCC 4.4.7 (except for opencv, which overrides this by preferring GCC 4.9).
+These options are used to fill in implicit defaults.  Any of them can be overwritten
+on the command line if explicitly requested.
+
+Package preferences accept the follow keys or components under
+the specific package (or ``all``) section: ``compiler``, ``variants``,
+``version``, ``providers``, and ``target``.  Each component has an
+ordered list of spec ``constraints``, with earlier entries in the
+list being preferred over later entries.
+
+Sometimes a package installation may have constraints that forbid
+the first concretization rule, in which case Spack will use the first
+legal concretization rule.  Going back to the example, if a user
+requests gperftools 2.3 or later, then Spack will install version 2.4
+as the 2.4 version of gperftools is preferred over 2.3.
+
+An explicit concretization rule in the preferred section will always
+take preference over unlisted concretizations.  In the above example,
+xlc isn't listed in the compiler list.  Every listed compiler from
+gcc to pgi will thus be preferred over the xlc compiler.
+
+The syntax for the ``provider`` section differs slightly from other
+concretization rules.  A provider lists a value that packages may
+``depends_on`` (e.g, MPI) and a list of rules for fulfilling that
+dependency.
+
 .. _package_permissions:
 
 -------------------
@@ -531,3 +534,25 @@ directories inside the install prefix. This will ensure that even
 manually placed files within the install prefix are owned by the
 assigned group. If no group is assigned, Spack will allow the OS
 default behavior to go as expected.
+
+----------------------------
+Assigning Package Attributes
+----------------------------
+
+You can assign class-level attributes in the configuration:
+
+.. code-block:: yaml
+
+  packages:
+    mpileaks:
+      # Override existing attributes
+      url: http://www.somewhereelse.com/mpileaks-1.0.tar.gz
+      # ... or add new ones
+      x: 1
+
+Attributes set this way will be accessible to any method executed
+in the package.py file (e.g. the ``install()`` method). Values for these
+attributes may be any value parseable by yaml.
+
+These can only be applied to specific packages, not "all" or
+virtual packages.

lib/spack/docs/build_systems.rst

@@ -65,7 +65,6 @@ on these ideas for each distinct build system that Spack supports:
    build_systems/custompackage
    build_systems/inteloneapipackage
    build_systems/intelpackage
-   build_systems/multiplepackage
    build_systems/rocmpackage
    build_systems/sourceforgepackage
 

lib/spack/docs/build_systems/autotoolspackage.rst

@@ -5,9 +5,9 @@
 
 .. _autotoolspackage:
 
-----------------
-AutotoolsPackage
-----------------
+---------
+Autotools
+---------
 
 Autotools is a GNU build system that provides a build-script generator.
 By running the platform-independent ``./configure`` script that comes
@@ -17,7 +17,7 @@ with the package, you can generate a platform-dependent Makefile.
 Phases
 ^^^^^^
 
-The ``AutotoolsPackage`` base class comes with the following phases:
+The ``AutotoolsBuilder`` and ``AutotoolsPackage`` base classes come with the following phases:
 
 #. ``autoreconf`` - generate the configure script
 #. ``configure`` - generate the Makefiles

lib/spack/docs/build_systems/bundlepackage.rst

@@ -5,9 +5,9 @@
 
 .. _bundlepackage:
 
--------------
-BundlePackage
--------------
+------
+Bundle
+------
 
 ``BundlePackage`` represents a set of packages that are expected to work well
 together, such as a collection of commonly used software libraries.  The

lib/spack/docs/build_systems/cmakepackage.rst

@@ -5,9 +5,9 @@
 
 .. _cmakepackage:
 
-------------
-CMakePackage
-------------
+-----
+CMake
+-----
 
 Like Autotools, CMake is a widely-used build-script generator. Designed
 by Kitware, CMake is the most popular build system for new C, C++, and
@@ -21,7 +21,7 @@ whereas Autotools is Unix-only.
 Phases
 ^^^^^^
 
-The ``CMakePackage`` base class comes with the following phases:
+The ``CMakeBuilder`` and ``CMakePackage`` base classes come with the following phases:
 
 #. ``cmake`` - generate the Makefile
 #. ``build`` - build the package
@@ -130,8 +130,8 @@ Adding flags to cmake
 To add additional flags to the ``cmake`` call, simply override the
 ``cmake_args`` function. The following example defines values for the flags
 ``WHATEVER``, ``ENABLE_BROKEN_FEATURE``, ``DETECT_HDF5``, and ``THREADS`` with
-and without the :meth:`~spack.build_systems.cmake.CMakePackage.define` and
-:meth:`~spack.build_systems.cmake.CMakePackage.define_from_variant` helper functions:
+and without the :meth:`~spack.build_systems.cmake.CMakeBuilder.define` and
+:meth:`~spack.build_systems.cmake.CMakeBuilder.define_from_variant` helper functions:
 
 .. code-block:: python
 

lib/spack/docs/build_systems/inteloneapipackage.rst

@@ -32,7 +32,7 @@ oneAPI packages or use::
 
 For more information on a specific package, do::
 
-  spack info <package-name>
+  spack info --all <package-name>
 
 Intel no longer releases new versions of Parallel Studio, which can be
 used in Spack via the :ref:`intelpackage`. All of its components can

lib/spack/docs/build_systems/luapackage.rst

@@ -5,11 +5,11 @@
 
 .. _luapackage:
 
-------------
-LuaPackage
-------------
+---
+Lua
+---
 
-LuaPackage is a helper for the common case of Lua packages that provide
+The ``Lua`` build-system is a helper for the common case of Lua packages that provide
 a rockspec file.  This is not meant to take a rock archive, but to build
 a source archive or repository that provides a rockspec, which should cover
 most lua packages. In the case a Lua package builds by Make rather than
@@ -19,7 +19,7 @@ luarocks, prefer MakefilePackage.
 Phases
 ^^^^^^
 
-The ``LuaPackage`` base class comes with the following phases:
+The ``LuaBuilder`` and `LuaPackage`` base classes come with the following phases:
 
 #. ``unpack`` - if using a rock, unpacks the rock and moves into the source directory
 #. ``preprocess`` - adjust sources or rockspec to fix build

lib/spack/docs/build_systems/makefilepackage.rst

@@ -5,9 +5,9 @@
 
 .. _makefilepackage:
 
----------------
-MakefilePackage
----------------
+--------
+Makefile
+--------
 
 The most primitive build system a package can use is a plain Makefile.
 Makefiles are simple to write for small projects, but they usually
@@ -18,7 +18,7 @@ variables.
 Phases
 ^^^^^^
 
-The ``MakefilePackage`` base class comes with 3 phases:
+The ``MakefileBuilder`` and ``MakefilePackage`` base classes come with 3 phases:
 
 #. ``edit`` - edit the Makefile
 #. ``build`` - build the project

lib/spack/docs/build_systems/mavenpackage.rst

@@ -5,9 +5,9 @@
 
 .. _mavenpackage:
 
-------------
-MavenPackage
-------------
+-----
+Maven
+-----
 
 Apache Maven is a general-purpose build system that does not rely
 on Makefiles to build software. It is designed for building and
@@ -17,7 +17,7 @@ managing and Java-based project.
 Phases
 ^^^^^^
 
-The ``MavenPackage`` base class comes with the following phases:
+The ``MavenBuilder`` and ``MavenPackage`` base classes come with the following phases:
 
 #. ``build`` - compile code and package into a JAR file
 #. ``install`` - copy to installation prefix

lib/spack/docs/build_systems/mesonpackage.rst

@@ -5,9 +5,9 @@
 
 .. _mesonpackage:
 
-------------
-MesonPackage
-------------
+-----
+Meson
+-----
 
 Much like Autotools and CMake, Meson is a build system.  But it is
 meant to be both fast and as user friendly as possible.  GNOME's goal
@@ -17,7 +17,7 @@ is to port modules to use the Meson build system.
 Phases
 ^^^^^^
 
-The ``MesonPackage`` base class comes with the following phases:
+The ``MesonBuilder`` and ``MesonPackage`` base classes come with the following phases:
 
 #. ``meson`` - generate ninja files
 #. ``build`` - build the project

lib/spack/docs/build_systems/multiplepackage.rst

@@ -1,350 +0,0 @@
-.. Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
-   Spack Project Developers. See the top-level COPYRIGHT file for details.
-
-   SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-.. _multiplepackage:
-
-----------------------
-Multiple Build Systems
-----------------------
-
-Quite frequently, a package will change build systems from one version to the
-next. For example, a small project that once used a single Makefile to build
-may now require Autotools to handle the increased number of files that need to
-be compiled. Or, a package that once used Autotools may switch to CMake for
-Windows support. In this case, it becomes a bit more challenging to write a
-single build recipe for this package in Spack.
-
-There are several ways that this can be handled in Spack:
-
-#. Subclass the new build system, and override phases as needed (preferred)
-#. Subclass ``Package`` and implement ``install`` as needed
-#. Create separate ``*-cmake``, ``*-autotools``, etc. packages for each build system
-#. Rename the old package to ``*-legacy`` and create a new package
-#. Move the old package to a ``legacy`` repository and create a new package
-#. Drop older versions that only support the older build system
-
-Of these options, 1 is preferred, and will be demonstrated in this
-documentation. Options 3-5 have issues with concretization, so shouldn't be
-used. Options 4-5 also don't support more than two build systems. Option 6 only
-works if the old versions are no longer needed. Option 1 is preferred over 2
-because it makes it easier to drop the old build system entirely.
-
-The exact syntax of the package depends on which build systems you need to
-support. Below are a couple of common examples.
-
-^^^^^^^^^^^^^^^^^^^^^
-Makefile -> Autotools
-^^^^^^^^^^^^^^^^^^^^^
-
-Let's say we have the following package:
-
-.. code-block:: python
-
-   class Foo(MakefilePackage):
-       version("1.2.0", sha256="...")
-
-       def edit(self, spec, prefix):
-           filter_file("CC=", "CC=" + spack_cc, "Makefile")
-
-       def install(self, spec, prefix):
-           install_tree(".", prefix)
-
-
-The package subclasses from :ref:`makefilepackage`, which has three phases:
-
-#. ``edit`` (does nothing by default)
-#. ``build`` (runs ``make`` by default)
-#. ``install`` (runs ``make install`` by default)
-
-In this case, the ``install`` phase needed to be overridden because the
-Makefile did not have an install target. We also modify the Makefile to use
-Spack's compiler wrappers. The default ``build`` phase is not changed.
-
-Starting with version 1.3.0, we want to use Autotools to build instead.
-:ref:`autotoolspackage` has four phases:
-
-#. ``autoreconf`` (does not if a configure script already exists)
-#. ``configure`` (runs ``./configure --prefix=...`` by default)
-#. ``build`` (runs ``make`` by default)
-#. ``install`` (runs ``make install`` by default)
-
-If the only version we need to support is 1.3.0, the package would look as
-simple as:
-
-.. code-block:: python
-
-   class Foo(AutotoolsPackage):
-       version("1.3.0", sha256="...")
-
-       def configure_args(self):
-           return ["--enable-shared"]
-
-
-In this case, we use the default methods for each phase and only override
-``configure_args`` to specify additional flags to pass to ``./configure``.
-
-If we wanted to write a single package that supports both versions 1.2.0 and
-1.3.0, it would look something like:
-
-.. code-block:: python
-
-   class Foo(AutotoolsPackage):
-       version("1.3.0", sha256="...")
-       version("1.2.0", sha256="...", deprecated=True)
-
-       def configure_args(self):
-           return ["--enable-shared"]
-
-       # Remove the following once version 1.2.0 is dropped
-       @when("@:1.2")
-       def patch(self):
-           filter_file("CC=", "CC=" + spack_cc, "Makefile")
-
-       @when("@:1.2")
-       def autoreconf(self, spec, prefix):
-           pass
-
-       @when("@:1.2")
-       def configure(self, spec, prefix):
-           pass
-
-       @when("@:1.2")
-       def install(self, spec, prefix):
-           install_tree(".", prefix)
-
-
-There are a few interesting things to note here:
-
-* We added ``deprecated=True`` to version 1.2.0. This signifies that version
-  1.2.0 is deprecated and shouldn't be used. However, if a user still relies
-  on version 1.2.0, it's still there and builds just fine.
-* We moved the contents of the ``edit`` phase to the ``patch`` function. Since
-  ``AutotoolsPackage`` doesn't have an ``edit`` phase, the only way for this
-  step to be executed is to move it to the ``patch`` function, which always
-  gets run.
-* The ``autoreconf`` and ``configure`` phases become no-ops. Since the old
-  Makefile-based build system doesn't use these, we ignore these phases when
-  building ``foo@1.2.0``.
-* The ``@when`` decorator is used to override these phases only for older
-  versions. The default methods are used for ``foo@1.3:``.
-
-Once a new Spack release comes out, version 1.2.0 and everything below the
-comment can be safely deleted. The result is the same as if we had written a
-package for version 1.3.0 from scratch.
-
-^^^^^^^^^^^^^^^^^^
-Autotools -> CMake
-^^^^^^^^^^^^^^^^^^
-
-Let's say we have the following package:
-
-.. code-block:: python
-
-   class Bar(AutotoolsPackage):
-       version("1.2.0", sha256="...")
-
-       def configure_args(self):
-           return ["--enable-shared"]
-
-
-The package subclasses from :ref:`autotoolspackage`, which has four phases:
-
-#. ``autoreconf`` (does not if a configure script already exists)
-#. ``configure`` (runs ``./configure --prefix=...`` by default)
-#. ``build`` (runs ``make`` by default)
-#. ``install`` (runs ``make install`` by default)
-
-In this case, we use the default methods for each phase and only override
-``configure_args`` to specify additional flags to pass to ``./configure``.
-
-Starting with version 1.3.0, we want to use CMake to build instead.
-:ref:`cmakepackage` has three phases:
-
-#. ``cmake`` (runs ``cmake ...`` by default)
-#. ``build`` (runs ``make`` by default)
-#. ``install`` (runs ``make install`` by default)
-
-If the only version we need to support is 1.3.0, the package would look as
-simple as:
-
-.. code-block:: python
-
-   class Bar(CMakePackage):
-       version("1.3.0", sha256="...")
-
-       def cmake_args(self):
-           return [self.define("BUILD_SHARED_LIBS", True)]
-
-
-In this case, we use the default methods for each phase and only override
-``cmake_args`` to specify additional flags to pass to ``cmake``.
-
-If we wanted to write a single package that supports both versions 1.2.0 and
-1.3.0, it would look something like:
-
-.. code-block:: python
-
-   class Bar(CMakePackage):
-       version("1.3.0", sha256="...")
-       version("1.2.0", sha256="...", deprecated=True)
-
-       def cmake_args(self):
-           return [self.define("BUILD_SHARED_LIBS", True)]
-
-       # Remove the following once version 1.2.0 is dropped
-       def configure_args(self):
-           return ["--enable-shared"]
-
-       @when("@:1.2")
-       def cmake(self, spec, prefix):
-           configure("--prefix=" + prefix, *self.configure_args())
-
-
-There are a few interesting things to note here:
-
-* We added ``deprecated=True`` to version 1.2.0. This signifies that version
-  1.2.0 is deprecated and shouldn't be used. However, if a user still relies
-  on version 1.2.0, it's still there and builds just fine.
-* Since CMake and Autotools are so similar, we only need to override the
-  ``cmake`` phase, we can use the default ``build`` and ``install`` phases.
-* We override ``cmake`` to run ``./configure`` for older versions.
-  ``configure_args`` remains the same.
-* The ``@when`` decorator is used to override these phases only for older
-  versions. The default methods are used for ``bar@1.3:``.
-
-Once a new Spack release comes out, version 1.2.0 and everything below the
-comment can be safely deleted. The result is the same as if we had written a
-package for version 1.3.0 from scratch.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Multiple build systems for the same version
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-During the transition from one build system to another, developers often
-support multiple build systems at the same time. Spack can only use a single
-build system for a single version. To decide which build system to use for a
-particular version, take the following things into account:
-
-1. If the developers explicitly state that one build system is preferred over
-   another, use that one.
-2. If one build system is considered "experimental" while another is considered
-   "stable", use the stable build system.
-3. Otherwise, use the newer build system.
-
-The developer preference for which build system to use can change over time as
-a newer build system becomes stable/recommended.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Dropping support for old build systems
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When older versions of a package don't support a newer build system, it can be
-tempting to simply delete them from a package. This significantly reduces
-package complexity and makes the build recipe much easier to maintain. However,
-other packages or Spack users may rely on these older versions. The recommended
-approach is to first support both build systems (as demonstrated above),
-:ref:`deprecate <deprecate>` versions that rely on the old build system, and
-remove those versions and any phases that needed to be overridden in the next
-Spack release.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Three or more build systems
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-In rare cases, a package may change build systems multiple times. For example,
-a package may start with Makefiles, then switch to Autotools, then switch to
-CMake. The same logic used above can be extended to any number of build systems.
-For example:
-
-.. code-block:: python
-
-   class Baz(CMakePackage):
-       version("1.4.0", sha256="...")  # CMake
-       version("1.3.0", sha256="...")  # Autotools
-       version("1.2.0", sha256="...")  # Makefile
-
-       def cmake_args(self):
-           return [self.define("BUILD_SHARED_LIBS", True)]
-
-       # Remove the following once version 1.3.0 is dropped
-       def configure_args(self):
-           return ["--enable-shared"]
-
-       @when("@1.3")
-       def cmake(self, spec, prefix):
-           configure("--prefix=" + prefix, *self.configure_args())
-
-       # Remove the following once version 1.2.0 is dropped
-       @when("@:1.2")
-       def patch(self):
-           filter_file("CC=", "CC=" + spack_cc, "Makefile")
-
-       @when("@:1.2")
-       def cmake(self, spec, prefix):
-           pass
-
-       @when("@:1.2")
-       def install(self, spec, prefix):
-           install_tree(".", prefix)
-
-
-^^^^^^^^^^^^^^^^^^^
-Additional examples
-^^^^^^^^^^^^^^^^^^^
-
-When writing new packages, it often helps to see examples of existing packages.
-Here is an incomplete list of existing Spack packages that have changed build
-systems before:
-
-================  =====================  ================
-Package           Previous Build System  New Build System
-================  =====================  ================
-amber             custom                 CMake
-arpack-ng         Autotools              CMake
-atk               Autotools              Meson
-blast             None                   Autotools
-dyninst           Autotools              CMake
-evtgen            Autotools              CMake
-fish              Autotools              CMake
-gdk-pixbuf        Autotools              Meson
-glib              Autotools              Meson
-glog              Autotools              CMake
-gmt               Autotools              CMake
-gtkplus           Autotools              Meson
-hpl               Makefile               Autotools
-interproscan      Perl                   Maven
-jasper            Autotools              CMake
-kahip             SCons                  CMake
-kokkos            Makefile               CMake
-kokkos-kernels    Makefile               CMake
-leveldb           Makefile               CMake
-libdrm            Autotools              Meson
-libjpeg-turbo     Autotools              CMake
-mesa              Autotools              Meson
-metis             None                   CMake
-mpifileutils      Autotools              CMake
-muparser          Autotools              CMake
-mxnet             Makefile               CMake
-nest              Autotools              CMake
-neuron            Autotools              CMake
-nsimd             CMake                  nsconfig
-opennurbs         Makefile               CMake
-optional-lite     None                   CMake
-plasma            Makefile               CMake
-preseq            Makefile               Autotools
-protobuf          Autotools              CMake
-py-pygobject      Autotools              Python
-singularity       Autotools              Makefile
-span-lite         None                   CMake
-ssht              Makefile               CMake
-string-view-lite  None                   CMake
-superlu           Makefile               CMake
-superlu-dist      Makefile               CMake
-uncrustify        Autotools              CMake
-================  =====================  ================
-
-Packages that support multiple build systems can be a bit confusing to write.
-Don't hesitate to open an issue or draft pull request and ask for advice from
-other Spack developers!

lib/spack/docs/build_systems/octavepackage.rst

@@ -5,9 +5,9 @@
 
 .. _octavepackage:
 
--------------
-OctavePackage
--------------
+------
+Octave
+------
 
 Octave has its own build system for installing packages.
 
@@ -15,7 +15,7 @@ Octave has its own build system for installing packages.
 Phases
 ^^^^^^
 
-The ``OctavePackage`` base class has a single phase:
+The ``OctaveBuilder`` and ``OctavePackage`` base classes have a single phase:
 
 #. ``install`` - install the package
 

lib/spack/docs/build_systems/perlpackage.rst

@@ -5,9 +5,9 @@
 
 .. _perlpackage:
 
------------
-PerlPackage
------------
+----
+Perl
+----
 
 Much like Octave, Perl has its own language-specific
 build system.
@@ -16,7 +16,7 @@ build system.
 Phases
 ^^^^^^
 
-The ``PerlPackage`` base class comes with 3 phases that can be overridden:
+The ``PerlBuilder`` and ``PerlPackage`` base classes come with 3 phases that can be overridden:
 
 #. ``configure`` - configure the package
 #. ``build`` - build the package

lib/spack/docs/build_systems/pythonpackage.rst

@@ -724,10 +724,9 @@ extends vs. depends_on
 
 This is very similar to the naming dilemma above, with a slight twist.
 As mentioned in the :ref:`Packaging Guide <packaging_extensions>`,
-``extends`` and ``depends_on`` are very similar, but ``extends`` adds
-the ability to *activate* the package. Activation involves symlinking
-everything in the installation prefix of the package to the installation
-prefix of Python. This allows the user to import a Python module without
+``extends`` and ``depends_on`` are very similar, but ``extends`` ensures
+that the extension and extendee share the same prefix in views.
+This allows the user to import a Python module without
 having to add that module to ``PYTHONPATH``.
 
 When deciding between ``extends`` and ``depends_on``, the best rule of
@@ -735,7 +734,7 @@ thumb is to check the installation prefix. If Python libraries are
 installed to ``<prefix>/lib/pythonX.Y/site-packages``, then you
 should use ``extends``. If Python libraries are installed elsewhere
 or the only files that get installed reside in ``<prefix>/bin``, then
-don't use ``extends``, as symlinking the package wouldn't be useful.
+don't use ``extends``.
 
 ^^^^^^^^^^^^^^^^^^^^^
 Alternatives to Spack

lib/spack/docs/build_systems/qmakepackage.rst

@@ -5,9 +5,9 @@
 
 .. _qmakepackage:
 
-------------
-QMakePackage
-------------
+-----
+QMake
+-----
 
 Much like Autotools and CMake, QMake is a build-script generator
 designed by the developers of Qt. In its simplest form, Spack's
@@ -29,7 +29,7 @@ variables or edit ``*.pro`` files to get things working properly.
 Phases
 ^^^^^^
 
-The ``QMakePackage`` base class comes with the following phases:
+The ``QMakeBuilder`` and ``QMakePackage`` base classes come with the following phases:
 
 #. ``qmake`` - generate Makefiles
 #. ``build`` - build the project

lib/spack/docs/build_systems/racketpackage.rst

@@ -5,9 +5,9 @@
 
 .. _racketpackage:
 
--------------
-RacketPackage
--------------
+------
+Racket
+------
 
 Much like Python, Racket packages and modules have their own special build system.
 To learn more about the specifics of Racket package system, please refer to the
@@ -17,7 +17,7 @@ To learn more about the specifics of Racket package system, please refer to the
 Phases
 ^^^^^^
 
-The ``RacketPackage`` base class provides an ``install`` phase that
+The ``RacketBuilder`` and ``RacketPackage`` base classes provides an ``install`` phase that
 can be overridden, corresponding to the use of:
 
 .. code-block:: console

lib/spack/docs/build_systems/rpackage.rst

@@ -19,7 +19,7 @@ new Spack packages for.
 Phases
 ^^^^^^
 
-The ``RPackage`` base class has a single phase:
+The ``RBuilder`` and ``RPackage`` base classes have a single phase:
 
 #. ``install`` - install the package
 
@@ -193,10 +193,10 @@ Build system dependencies
 
 As an extension of the R ecosystem, your package will obviously depend
 on R to build and run. Normally, we would use ``depends_on`` to express
-this, but for R packages, we use ``extends``. ``extends`` is similar to
-``depends_on``, but adds an additional feature: the ability to "activate"
-the package by symlinking it to the R installation directory. Since
-every R package needs this, the ``RPackage`` base class contains:
+this, but for R packages, we use ``extends``. This implies a special
+dependency on R, which is used to set environment variables such as
+``R_LIBS`` uniformly. Since every R package needs this, the ``RPackage``
+base class contains:
 
 .. code-block:: python
 

lib/spack/docs/build_systems/rubypackage.rst

@@ -5,9 +5,9 @@
 
 .. _rubypackage:
 
------------
-RubyPackage
------------
+----
+Ruby
+----
 
 Like Perl, Python, and R, Ruby has its own build system for
 installing Ruby gems.
@@ -16,7 +16,7 @@ installing Ruby gems.
 Phases
 ^^^^^^
 
-The ``RubyPackage`` base class provides the following phases that
+The ``RubyBuilder`` and ``RubyPackage`` base classes provide the following phases that
 can be overridden:
 
 #. ``build`` - build everything needed to install

lib/spack/docs/build_systems/sconspackage.rst

@@ -5,9 +5,9 @@
 
 .. _sconspackage:
 
-------------
-SConsPackage
-------------
+-----
+SCons
+-----
 
 SCons is a general-purpose build system that does not rely on
 Makefiles to build software. SCons is written in Python, and handles
@@ -42,7 +42,7 @@ As previously mentioned, SCons allows developers to add subcommands like
    $ scons install
 
 
-To facilitate this, the ``SConsPackage`` base class provides the
+To facilitate this, the ``SConsBuilder`` and ``SconsPackage`` base classes provide the
 following phases:
 
 #. ``build`` - build the package

lib/spack/docs/build_systems/sippackage.rst

@@ -5,9 +5,9 @@
 
 .. _sippackage:
 
-----------
-SIPPackage
-----------
+---
+SIP
+---
 
 SIP is a tool that makes it very easy to create Python bindings for C and C++
 libraries. It was originally developed to create PyQt, the Python bindings for
@@ -22,7 +22,7 @@ provides support functions to the automatically generated code.
 Phases
 ^^^^^^
 
-The ``SIPPackage`` base class comes with the following phases:
+The ``SIPBuilder`` and ``SIPPackage`` base classes come with the following phases:
 
 #. ``configure`` - configure the package
 #. ``build`` - build the package

lib/spack/docs/build_systems/wafpackage.rst

@@ -5,9 +5,9 @@
 
 .. _wafpackage:
 
-----------
-WafPackage
-----------
+---
+Waf
+---
 
 Like SCons, Waf is a general-purpose build system that does not rely
 on Makefiles to build software.
@@ -16,7 +16,7 @@ on Makefiles to build software.
 Phases
 ^^^^^^
 
-The ``WafPackage`` base class comes with the following phases:
+The ``WafBuilder`` and ``WafPackage`` base classes come with the following phases:
 
 #. ``configure`` - configure the project
 #. ``build`` - build the project

lib/spack/docs/conf.py

@@ -32,6 +32,9 @@
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
+link_name = os.path.abspath("_spack_root")
+if not os.path.exists(link_name):
+    os.symlink(os.path.abspath("../../.."), link_name, target_is_directory=True)
 sys.path.insert(0, os.path.abspath("_spack_root/lib/spack/external"))
 sys.path.insert(0, os.path.abspath("_spack_root/lib/spack/external/pytest-fallback"))
 
@@ -206,6 +209,9 @@ def setup(sphinx):
     # Spack classes that are private and we don't want to expose
     ("py:class", "spack.provider_index._IndexBase"),
     ("py:class", "spack.repo._PrependFileLoader"),
+    ("py:class", "spack.build_systems._checks.BaseBuilder"),
+    # Spack classes that intersphinx is unable to resolve
+    ("py:class", "spack.version.VersionBase"),
 ]
 
 # The reST default role (used for this markup: `text`) to use for all documents.

lib/spack/docs/config_yaml.rst

@@ -224,9 +224,9 @@ them). Please note that we currently disable ccache's ``hash_dir``
 feature to avoid an issue with the stage directory (see
 https://github.com/LLNL/spack/pull/3761#issuecomment-294352232).
 
-------------------
-``shared_linking``
-------------------
+-----------------------
+``shared_linking:type``
+-----------------------
 
 Control whether Spack embeds ``RPATH`` or ``RUNPATH`` attributes in ELF binaries
 so that they can find their dependencies. Has no effect on macOS.
@@ -245,6 +245,52 @@ the loading object.
 
 DO NOT MIX the two options within the same install tree.
 
+-----------------------
+``shared_linking:bind``
+-----------------------
+
+This is an *experimental option* that controls whether Spack embeds absolute paths
+to needed shared libraries in ELF executables and shared libraries on Linux. Setting
+this option to ``true`` has two advantages:
+
+1. **Improved startup time**: when running an executable, the dynamic loader does not
+   have to perform a search for needed libraries, they are loaded directly.
+2. **Reliability**: libraries loaded at runtime are those that were linked to. This
+   minimizes the risk of accidentally picking up system libraries.
+
+In the current implementation, Spack sets the soname (shared object name) of
+libraries to their install path upon installation. This has two implications:
+
+1. binding does not apply to libraries installed *before* the option was enabled;
+2. toggling the option off does *not* prevent binding of libraries installed when
+   the option was still enabled.
+
+It is also worth noting that:
+
+1. Applications relying on ``dlopen(3)`` will continue to work, even when they open
+   a library by name. This is because ``RPATH``\s are retained in binaries also
+   when ``bind`` is enabled.
+2. ``LD_PRELOAD`` continues to work for the typical use case of overriding
+   symbols, such as preloading a library with a more efficient ``malloc``.
+   However, the preloaded library will be loaded *additionally to*, instead of
+   *in place of* another library with the same name --- this can be problematic
+   in very rare cases where libraries rely on a particular ``init`` or ``fini``
+   order.
+
+.. note::
+
+   In some cases packages provide *stub libraries* that only contain an interface
+   for linking, but lack an implementation for runtime. An example of this is
+   ``libcuda.so``, provided by the CUDA toolkit; it can be used to link against,
+   but the library needed at runtime is the one installed with the CUDA driver.
+   To avoid binding those libraries, they can be marked as non-bindable using
+   a property in the package:
+
+   .. code-block:: python
+
+      class Example(Package):
+         non_bindable_shared_objects = ["libinterface.so"]
+
 ----------------------
 ``terminal_title``
 ----------------------

lib/spack/docs/configuration.rst

@@ -405,6 +405,17 @@ Spack understands several special variables. These are:
 * ``$user``: name of the current user
 * ``$user_cache_path``: user cache directory (``~/.spack`` unless
   :ref:`overridden <local-config-overrides>`)
+* ``$architecture``: the architecture triple of the current host, as
+  detected by Spack.
+* ``$arch``: alias for ``$architecture``.
+* ``$platform``: the platform of the current host, as detected by Spack.
+* ``$operating_system``: the operating system of the current host, as
+  detected by the ``distro`` python module.
+* ``$os``: alias for ``$operating_system``.
+* ``$target``: the ISA target for the current host, as detected by
+  ArchSpec. E.g. ``skylake`` or ``neoverse-n1``.
+* ``$target_family``. The target family for the current host, as
+  detected by ArchSpec. E.g. ``x86_64`` or ``aarch64``.
 
 Note that, as with shell variables, you can write these as ``$varname``
 or with braces to distinguish the variable from surrounding characters:
@@ -549,7 +560,7 @@ down the problem:
 
 You can see above that the ``build_jobs`` and ``debug`` settings are
 built in and are not overridden by a configuration file. The
-``verify_ssl`` setting comes from the ``--insceure`` option on the
+``verify_ssl`` setting comes from the ``--insecure`` option on the
 command line. ``dirty`` and ``install_tree`` come from the custom
 scopes ``./my-scope`` and ``./my-scope-2``, and all other configuration
 options come from the default configuration files that ship with Spack.

lib/spack/docs/contribution_guide.rst

@@ -253,27 +253,6 @@ to update them.
    multiple runs of ``spack style`` just to re-compute line numbers and
    makes it much easier to fix errors directly off of the CI output.
 
-.. warning::
-
-   Flake8 and ``pep8-naming`` require a number of dependencies in order
-   to run.  If you installed ``py-flake8`` and ``py-pep8-naming``, the
-   easiest way to ensure the right packages are on your ``PYTHONPATH`` is
-   to run::
-
-     spack activate py-flake8
-     spack activate pep8-naming
-
-   so that all of the dependencies are symlinked to a central
-   location. If you see an error message like:
-
-   .. code-block:: console
-
-      Traceback (most recent call last):
-        File: "/usr/bin/flake8", line 5, in <module>
-          from pkg_resources import load_entry_point
-      ImportError: No module named pkg_resources
-
-   that means Flake8 couldn't find setuptools in your ``PYTHONPATH``.
 
 ^^^^^^^^^^^^^^^^^^^
 Documentation Tests
@@ -309,13 +288,9 @@ All of these can be installed with Spack, e.g.
 
    .. code-block:: console
 
-      $ spack activate py-sphinx
-      $ spack activate py-sphinx-rtd-theme
-      $ spack activate py-sphinxcontrib-programoutput
+      $ spack load py-sphinx py-sphinx-rtd-theme py-sphinxcontrib-programoutput
 
-   so that all of the dependencies are symlinked into that Python's
-   tree.  Alternatively, you could arrange for their library
-   directories to be added to PYTHONPATH.  If you see an error message
+   so that all of the dependencies are added to PYTHONPATH.  If you see an error message
    like:
 
    .. code-block:: console

lib/spack/docs/developer_guide.rst

@@ -149,11 +149,9 @@ grouped by functionality.
 Package-related modules
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-:mod:`spack.package`
-  Contains the :class:`~spack.package_base.Package` class, which
-  is the superclass for all packages in Spack.  Methods on ``Package``
-  implement all phases of the :ref:`package lifecycle
-  <package-lifecycle>` and manage the build process.
+:mod:`spack.package_base`
+  Contains the :class:`~spack.package_base.PackageBase` class, which
+  is the superclass for all packages in Spack.
 
 :mod:`spack.util.naming`
   Contains functions for mapping between Spack package names,

lib/spack/docs/environments.rst

@@ -233,8 +233,8 @@ packages will be listed as roots of the Environment.
 
 All of the Spack commands that act on the list of installed specs are
 Environment-sensitive in this way, including ``install``,
-``uninstall``, ``activate``, ``deactivate``, ``find``, ``extensions``,
-and more. In the :ref:`environment-configuration` section we will discuss
+``uninstall``, ``find``, ``extensions``, and more. In the
+:ref:`environment-configuration` section we will discuss
 Environment-sensitive commands further.
 
 ^^^^^^^^^^^^^^^^^^^^^
@@ -519,27 +519,33 @@ available from the yaml file.
 ^^^^^^^^^^^^^^^^^^^
 Spec concretization
 ^^^^^^^^^^^^^^^^^^^
-An environment can be concretized in three different modes and the behavior active under any environment
-is determined by the ``concretizer:unify`` property. By default specs are concretized *separately*, one after the other:
+An environment can be concretized in three different modes and the behavior active under
+any environment is determined by the ``concretizer:unify`` configuration option.
+
+The *default* mode is to unify all specs:
 
 .. code-block:: yaml
 
    spack:
        specs:
-         - hdf5~mpi
          - hdf5+mpi
          - zlib@1.2.8
        concretizer:
-         unify: false
+         unify: true
 
-This mode of operation permits to deploy a full software stack where multiple configurations of the same package
-need to be installed alongside each other using the best possible selection of transitive dependencies. The downside
-is that redundancy of installations is disregarded completely, and thus environments might be more bloated than
-strictly needed. In the example above, for instance, if a version of ``zlib`` newer than ``1.2.8`` is known to Spack,
-then it will be used for both ``hdf5`` installations.
+This means that any package in the environment corresponds to a single concrete spec. In
+the above example, when ``hdf5`` depends down the line of ``zlib``, it is required to
+take ``zlib@1.2.8`` instead of a newer version. This mode of concretization is
+particularly useful when environment views are used: if every package occurs in
+only one flavor, it is usually possible to merge all install directories into a view.
 
-If redundancy of the environment is a concern, Spack provides a way to install it *together where possible*,
-i.e. trying to maximize reuse of dependencies across different specs:
+A downside of unified concretization is that it can be overly strict. For example, a
+concretization error would happen when both ``hdf5+mpi`` and ``hdf5~mpi`` are specified
+in an environment.
+
+The second mode is to *unify when possible*: this makes concretization of root specs
+more independendent. Instead of requiring reuse of dependencies across different root
+specs, it is only maximized:
 
 .. code-block:: yaml
 
@@ -551,26 +557,27 @@ i.e. trying to maximize reuse of dependencies across different specs:
        concretizer:
          unify: when_possible
 
-Also in this case Spack allows having multiple configurations of the same package, but privileges the reuse of
-specs over other factors. Going back to our example, this means that both ``hdf5`` installations will use
-``zlib@1.2.8`` as a dependency even if newer versions of that library are available.
-Central installations done at HPC centers by system administrators or user support groups are a common case
-that fits either of these two modes.
+This means that both ``hdf5`` installations will use ``zlib@1.2.8`` as a dependency even
+if newer versions of that library are available.
 
-Environments can also be configured to concretize all the root specs *together*, in a self-consistent way, to
-ensure that each package in the environment comes with a single configuration:
+The third mode of operation is to concretize root specs entirely independently by
+disabling unified concretization:
 
 .. code-block:: yaml
 
    spack:
        specs:
+         - hdf5~mpi
          - hdf5+mpi
          - zlib@1.2.8
        concretizer:
-         unify: true
+         unify: false
 
-This mode of operation is usually what is required by software developers that want to deploy their development
-environment and have a single view of it in the filesystem.
+In this example ``hdf5`` is concretized separately, and does not consider ``zlib@1.2.8``
+as a constraint or preference. Instead, it will take the latest possible version.
+
+The last two concretization options are typically useful for system administrators and
+user support groups providing a large software stack for their HPC center.
 
 .. note::
 
@@ -581,10 +588,10 @@ environment and have a single view of it in the filesystem.
 
 .. admonition:: Re-concretization of user specs
 
-   When concretizing specs *together* or *together where possible* the entire set of specs will be
+   When using *unified* concretization (when possible), the entire set of specs will be
    re-concretized after any addition of new user specs, to ensure that
-   the environment remains consistent / minimal. When instead the specs are concretized
-   separately only the new specs will be re-concretized after any addition.
+   the environment remains consistent / minimal. When instead unified concretization is
+   disabled, only the new specs will be concretized after any addition.
 
 ^^^^^^^^^^^^^
 Spec Matrices

lib/spack/docs/features.rst

@@ -98,40 +98,42 @@ For example, this command:
 
 .. code-block:: console
 
-   $ spack create http://www.mr511.de/software/libelf-0.8.13.tar.gz
+   $ spack create https://ftp.osuosl.org/pub/blfs/conglomeration/libelf/libelf-0.8.13.tar.gz
 
 creates a simple python file:
 
 .. code-block:: python
 
-   from spack import *
+   from spack.package import *
 
 
-   class Libelf(Package):
+   class Libelf(AutotoolsPackage):
        """FIXME: Put a proper description of your package here."""
 
        # FIXME: Add a proper url for your package's homepage here.
-       homepage = "http://www.example.com"
-       url      = "http://www.mr511.de/software/libelf-0.8.13.tar.gz"
+       homepage = "https://www.example.com"
+       url = "https://ftp.osuosl.org/pub/blfs/conglomeration/libelf/libelf-0.8.13.tar.gz"
 
-       version('0.8.13', '4136d7b4c04df68b686570afa26988ac')
+       # FIXME: Add a list of GitHub accounts to
+       # notify when the package is updated.
+       # maintainers = ["github_user1", "github_user2"]
+
+       version("0.8.13", sha256="591a9b4ec81c1f2042a97aa60564e0cb79d041c52faa7416acb38bc95bd2c76d")
 
        # FIXME: Add dependencies if required.
-       # depends_on('foo')
+       # depends_on("foo")
 
-       def install(self, spec, prefix):
-           # FIXME: Modify the configure line to suit your build system here.
-           configure('--prefix={0}'.format(prefix))
-
-           # FIXME: Add logic to build and install here.
-           make()
-           make('install')
+       def configure_args(self):
+           # FIXME: Add arguments other than --prefix
+           # FIXME: If not needed delete this function
+           args = []
+           return args
 
 It doesn't take much python coding to get from there to a working
 package:
 
 .. literalinclude:: _spack_root/var/spack/repos/builtin/packages/libelf/package.py
-   :lines: 6-
+   :lines: 5-
 
 Spack also provides wrapper functions around common commands like
 ``configure``, ``make``, and ``cmake`` to make writing packages

lib/spack/docs/getting_started.rst

@@ -44,7 +44,7 @@ A build matrix showing which packages are working on which systems is shown belo
          yum install -y epel-release
          yum update -y
          yum --enablerepo epel groupinstall -y "Development Tools"
-         yum --enablerepo epel install -y curl findutils gcc-c++ gcc gcc-gfortran git gnupg2 hostname iproute make patch python3 python3-pip python3-setuptools unzip
+         yum --enablerepo epel install -y curl findutils gcc-c++ gcc gcc-gfortran git gnupg2 hostname iproute redhat-lsb-core make patch python3 python3-pip python3-setuptools unzip
          python3 -m pip install boto3
 
    .. tab-item:: macOS Brew
@@ -124,88 +124,41 @@ Spack provides two ways of bootstrapping ``clingo``: from pre-built binaries
 (default), or from sources. The fastest way to get started is to bootstrap from
 pre-built binaries.
 
-.. note::
-
-   When bootstrapping from pre-built binaries, Spack currently requires 
-   ``patchelf`` on Linux and ``otool`` on macOS. If ``patchelf`` is not in the
-   ``PATH``, Spack will build it from sources, and a C++ compiler is required.
-
-The first time you concretize a spec, Spack will bootstrap in the background:
+The first time you concretize a spec, Spack will bootstrap automatically:
 
 .. code-block:: console
 
-   $ time spack spec zlib
+   $ spack spec zlib
+   ==> Bootstrapping clingo from pre-built binaries
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.4/build_cache/linux-centos7-x86_64-gcc-10.2.1-clingo-bootstrap-spack-ba5ijauisd3uuixtmactc36vps7yfsrl.spec.json
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.4/build_cache/linux-centos7-x86_64/gcc-10.2.1/clingo-bootstrap-spack/linux-centos7-x86_64-gcc-10.2.1-clingo-bootstrap-spack-ba5ijauisd3uuixtmactc36vps7yfsrl.spack
+   ==> Installing "clingo-bootstrap@spack%gcc@10.2.1~docs~ipo+python+static_libstdcpp build_type=Release arch=linux-centos7-x86_64" from a buildcache
+   ==> Bootstrapping patchelf from pre-built binaries
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.4/build_cache/linux-centos7-x86_64-gcc-10.2.1-patchelf-0.16.1-p72zyan5wrzuabtmzq7isa5mzyh6ahdp.spec.json
+   ==> Fetching https://mirror.spack.io/bootstrap/github-actions/v0.4/build_cache/linux-centos7-x86_64/gcc-10.2.1/patchelf-0.16.1/linux-centos7-x86_64-gcc-10.2.1-patchelf-0.16.1-p72zyan5wrzuabtmzq7isa5mzyh6ahdp.spack
+   ==> Installing "patchelf@0.16.1%gcc@10.2.1 ldflags="-static-libstdc++ -static-libgcc"  build_system=autotools arch=linux-centos7-x86_64" from a buildcache
    Input spec
    --------------------------------
    zlib
 
    Concretized
    --------------------------------
-   zlib@1.2.11%gcc@7.5.0+optimize+pic+shared arch=linux-ubuntu18.04-zen
-
-   real	0m20.023s
-   user	0m18.351s
-   sys	0m0.784s
-
-After this command you'll see that ``clingo`` has been installed for Spack's own use:
-
-.. code-block:: console
-
-   $ spack find -b
-   ==> Showing internal bootstrap store at "/root/.spack/bootstrap/store"
-   ==> 3 installed packages
-   -- linux-rhel5-x86_64 / gcc@9.3.0 -------------------------------
-   clingo-bootstrap@spack  python@3.6
-
-   -- linux-ubuntu18.04-zen / gcc@7.5.0 ----------------------------
-   patchelf@0.13
-
-Subsequent calls to the concretizer will then be much faster:
-
-.. code-block:: console
-
-   $ time spack spec zlib
-   [ ... ]
-   real	0m0.490s
-   user	0m0.431s
-   sys	0m0.041s
-
+   zlib@1.2.13%gcc@9.4.0+optimize+pic+shared build_system=makefile arch=linux-ubuntu20.04-icelake
 
 If for security concerns you cannot bootstrap ``clingo`` from pre-built
-binaries, you have to mark this bootstrapping method as untrusted. This makes
-Spack fall back to bootstrapping from sources:
+binaries, you have to disable fetching the binaries we generated with Github Actions.
 
 .. code-block:: console
 
-   $ spack bootstrap untrust github-actions-v0.2
-   ==> "github-actions-v0.2" is now untrusted and will not be used for bootstrapping
+   $ spack bootstrap disable github-actions-v0.4
+   ==> "github-actions-v0.4" is now disabled and will not be used for bootstrapping
+   $ spack bootstrap disable github-actions-v0.3
+   ==> "github-actions-v0.3" is now disabled and will not be used for bootstrapping
 
 You can verify that the new settings are effective with:
 
-.. code-block:: console
+.. command-output:: spack bootstrap list
 
-   $ spack bootstrap list
-   Name: github-actions-v0.2 UNTRUSTED
-
-     Type: buildcache
-
-     Info:
-       url: https://mirror.spack.io/bootstrap/github-actions/v0.2
-       homepage: https://github.com/spack/spack-bootstrap-mirrors
-       releases: https://github.com/spack/spack-bootstrap-mirrors/releases
-
-     Description:
-       Buildcache generated from a public workflow using Github Actions.
-       The sha256 checksum of binaries is checked before installation.
-
-   [ ... ]
-
-   Name: spack-install TRUSTED
-
-     Type: install
-
-     Description:
-       Specs built from sources by Spack. May take a long time.
 
 .. note::
 
@@ -235,9 +188,7 @@ under the ``${HOME}/.spack`` directory. The software installed there can be quer
 
 .. code-block:: console
 
-   $ spack find --bootstrap
-   ==> Showing internal bootstrap store at "/home/spack/.spack/bootstrap/store"
-   ==> 3 installed packages
+   $ spack -b find
    -- linux-ubuntu18.04-x86_64 / gcc@10.1.0 ------------------------
    clingo-bootstrap@spack  python@3.6.9  re2c@1.2.1
 
@@ -246,7 +197,7 @@ In case it's needed the bootstrap store can also be cleaned with:
 .. code-block:: console
 
    $ spack clean -b
-   ==> Removing software in "/home/spack/.spack/bootstrap/store"
+   ==> Removing bootstrapped software and configuration in "/home/spack/.spack/bootstrap"
 
 ^^^^^^^^^^^^^^^^^^
 Check Installation

lib/spack/docs/index.rst

@@ -56,7 +56,6 @@ or refer to the full manual below.
    basic_usage
    Tutorial: Spack 101 <https://spack-tutorial.readthedocs.io>
    replace_conda_homebrew
-   known_issues
 
 .. toctree::
    :maxdepth: 2

lib/spack/docs/known_issues.rst

@@ -1,40 +0,0 @@
-.. Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
-   Spack Project Developers. See the top-level COPYRIGHT file for details.
-
-   SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-============
-Known Issues
-============
-
-This is a list of known issues in Spack. It provides ways of getting around these
-problems if you encounter them.
-
-------------------------------------------------
-Spack does not seem to respect ``packages.yaml``
-------------------------------------------------
-
-.. note::
-
-   This issue is **resolved** as of v0.19.0.dev0 commit
-   `8281a0c5feabfc4fe180846d6fe95cfe53420bc5`, through the introduction of package
-   requirements. See :ref:`package-requirements`.
-
-A common problem in Spack v0.18.0 up to v0.19.0.dev0 is that package, compiler and target
-preferences specified in ``packages.yaml`` do not seem to be respected. Spack picks the
-"wrong" compilers and their versions, package versions and variants, and
-micro-architectures.
-
-This is however not a bug. In order to reduce the number of builds of the same
-packages, the concretizer values reuse of installed packages higher than preferences
-set in ``packages.yaml``. Note that ``packages.yaml`` specifies only preferences, not
-hard constraints.
-
-There are multiple workarounds:
-
-1. Disable reuse during concretization: ``spack install --fresh <spec>`` when installing
-   from the command line, or ``spack concretize --fresh --force`` when using
-   environments.  
-2. Turn preferences into constrains, by moving them to the input spec. For example,
-   use ``spack spec zlib%gcc@12`` when you want to force GCC 12 even if ``zlib`` was
-   already installed with GCC 10.

lib/spack/docs/packaging_guide.rst

@@ -34,24 +34,155 @@ ubiquitous in the scientific software community. Second, it's a modern
 language and has many powerful features to help make package writing
 easy.
 
----------------------------
-Creating & editing packages
----------------------------
+
+.. _installation_procedure:
+
+--------------------------------------
+Overview of the installation procedure
+--------------------------------------
+
+Whenever Spack installs software, it goes through a series of predefined steps:
+
+.. image:: images/installation_pipeline.png
+  :scale: 60 %
+  :align: center
+
+All these steps are influenced by the metadata in each ``package.py`` and
+by the current Spack configuration.
+Since build systems are different from one another, the execution of the
+last block in the figure is further expanded in a build system specific way.
+An example for ``CMake`` is, for instance:
+
+.. image:: images/builder_phases.png
+   :align: center
+   :scale: 60 %
+
+The predefined steps for each build system are called "phases".
+In general, the name and order in which the phases will be executed can be
+obtained by either reading the API docs at :py:mod:`~.spack.build_systems`, or
+using the ``spack info`` command:
+
+.. code-block:: console
+    :emphasize-lines: 13,14
+
+    $ spack info --phases m4
+    AutotoolsPackage:    m4
+    Homepage:            https://www.gnu.org/software/m4/m4.html
+
+    Safe versions:
+        1.4.17    ftp://ftp.gnu.org/gnu/m4/m4-1.4.17.tar.gz
+
+    Variants:
+        Name       Default   Description
+
+        sigsegv    on        Build the libsigsegv dependency
+
+    Installation Phases:
+        autoreconf    configure    build    install
+
+    Build Dependencies:
+        libsigsegv
+
+    ...
+
+An extensive list of available build systems and phases is provided in :ref:`installation_process`.
+
+
+------------------------
+Writing a package recipe
+------------------------
+
+Since v0.19, Spack supports  two ways of writing a package recipe. The most commonly used is to encode both the metadata
+(directives, etc.) and the build behavior in a single class, like shown in the following example:
+
+.. code-block:: python
+
+   class Openjpeg(CMakePackage):
+       """OpenJPEG is an open-source JPEG 2000 codec written in C language"""
+
+       homepage = "https://github.com/uclouvain/openjpeg"
+       url = "https://github.com/uclouvain/openjpeg/archive/v2.3.1.tar.gz"
+
+       version("2.4.0", sha256="8702ba68b442657f11aaeb2b338443ca8d5fb95b0d845757968a7be31ef7f16d")
+
+       variant("codec", default=False, description="Build the CODEC executables")
+       depends_on("libpng", when="+codec")
+
+       def url_for_version(self, version):
+           if version >= Version("2.1.1"):
+               return super(Openjpeg, self).url_for_version(version)
+           url_fmt = "https://github.com/uclouvain/openjpeg/archive/version.{0}.tar.gz"
+           return url_fmt.format(version)
+
+       def cmake_args(self):
+           args = [
+               self.define_from_variant("BUILD_CODEC", "codec"),
+               self.define("BUILD_MJ2", False),
+               self.define("BUILD_THIRDPARTY", False),
+           ]
+           return args
+
+A package encoded with a single class is backward compatible with versions of Spack
+lower than v0.19, and so are custom repositories containing only recipes of this kind.
+The downside is that *this format doesn't allow packagers to use more than one build system in a single recipe*.
+
+To do that, we have to resort to the second way Spack has of writing packages, which involves writing a
+builder class explicitly. Using the same example as above, this reads:
+
+.. code-block:: python
+
+   class Openjpeg(CMakePackage):
+       """OpenJPEG is an open-source JPEG 2000 codec written in C language"""
+
+       homepage = "https://github.com/uclouvain/openjpeg"
+       url = "https://github.com/uclouvain/openjpeg/archive/v2.3.1.tar.gz"
+
+       version("2.4.0", sha256="8702ba68b442657f11aaeb2b338443ca8d5fb95b0d845757968a7be31ef7f16d")
+
+       variant("codec", default=False, description="Build the CODEC executables")
+       depends_on("libpng", when="+codec")
+
+       def url_for_version(self, version):
+           if version >= Version("2.1.1"):
+               return super(Openjpeg, self).url_for_version(version)
+           url_fmt = "https://github.com/uclouvain/openjpeg/archive/version.{0}.tar.gz"
+           return url_fmt.format(version)
+
+   class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
+       def cmake_args(self):
+           args = [
+               self.define_from_variant("BUILD_CODEC", "codec"),
+               self.define("BUILD_MJ2", False),
+               self.define("BUILD_THIRDPARTY", False),
+           ]
+           return args
+
+This way of writing packages allows extending the recipe to support multiple build systems,
+see :ref:`multiple_build_systems` for more details. The downside is that recipes of this kind
+are only understood by Spack since v0.19+. More information on the internal architecture of
+Spack can be found at :ref:`package_class_structure`.
+
+.. note::
+
+   If a builder is implemented in ``package.py``, all build-specific methods must be moved
+   to the builder. This means that if you have a package like
+
+   .. code-block:: python
+
+      class Foo(CmakePackage):
+          def cmake_args(self):
+              ...
+
+   and you add a builder to the ``package.py``, you must move ``cmake_args`` to the builder.
 
 .. _cmd-spack-create:
 
-^^^^^^^^^^^^^^^^
-``spack create``
-^^^^^^^^^^^^^^^^
+---------------------
+Creating new packages
+---------------------
 
-The ``spack create`` command creates a directory with the package name and
-generates a ``package.py`` file with a boilerplate package template. If given
-a URL pointing to a tarball or other software archive, ``spack create`` is
-smart enough to determine basic information about the package, including its name
-and build system. In most cases, ``spack create`` plus a few modifications is
-all you need to get a package working.
-
-Here's an example:
+To help creating a new package Spack provides a command that generates a ``package.py``
+file in an existing repository, with a boilerplate package template. Here's an example:
 
 .. code-block:: console
 
@@ -87,23 +218,6 @@ You do not *have* to download all of the versions up front. You can
 always choose to download just one tarball initially, and run
 :ref:`cmd-spack-checksum` later if you need more versions.
 
-Let's say you download 3 tarballs:
-
-.. code-block:: console
-
-	How many would you like to checksum? (default is 1, q to abort) 3
-	==> Downloading...
-	==> Fetching https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2
-	######################################################################## 100.0%
-	==> Fetching https://gmplib.org/download/gmp/gmp-6.1.1.tar.bz2
-	######################################################################## 100.0%
-	==> Fetching https://gmplib.org/download/gmp/gmp-6.1.0.tar.bz2
-	######################################################################## 100.0%
-	==> Checksummed 3 versions of gmp:
-	==> This package looks like it uses the autotools build system
-	==> Created template for gmp package
-	==> Created package file: /Users/Adam/spack/var/spack/repos/builtin/packages/gmp/package.py
-
 Spack automatically creates a directory in the appropriate repository,
 generates a boilerplate template for your package, and opens up the new
 ``package.py`` in your favorite ``$EDITOR``:
@@ -111,6 +225,14 @@ generates a boilerplate template for your package, and opens up the new
 .. code-block:: python
    :linenos:
 
+   # Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+   # Spack Project Developers. See the top-level COPYRIGHT file for details.
+   #
+   # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+   # ----------------------------------------------------------------------------
+   # If you submit this package back to Spack as a pull request,
+   # please first remove this boilerplate and all FIXME comments.
    #
    # This is a template package file for Spack.  We've put "FIXME"
    # next to all the things you'll want to change. Once you've handled
@@ -123,9 +245,8 @@ generates a boilerplate template for your package, and opens up the new
    #     spack edit gmp
    #
    # See the Spack documentation for more information on packaging.
-   # If you submit this package back to Spack as a pull request,
-   # please first remove this boilerplate and all FIXME comments.
-   #
+   # ----------------------------------------------------------------------------
+   import spack.build_systems.autotools
    from spack.package import *
 
 
@@ -133,19 +254,17 @@ generates a boilerplate template for your package, and opens up the new
        """FIXME: Put a proper description of your package here."""
 
        # FIXME: Add a proper url for your package's homepage here.
-       homepage = "http://www.example.com"
-       url      = "https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2"
+       homepage = "https://www.example.com"
+       url = "https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2"
 
        # FIXME: Add a list of GitHub accounts to
        # notify when the package is updated.
-       # maintainers = ['github_user1', 'github_user2']
+       # maintainers = ["github_user1", "github_user2"]
 
-       version('6.1.2', '8ddbb26dc3bd4e2302984debba1406a5')
-       version('6.1.1', '4c175f86e11eb32d8bf9872ca3a8e11d')
-       version('6.1.0', '86ee6e54ebfc4a90b643a65e402c4048')
+       version("6.2.1", sha256="eae9326beb4158c386e39a356818031bd28f3124cf915f8c5b1dc4c7a36b4d7c")
 
        # FIXME: Add dependencies if required.
-       # depends_on('foo')
+       # depends_on("foo")
 
        def configure_args(self):
            # FIXME: Add arguments other than --prefix
@@ -154,15 +273,16 @@ generates a boilerplate template for your package, and opens up the new
            return args
 
 The tedious stuff (creating the class, checksumming archives) has been
-done for you. You'll notice that ``spack create`` correctly detected that
-``gmp`` uses the Autotools build system. It created a new ``Gmp`` package
-that subclasses the ``AutotoolsPackage`` base class. This base class
-provides basic installation methods common to all Autotools packages:
+done for you. Spack correctly detected that ``gmp`` uses the ``autotools``
+build system, so it created a new ``Gmp`` package that subclasses the
+``AutotoolsPackage`` base class.
+
+The default installation procedure for a package subclassing the ``AutotoolsPackage``
+is to go through the typical process of:
 
 .. code-block:: bash
 
    ./configure --prefix=/path/to/installation/directory
-
    make
    make check
    make install
@@ -209,12 +329,14 @@ The rest of the tasks you need to do are as follows:
    Your new package may require specific flags during ``configure``.
    These can be added via ``configure_args``. Specifics will differ
    depending on the package and its build system.
-   :ref:`Implementing the install method <install-method>` is
+   :ref:`installation_process` is
    covered in detail later.
 
-Passing a URL to ``spack create`` is a convenient and easy way to get
-a basic package template, but what if your software is licensed and
-cannot be downloaded from a URL? You can still create a boilerplate
+^^^^^^^^^^^^^^^^^^^^^^^^^
+Non-downloadable software
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If your software cannot be downloaded from a URL you can still create a boilerplate
 ``package.py`` by telling ``spack create`` what name you want to use:
 
 .. code-block:: console
@@ -223,40 +345,23 @@ cannot be downloaded from a URL? You can still create a boilerplate
 
 This will create a simple ``intel`` package with an ``install()``
 method that you can craft to install your package.
-
-What if ``spack create <url>`` guessed the wrong name or build system?
-For example, if your package uses the Autotools build system but does
-not come with a ``configure`` script, Spack won't realize it uses
-Autotools. You can overwrite the old package with ``--force`` and specify
-a name with ``--name`` or a build system template to use with ``--template``:
+Likewise, you can force the build system to be used with ``--template`` and,
+in case it's needed, you can overwrite a package already in the repository
+with ``--force``:
 
 .. code-block:: console
 
    $ spack create --name gmp https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2
    $ spack create --force --template autotools https://gmplib.org/download/gmp/gmp-6.1.2.tar.bz2
 
-.. note::
-
-   If you are creating a package that uses the Autotools build system
-   but does not come with a ``configure`` script, you'll need to add an
-   ``autoreconf`` method to your package that explains how to generate
-   the ``configure`` script. You may also need the following dependencies:
-
-   .. code-block:: python
-
-      depends_on('autoconf', type='build')
-      depends_on('automake', type='build')
-      depends_on('libtool',  type='build')
-      depends_on('m4',       type='build')
-
 A complete list of available build system templates can be found by running
 ``spack create --help``.
 
 .. _cmd-spack-edit:
 
-^^^^^^^^^^^^^^
-``spack edit``
-^^^^^^^^^^^^^^
+-------------------------
+Editing existing packages
+-------------------------
 
 One of the easiest ways to learn how to write packages is to look at
 existing ones.  You can edit a package file by name with the ``spack
@@ -266,10 +371,15 @@ edit`` command:
 
    $ spack edit gmp
 
-So, if you used ``spack create`` to create a package, then saved and
-closed the resulting file, you can get back to it with ``spack edit``.
-The ``gmp`` package actually lives in
-``$SPACK_ROOT/var/spack/repos/builtin/packages/gmp/package.py``,
+If you used ``spack create`` to create a package, you can get back to
+it later with ``spack edit``. For instance, the ``gmp`` package actually
+lives in:
+
+.. code-block:: console
+
+   $ spack location -p gmp
+   ${SPACK_ROOT}/var/spack/repos/builtin/packages/gmp/package.py
+
 but ``spack edit`` provides a much simpler shortcut and saves you the
 trouble of typing the full path.
 
@@ -2422,7 +2532,7 @@ Spack provides a mechanism for dependencies to influence the
 environment of their dependents by overriding  the
 :meth:`setup_dependent_run_environment <spack.package_base.PackageBase.setup_dependent_run_environment>`
 or the
-:meth:`setup_dependent_build_environment <spack.package_base.PackageBase.setup_dependent_build_environment>`
+:meth:`setup_dependent_build_environment <spack.builder.Builder.setup_dependent_build_environment>`
 methods.
 The Qt package, for instance, uses this call:
 
@@ -2524,9 +2634,12 @@ extendable package:
        extends('python')
        ...
 
-Now, the ``py-numpy`` package can be used as an argument to ``spack
-activate``.  When it is activated, all the files in its prefix will be
-symbolically linked into the prefix of the python package.
+This accomplishes a few things. Firstly, the Python package can set special
+variables such as ``PYTHONPATH`` for all extensions when the run or build
+environment is set up. Secondly, filesystem views can ensure that extensions
+are put in the same prefix as their extendee. This ensures that Python in
+a view can always locate its Python packages, even without environment
+variables set.
 
 A package can only extend one other package at a time.  To support packages
 that may extend one of a list of other packages, Spack supports multiple
@@ -2574,9 +2687,8 @@ variant(s) are selected.  This may be accomplished with conditional
        ...
 
 Sometimes, certain files in one package will conflict with those in
-another, which means they cannot both be activated (symlinked) at the
-same time.  In this case, you can tell Spack to ignore those files
-when it does the activation:
+another, which means they cannot both be used in a view at the
+same time.  In this case, you can tell Spack to ignore those files:
 
 .. code-block:: python
 
@@ -2588,7 +2700,7 @@ when it does the activation:
        ...
 
 The code above will prevent everything in the ``$prefix/bin/`` directory
-from being linked in at activation time.
+from being linked in a view.
 
 .. note::
 
@@ -2612,67 +2724,6 @@ extensions; as a consequence python extension packages (those inheriting from
 ``PythonPackage``) likewise override ``add_files_to_view`` in order to rewrite
 shebang lines which point to the Python interpreter.
 
-^^^^^^^^^^^^^^^^^^^^^^^^^
-Activation & deactivation
-^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Adding an extension to a view is referred to as an activation. If the view is
-maintained in the Spack installation prefix of the extendee this is called a
-global activation. Activations may involve updating some centralized state
-that is maintained by the extendee package, so there can be additional work
-for adding extensions compared with non-extension packages.
-
-Spack's ``Package`` class has default ``activate`` and ``deactivate``
-implementations that handle symbolically linking extensions' prefixes
-into a specified view. Extendable packages can override these methods
-to add custom activate/deactivate logic of their own.  For example,
-the ``activate`` and ``deactivate`` methods in the Python class handle
-symbolic linking of extensions, but they also handle details surrounding
-Python's ``.pth`` files, and other aspects of Python packaging.
-
-Spack's extensions mechanism is designed to be extensible, so that
-other packages (like Ruby, R, Perl, etc.)  can provide their own
-custom extension management logic, as they may not handle modules the
-same way that Python does.
-
-Let's look at Python's activate function:
-
-.. literalinclude:: _spack_root/var/spack/repos/builtin/packages/python/package.py
-   :pyobject: Python.activate
-   :linenos:
-
-This function is called on the *extendee* (Python).  It first calls
-``activate`` in the superclass, which handles symlinking the
-extension package's prefix into the specified view.  It then does
-some special handling of the ``easy-install.pth`` file, part of
-Python's setuptools.
-
-Deactivate behaves similarly to activate, but it unlinks files:
-
-.. literalinclude:: _spack_root/var/spack/repos/builtin/packages/python/package.py
-   :pyobject: Python.deactivate
-   :linenos:
-
-Both of these methods call some custom functions in the Python
-package.  See the source for Spack's Python package for details.
-
-^^^^^^^^^^^^^^^^^^^^
-Activation arguments
-^^^^^^^^^^^^^^^^^^^^
-
-You may have noticed that the ``activate`` function defined above
-takes keyword arguments.  These are the keyword arguments from
-``extends()``, and they are passed to both activate and deactivate.
-
-This capability allows an extension to customize its own activation by
-passing arguments to the extendee.  Extendees can likewise implement
-custom ``activate()`` and ``deactivate()`` functions to suit their
-needs.
-
-The only keyword argument supported by default is the ``ignore``
-argument, which can take a regex, list of regexes, or a predicate to
-determine which files *not* to symlink during activation.
-
 .. _virtual-dependencies:
 
 --------------------
@@ -3280,67 +3331,91 @@ the Python extensions provided by them: once for ``+python`` and once
 for ``~python``.  Other than using a little extra disk space, that
 solution has no serious problems.
 
-.. _installation_procedure:
+.. _installation_process:
 
----------------------------------------
-Implementing the installation procedure
----------------------------------------
+--------------------------------
+Overriding build system defaults
+--------------------------------
 
-The last element of a package is its **installation procedure**.  This is
-where the real work of installation happens, and it's the main part of
-the package you'll need to customize for each piece of software.
+.. note::
 
-Defining an installation procedure means overriding a set of methods or attributes
-that will be called at some point during the installation of the package.
-The package base class, usually specialized for a given build system, determines the
-actual set of entities available for overriding.
-The classes that are currently provided by Spack are:
+   If you code a single class in ``package.py`` all the functions shown in the table below
+   can be implemented with the same signature on the ``*Package`` instead of the corresponding builder.
+
+
+Most of the time the default implementation of methods or attributes in build system base classes
+is what a packager needs, and just a very few entities need to be overwritten. Typically we just
+need to override methods like ``configure_args``:
+
+.. code-block:: python
+
+   def configure_args(self):
+        args = ["--enable-cxx"] + self.enable_or_disable("libs")
+        if "libs=static" in self.spec:
+            args.append("--with-pic")
+        return args
+
+The actual set of entities available for overriding in ``package.py`` depend on
+the build system. The build systems currently supported by Spack are:
 
 +----------------------------------------------------------+----------------------------------+
-|     **Base Class**                                       |           **Purpose**            |
+|     **API docs**                                         |           **Description**        |
 +==========================================================+==================================+
-| :class:`~spack.package_base.Package`                     | General base class not           |
-|                                                          | specialized for any build system |
+| :class:`~spack.build_systems.generic`                    | Generic build system without any |
+|                                                          | base implementation              |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.makefile.MakefilePackage`   | Specialized class for packages   |
-|                                                          | built invoking                   |
+| :class:`~spack.build_systems.makefile`                   | Specialized build system for     |
+|                                                          | software built invoking          |
 |                                                          | hand-written Makefiles           |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.autotools.AutotoolsPackage` | Specialized class for packages   |
-|                                                          | built using GNU Autotools        |
+| :class:`~spack.build_systems.autotools`                  | Specialized build system for     |
+|                                                          | software built using             |
+|                                                          | GNU Autotools                    |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.cmake.CMakePackage`         | Specialized class for packages   |
-|                                                          | built using CMake                |
+| :class:`~spack.build_systems.cmake`                      | Specialized build system for     |
+|                                                          | software built using CMake       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.cuda.CudaPackage`           | A helper class for packages that |
-|                                                          | use CUDA                         |
+| :class:`~spack.build_systems.maven`                      | Specialized build system for     |
+|                                                          | software built using Maven       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.qmake.QMakePackage`         | Specialized class for packages   |
-|                                                          | built using QMake                |
+| :class:`~spack.build_systems.meson`                      | Specialized build system for     |
+|                                                          | software built using Meson       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.rocm.ROCmPackage`           | A helper class for packages that |
-|                                                          | use ROCm                         |
+| :class:`~spack.build_systems.nmake`                      | Specialized build system for     |
+|                                                          | software built using NMake       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.scons.SConsPackage`         | Specialized class for packages   |
-|                                                          | built using SCons                |
+| :class:`~spack.build_systems.qmake`                      | Specialized build system for     |
+|                                                          | software built using QMake       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.waf.WafPackage`             | Specialized class for packages   |
-|                                                          | built using Waf                  |
+| :class:`~spack.build_systems.scons`                      | Specialized build system for     |
+|                                                          | software built using SCons       |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.r.RPackage`                 | Specialized class for            |
+| :class:`~spack.build_systems.waf`                        | Specialized build system for     |
+|                                                          | software built using Waf         |
++----------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.r`                          | Specialized build system for     |
 |                                                          | R extensions                     |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.octave.OctavePackage`       | Specialized class for            |
+| :class:`~spack.build_systems.octave`                     | Specialized build system for     |
 |                                                          | Octave packages                  |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.python.PythonPackage`       | Specialized class for            |
+| :class:`~spack.build_systems.python`                     | Specialized build system for     |
 |                                                          | Python extensions                |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.perl.PerlPackage`           | Specialized class for            |
+| :class:`~spack.build_systems.perl`                       | Specialized build system for     |
 |                                                          | Perl extensions                  |
 +----------------------------------------------------------+----------------------------------+
-| :class:`~spack.build_systems.intel.IntelPackage`         | Specialized class for licensed   |
-|                                                          | Intel software                   |
+| :class:`~spack.build_systems.ruby`                       | Specialized build system for     |
+|                                                          | Ruby extensions                  |
++----------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.intel`                      | Specialized build system for     |
+|                                                          | licensed Intel software          |
++----------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.oneapi`                     | Specialized build system for     |
+|                                                          | Intel onaAPI software            |
++----------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.aspell_dict`                | Specialized build system for     |
+|                                                          | Aspell dictionaries              |
 +----------------------------------------------------------+----------------------------------+
 
 
@@ -3353,52 +3428,17 @@ The classes that are currently provided by Spack are:
         For example, a Python extension installed with CMake would ``extends('python')`` and
         subclass from :class:`~spack.build_systems.cmake.CMakePackage`.
 
-^^^^^^^^^^^^^^^^^^^^^
-Installation pipeline
-^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+Overriding builder methods
+^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-When a user runs ``spack install``, Spack:
-
-1. Fetches an archive for the correct version of the software.
-2. Expands the archive.
-3. Sets the current working directory to the root directory of the expanded archive.
-
-Then, depending on the base class of the package under consideration, it will execute
-a certain number of **phases** that reflect the way a package of that type is usually built.
-The name and order in which the phases will be executed can be obtained either reading the API
-docs at :py:mod:`~.spack.build_systems`, or using the ``spack info`` command:
-
-.. code-block:: console
-    :emphasize-lines: 13,14
-
-    $ spack info m4
-    AutotoolsPackage:    m4
-    Homepage:            https://www.gnu.org/software/m4/m4.html
-
-    Safe versions:
-        1.4.17    ftp://ftp.gnu.org/gnu/m4/m4-1.4.17.tar.gz
-
-    Variants:
-        Name       Default   Description
-
-        sigsegv    on        Build the libsigsegv dependency
-
-    Installation Phases:
-        autoreconf    configure    build    install
-
-    Build Dependencies:
-        libsigsegv
-
-    ...
-
-
-Typically, phases have default implementations that fit most of the common cases:
+Build-system "phases" have default implementations that fit most of the common cases:
 
 .. literalinclude:: _spack_root/lib/spack/spack/build_systems/autotools.py
-    :pyobject: AutotoolsPackage.configure
+    :pyobject: AutotoolsBuilder.configure
     :linenos:
 
-It is thus just sufficient for a packager to override a few
+It is usually sufficient for a packager to override a few
 build system specific helper methods or attributes to provide, for instance,
 configure arguments:
 
@@ -3406,31 +3446,31 @@ configure arguments:
     :pyobject: M4.configure_args
     :linenos:
 
-.. note::
-    Each specific build system has a list of attributes that can be overridden to
-    fine-tune the installation of a package without overriding an entire phase. To
-    have more information on them the place to go is the API docs of the :py:mod:`~.spack.build_systems`
-    module.
+Each specific build system has a list of attributes and methods that can be overridden to
+fine-tune the installation of a package without overriding an entire phase. To
+have more information on them the place to go is the API docs of the :py:mod:`~.spack.build_systems`
+module.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 Overriding an entire phase
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-In extreme cases it may be necessary to override an entire phase. Regardless
-of the build system, the signature is the same. For example, the signature
-for the install phase is:
+Sometimes it is necessary to override an entire phase. If the ``package.py`` contains
+a single class recipe, see :ref:`package_class_structure`, then the signature for a
+phase is:
 
 .. code-block:: python
 
-   class Foo(Package):
+   class Openjpeg(CMakePackage):
        def install(self, spec, prefix):
            ...
 
+regardless of the build system. The arguments for the phase are:
+
 ``self``
-    For those not used to Python instance methods, this is the
-    package itself.  In this case it's an instance of ``Foo``, which
-    extends ``Package``.  For API docs on Package objects, see
-    :py:class:`Package <spack.package_base.Package>`.
+    This is the package object, which extends ``CMakePackage``.
+    For API docs on Package objects, see
+    :py:class:`Package <spack.package_base.PackageBase>`.
 
 ``spec``
     This is the concrete spec object created by Spack from an
@@ -3445,12 +3485,111 @@ for the install phase is:
 The arguments ``spec`` and ``prefix`` are passed only for convenience, as they always
 correspond to ``self.spec`` and ``self.spec.prefix`` respectively.
 
-As mentioned in :ref:`install-environment`, you will usually not need to refer
-to dependencies explicitly in your package file, as the compiler wrappers take care of most of
-the heavy lifting here.  There will be times, though, when you need to refer to
-the install locations of dependencies, or when you need to do something different
-depending on the version, compiler, dependencies, etc. that your package is
-built with.  These parameters give you access to this type of information.
+If the ``package.py`` encodes builders explicitly, the signature for a phase changes slightly:
+
+.. code-block:: python
+
+   class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
+       def install(self, pkg, spec, prefix):
+           ...
+
+In this case the package is passed as the second argument, and ``self`` is the builder instance.
+
+.. _multiple_build_systems:
+
+^^^^^^^^^^^^^^^^^^^^^^
+Multiple build systems
+^^^^^^^^^^^^^^^^^^^^^^
+
+There are cases where a software actively supports two build systems, or changes build systems
+as it evolves, or needs different build systems on different platforms. Spack allows dealing with
+these cases natively, if a recipe is written using builders explicitly.
+
+For instance, software that supports two build systems unconditionally should derive from
+both ``*Package`` base classes, and declare the possible use of multiple build systems using
+a directive:
+
+.. code-block:: python
+
+   class ArpackNg(CMakePackage, AutotoolsPackage):
+
+       build_system("cmake", "autotools", default="cmake")
+
+In this case the software can be built with both ``autotools`` and ``cmake``. Since the package
+supports multiple build systems, it is necessary to declare which one is the default. The ``package.py``
+will likely contain some overriding of default builder methods:
+
+.. code-block:: python
+
+   class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
+       def cmake_args(self):
+           pass
+
+   class Autotoolsbuilder(spack.build_systems.autotools.AutotoolsBuilder):
+       def configure_args(self):
+           pass
+
+In more complex cases it might happen that the build system changes according to certain conditions,
+for instance across versions. That can be expressed with conditional variant values:
+
+.. code-block:: python
+
+   class ArpackNg(CMakePackage, AutotoolsPackage):
+
+       build_system(
+           conditional("cmake", when="@0.64:"),
+           conditional("autotools", when="@:0.63"),
+           default="cmake",
+       )
+
+In the example the directive impose a change from ``Autotools`` to ``CMake`` going
+from ``v0.63`` to ``v0.64``.
+
+^^^^^^^^^^^^^^^^^^
+Mixin base classes
+^^^^^^^^^^^^^^^^^^
+
+Besides build systems, there are other cases where common metadata and behavior can be extracted
+and reused by many packages. For instance, packages that depend on ``Cuda`` or ``Rocm``, share
+common dependencies and constraints. To factor these attributes into a single place, Spack provides
+a few mixin classes in the ``spack.build_systems`` module:
+
++---------------------------------------------------------------+----------------------------------+
+|     **API docs**                                              |           **Description**        |
++===============================================================+==================================+
+| :class:`~spack.build_systems.cuda.CudaPackage`                | A helper class for packages that |
+|                                                               | use CUDA                         |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.rocm.ROCmPackage`                | A helper class for packages that |
+|                                                               | use ROCm                         |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.gnu.GNUMirrorPackage`            | A helper class for GNU packages  |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.python.PythonExtension`          | A helper class for Python        |
+|                                                               | extensions                       |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.sourceforge.SourceforgePackage`  | A helper class for packages      |
+|                                                               | from sourceforge.org             |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.sourceware.SourcewarePackage`    | A helper class for packages      |
+|                                                               | from sourceware.org              |
++---------------------------------------------------------------+----------------------------------+
+| :class:`~spack.build_systems.xorg.XorgPackage`                | A helper class for x.org         |
+|                                                               | packages                         |
++---------------------------------------------------------------+----------------------------------+
+
+These classes should be used by adding them to the inheritance tree of the package that needs them,
+for instance:
+
+.. code-block:: python
+
+   class Cp2k(MakefilePackage, CudaPackage):
+       """CP2K is a quantum chemistry and solid state physics software package
+       that can perform atomistic simulations of solid state, liquid, molecular,
+       periodic, material, crystal, and biological systems
+       """
+
+In the example above ``Cp2k`` inherits all the conflicts and variants that ``CudaPackage`` defines.
 
 .. _install-environment:
 
@@ -4208,16 +4347,9 @@ In addition to invoking the right compiler, the compiler wrappers add
 flags to the compile line so that dependencies can be easily found.
 These flags are added for each dependency, if they exist:
 
-Compile-time library search paths
-* ``-L$dep_prefix/lib``
-* ``-L$dep_prefix/lib64``
-
-Runtime library search paths (RPATHs)
-* ``$rpath_flag$dep_prefix/lib``
-* ``$rpath_flag$dep_prefix/lib64``
-
-Include search paths
-* ``-I$dep_prefix/include``
+* Compile-time library search paths: ``-L$dep_prefix/lib``, ``-L$dep_prefix/lib64``
+* Runtime library search paths (RPATHs): ``$rpath_flag$dep_prefix/lib``, ``$rpath_flag$dep_prefix/lib64``
+* Include search paths: ``-I$dep_prefix/include``
 
 An example of this would be the ``libdwarf`` build, which has one
 dependency: ``libelf``.  Every call to ``cc`` in the ``libdwarf``
@@ -5062,6 +5194,16 @@ where each argument has the following meaning:
   will run.
 
   The default of ``None`` corresponds to the current directory (``'.'``).
+  Each call starts with the working directory set to the spec's test stage
+  directory (i.e., ``self.test_suite.test_dir_for_spec(self.spec)``).
+
+.. warning::
+
+   Use of the package spec's installation directory for building and running
+   tests is **strongly** discouraged. Doing so has caused permission errors
+   for shared spack instances *and* for facilities that install the software
+   in read-only file systems or directories.
+
 
 """""""""""""""""""""""""""""""""""""""""
 Accessing package- and test-related files
@@ -5069,10 +5211,10 @@ Accessing package- and test-related files
 
 You may need to access files from one or more locations when writing
 stand-alone tests. This can happen if the software's repository does not
-include test source files or includes files but no way to build the
-executables using the installed headers and libraries. In these
-cases, you may need to reference the files relative to one or more
-root directory. The properties containing package- and test-related
+include test source files or includes files but has no way to build the
+executables using the installed headers and libraries. In these cases,
+you may need to reference the files relative to one or more root
+directory. The properties containing package- (or spec-) and test-related
 directory paths are provided in the table below.
 
 .. list-table:: Directory-to-property mapping
@@ -5081,19 +5223,22 @@ directory paths are provided in the table below.
    * - Root Directory
      - Package Property
      - Example(s)
-   * - Package Installation Files
+   * - Package (Spec) Installation
      - ``self.prefix``
      - ``self.prefix.include``, ``self.prefix.lib``
-   * - Package Dependency's Files
+   * - Dependency Installation
      - ``self.spec['<dependency-package>'].prefix``
      - ``self.spec['trilinos'].prefix.include``
-   * - Test Suite Stage Files
+   * - Test Suite Stage
      - ``self.test_suite.stage``
      - ``join_path(self.test_suite.stage, 'results.txt')``
-   * - Staged Cached Build-time Files
+   * - Spec's Test Stage
+     - ``self.test_suite.test_dir_for_spec``
+     - ``self.test_suite.test_dir_for_spec(self.spec)``
+   * - Current Spec's Build-time Files
      - ``self.test_suite.current_test_cache_dir``
      - ``join_path(self.test_suite.current_test_cache_dir, 'examples', 'foo.c')``
-   * - Staged Custom Package Files
+   * - Current Spec's Custom Test Files
      - ``self.test_suite.current_test_data_dir``
      - ``join_path(self.test_suite.current_test_data_dir, 'hello.f90')``
 
@@ -6099,3 +6244,82 @@ might write:
    DWARF_PREFIX = $(spack location --install-dir libdwarf)
    CXXFLAGS += -I$DWARF_PREFIX/include
    CXXFLAGS += -L$DWARF_PREFIX/lib
+
+
+.. _package_class_structure:
+
+--------------------------
+Package class architecture
+--------------------------
+
+.. note::
+
+   This section aims to provide a high-level knowledge of how the package class architecture evolved
+   in Spack, and provides some insights on the current design.
+
+Packages in Spack were originally designed to support only a single build system. The overall
+class structure for a package looked like:
+
+.. image:: images/original_package_architecture.png
+   :scale: 60 %
+   :align: center
+
+In this architecture the base class ``AutotoolsPackage`` was responsible for both the metadata
+related to the ``autotools`` build system (e.g. dependencies or variants common to all packages
+using it), and for encoding the default installation procedure.
+
+In reality, a non-negligible number of packages are either changing their build system during the evolution of the
+project, or using different build systems for different platforms. An architecture based on a single class
+requires hacks or other workarounds to deal with these cases.
+
+To support a model more adherent to reality, Spack v0.19 changed its internal design by extracting
+the attributes and methods related to building a software into a separate hierarchy:
+
+.. image:: images/builder_package_architecture.png
+   :scale: 60 %
+   :align: center
+
+In this new format each ``package.py`` contains one ``*Package`` class that gathers all the metadata,
+and one or more ``*Builder`` classes that encode the installation procedure. A specific builder object
+is created just before the software is built, so at a time where Spack knows which build system needs
+to be used for the current installation, and receives a ``package`` object during initialization.
+
+^^^^^^^^^^^^^^^^^^^^^^^^
+``build_system`` variant
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+To allow imposing conditions based on the build system, each package must a have ``build_system`` variant,
+which is usually inherited from base classes. This variant allows for writing metadata that is conditional
+on the build system:
+
+.. code-block:: python
+
+   with when("build_system=cmake"):
+       depends_on("cmake", type="build")
+
+and also for selecting a specific build system from a spec literal, like in the following command:
+
+.. code-block:: console
+
+   $ spack install arpack-ng build_system=autotools
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Compatibility with single-class format
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Internally, Spack always uses builders to perform operations related to the installation of a specific software.
+The builders are created in the ``spack.builder.create`` function
+
+.. literalinclude:: _spack_root/lib/spack/spack/builder.py
+   :pyobject: create
+
+To achieve backward compatibility with the single-class format Spack creates in this function a special
+"adapter builder", if no custom builder is detected in the recipe:
+
+.. image:: images/adapter.png
+   :scale: 60 %
+   :align: center
+
+Overall the role of the adapter is to route access to attributes of methods first through the ``*Package``
+hierarchy, and then back to the base class builder. This is schematically shown in the diagram above, where
+the adapter role is to "emulate" a method resolution order like the one represented by the red arrows.

lib/spack/docs/tables/system_prerequisites.csv

@@ -1,5 +1,5 @@
 Name, Supported Versions, Notes, Requirement Reason
-Python, 2.7/3.6-3.10, , Interpreter for Spack
+Python, 2.7/3.6-3.11, , Interpreter for Spack
 C/C++ Compilers, , , Building software
 make, , , Build software
 patch, , , Build software
@@ -11,6 +11,7 @@ bzip2, , , Compress/Decompress archives
 xz, , , Compress/Decompress archives
 zstd, , Optional, Compress/Decompress archives
 file, , , Create/Use Buildcaches
+lsb-release, , , Linux: identify operating system version
 gnupg2, , , Sign/Verify Buildcaches
 git, , , Manage Software Repositories
 svn, , Optional, Manage Software Repositories

lib/spack/env/cc

@@ -241,28 +241,28 @@ case "$command" in
         mode=cpp
         debug_flags="-g"
         ;;
-    cc|c89|c99|gcc|clang|armclang|icc|icx|pgcc|nvc|xlc|xlc_r|fcc|amdclang|cl.exe)
+    cc|c89|c99|gcc|clang|armclang|icc|icx|pgcc|nvc|xlc|xlc_r|fcc|amdclang|cl.exe|craycc)
         command="$SPACK_CC"
         language="C"
         comp="CC"
         lang_flags=C
         debug_flags="-g"
         ;;
-    c++|CC|g++|clang++|armclang++|icpc|icpx|dpcpp|pgc++|nvc++|xlc++|xlc++_r|FCC|amdclang++)
+    c++|CC|g++|clang++|armclang++|icpc|icpx|dpcpp|pgc++|nvc++|xlc++|xlc++_r|FCC|amdclang++|crayCC)
         command="$SPACK_CXX"
         language="C++"
         comp="CXX"
         lang_flags=CXX
         debug_flags="-g"
         ;;
-    ftn|f90|fc|f95|gfortran|flang|armflang|ifort|ifx|pgfortran|nvfortran|xlf90|xlf90_r|nagfor|frt|amdflang)
+    ftn|f90|fc|f95|gfortran|flang|armflang|ifort|ifx|pgfortran|nvfortran|xlf90|xlf90_r|nagfor|frt|amdflang|crayftn)
         command="$SPACK_FC"
         language="Fortran 90"
         comp="FC"
         lang_flags=F
         debug_flags="-g"
         ;;
-    f77|xlf|xlf_r|pgf77|amdflang)
+    f77|xlf|xlf_r|pgf77)
         command="$SPACK_F77"
         language="Fortran 77"
         comp="F77"

lib/spack/env/cce/case-insensitive/crayCC

@@ -0,0 +1 @@
+../../cc

lib/spack/env/cce/craycc

@@ -0,0 +1 @@
+../cc

lib/spack/env/cce/crayftn

@@ -0,0 +1 @@
+../cc

lib/spack/external/__init__.py

@@ -18,7 +18,7 @@
 
 * Homepage: https://pypi.python.org/pypi/archspec
 * Usage: Labeling, comparison and detection of microarchitectures
-* Version: 0.1.4 (commit e2cfdc266174488dee78b8c9058e36d60dc1b548)
+* Version: 0.2.0 (commit 77640e572725ad97f18e63a04857155752ace045)
 
 argparse
 --------

lib/spack/external/archspec/cpu/detect.py

@@ -132,9 +132,15 @@ def sysctl(*args):
             "model name": sysctl("-n", "machdep.cpu.brand_string"),
         }
     else:
-        model = (
-            "m1" if "Apple" in sysctl("-n", "machdep.cpu.brand_string") else "unknown"
-        )
+        model = "unknown"
+        model_str = sysctl("-n", "machdep.cpu.brand_string").lower()
+        if "m2" in model_str:
+            model = "m2"
+        elif "m1" in model_str:
+            model = "m1"
+        elif "apple" in model_str:
+            model = "m1"
+
         info = {
             "vendor_id": "Apple",
             "flags": [],
@@ -322,14 +328,26 @@ def compatibility_check_for_aarch64(info, target):
     features = set(info.get("Features", "").split())
     vendor = info.get("CPU implementer", "generic")
 
+    # At the moment it's not clear how to detect compatibility with
+    # a specific version of the architecture
+    if target.vendor == "generic" and target.name != "aarch64":
+        return False
+
     arch_root = TARGETS[basename]
-    return (
-        (target == arch_root or arch_root in target.ancestors)
-        and target.vendor in (vendor, "generic")
-        # On macOS it seems impossible to get all the CPU features with syctl info
-        and (target.features.issubset(features) or platform.system() == "Darwin")
+    arch_root_and_vendor = arch_root == target.family and target.vendor in (
+        vendor,
+        "generic",
     )
 
+    # On macOS it seems impossible to get all the CPU features
+    # with syctl info, but for ARM we can get the exact model
+    if platform.system() == "Darwin":
+        model_key = info.get("model", basename)
+        model = TARGETS[model_key]
+        return arch_root_and_vendor and (target == model or target in model.ancestors)
+
+    return arch_root_and_vendor and target.features.issubset(features)
+
 
 @compatibility_check(architecture_family="riscv64")
 def compatibility_check_for_riscv64(info, target):

lib/spack/external/archspec/json/cpu/microarchitectures.json

@@ -85,7 +85,7 @@
         "intel": [
           {
             "versions": ":",
-            "name": "x86-64",
+            "name": "pentium4",
             "flags": "-march={name} -mtune=generic"
           }
         ],
@@ -2093,8 +2093,163 @@
         ]
       }
     },
-    "thunderx2": {
+    "armv8.1a": {
       "from": ["aarch64"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "5:",
+            "flags": "-march=armv8.1-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.1-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.1-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.1-a -mtune=generic"
+          }
+        ]
+      }
+    },
+    "armv8.2a": {
+      "from": ["armv8.1a"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "6:",
+            "flags": "-march=armv8.2-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.2-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.2-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.2-a -mtune=generic"
+          }
+        ]
+      }
+    },
+    "armv8.3a": {
+      "from": ["armv8.2a"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "6:",
+            "flags": "-march=armv8.3-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "6:",
+            "flags": "-march=armv8.3-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.3-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.3-a -mtune=generic"
+          }
+        ]
+      }
+    },
+    "armv8.4a": {
+      "from": ["armv8.3a"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "8:",
+            "flags": "-march=armv8.4-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "8:",
+            "flags": "-march=armv8.4-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.4-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.4-a -mtune=generic"
+          }
+        ]
+      }
+    },
+    "armv8.5a": {
+      "from": ["armv8.4a"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "9:",
+            "flags": "-march=armv8.5-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "11:",
+            "flags": "-march=armv8.5-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.5-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv8.5-a -mtune=generic"
+          }
+        ]
+      }
+    },
+    "thunderx2": {
+      "from": ["armv8.1a"],
       "vendor": "Cavium",
       "features": [
         "fp",
@@ -2141,7 +2296,7 @@
       }
     },
     "a64fx": {
-      "from": ["aarch64"],
+      "from": ["armv8.2a"],
       "vendor": "Fujitsu",
       "features": [
         "fp",
@@ -2209,7 +2364,7 @@
         ]
       }
     },
-    "graviton": {
+    "cortex_a72": {
       "from": ["aarch64"],
       "vendor": "ARM",
       "features": [
@@ -2235,19 +2390,19 @@
               },
               {
                   "versions": "6:",
-                  "flags" : "-march=armv8-a+crc+crypto -mtune=cortex-a72"
+                  "flags" : "-mcpu=cortex-a72"
               }
           ],
           "clang" : [
               {
                   "versions": "3.9:",
-                  "flags" : "-march=armv8-a+crc+crypto"
+                  "flags" : "-mcpu=cortex-a72"
               }
           ]
       }
     },
-    "graviton2": {
-      "from": ["graviton"],
+    "neoverse_n1": {
+      "from": ["cortex_a72", "armv8.2a"],
       "vendor": "ARM",
       "features": [
           "fp",
@@ -2296,7 +2451,7 @@
               },
               {
                   "versions": "9.0:",
-                  "flags" : "-march=armv8.2-a+fp16+rcpc+dotprod+crypto -mtune=neoverse-n1"
+                  "flags" : "-mcpu=neoverse-n1"
               }
           ],
           "clang" : [
@@ -2307,6 +2462,10 @@
               {
                   "versions": "5:",
                   "flags" : "-march=armv8.2-a+fp16+rcpc+dotprod+crypto"
+              },
+              {
+                  "versions": "10:",
+                  "flags" : "-mcpu=neoverse-n1"
               }
           ],
           "arm" : [
@@ -2317,11 +2476,11 @@
           ]
       }
     },
-    "graviton3": {
-      "from": ["graviton2"],
+    "neoverse_v1": {
+      "from": ["neoverse_n1", "armv8.4a"],
       "vendor": "ARM",
       "features": [
-	  "fp",
+          "fp",
           "asimd",
           "evtstrm",
           "aes",
@@ -2384,11 +2543,11 @@
               },
               {
                   "versions": "9.0:9.9",
-                  "flags" : "-march=armv8.4-a+crypto+rcpc+sha3+sm4+sve+rng+nodotprod -mtune=neoverse-v1"
+                  "flags" : "-mcpu=neoverse-v1"
               },
 	            {
                   "versions": "10.0:",
-                  "flags" : "-march=armv8.4-a+crypto+rcpc+sha3+sm4+sve+rng+ssbs+i8mm+bf16+nodotprod -mtune=neoverse-v1"
+                  "flags" : "-mcpu=neoverse-v1"
               }
 
           ],
@@ -2404,6 +2563,10 @@
               {
                   "versions": "11:",
                   "flags" : "-march=armv8.4-a+sve+ssbs+fp16+bf16+crypto+i8mm+rng"
+              },
+              {
+                  "versions": "12:",
+                  "flags" : "-mcpu=neoverse-v1"
               }
           ],
           "arm" : [
@@ -2419,7 +2582,7 @@
       }
     },
     "m1": {
-      "from": ["aarch64"],
+      "from": ["armv8.4a"],
       "vendor": "Apple",
       "features": [
           "fp",
@@ -2484,6 +2647,76 @@
         ]
       }
     },
+    "m2": {
+      "from": ["m1", "armv8.5a"],
+      "vendor": "Apple",
+      "features": [
+          "fp",
+          "asimd",
+          "evtstrm",
+          "aes",
+          "pmull",
+          "sha1",
+          "sha2",
+          "crc32",
+          "atomics",
+          "fphp",
+          "asimdhp",
+          "cpuid",
+          "asimdrdm",
+          "jscvt",
+          "fcma",
+          "lrcpc",
+          "dcpop",
+          "sha3",
+          "asimddp",
+          "sha512",
+          "asimdfhm",
+          "dit",
+          "uscat",
+          "ilrcpc",
+          "flagm",
+          "ssbs",
+          "sb",
+          "paca",
+          "pacg",
+          "dcpodp",
+          "flagm2",
+          "frint",
+          "ecv",
+          "bf16",
+          "i8mm",
+          "bti"
+      ],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "8.0:",
+            "flags" : "-march=armv8.5-a -mtune=generic"
+          }
+        ],
+        "clang" : [
+          {
+            "versions": "9.0:12.0",
+            "flags" : "-march=armv8.5-a"
+          },
+          {
+            "versions": "13.0:",
+            "flags" : "-mcpu=apple-m1"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": "11.0:12.5",
+            "flags" : "-march=armv8.5-a"
+          },
+          {
+            "versions": "13.0:",
+            "flags" : "-mcpu=vortex"
+          }
+        ]
+      }
+    },
     "arm": {
       "from": [],
       "vendor": "generic",

lib/spack/llnl/util/filesystem.py

@@ -505,8 +505,15 @@ def group_ids(uid=None):
 
     if uid is None:
         uid = getuid()
-    user = pwd.getpwuid(uid).pw_name
-    return [g.gr_gid for g in grp.getgrall() if user in g.gr_mem]
+
+    pwd_entry = pwd.getpwuid(uid)
+    user = pwd_entry.pw_name
+
+    # user's primary group id may not be listed in grp (i.e. /etc/group)
+    # you have to check pwd for that, so start the list with that
+    gids = [pwd_entry.pw_gid]
+
+    return sorted(set(gids + [g.gr_gid for g in grp.getgrall() if user in g.gr_mem]))
 
 
 @system_path_filter(arg_slice=slice(1))
@@ -1083,7 +1090,11 @@ def temp_cwd():
         with working_dir(tmp_dir):
             yield tmp_dir
     finally:
-        shutil.rmtree(tmp_dir)
+        kwargs = {}
+        if is_windows:
+            kwargs["ignore_errors"] = False
+            kwargs["onerror"] = readonly_file_handler(ignore_errors=True)
+        shutil.rmtree(tmp_dir, **kwargs)
 
 
 @contextmanager
@@ -2095,7 +2106,7 @@ def find_system_libraries(libraries, shared=True):
     return libraries_found
 
 
-def find_libraries(libraries, root, shared=True, recursive=False):
+def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
     """Returns an iterable of full paths to libraries found in a root dir.
 
     Accepts any glob characters accepted by fnmatch:
@@ -2116,6 +2127,10 @@ def find_libraries(libraries, root, shared=True, recursive=False):
             otherwise for static. Defaults to True.
         recursive (bool): if False search only root folder,
             if True descends top-down from the root. Defaults to False.
+        runtime (bool): Windows only option, no-op elsewhere. If true,
+            search for runtime shared libs (.DLL), otherwise, search
+            for .Lib files. If shared is false, this has no meaning.
+            Defaults to True.
 
     Returns:
         LibraryList: The libraries that have been found
@@ -2130,7 +2145,9 @@ def find_libraries(libraries, root, shared=True, recursive=False):
 
     if is_windows:
         static_ext = "lib"
-        shared_ext = "dll"
+        # For linking (runtime=False) you need the .lib files regardless of
+        # whether you are doing a shared or static link
+        shared_ext = "dll" if runtime else "lib"
     else:
         # Used on both Linux and macOS
         static_ext = "a"
@@ -2174,13 +2191,13 @@ def find_libraries(libraries, root, shared=True, recursive=False):
     return LibraryList(found_libs)
 
 
-def find_all_shared_libraries(root, recursive=False):
+def find_all_shared_libraries(root, recursive=False, runtime=True):
     """Convenience function that returns the list of all shared libraries found
     in the directory passed as argument.
 
     See documentation for `llnl.util.filesystem.find_libraries` for more information
     """
-    return find_libraries("*", root=root, shared=True, recursive=recursive)
+    return find_libraries("*", root=root, shared=True, recursive=recursive, runtime=runtime)
 
 
 def find_all_static_libraries(root, recursive=False):
@@ -2226,48 +2243,36 @@ def __init__(self, package, link_install_prefix=True):
         self.pkg = package
         self._addl_rpaths = set()
         self.link_install_prefix = link_install_prefix
-        self._internal_links = set()
+        self._additional_library_dependents = set()
 
     @property
-    def link_dest(self):
+    def library_dependents(self):
         """
         Set of directories where package binaries/libraries are located.
         """
-        if hasattr(self.pkg, "libs") and self.pkg.libs:
-            pkg_libs = set(self.pkg.libs.directories)
-        else:
-            pkg_libs = set((self.pkg.prefix.lib, self.pkg.prefix.lib64))
+        return set([self.pkg.prefix.bin]) | self._additional_library_dependents
 
-        return pkg_libs | set([self.pkg.prefix.bin]) | self.internal_links
-
-    @property
-    def internal_links(self):
+    def add_library_dependent(self, *dest):
         """
-        linking that would need to be established within the package itself. Useful for links
-        against extension modules/build time executables/internal linkage
-        """
-        return self._internal_links
+        Add paths to directories or libraries/binaries to set of
+        common paths that need to link against other libraries
 
-    def add_internal_links(self, *dest):
-        """
-        Incorporate additional paths into the rpath (sym)linking scheme.
-
-        Paths provided to this method are linked against by a package's libraries
-        and libraries found at these paths are linked against a package's binaries.
-        (i.e. /site-packages -> /bin and /bin -> /site-packages)
-
-        Specified paths should be outside of a package's lib, lib64, and bin
+        Specified paths should fall outside of a package's common
+        link paths, i.e. the bin
         directories.
         """
-        self._internal_links = self._internal_links | set(*dest)
+        for pth in dest:
+            if os.path.isfile(pth):
+                self._additional_library_dependents.add(os.path.dirname)
+            else:
+                self._additional_library_dependents.add(pth)
 
     @property
-    def link_targets(self):
+    def rpaths(self):
         """
         Set of libraries this package needs to link against during runtime
         These packages will each be symlinked into the packages lib and binary dir
         """
-
         dependent_libs = []
         for path in self.pkg.rpath:
             dependent_libs.extend(list(find_all_shared_libraries(path, recursive=True)))
@@ -2275,18 +2280,43 @@ def link_targets(self):
             dependent_libs.extend(list(find_all_shared_libraries(extra_path, recursive=True)))
         return set(dependent_libs)
 
-    def include_additional_link_paths(self, *paths):
+    def add_rpath(self, *paths):
         """
         Add libraries found at the root of provided paths to runtime linking
 
         These are libraries found outside of the typical scope of rpath linking
-        that require manual inclusion in a runtime linking scheme
+        that require manual inclusion in a runtime linking scheme.
+        These links are unidirectional, and are only
+        intended to bring outside dependencies into this package
 
         Args:
             *paths (str): arbitrary number of paths to be added to runtime linking
         """
         self._addl_rpaths = self._addl_rpaths | set(paths)
 
+    def _link(self, path, dest):
+        file_name = os.path.basename(path)
+        dest_file = os.path.join(dest, file_name)
+        if os.path.exists(dest):
+            try:
+                symlink(path, dest_file)
+            # For py2 compatibility, we have to catch the specific Windows error code
+            # associate with trying to create a file that already exists (winerror 183)
+            except OSError as e:
+                if e.winerror == 183:
+                    # We have either already symlinked or we are encoutering a naming clash
+                    # either way, we don't want to overwrite existing libraries
+                    already_linked = islink(dest_file)
+                    tty.debug(
+                        "Linking library %s to %s failed, " % (path, dest_file) + "already linked."
+                        if already_linked
+                        else "library with name %s already exists at location %s."
+                        % (file_name, dest)
+                    )
+                    pass
+                else:
+                    raise e
+
     def establish_link(self):
         """
         (sym)link packages to runtime dependencies based on RPath configuration for
@@ -2298,29 +2328,8 @@ def establish_link(self):
 
         # for each binary install dir in self.pkg (i.e. pkg.prefix.bin, pkg.prefix.lib)
         # install a symlink to each dependent library
-        for library, lib_dir in itertools.product(self.link_targets, self.link_dest):
-            if not path_contains_subdirectory(library, lib_dir):
-                file_name = os.path.basename(library)
-                dest_file = os.path.join(lib_dir, file_name)
-                if os.path.exists(lib_dir):
-                    try:
-                        symlink(library, dest_file)
-                    # For py2 compatibility, we have to catch the specific Windows error code
-                    # associate with trying to create a file that already exists (winerror 183)
-                    except OSError as e:
-                        if e.winerror == 183:
-                            # We have either already symlinked or we are encoutering a naming clash
-                            # either way, we don't want to overwrite existing libraries
-                            already_linked = islink(dest_file)
-                            tty.debug(
-                                "Linking library %s to %s failed, " % (library, dest_file)
-                                + "already linked."
-                                if already_linked
-                                else "library with name %s already exists." % file_name
-                            )
-                            pass
-                        else:
-                            raise e
+        for library, lib_dir in itertools.product(self.rpaths, self.library_dependents):
+            self._link(library, lib_dir)
 
 
 @system_path_filter

lib/spack/llnl/util/lang.py

@@ -749,6 +749,26 @@ def _n_xxx_ago(x):
     raise ValueError(msg)
 
 
+def pretty_seconds(seconds):
+    """Seconds to string with appropriate units
+
+    Arguments:
+        seconds (float): Number of seconds
+
+    Returns:
+        str: Time string with units
+    """
+    if seconds >= 1:
+        value, unit = seconds, "s"
+    elif seconds >= 1e-3:
+        value, unit = seconds * 1e3, "ms"
+    elif seconds >= 1e-6:
+        value, unit = seconds * 1e6, "us"
+    else:
+        value, unit = seconds * 1e9, "ns"
+    return "%.3f%s" % (value, unit)
+
+
 class RequiredAttributeError(ValueError):
     def __init__(self, message):
         super(RequiredAttributeError, self).__init__(message)
@@ -1002,6 +1022,14 @@ def stable_partition(
     return true_items, false_items
 
 
+def ensure_last(lst, *elements):
+    """Performs a stable partition of lst, ensuring that ``elements``
+    occur at the end of ``lst`` in specified order. Mutates ``lst``.
+    Raises ``ValueError`` if any ``elements`` are not already in ``lst``."""
+    for elt in elements:
+        lst.append(lst.pop(lst.index(elt)))
+
+
 class TypedMutableSequence(MutableSequence):
     """Base class that behaves like a list, just with a different type.
 

lib/spack/llnl/util/lock.py

@@ -12,6 +12,7 @@
 from typing import Dict, Tuple  # novm
 
 import llnl.util.tty as tty
+from llnl.util.lang import pretty_seconds
 
 import spack.util.string
 
@@ -166,7 +167,7 @@ def _attempts_str(wait_time, nattempts):
         return ""
 
     attempts = spack.util.string.plural(nattempts, "attempt")
-    return " after {0:0.2f}s and {1}".format(wait_time, attempts)
+    return " after {} and {}".format(pretty_seconds(wait_time), attempts)
 
 
 class LockType(object):
@@ -318,8 +319,8 @@ def _lock(self, op, timeout=None):
             raise LockROFileError(self.path)
 
         self._log_debug(
-            "{0} locking [{1}:{2}]: timeout {3} sec".format(
-                op_str.lower(), self._start, self._length, timeout
+            "{} locking [{}:{}]: timeout {}".format(
+                op_str.lower(), self._start, self._length, pretty_seconds(timeout or 0)
             )
         )
 
@@ -340,7 +341,8 @@ def _lock(self, op, timeout=None):
             total_wait_time = time.time() - start_time
             return total_wait_time, num_attempts
 
-        raise LockTimeoutError("Timed out waiting for a {0} lock.".format(op_str.lower()))
+        total_wait_time = time.time() - start_time
+        raise LockTimeoutError(op_str.lower(), self.path, total_wait_time, num_attempts)
 
     def _poll_lock(self, op):
         """Attempt to acquire the lock in a non-blocking manner. Return whether
@@ -780,6 +782,18 @@ class LockLimitError(LockError):
 class LockTimeoutError(LockError):
     """Raised when an attempt to acquire a lock times out."""
 
+    def __init__(self, lock_type, path, time, attempts):
+        fmt = "Timed out waiting for a {} lock after {}.\n    Made {} {} on file: {}"
+        super(LockTimeoutError, self).__init__(
+            fmt.format(
+                lock_type,
+                pretty_seconds(time),
+                attempts,
+                "attempt" if attempts == 1 else "attempts",
+                path,
+            )
+        )
+
 
 class LockUpgradeError(LockError):
     """Raised when unable to upgrade from a read to a write lock."""

lib/spack/spack/__init__.py

@@ -3,11 +3,20 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-#: (major, minor, micro, dev release) tuple
-spack_version_info = (0, 19, 0, "dev0")
-
 #: PEP440 canonical <major>.<minor>.<micro>.<devN> string
-spack_version = ".".join(str(s) for s in spack_version_info)
+__version__ = "0.19.0"
+spack_version = __version__
+
+
+def __try_int(v):
+    try:
+        return int(v)
+    except ValueError:
+        return v
+
+
+#: (major, minor, micro, dev release) tuple
+spack_version_info = tuple([__try_int(v) for v in __version__.split(".")])
+
 
 __all__ = ["spack_version_info", "spack_version"]
-__version__ = spack_version

lib/spack/spack/audit.py

@@ -503,6 +503,33 @@ def invalid_sha256_digest(fetcher):
     return errors
 
 
+@package_properties
+def _ensure_env_methods_are_ported_to_builders(pkgs, error_cls):
+    """Ensure that methods modifying the build environment are ported to builder classes."""
+    errors = []
+    for pkg_name in pkgs:
+        pkg_cls = spack.repo.path.get_pkg_class(pkg_name)
+        buildsystem_variant, _ = pkg_cls.variants["build_system"]
+        buildsystem_names = [getattr(x, "value", x) for x in buildsystem_variant.values]
+        builder_cls_names = [spack.builder.BUILDER_CLS[x].__name__ for x in buildsystem_names]
+        module = pkg_cls.module
+        has_builders_in_package_py = any(
+            getattr(module, name, False) for name in builder_cls_names
+        )
+        if not has_builders_in_package_py:
+            continue
+
+        for method_name in ("setup_build_environment", "setup_dependent_build_environment"):
+            if hasattr(pkg_cls, method_name):
+                msg = (
+                    "Package '{}' need to move the '{}' method from the package class to the"
+                    " appropriate builder class".format(pkg_name, method_name)
+                )
+                errors.append(error_cls(msg, []))
+
+    return errors
+
+
 @package_https_directives
 def _linting_package_file(pkgs, error_cls):
     """Check for correctness of links"""
@@ -660,7 +687,13 @@ def _ensure_variant_defaults_are_parsable(pkgs, error_cls):
                 errors.append(error_cls(error_msg.format(variant_name, pkg_name), []))
                 continue
 
-            vspec = variant.make_default()
+            try:
+                vspec = variant.make_default()
+            except spack.variant.MultipleValuesInExclusiveVariantError:
+                error_msg = "Cannot create a default value for the variant '{}' in package '{}'"
+                errors.append(error_cls(error_msg.format(variant_name, pkg_name), []))
+                continue
+
             try:
                 variant.validate_or_raise(vspec, pkg_cls=pkg_cls)
             except spack.variant.InvalidVariantValueError:

lib/spack/spack/binary_distribution.py

@@ -7,11 +7,13 @@
 import collections
 import hashlib
 import json
+import multiprocessing.pool
 import os
 import shutil
 import sys
 import tarfile
 import tempfile
+import time
 import traceback
 import warnings
 from contextlib import closing
@@ -22,7 +24,7 @@
 import llnl.util.filesystem as fsys
 import llnl.util.lang
 import llnl.util.tty as tty
-from llnl.util.filesystem import mkdirp
+from llnl.util.filesystem import BaseDirectoryVisitor, mkdirp, visit_directory_tree
 
 import spack.cmd
 import spack.config as config
@@ -41,8 +43,10 @@
 import spack.util.url as url_util
 import spack.util.web as web_util
 from spack.caches import misc_cache_location
+from spack.relocate import utf8_paths_to_single_binary_regex
 from spack.spec import Spec
 from spack.stage import Stage
+from spack.util.executable import which
 
 _build_cache_relative_path = "build_cache"
 _build_cache_keys_relative_path = "_pgp"
@@ -70,6 +74,10 @@ def __init__(self, errors):
         super(FetchCacheError, self).__init__(self.message)
 
 
+class ListMirrorSpecsError(spack.error.SpackError):
+    """Raised when unable to retrieve list of specs from the mirror"""
+
+
 class BinaryCacheIndex(object):
     """
     The BinaryCacheIndex tracks what specs are available on (usually remote)
@@ -105,6 +113,10 @@ def __init__(self, cache_root):
         # cache (_mirrors_for_spec)
         self._specs_already_associated = set()
 
+        # mapping from mirror urls to the time.time() of the last index fetch and a bool indicating
+        # whether the fetch succeeded or not.
+        self._last_fetch_times = {}
+
         # _mirrors_for_spec is a dictionary mapping DAG hashes to lists of
         # entries indicating mirrors where that concrete spec can be found.
         # Each entry is a dictionary consisting of:
@@ -137,6 +149,7 @@ def clear(self):
             self._index_file_cache = None
         self._local_index_cache = None
         self._specs_already_associated = set()
+        self._last_fetch_times = {}
         self._mirrors_for_spec = {}
 
     def _write_local_index_cache(self):
@@ -242,7 +255,6 @@ def find_built_spec(self, spec, mirrors_to_check=None):
                         }
                     ]
         """
-        self.regenerate_spec_cache()
         return self.find_by_hash(spec.dag_hash(), mirrors_to_check=mirrors_to_check)
 
     def find_by_hash(self, find_hash, mirrors_to_check=None):
@@ -253,6 +265,9 @@ def find_by_hash(self, find_hash, mirrors_to_check=None):
             mirrors_to_check: Optional mapping containing mirrors to check.  If
                 None, just assumes all configured mirrors.
         """
+        if find_hash not in self._mirrors_for_spec:
+            # Not found in the cached index, pull the latest from the server.
+            self.update(with_cooldown=True)
         if find_hash not in self._mirrors_for_spec:
             return None
         results = self._mirrors_for_spec[find_hash]
@@ -283,7 +298,7 @@ def update_spec(self, spec, found_list):
                         "spec": new_entry["spec"],
                     }
 
-    def update(self):
+    def update(self, with_cooldown=False):
         """Make sure local cache of buildcache index files is up to date.
         If the same mirrors are configured as the last time this was called
         and none of the remote buildcache indices have changed, calling this
@@ -325,24 +340,41 @@ def update(self):
 
         fetch_errors = []
         all_methods_failed = True
+        ttl = spack.config.get("config:binary_index_ttl", 600)
+        now = time.time()
 
         for cached_mirror_url in self._local_index_cache:
             cache_entry = self._local_index_cache[cached_mirror_url]
             cached_index_hash = cache_entry["index_hash"]
             cached_index_path = cache_entry["index_path"]
             if cached_mirror_url in configured_mirror_urls:
-                # May need to fetch the index and update the local caches
-                try:
-                    needs_regen = self._fetch_and_cache_index(
-                        cached_mirror_url, expect_hash=cached_index_hash
-                    )
-                    all_methods_failed = False
-                except FetchCacheError as fetch_error:
-                    needs_regen = False
-                    fetch_errors.extend(fetch_error.errors)
-                # The need to regenerate implies a need to clear as well.
-                spec_cache_clear_needed |= needs_regen
-                spec_cache_regenerate_needed |= needs_regen
+                # Only do a fetch if the last fetch was longer than TTL ago
+                if (
+                    with_cooldown
+                    and ttl > 0
+                    and cached_mirror_url in self._last_fetch_times
+                    and now - self._last_fetch_times[cached_mirror_url][0] < ttl
+                ):
+                    # We're in the cooldown period, don't try to fetch again
+                    # If the fetch succeeded last time, consider this update a success, otherwise
+                    # re-report the error here
+                    if self._last_fetch_times[cached_mirror_url][1]:
+                        all_methods_failed = False
+                else:
+                    # May need to fetch the index and update the local caches
+                    try:
+                        needs_regen = self._fetch_and_cache_index(
+                            cached_mirror_url, expect_hash=cached_index_hash
+                        )
+                        self._last_fetch_times[cached_mirror_url] = (now, True)
+                        all_methods_failed = False
+                    except FetchCacheError as fetch_error:
+                        needs_regen = False
+                        fetch_errors.extend(fetch_error.errors)
+                        self._last_fetch_times[cached_mirror_url] = (now, False)
+                    # The need to regenerate implies a need to clear as well.
+                    spec_cache_clear_needed |= needs_regen
+                    spec_cache_regenerate_needed |= needs_regen
             else:
                 # No longer have this mirror, cached index should be removed
                 items_to_remove.append(
@@ -351,6 +383,8 @@ def update(self):
                         "cache_key": os.path.join(self._index_cache_root, cached_index_path),
                     }
                 )
+                if cached_mirror_url in self._last_fetch_times:
+                    del self._last_fetch_times[cached_mirror_url]
                 spec_cache_clear_needed = True
                 spec_cache_regenerate_needed = True
 
@@ -369,10 +403,12 @@ def update(self):
                 # Need to fetch the index and update the local caches
                 try:
                     needs_regen = self._fetch_and_cache_index(mirror_url)
+                    self._last_fetch_times[mirror_url] = (now, True)
                     all_methods_failed = False
                 except FetchCacheError as fetch_error:
                     fetch_errors.extend(fetch_error.errors)
                     needs_regen = False
+                    self._last_fetch_times[mirror_url] = (now, False)
                 # Generally speaking, a new mirror wouldn't imply the need to
                 # clear the spec cache, so leave it as is.
                 if needs_regen:
@@ -619,6 +655,57 @@ def read_buildinfo_file(prefix):
     return buildinfo
 
 
+class BuildManifestVisitor(BaseDirectoryVisitor):
+    """Visitor that collects a list of files and symlinks
+    that can be checked for need of relocation. It knows how
+    to dedupe hardlinks and deal with symlinks to files and
+    directories."""
+
+    def __init__(self):
+        # Save unique identifiers of files to avoid
+        # relocating hardlink files for each path.
+        self.visited = set()
+
+        # Lists of files we will check
+        self.files = []
+        self.symlinks = []
+
+    def seen_before(self, root, rel_path):
+        stat_result = os.lstat(os.path.join(root, rel_path))
+        identifier = (stat_result.st_dev, stat_result.st_ino)
+        if identifier in self.visited:
+            return True
+        else:
+            self.visited.add(identifier)
+            return False
+
+    def visit_file(self, root, rel_path, depth):
+        if self.seen_before(root, rel_path):
+            return
+        self.files.append(rel_path)
+
+    def visit_symlinked_file(self, root, rel_path, depth):
+        # Note: symlinks *can* be hardlinked, but it is unclear if
+        # symlinks can be relinked in-place (preserving inode).
+        # Therefore, we do *not* de-dupe hardlinked symlinks.
+        self.symlinks.append(rel_path)
+
+    def before_visit_dir(self, root, rel_path, depth):
+        return os.path.basename(rel_path) not in (".spack", "man")
+
+    def before_visit_symlinked_dir(self, root, rel_path, depth):
+        # Treat symlinked directories simply as symlinks.
+        self.visit_symlinked_file(root, rel_path, depth)
+        # Never recurse into symlinked directories.
+        return False
+
+
+def file_matches(path, regex):
+    with open(path, "rb") as f:
+        contents = f.read()
+    return bool(regex.search(contents))
+
+
 def get_buildfile_manifest(spec):
     """
     Return a data structure with information about a build, including
@@ -634,57 +721,61 @@ def get_buildfile_manifest(spec):
         "link_to_relocate": [],
         "other": [],
         "binary_to_relocate_fullpath": [],
+        "hardlinks_deduped": True,
     }
 
-    exclude_list = (".spack", "man")
+    # Guard against filesystem footguns of hardlinks and symlinks by using
+    # a visitor to retrieve a list of files and symlinks, so we don't have
+    # to worry about hardlinks of symlinked dirs and what not.
+    visitor = BuildManifestVisitor()
+    root = spec.prefix
+    visit_directory_tree(root, visitor)
 
-    # Do this at during tarball creation to save time when tarball unpacked.
-    # Used by make_package_relative to determine binaries to change.
-    for root, dirs, files in os.walk(spec.prefix, topdown=True):
-        dirs[:] = [d for d in dirs if d not in exclude_list]
+    # Collect a list of prefixes for this package and it's dependencies, Spack will
+    # look for them to decide if text file needs to be relocated or not
+    prefixes = [d.prefix for d in spec.traverse(root=True, deptype="all") if not d.external]
+    prefixes.append(spack.hooks.sbang.sbang_install_path())
+    prefixes.append(str(spack.store.layout.root))
 
-        # Directories may need to be relocated too.
-        for directory in dirs:
-            dir_path_name = os.path.join(root, directory)
-            rel_path_name = os.path.relpath(dir_path_name, spec.prefix)
-            if os.path.islink(dir_path_name):
-                link = os.readlink(dir_path_name)
-                if os.path.isabs(link) and link.startswith(spack.store.layout.root):
-                    data["link_to_relocate"].append(rel_path_name)
+    # Create a giant regex that matches all prefixes
+    regex = utf8_paths_to_single_binary_regex(prefixes)
 
-        for filename in files:
-            path_name = os.path.join(root, filename)
-            m_type, m_subtype = fsys.mime_type(path_name)
-            rel_path_name = os.path.relpath(path_name, spec.prefix)
-            added = False
+    # Symlinks.
 
-            if os.path.islink(path_name):
-                link = os.readlink(path_name)
-                if os.path.isabs(link):
-                    # Relocate absolute links into the spack tree
-                    if link.startswith(spack.store.layout.root):
-                        data["link_to_relocate"].append(rel_path_name)
-                    added = True
+    # Obvious bugs:
+    #   1. relative links are not relocated.
+    #   2. paths are used as strings.
+    for rel_path in visitor.symlinks:
+        abs_path = os.path.join(root, rel_path)
+        link = os.readlink(abs_path)
+        if os.path.isabs(link) and link.startswith(spack.store.layout.root):
+            data["link_to_relocate"].append(rel_path)
 
-            if relocate.needs_binary_relocation(m_type, m_subtype):
-                if (
-                    (
-                        m_subtype in ("x-executable", "x-sharedlib", "x-pie-executable")
-                        and sys.platform != "darwin"
-                    )
-                    or (m_subtype in ("x-mach-binary") and sys.platform == "darwin")
-                    or (not filename.endswith(".o"))
-                ):
-                    data["binary_to_relocate"].append(rel_path_name)
-                    data["binary_to_relocate_fullpath"].append(path_name)
-                    added = True
+    # Non-symlinks.
+    for rel_path in visitor.files:
+        abs_path = os.path.join(root, rel_path)
+        m_type, m_subtype = fsys.mime_type(abs_path)
 
-            if relocate.needs_text_relocation(m_type, m_subtype):
-                data["text_to_relocate"].append(rel_path_name)
-                added = True
+        if relocate.needs_binary_relocation(m_type, m_subtype):
+            # Why is this branch not part of needs_binary_relocation? :(
+            if (
+                (
+                    m_subtype in ("x-executable", "x-sharedlib", "x-pie-executable")
+                    and sys.platform != "darwin"
+                )
+                or (m_subtype in ("x-mach-binary") and sys.platform == "darwin")
+                or (not rel_path.endswith(".o"))
+            ):
+                data["binary_to_relocate"].append(rel_path)
+                data["binary_to_relocate_fullpath"].append(abs_path)
+                continue
+
+        elif relocate.needs_text_relocation(m_type, m_subtype) and file_matches(abs_path, regex):
+            data["text_to_relocate"].append(rel_path)
+            continue
+
+        data["other"].append(abs_path)
 
-            if not added:
-                data["other"].append(path_name)
     return data
 
 
@@ -698,7 +789,7 @@ def write_buildinfo_file(spec, workdir, rel=False):
     prefix_to_hash = dict()
     prefix_to_hash[str(spec.package.prefix)] = spec.dag_hash()
     deps = spack.build_environment.get_rpath_deps(spec.package)
-    for d in deps:
+    for d in deps + spec.dependencies(deptype="run"):
         prefix_to_hash[str(d.prefix)] = d.dag_hash()
 
     # Create buildinfo data and write it to disk
@@ -711,6 +802,7 @@ def write_buildinfo_file(spec, workdir, rel=False):
     buildinfo["relocate_textfiles"] = manifest["text_to_relocate"]
     buildinfo["relocate_binaries"] = manifest["binary_to_relocate"]
     buildinfo["relocate_links"] = manifest["link_to_relocate"]
+    buildinfo["hardlinks_deduped"] = manifest["hardlinks_deduped"]
     buildinfo["prefix_to_hash"] = prefix_to_hash
     filename = buildinfo_file_name(workdir)
     with open(filename, "w") as outfile:
@@ -795,37 +887,52 @@ def sign_specfile(key, force, specfile_path):
     spack.util.gpg.sign(key, specfile_path, signed_specfile_path, clearsign=True)
 
 
-def _fetch_spec_from_mirror(spec_url):
-    s = None
-    tty.debug("fetching {0}".format(spec_url))
-    _, _, spec_file = web_util.read_from_url(spec_url)
-    spec_file_contents = codecs.getreader("utf-8")(spec_file).read()
-    # Need full spec.json name or this gets confused with index.json.
-    if spec_url.endswith(".json.sig"):
-        specfile_json = Spec.extract_json_from_clearsig(spec_file_contents)
-        s = Spec.from_dict(specfile_json)
-    elif spec_url.endswith(".json"):
-        s = Spec.from_json(spec_file_contents)
-    elif spec_url.endswith(".yaml"):
-        s = Spec.from_yaml(spec_file_contents)
-    return s
+def _read_specs_and_push_index(file_list, read_method, cache_prefix, db, temp_dir, concurrency):
+    """Read all the specs listed in the provided list, using thread given thread parallelism,
+        generate the index, and push it to the mirror.
 
+    Args:
+        file_list (list(str)): List of urls or file paths pointing at spec files to read
+        read_method: A function taking a single argument, either a url or a file path,
+            and which reads the spec file at that location, and returns the spec.
+        cache_prefix (str): prefix of the build cache on s3 where index should be pushed.
+        db: A spack database used for adding specs and then writing the index.
+        temp_dir (str): Location to write index.json and hash for pushing
+        concurrency (int): Number of parallel processes to use when fetching
 
-def _read_specs_and_push_index(file_list, cache_prefix, db, db_root_dir):
-    for file_path in file_list:
-        try:
-            s = _fetch_spec_from_mirror(url_util.join(cache_prefix, file_path))
-        except (URLError, web_util.SpackWebError) as url_err:
-            tty.error("Error reading specfile: {0}".format(file_path))
-            tty.error(url_err)
+    Return:
+        None
+    """
 
-        if s:
-            db.add(s, None)
-            db.mark(s, "in_buildcache", True)
+    def _fetch_spec_from_mirror(spec_url):
+        spec_file_contents = read_method(spec_url)
+
+        if spec_file_contents:
+            # Need full spec.json name or this gets confused with index.json.
+            if spec_url.endswith(".json.sig"):
+                specfile_json = Spec.extract_json_from_clearsig(spec_file_contents)
+                return Spec.from_dict(specfile_json)
+            if spec_url.endswith(".json"):
+                return Spec.from_json(spec_file_contents)
+            if spec_url.endswith(".yaml"):
+                return Spec.from_yaml(spec_file_contents)
+
+    tp = multiprocessing.pool.ThreadPool(processes=concurrency)
+    try:
+        fetched_specs = tp.map(
+            llnl.util.lang.star(_fetch_spec_from_mirror), [(f,) for f in file_list]
+        )
+    finally:
+        tp.terminate()
+        tp.join()
+
+    for fetched_spec in fetched_specs:
+        db.add(fetched_spec, None)
+        db.mark(fetched_spec, "in_buildcache", True)
 
     # Now generate the index, compute its hash, and push the two files to
     # the mirror.
-    index_json_path = os.path.join(db_root_dir, "index.json")
+    index_json_path = os.path.join(temp_dir, "index.json")
     with open(index_json_path, "w") as f:
         db._write_to_file(f)
 
@@ -835,7 +942,7 @@ def _read_specs_and_push_index(file_list, cache_prefix, db, db_root_dir):
         index_hash = compute_hash(index_string)
 
     # Write the hash out to a local file
-    index_hash_path = os.path.join(db_root_dir, "index.json.hash")
+    index_hash_path = os.path.join(temp_dir, "index.json.hash")
     with open(index_hash_path, "w") as f:
         f.write(index_hash)
 
@@ -856,33 +963,152 @@ def _read_specs_and_push_index(file_list, cache_prefix, db, db_root_dir):
     )
 
 
-def generate_package_index(cache_prefix):
-    """Create the build cache index page.
+def _specs_from_cache_aws_cli(cache_prefix):
+    """Use aws cli to sync all the specs into a local temporary directory.
 
-    Creates (or replaces) the "index.json" page at the location given in
-    cache_prefix.  This page contains a link for each binary package (.yaml or
-    .json) under cache_prefix.
+    Args:
+        cache_prefix (str): prefix of the build cache on s3
+
+    Return:
+        List of the local file paths and a function that can read each one from the file system.
     """
+    read_fn = None
+    file_list = None
+    aws = which("aws")
+
+    def file_read_method(file_path):
+        with open(file_path) as fd:
+            return fd.read()
+
+    tmpspecsdir = tempfile.mkdtemp()
+    sync_command_args = [
+        "s3",
+        "sync",
+        "--exclude",
+        "*",
+        "--include",
+        "*.spec.json.sig",
+        "--include",
+        "*.spec.json",
+        "--include",
+        "*.spec.yaml",
+        cache_prefix,
+        tmpspecsdir,
+    ]
+
     try:
-        file_list = (
-            entry
+        tty.debug(
+            "Using aws s3 sync to download specs from {0} to {1}".format(cache_prefix, tmpspecsdir)
+        )
+        aws(*sync_command_args, output=os.devnull, error=os.devnull)
+        file_list = fsys.find(tmpspecsdir, ["*.spec.json.sig", "*.spec.json", "*.spec.yaml"])
+        read_fn = file_read_method
+    except Exception:
+        tty.warn("Failed to use aws s3 sync to retrieve specs, falling back to parallel fetch")
+        shutil.rmtree(tmpspecsdir)
+
+    return file_list, read_fn
+
+
+def _specs_from_cache_fallback(cache_prefix):
+    """Use spack.util.web module to get a list of all the specs at the remote url.
+
+    Args:
+        cache_prefix (str): Base url of mirror (location of spec files)
+
+    Return:
+        The list of complete spec file urls and a function that can read each one from its
+            remote location (also using the spack.util.web module).
+    """
+    read_fn = None
+    file_list = None
+
+    def url_read_method(url):
+        contents = None
+        try:
+            _, _, spec_file = web_util.read_from_url(url)
+            contents = codecs.getreader("utf-8")(spec_file).read()
+        except (URLError, web_util.SpackWebError) as url_err:
+            tty.error("Error reading specfile: {0}".format(url))
+            tty.error(url_err)
+        return contents
+
+    try:
+        file_list = [
+            url_util.join(cache_prefix, entry)
             for entry in web_util.list_url(cache_prefix)
             if entry.endswith(".yaml")
             or entry.endswith("spec.json")
             or entry.endswith("spec.json.sig")
-        )
+        ]
+        read_fn = url_read_method
     except KeyError as inst:
         msg = "No packages at {0}: {1}".format(cache_prefix, inst)
         tty.warn(msg)
-        return
     except Exception as err:
         # If we got some kind of S3 (access denied or other connection
         # error), the first non boto-specific class in the exception
         # hierarchy is Exception.  Just print a warning and return
         msg = "Encountered problem listing packages at {0}: {1}".format(cache_prefix, err)
         tty.warn(msg)
+
+    return file_list, read_fn
+
+
+def _spec_files_from_cache(cache_prefix):
+    """Get a list of all the spec files in the mirror and a function to
+    read them.
+
+    Args:
+        cache_prefix (str): Base url of mirror (location of spec files)
+
+    Return:
+        A tuple where the first item is a list of absolute file paths or
+        urls pointing to the specs that should be read from the mirror,
+        and the second item is a function taking a url or file path and
+        returning the spec read from that location.
+    """
+    callbacks = []
+    if cache_prefix.startswith("s3"):
+        callbacks.append(_specs_from_cache_aws_cli)
+
+    callbacks.append(_specs_from_cache_fallback)
+
+    for specs_from_cache_fn in callbacks:
+        file_list, read_fn = specs_from_cache_fn(cache_prefix)
+        if file_list:
+            return file_list, read_fn
+
+    raise ListMirrorSpecsError("Failed to get list of specs from {0}".format(cache_prefix))
+
+
+def generate_package_index(cache_prefix, concurrency=32):
+    """Create or replace the build cache index on the given mirror.  The
+    buildcache index contains an entry for each binary package under the
+    cache_prefix.
+
+    Args:
+        cache_prefix(str): Base url of binary mirror.
+        concurrency: (int): The desired threading concurrency to use when
+            fetching the spec files from the mirror.
+
+    Return:
+        None
+    """
+    try:
+        file_list, read_fn = _spec_files_from_cache(cache_prefix)
+    except ListMirrorSpecsError as err:
+        tty.error("Unabled to generate package index, {0}".format(err))
         return
 
+    if any(x.endswith(".yaml") for x in file_list):
+        msg = (
+            "The mirror in '{}' contains specs in the deprecated YAML format.\n\n\tSupport for "
+            "this format will be removed in v0.20, please regenerate the build cache with a "
+            "recent Spack\n"
+        ).format(cache_prefix)
+        warnings.warn(msg)
+
     tty.debug("Retrieving spec descriptor files from {0} to build index".format(cache_prefix))
 
     tmpdir = tempfile.mkdtemp()
@@ -895,7 +1121,7 @@ def generate_package_index(cache_prefix):
     )
 
     try:
-        _read_specs_and_push_index(file_list, cache_prefix, db, db_root_dir)
+        _read_specs_and_push_index(file_list, read_fn, cache_prefix, db, db_root_dir, concurrency)
     except Exception as err:
         msg = "Encountered problem pushing package index to {0}: {1}".format(cache_prefix, err)
         tty.warn(msg)
@@ -1071,7 +1297,11 @@ def _build_tarball(
             tty.die(e)
 
     # create gzip compressed tarball of the install prefix
-    with closing(tarfile.open(tarfile_path, "w:gz")) as tar:
+    # On AMD Ryzen 3700X and an SSD disk, we have the following on compression speed:
+    # compresslevel=6 gzip default: llvm takes 4mins, roughly 2.1GB
+    # compresslevel=9 python default: llvm takes 12mins, roughly 2.1GB
+    # So we follow gzip.
+    with closing(tarfile.open(tarfile_path, "w:gz", compresslevel=6)) as tar:
         tar.add(name="%s" % workdir, arcname="%s" % os.path.basename(spec.prefix))
     # remove copy of install directory
     shutil.rmtree(workdir)
@@ -1346,6 +1576,13 @@ def download_tarball(spec, unsigned=False, mirrors_for_spec=None):
                     #     the remaining mirrors, looking for one we can use.
                     tarball_stage = try_fetch(spackfile_url)
                     if tarball_stage:
+                        if ext == "yaml":
+                            msg = (
+                                "Reading {} from mirror.\n\n\tThe YAML format for buildcaches is "
+                                "deprecated and will be removed in v0.20\n"
+                            ).format(spackfile_url)
+                            warnings.warn(msg)
+
                         return {
                             "tarball_stage": tarball_stage,
                             "specfile_stage": local_specfile_stage,
@@ -1418,6 +1655,38 @@ def check_package_relocatable(workdir, spec, allow_root):
     relocate.raise_if_not_relocatable(cur_path_names, allow_root)
 
 
+def dedupe_hardlinks_if_necessary(root, buildinfo):
+    """Updates a buildinfo dict for old archives that did
+    not dedupe hardlinks. De-duping hardlinks is necessary
+    when relocating files in parallel and in-place. This
+    means we must preserve inodes when relocating."""
+
+    # New archives don't need this.
+    if buildinfo.get("hardlinks_deduped", False):
+        return
+
+    # Clearly we can assume that an inode is either in the
+    # textfile or binary group, but let's just stick to
+    # a single set of visited nodes.
+    visited = set()
+
+    # Note: we do *not* dedupe hardlinked symlinks, since
+    # it seems difficult or even impossible to relink
+    # symlinks while preserving inode.
+    for key in ("relocate_textfiles", "relocate_binaries"):
+        if key not in buildinfo:
+            continue
+        new_list = []
+        for rel_path in buildinfo[key]:
+            stat_result = os.lstat(os.path.join(root, rel_path))
+            identifier = (stat_result.st_dev, stat_result.st_ino)
+            if identifier in visited:
+                continue
+            visited.add(identifier)
+            new_list.append(rel_path)
+        buildinfo[key] = new_list
+
+
 def relocate_package(spec, allow_root):
     """
     Relocate the given package
@@ -1451,7 +1720,7 @@ def relocate_package(spec, allow_root):
     hash_to_prefix = dict()
     hash_to_prefix[spec.format("{hash}")] = str(spec.package.prefix)
     new_deps = spack.build_environment.get_rpath_deps(spec.package)
-    for d in new_deps:
+    for d in new_deps + spec.dependencies(deptype="run"):
         hash_to_prefix[d.format("{hash}")] = str(d.prefix)
     # Spurious replacements (e.g. sbang) will cause issues with binaries
     # For example, the new sbang can be longer than the old one.
@@ -1463,13 +1732,19 @@ def relocate_package(spec, allow_root):
         install_path = spack.hooks.sbang.sbang_install_path()
         prefix_to_prefix_text[old_sbang_install_path] = install_path
 
+    # First match specific prefix paths. Possibly the *local* install prefix
+    # of some dependency is in an upstream, so we cannot assume the original
+    # spack store root can be mapped uniformly to the new spack store root.
+    for orig_prefix, hash in prefix_to_hash.items():
+        prefix_to_prefix_text[orig_prefix] = hash_to_prefix.get(hash, None)
+        prefix_to_prefix_bin[orig_prefix] = hash_to_prefix.get(hash, None)
+
+    # Only then add the generic fallback of install prefix -> install prefix.
     prefix_to_prefix_text[old_prefix] = new_prefix
     prefix_to_prefix_bin[old_prefix] = new_prefix
     prefix_to_prefix_text[old_layout_root] = new_layout_root
     prefix_to_prefix_bin[old_layout_root] = new_layout_root
-    for orig_prefix, hash in prefix_to_hash.items():
-        prefix_to_prefix_text[orig_prefix] = hash_to_prefix.get(hash, None)
-        prefix_to_prefix_bin[orig_prefix] = hash_to_prefix.get(hash, None)
+
     # This is vestigial code for the *old* location of sbang. Previously,
     # sbang was a bash script, and it lived in the spack prefix. It is
     # now a POSIX script that lives in the install prefix. Old packages
@@ -1480,6 +1755,9 @@ def relocate_package(spec, allow_root):
 
     tty.debug("Relocating package from", "%s to %s." % (old_layout_root, new_layout_root))
 
+    # Old archives maybe have hardlinks repeated.
+    dedupe_hardlinks_if_necessary(workdir, buildinfo)
+
     def is_backup_file(file):
         return file.endswith("~")
 
@@ -1509,7 +1787,11 @@ def is_backup_file(file):
                 old_prefix,
                 new_prefix,
             )
-        if "elf" in platform.binary_formats:
+        elif "elf" in platform.binary_formats and not rel:
+            # The new ELF dynamic section relocation logic only handles absolute to
+            # absolute relocation.
+            relocate.new_relocate_elf_binaries(files_to_relocate, prefix_to_prefix_bin)
+        elif "elf" in platform.binary_formats and rel:
             relocate.relocate_elf_binaries(
                 files_to_relocate,
                 old_layout_root,
@@ -1519,35 +1801,23 @@ def is_backup_file(file):
                 old_prefix,
                 new_prefix,
             )
-            # Relocate links to the new install prefix
-            links = [link for link in buildinfo.get("relocate_links", [])]
-            relocate.relocate_links(links, old_layout_root, old_prefix, new_prefix)
+
+        # Relocate links to the new install prefix
+        links = [os.path.join(workdir, f) for f in buildinfo.get("relocate_links", [])]
+        relocate.relocate_links(links, prefix_to_prefix_bin)
 
         # For all buildcaches
         # relocate the install prefixes in text files including dependencies
-        relocate.relocate_text(text_names, prefix_to_prefix_text)
+        relocate.unsafe_relocate_text(text_names, prefix_to_prefix_text)
 
-        paths_to_relocate = [old_prefix, old_layout_root]
-        paths_to_relocate.extend(prefix_to_hash.keys())
-        files_to_relocate = list(
-            filter(
-                lambda pathname: not relocate.file_is_relocatable(
-                    pathname, paths_to_relocate=paths_to_relocate
-                ),
-                map(
-                    lambda filename: os.path.join(workdir, filename),
-                    buildinfo["relocate_binaries"],
-                ),
-            )
-        )
         # relocate the install prefixes in binary files including dependencies
-        relocate.relocate_text_bin(files_to_relocate, prefix_to_prefix_bin)
+        relocate.unsafe_relocate_text_bin(files_to_relocate, prefix_to_prefix_bin)
 
     # If we are installing back to the same location
     # relocate the sbang location if the spack directory changed
     else:
         if old_spack_prefix != new_spack_prefix:
-            relocate.relocate_text(text_names, prefix_to_prefix_text)
+            relocate.unsafe_relocate_text(text_names, prefix_to_prefix_text)
 
 
 def _extract_inner_tarball(spec, filename, extract_to, unsigned, remote_checksum):
@@ -1878,8 +2148,8 @@ def get_mirrors_for_spec(spec=None, mirrors_to_check=None, index_only=False):
 
     results = binary_index.find_built_spec(spec, mirrors_to_check=mirrors_to_check)
 
-    # Maybe we just didn't have the latest information from the mirror, so
-    # try to fetch directly, unless we are only considering the indices.
+    # The index may be out-of-date. If we aren't only considering indices, try
+    # to fetch directly since we know where the file should be.
     if not results and not index_only:
         results = try_direct_fetch(spec, mirrors=mirrors_to_check)
         # We found a spec by the direct fetch approach, we might as well

lib/spack/spack/bootstrap.py

@@ -91,6 +91,14 @@ def _try_import_from_store(module, query_spec, query_info=None):
             os.path.join(candidate_spec.prefix, pkg.platlib),
         ]  # type: list[str]
         path_before = list(sys.path)
+
+        # Python 3.8+ on Windows does not search dependent DLLs in PATH,
+        # so we need to manually add it using os.add_dll_directory
+        # https://docs.python.org/3/whatsnew/3.8.html#bpo-36085-whatsnew
+        if sys.version_info[:2] >= (3, 8) and sys.platform == "win32":
+            if os.path.isdir(candidate_spec.prefix.bin):
+                os.add_dll_directory(candidate_spec.prefix.bin)  # novermin
+
         # NOTE: try module_paths first and last, last allows an existing version in path
         # to be picked up and used, possibly depending on something in the store, first
         # allows the bootstrap version to work when an incompatible version is in
@@ -667,6 +675,11 @@ def _add_externals_if_missing():
 _REF_COUNT = 0
 
 
+def is_bootstrapping():
+    global _REF_COUNT
+    return _REF_COUNT > 0
+
+
 @contextlib.contextmanager
 def ensure_bootstrap_configuration():
     # The context manager is reference counted to ensure we don't swap multiple

lib/spack/spack/build_environment.py

@@ -52,6 +52,7 @@
 
 import spack.build_systems.cmake
 import spack.build_systems.meson
+import spack.builder
 import spack.config
 import spack.install_test
 import spack.main
@@ -120,18 +121,18 @@
 stat_suffix = "lib" if sys.platform == "win32" else "a"
 
 
-def should_set_parallel_jobs(jobserver_support=False):
-    """Returns true in general, except when:
-    - The env variable SPACK_NO_PARALLEL_MAKE=1 is set
-    - jobserver_support is enabled, and a jobserver was found.
-    """
-    if (
-        jobserver_support
-        and "MAKEFLAGS" in os.environ
-        and "--jobserver" in os.environ["MAKEFLAGS"]
-    ):
-        return False
-    return not env_flag(SPACK_NO_PARALLEL_MAKE)
+def jobserver_enabled():
+    """Returns true if a posix jobserver (make) is detected."""
+    return "MAKEFLAGS" in os.environ and "--jobserver" in os.environ["MAKEFLAGS"]
+
+
+def get_effective_jobs(jobs, parallel=True, supports_jobserver=False):
+    """Return the number of jobs, or None if supports_jobserver and a jobserver is detected."""
+    if not parallel or jobs <= 1 or env_flag(SPACK_NO_PARALLEL_MAKE):
+        return 1
+    if supports_jobserver and jobserver_enabled():
+        return None
+    return jobs
 
 
 class MakeExecutable(Executable):
@@ -146,26 +147,33 @@ class MakeExecutable(Executable):
     """
 
     def __init__(self, name, jobs, **kwargs):
+        supports_jobserver = kwargs.pop("supports_jobserver", True)
         super(MakeExecutable, self).__init__(name, **kwargs)
+        self.supports_jobserver = supports_jobserver
         self.jobs = jobs
 
     def __call__(self, *args, **kwargs):
         """parallel, and jobs_env from kwargs are swallowed and used here;
         remaining arguments are passed through to the superclass.
         """
-        # TODO: figure out how to check if we are using a jobserver-supporting ninja,
-        # the two split ninja packages make this very difficult right now
-        parallel = should_set_parallel_jobs(jobserver_support=True) and kwargs.pop(
-            "parallel", self.jobs > 1
-        )
+        parallel = kwargs.pop("parallel", True)
+        jobs_env = kwargs.pop("jobs_env", None)
+        jobs_env_supports_jobserver = kwargs.pop("jobs_env_supports_jobserver", False)
 
-        if parallel:
-            args = ("-j{0}".format(self.jobs),) + args
-            jobs_env = kwargs.pop("jobs_env", None)
-            if jobs_env:
-                # Caller wants us to set an environment variable to
-                # control the parallelism.
-                kwargs["extra_env"] = {jobs_env: str(self.jobs)}
+        jobs = get_effective_jobs(
+            self.jobs, parallel=parallel, supports_jobserver=self.supports_jobserver
+        )
+        if jobs is not None:
+            args = ("-j{0}".format(jobs),) + args
+
+        if jobs_env:
+            # Caller wants us to set an environment variable to
+            # control the parallelism.
+            jobs_env_jobs = get_effective_jobs(
+                self.jobs, parallel=parallel, supports_jobserver=jobs_env_supports_jobserver
+            )
+            if jobs_env_jobs is not None:
+                kwargs["extra_env"] = {jobs_env: str(jobs_env_jobs)}
 
         return super(MakeExecutable, self).__call__(*args, **kwargs)
 
@@ -316,7 +324,7 @@ def set_compiler_environment_variables(pkg, env):
     env.set("SPACK_LINKER_ARG", compiler.linker_arg)
 
     # Check whether we want to force RPATH or RUNPATH
-    if spack.config.get("config:shared_linking") == "rpath":
+    if spack.config.get("config:shared_linking:type") == "rpath":
         env.set("SPACK_DTAGS_TO_STRIP", compiler.enable_new_dtags)
         env.set("SPACK_DTAGS_TO_ADD", compiler.disable_new_dtags)
     else:
@@ -324,7 +332,11 @@ def set_compiler_environment_variables(pkg, env):
         env.set("SPACK_DTAGS_TO_ADD", compiler.enable_new_dtags)
 
     # Set the target parameters that the compiler will add
-    isa_arg = spec.architecture.target.optimization_flags(compiler)
+    # Don't set on cray platform because the targeting module handles this
+    if spec.satisfies("platform=cray"):
+        isa_arg = ""
+    else:
+        isa_arg = spec.architecture.target.optimization_flags(compiler)
     env.set("SPACK_TARGET_ARGS", isa_arg)
 
     # Trap spack-tracked compiler flags as appropriate.
@@ -345,7 +357,7 @@ def set_compiler_environment_variables(pkg, env):
                 handler = pkg.flag_handler.__func__
             else:
                 handler = pkg.flag_handler.im_func
-        injf, envf, bsf = handler(pkg, flag, spec.compiler_flags[flag])
+        injf, envf, bsf = handler(pkg, flag, spec.compiler_flags[flag][:])
         inject_flags[flag] = injf or []
         env_flags[flag] = envf or []
         build_system_flags[flag] = bsf or []
@@ -546,7 +558,7 @@ def _set_variables_for_single_module(pkg, module):
     # TODO: make these build deps that can be installed if not found.
     m.make = MakeExecutable("make", jobs)
     m.gmake = MakeExecutable("gmake", jobs)
-    m.ninja = MakeExecutable("ninja", jobs)
+    m.ninja = MakeExecutable("ninja", jobs, supports_jobserver=False)
 
     # easy shortcut to os.environ
     m.env = os.environ
@@ -558,9 +570,9 @@ def _set_variables_for_single_module(pkg, module):
     if sys.platform == "win32":
         m.nmake = Executable("nmake")
     # Standard CMake arguments
-    m.std_cmake_args = spack.build_systems.cmake.CMakePackage._std_args(pkg)
-    m.std_meson_args = spack.build_systems.meson.MesonPackage._std_args(pkg)
-    m.std_pip_args = spack.build_systems.python.PythonPackage._std_args(pkg)
+    m.std_cmake_args = spack.build_systems.cmake.CMakeBuilder.std_args(pkg)
+    m.std_meson_args = spack.build_systems.meson.MesonBuilder.std_args(pkg)
+    m.std_pip_args = spack.build_systems.python.PythonPipBuilder.std_args(pkg)
 
     # Put spack compiler paths in module scope.
     link_dir = spack.paths.build_env_path
@@ -727,38 +739,6 @@ def get_rpaths(pkg):
     return list(dedupe(filter_system_paths(rpaths)))
 
 
-def get_std_cmake_args(pkg):
-    """List of standard arguments used if a package is a CMakePackage.
-
-    Returns:
-        list: standard arguments that would be used if this
-        package were a CMakePackage instance.
-
-    Args:
-        pkg (spack.package_base.PackageBase): package under consideration
-
-    Returns:
-        list: arguments for cmake
-    """
-    return spack.build_systems.cmake.CMakePackage._std_args(pkg)
-
-
-def get_std_meson_args(pkg):
-    """List of standard arguments used if a package is a MesonPackage.
-
-    Returns:
-        list: standard arguments that would be used if this
-        package were a MesonPackage instance.
-
-    Args:
-        pkg (spack.package_base.PackageBase): package under consideration
-
-    Returns:
-        list: arguments for meson
-    """
-    return spack.build_systems.meson.MesonPackage._std_args(pkg)
-
-
 def parent_class_modules(cls):
     """
     Get list of superclass modules that descend from spack.package_base.PackageBase
@@ -819,7 +799,8 @@ def setup_package(pkg, dirty, context="build"):
     platform.setup_platform_environment(pkg, env_mods)
 
     if context == "build":
-        pkg.setup_build_environment(env_mods)
+        builder = spack.builder.create(pkg)
+        builder.setup_build_environment(env_mods)
 
         if (not dirty) and (not env_mods.is_unset("CPATH")):
             tty.debug(
@@ -1015,7 +996,8 @@ def add_modifications_for_dep(dep):
                 module.__dict__.update(changes.__dict__)
 
             if context == "build":
-                dpkg.setup_dependent_build_environment(env, spec)
+                builder = spack.builder.create(dpkg)
+                builder.setup_dependent_build_environment(env, spec)
             else:
                 dpkg.setup_dependent_run_environment(env, spec)
 
@@ -1117,8 +1099,20 @@ def _setup_pkg_and_run(
                 pkg.test_suite.stage, spack.install_test.TestSuite.test_log_name(pkg.spec)
             )
 
+        error_msg = str(exc)
+        if isinstance(exc, (spack.multimethod.NoSuchMethodError, AttributeError)):
+            error_msg = (
+                "The '{}' package cannot find an attribute while trying to build "
+                "from sources. This might be due to a change in Spack's package format "
+                "to support multiple build-systems for a single package. You can fix this "
+                "by updating the build recipe, and you can also report the issue as a bug. "
+                "More information at https://spack.readthedocs.io/en/latest/packaging_guide.html#installation-procedure"
+            ).format(pkg.name)
+            error_msg = colorize("@*R{{{}}}".format(error_msg))
+            error_msg = "{}\n\n{}".format(str(exc), error_msg)
+
         # make a pickleable exception to send to parent.
-        msg = "%s: %s" % (exc_type.__name__, str(exc))
+        msg = "%s: %s" % (exc_type.__name__, error_msg)
 
         ce = ChildError(
             msg,

lib/spack/spack/build_systems/_checks.py

@@ -0,0 +1,124 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os
+
+import six
+
+import llnl.util.lang
+
+import spack.builder
+import spack.installer
+import spack.relocate
+import spack.store
+
+
+def sanity_check_prefix(builder):
+    """Check that specific directories and files are created after installation.
+
+    The files to be checked are in the ``sanity_check_is_file`` attribute of the
+    package object, while the directories are in the ``sanity_check_is_dir``.
+
+    Args:
+        builder (spack.builder.Builder): builder that installed the package
+    """
+    pkg = builder.pkg
+
+    def check_paths(path_list, filetype, predicate):
+        if isinstance(path_list, six.string_types):
+            path_list = [path_list]
+
+        for path in path_list:
+            abs_path = os.path.join(pkg.prefix, path)
+            if not predicate(abs_path):
+                msg = "Install failed for {0}. No such {1} in prefix: {2}"
+                msg = msg.format(pkg.name, filetype, path)
+                raise spack.installer.InstallError(msg)
+
+    check_paths(pkg.sanity_check_is_file, "file", os.path.isfile)
+    check_paths(pkg.sanity_check_is_dir, "directory", os.path.isdir)
+
+    ignore_file = llnl.util.lang.match_predicate(spack.store.layout.hidden_file_regexes)
+    if all(map(ignore_file, os.listdir(pkg.prefix))):
+        msg = "Install failed for {0}.  Nothing was installed!"
+        raise spack.installer.InstallError(msg.format(pkg.name))
+
+
+def apply_macos_rpath_fixups(builder):
+    """On Darwin, make installed libraries more easily relocatable.
+
+    Some build systems (handrolled, autotools, makefiles) can set their own
+    rpaths that are duplicated by spack's compiler wrapper. This fixup
+    interrogates, and postprocesses if necessary, all libraries installed
+    by the code.
+
+    It should be added as a @run_after to packaging systems (or individual
+    packages) that do not install relocatable libraries by default.
+
+    Args:
+        builder (spack.builder.Builder): builder that installed the package
+    """
+    spack.relocate.fixup_macos_rpaths(builder.spec)
+
+
+def ensure_build_dependencies_or_raise(spec, dependencies, error_msg):
+    """Ensure that some build dependencies are present in the concrete spec.
+
+    If not, raise a RuntimeError with a helpful error message.
+
+    Args:
+        spec (spack.spec.Spec): concrete spec to be checked.
+        dependencies (list of spack.spec.Spec): list of abstract specs to be satisfied
+        error_msg (str): brief error message to be prepended to a longer description
+
+    Raises:
+          RuntimeError: when the required build dependencies are not found
+    """
+    assert spec.concrete, "Can ensure build dependencies only on concrete specs"
+    build_deps = [d.name for d in spec.dependencies(deptype="build")]
+    missing_deps = [x for x in dependencies if x not in build_deps]
+
+    if not missing_deps:
+        return
+
+    # Raise an exception on missing deps.
+    msg = (
+        "{0}: missing dependencies: {1}.\n\nPlease add "
+        "the following lines to the package:\n\n".format(error_msg, ", ".join(missing_deps))
+    )
+
+    for dep in missing_deps:
+        msg += "    depends_on('{0}', type='build', when='@{1} {2}')\n".format(
+            dep, spec.version, "build_system=autotools"
+        )
+
+    msg += "\nUpdate the version (when='@{0}') as needed.".format(spec.version)
+    raise RuntimeError(msg)
+
+
+def execute_build_time_tests(builder):
+    """Execute the build-time tests prescribed by builder.
+
+    Args:
+        builder (Builder): builder prescribing the test callbacks. The name of the callbacks is
+            stored as a list of strings in the ``build_time_test_callbacks`` attribute.
+    """
+    builder.pkg.run_test_callbacks(builder, builder.build_time_test_callbacks, "build")
+
+
+def execute_install_time_tests(builder):
+    """Execute the install-time tests prescribed by builder.
+
+    Args:
+        builder (Builder): builder prescribing the test callbacks. The name of the callbacks is
+            stored as a list of strings in the ``install_time_test_callbacks`` attribute.
+    """
+    builder.pkg.run_test_callbacks(builder, builder.install_time_test_callbacks, "install")
+
+
+class BaseBuilder(spack.builder.Builder):
+    """Base class for builders to register common checks"""
+
+    # Check that self.prefix is there after installation
+    spack.builder.run_after("install")(sanity_check_prefix)

lib/spack/spack/build_systems/aspell_dict.py

@@ -2,18 +2,36 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import llnl.util.filesystem as fs
 
-# Why doesn't this work for me?
-# from spack import *
-from llnl.util.filesystem import filter_file
+import spack.directives
+import spack.package_base
+import spack.util.executable
 
-from spack.build_systems.autotools import AutotoolsPackage
-from spack.directives import extends
-from spack.package_base import ExtensionError
-from spack.util.executable import which
+from .autotools import AutotoolsBuilder, AutotoolsPackage
+
+
+class AspellBuilder(AutotoolsBuilder):
+    """The Aspell builder is close enough to an autotools builder to allow
+    specializing the builder class, so to use variables that are specific
+    to the Aspell extensions.
+    """
+
+    def configure(self, pkg, spec, prefix):
+        aspell = spec["aspell"].prefix.bin.aspell
+        prezip = spec["aspell"].prefix.bin.prezip
+        destdir = prefix
+
+        sh = spack.util.executable.which("sh")
+        sh(
+            "./configure",
+            "--vars",
+            "ASPELL={0}".format(aspell),
+            "PREZIP={0}".format(prezip),
+            "DESTDIR={0}".format(destdir),
+        )
 
 
-#
 # Aspell dictionaries install their bits into their prefix.lib
 # and when activated they'll get symlinked into the appropriate aspell's
 # dict dir (see aspell's {de,}activate methods).
@@ -23,12 +41,17 @@
 class AspellDictPackage(AutotoolsPackage):
     """Specialized class for building aspell dictionairies."""
 
-    extends("aspell")
+    spack.directives.extends("aspell", when="build_system=autotools")
+
+    #: Override the default autotools builder
+    AutotoolsBuilder = AspellBuilder
 
     def view_destination(self, view):
         aspell_spec = self.spec["aspell"]
         if view.get_projection_for_spec(aspell_spec) != aspell_spec.prefix:
-            raise ExtensionError("aspell does not support non-global extensions")
+            raise spack.package_base.ExtensionError(
+                "aspell does not support non-global extensions"
+            )
         aspell = aspell_spec.command
         return aspell("dump", "config", "dict-dir", output=str).strip()
 
@@ -36,19 +59,5 @@ def view_source(self):
         return self.prefix.lib
 
     def patch(self):
-        filter_file(r"^dictdir=.*$", "dictdir=/lib", "configure")
-        filter_file(r"^datadir=.*$", "datadir=/lib", "configure")
-
-    def configure(self, spec, prefix):
-        aspell = spec["aspell"].prefix.bin.aspell
-        prezip = spec["aspell"].prefix.bin.prezip
-        destdir = prefix
-
-        sh = which("sh")
-        sh(
-            "./configure",
-            "--vars",
-            "ASPELL={0}".format(aspell),
-            "PREZIP={0}".format(prezip),
-            "DESTDIR={0}".format(destdir),
-        )
+        fs.filter_file(r"^dictdir=.*$", "dictdir=/lib", "configure")
+        fs.filter_file(r"^datadir=.*$", "datadir=/lib", "configure")

lib/spack/spack/build_systems/autotools.py

@@ -6,87 +6,140 @@
 import os
 import os.path
 import stat
-from subprocess import PIPE, check_call
+import subprocess
 from typing import List  # novm
 
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
-from llnl.util.filesystem import force_remove, working_dir
 
-from spack.build_environment import InstallError
-from spack.directives import conflicts, depends_on
+import spack.build_environment
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, conflicts, depends_on
+from spack.multimethod import when
 from spack.operating_systems.mac_os import macos_version
-from spack.package_base import PackageBase, run_after, run_before
 from spack.util.executable import Executable
 from spack.version import Version
 
+from ._checks import (
+    BaseBuilder,
+    apply_macos_rpath_fixups,
+    ensure_build_dependencies_or_raise,
+    execute_build_time_tests,
+    execute_install_time_tests,
+)
 
-class AutotoolsPackage(PackageBase):
-    """Specialized class for packages built using GNU Autotools.
 
-    This class provides four phases that can be overridden:
+class AutotoolsPackage(spack.package_base.PackageBase):
+    """Specialized class for packages built using GNU Autotools."""
 
-        1. :py:meth:`~.AutotoolsPackage.autoreconf`
-        2. :py:meth:`~.AutotoolsPackage.configure`
-        3. :py:meth:`~.AutotoolsPackage.build`
-        4. :py:meth:`~.AutotoolsPackage.install`
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "AutotoolsPackage"
+
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "autotools"
+
+    build_system("autotools")
+
+    with when("build_system=autotools"):
+        depends_on("gnuconfig", type="build", when="target=ppc64le:")
+        depends_on("gnuconfig", type="build", when="target=aarch64:")
+        depends_on("gnuconfig", type="build", when="target=riscv64:")
+        conflicts("platform=windows")
+
+    def flags_to_build_system_args(self, flags):
+        """Produces a list of all command line arguments to pass specified
+        compiler flags to configure."""
+        # Has to be dynamic attribute due to caching.
+        setattr(self, "configure_flag_args", [])
+        for flag, values in flags.items():
+            if values:
+                values_str = "{0}={1}".format(flag.upper(), " ".join(values))
+                self.configure_flag_args.append(values_str)
+        # Spack's fflags are meant for both F77 and FC, therefore we
+        # additionaly set FCFLAGS if required.
+        values = flags.get("fflags", None)
+        if values:
+            values_str = "FCFLAGS={0}".format(" ".join(values))
+            self.configure_flag_args.append(values_str)
+
+    # Legacy methods (used by too many packages to change them,
+    # need to forward to the builder)
+    def enable_or_disable(self, *args, **kwargs):
+        return self.builder.enable_or_disable(*args, **kwargs)
+
+    def with_or_without(self, *args, **kwargs):
+        return self.builder.with_or_without(*args, **kwargs)
+
+
+@spack.builder.builder("autotools")
+class AutotoolsBuilder(BaseBuilder):
+    """The autotools builder encodes the default way of installing software built
+    with autotools. It has four phases that can be overridden, if need be:
+
+        1. :py:meth:`~.AutotoolsBuilder.autoreconf`
+        2. :py:meth:`~.AutotoolsBuilder.configure`
+        3. :py:meth:`~.AutotoolsBuilder.build`
+        4. :py:meth:`~.AutotoolsBuilder.install`
+
+    They all have sensible defaults and for many packages the only thing necessary
+    is to override the helper method
+    :meth:`~spack.build_systems.autotools.AutotoolsBuilder.configure_args`.
 
-    They all have sensible defaults and for many packages the only thing
-    necessary will be to override the helper method
-    :meth:`~spack.build_systems.autotools.AutotoolsPackage.configure_args`.
     For a finer tuning you may also override:
 
         +-----------------------------------------------+--------------------+
         | **Method**                                    | **Purpose**        |
         +===============================================+====================+
-        | :py:attr:`~.AutotoolsPackage.build_targets`   | Specify ``make``   |
+        | :py:attr:`~.AutotoolsBuilder.build_targets`   | Specify ``make``   |
         |                                               | targets for the    |
         |                                               | build phase        |
         +-----------------------------------------------+--------------------+
-        | :py:attr:`~.AutotoolsPackage.install_targets` | Specify ``make``   |
+        | :py:attr:`~.AutotoolsBuilder.install_targets` | Specify ``make``   |
         |                                               | targets for the    |
         |                                               | install phase      |
         +-----------------------------------------------+--------------------+
-        | :py:meth:`~.AutotoolsPackage.check`           | Run  build time    |
+        | :py:meth:`~.AutotoolsBuilder.check`           | Run  build time    |
         |                                               | tests if required  |
         +-----------------------------------------------+--------------------+
 
     """
 
     #: Phases of a GNU Autotools package
-    phases = ["autoreconf", "configure", "build", "install"]
-    #: This attribute is used in UI queries that need to know the build
-    #: system base class
-    build_system_class = "AutotoolsPackage"
+    phases = ("autoreconf", "configure", "build", "install")
 
-    @property
-    def patch_config_files(self):
-        """
-        Whether or not to update old ``config.guess`` and ``config.sub`` files
-        distributed with the tarball. This currently only applies to
-        ``ppc64le:``, ``aarch64:``, and ``riscv64`` target architectures. The
-        substitutes are taken from the ``gnuconfig`` package, which is
-        automatically added as a build dependency for these architectures. In
-        case system versions of these config files are required, the
-        ``gnuconfig`` package can be marked external with a prefix pointing to
-        the directory containing the system ``config.guess`` and ``config.sub``
-        files.
-        """
-        return (
-            self.spec.satisfies("target=ppc64le:")
-            or self.spec.satisfies("target=aarch64:")
-            or self.spec.satisfies("target=riscv64:")
-        )
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = (
+        "configure_args",
+        "check",
+        "installcheck",
+    )
 
-    #: Whether or not to update ``libtool``
-    #: (currently only for Arm/Clang/Fujitsu/NVHPC compilers)
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "archive_files",
+        "patch_libtool",
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "install_time_test_callbacks",
+        "force_autoreconf",
+        "autoreconf_extra_args",
+        "install_libtool_archives",
+        "patch_config_files",
+        "configure_directory",
+        "configure_abs_path",
+        "build_directory",
+        "autoreconf_search_path_args",
+    )
+
+    #: Whether to update ``libtool`` (e.g. for Arm/Clang/Fujitsu/NVHPC compilers)
     patch_libtool = True
 
-    #: Targets for ``make`` during the :py:meth:`~.AutotoolsPackage.build`
-    #: phase
+    #: Targets for ``make`` during the :py:meth:`~.AutotoolsBuilder.build` phase
     build_targets = []  # type: List[str]
-    #: Targets for ``make`` during the :py:meth:`~.AutotoolsPackage.install`
-    #: phase
+    #: Targets for ``make`` during the :py:meth:`~.AutotoolsBuilder.install` phase
     install_targets = ["install"]
 
     #: Callback names for build-time test
@@ -97,24 +150,40 @@ def patch_config_files(self):
 
     #: Set to true to force the autoreconf step even if configure is present
     force_autoreconf = False
+
     #: Options to be passed to autoreconf when using the default implementation
     autoreconf_extra_args = []  # type: List[str]
 
-    #: If False deletes all the .la files in the prefix folder
-    #: after the installation. If True instead it installs them.
+    #: If False deletes all the .la files in the prefix folder after the installation.
+    #: If True instead it installs them.
     install_libtool_archives = False
 
-    depends_on("gnuconfig", type="build", when="target=ppc64le:")
-    depends_on("gnuconfig", type="build", when="target=aarch64:")
-    depends_on("gnuconfig", type="build", when="target=riscv64:")
-    conflicts("platform=windows")
+    @property
+    def patch_config_files(self):
+        """Whether to update old ``config.guess`` and ``config.sub`` files
+        distributed with the tarball.
+
+        This currently only applies to ``ppc64le:``, ``aarch64:``, and
+        ``riscv64`` target architectures.
+
+        The substitutes are taken from the ``gnuconfig`` package, which is
+        automatically added as a build dependency for these architectures. In case
+        system versions of these config files are required, the ``gnuconfig`` package
+        can be marked external, with a prefix pointing to the directory containing the
+        system ``config.guess`` and ``config.sub`` files.
+        """
+        return (
+            self.pkg.spec.satisfies("target=ppc64le:")
+            or self.pkg.spec.satisfies("target=aarch64:")
+            or self.pkg.spec.satisfies("target=riscv64:")
+        )
 
     @property
     def _removed_la_files_log(self):
-        """File containing the list of remove libtool archives"""
+        """File containing the list of removed libtool archives"""
         build_dir = self.build_directory
         if not os.path.isabs(self.build_directory):
-            build_dir = os.path.join(self.stage.path, build_dir)
+            build_dir = os.path.join(self.pkg.stage.path, build_dir)
         return os.path.join(build_dir, "removed_la_files.txt")
 
     @property
@@ -125,13 +194,13 @@ def archive_files(self):
             files.append(self._removed_la_files_log)
         return files
 
-    @run_after("autoreconf")
+    @spack.builder.run_after("autoreconf")
     def _do_patch_config_files(self):
-        """Some packages ship with older config.guess/config.sub files and
-        need to have these updated when installed on a newer architecture.
-        In particular, config.guess fails for PPC64LE for version prior
-        to a 2013-06-10 build date (automake 1.13.4) and for ARM (aarch64) and
-        RISC-V (riscv64).
+        """Some packages ship with older config.guess/config.sub files and need to
+        have these updated when installed on a newer architecture.
+
+        In particular, config.guess fails for PPC64LE for version prior to a
+        2013-06-10 build date (automake 1.13.4) and for AArch64 and RISC-V.
         """
         if not self.patch_config_files:
             return
@@ -139,11 +208,11 @@ def _do_patch_config_files(self):
         # TODO: Expand this to select the 'config.sub'-compatible architecture
         # for each platform (e.g. 'config.sub' doesn't accept 'power9le', but
         # does accept 'ppc64le').
-        if self.spec.satisfies("target=ppc64le:"):
+        if self.pkg.spec.satisfies("target=ppc64le:"):
             config_arch = "ppc64le"
-        elif self.spec.satisfies("target=aarch64:"):
+        elif self.pkg.spec.satisfies("target=aarch64:"):
             config_arch = "aarch64"
-        elif self.spec.satisfies("target=riscv64:"):
+        elif self.pkg.spec.satisfies("target=riscv64:"):
             config_arch = "riscv64"
         else:
             config_arch = "local"
@@ -155,7 +224,7 @@ def runs_ok(script_abs_path):
             args = [script_abs_path] + additional_args.get(script_name, [])
 
             try:
-                check_call(args, stdout=PIPE, stderr=PIPE)
+                subprocess.check_call(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
             except Exception as e:
                 tty.debug(e)
                 return False
@@ -163,7 +232,7 @@ def runs_ok(script_abs_path):
             return True
 
         # Get the list of files that needs to be patched
-        to_be_patched = fs.find(self.stage.path, files=["config.sub", "config.guess"])
+        to_be_patched = fs.find(self.pkg.stage.path, files=["config.sub", "config.guess"])
         to_be_patched = [f for f in to_be_patched if not runs_ok(f)]
 
         # If there are no files to be patched, return early
@@ -171,22 +240,21 @@ def runs_ok(script_abs_path):
             return
 
         # Otherwise, require `gnuconfig` to be a build dependency
-        self._require_build_deps(
-            pkgs=["gnuconfig"], spec=self.spec, err="Cannot patch config files"
+        ensure_build_dependencies_or_raise(
+            spec=self.pkg.spec, dependencies=["gnuconfig"], error_msg="Cannot patch config files"
         )
 
         # Get the config files we need to patch (config.sub / config.guess).
         to_be_found = list(set(os.path.basename(f) for f in to_be_patched))
-        gnuconfig = self.spec["gnuconfig"]
+        gnuconfig = self.pkg.spec["gnuconfig"]
         gnuconfig_dir = gnuconfig.prefix
 
         # An external gnuconfig may not not have a prefix.
         if gnuconfig_dir is None:
-            raise InstallError(
-                "Spack could not find substitutes for GNU config "
-                "files because no prefix is available for the "
-                "`gnuconfig` package. Make sure you set a prefix "
-                "path instead of modules for external `gnuconfig`."
+            raise spack.build_environment.InstallError(
+                "Spack could not find substitutes for GNU config files because no "
+                "prefix is available for the `gnuconfig` package. Make sure you set a "
+                "prefix path instead of modules for external `gnuconfig`."
             )
 
         candidates = fs.find(gnuconfig_dir, files=to_be_found, recursive=False)
@@ -203,7 +271,7 @@ def runs_ok(script_abs_path):
                 msg += (
                     " or the `gnuconfig` package prefix is misconfigured as" " an external package"
                 )
-            raise InstallError(msg)
+            raise spack.build_environment.InstallError(msg)
 
         # Filter working substitutes
         candidates = [f for f in candidates if runs_ok(f)]
@@ -228,7 +296,9 @@ def runs_ok(script_abs_path):
    and set the prefix to the directory containing the `config.guess` and
    `config.sub` files.
 """
-            raise InstallError(msg.format(", ".join(to_be_found), self.name))
+            raise spack.build_environment.InstallError(
+                msg.format(", ".join(to_be_found), self.name)
+            )
 
         # Copy the good files over the bad ones
         for abs_path in to_be_patched:
@@ -238,7 +308,7 @@ def runs_ok(script_abs_path):
             fs.copy(substitutes[name], abs_path)
             os.chmod(abs_path, mode)
 
-    @run_before("configure")
+    @spack.builder.run_before("configure")
     def _patch_usr_bin_file(self):
         """On NixOS file is not available in /usr/bin/file. Patch configure
         scripts to use file from path."""
@@ -250,7 +320,7 @@ def _patch_usr_bin_file(self):
             with fs.keep_modification_time(*x.filenames):
                 x.filter(regex="/usr/bin/file", repl="file", string=True)
 
-    @run_before("configure")
+    @spack.builder.run_before("configure")
     def _set_autotools_environment_variables(self):
         """Many autotools builds use a version of mknod.m4 that fails when
         running as root unless FORCE_UNSAFE_CONFIGURE is set to 1.
@@ -261,11 +331,10 @@ def _set_autotools_environment_variables(self):
         Without it, configure just fails halfway through, but it can
         still run things *before* this check. Forcing this just removes a
         nuisance -- this is not circumventing any real protection.
-
         """
         os.environ["FORCE_UNSAFE_CONFIGURE"] = "1"
 
-    @run_before("configure")
+    @spack.builder.run_before("configure")
     def _do_patch_libtool_configure(self):
         """Patch bugs that propagate from libtool macros into "configure" and
         further into "libtool". Note that patches that can be fixed by patching
@@ -293,7 +362,7 @@ def _do_patch_libtool_configure(self):
             # Support Libtool 2.4.2 and older:
             x.filter(regex=r'^(\s*test \$p = "-R")(; then\s*)$', repl=r'\1 || test x-l = x"$p"\2')
 
-    @run_after("configure")
+    @spack.builder.run_after("configure")
     def _do_patch_libtool(self):
         """If configure generates a "libtool" script that does not correctly
         detect the compiler (and patch_libtool is set), patch in the correct
@@ -328,31 +397,33 @@ def _do_patch_libtool(self):
             markers[tag] = "LIBTOOL TAG CONFIG: {0}".format(tag.upper())
 
         # Replace empty linker flag prefixes:
-        if self.compiler.name == "nag":
+        if self.pkg.compiler.name == "nag":
             # Nag is mixed with gcc and g++, which are recognized correctly.
             # Therefore, we change only Fortran values:
             for tag in ["fc", "f77"]:
                 marker = markers[tag]
                 x.filter(
                     regex='^wl=""$',
-                    repl='wl="{0}"'.format(self.compiler.linker_arg),
+                    repl='wl="{0}"'.format(self.pkg.compiler.linker_arg),
                     start_at="# ### BEGIN {0}".format(marker),
                     stop_at="# ### END {0}".format(marker),
                 )
         else:
-            x.filter(regex='^wl=""$', repl='wl="{0}"'.format(self.compiler.linker_arg))
+            x.filter(regex='^wl=""$', repl='wl="{0}"'.format(self.pkg.compiler.linker_arg))
 
         # Replace empty PIC flag values:
         for cc, marker in markers.items():
             x.filter(
                 regex='^pic_flag=""$',
-                repl='pic_flag="{0}"'.format(getattr(self.compiler, "{0}_pic_flag".format(cc))),
+                repl='pic_flag="{0}"'.format(
+                    getattr(self.pkg.compiler, "{0}_pic_flag".format(cc))
+                ),
                 start_at="# ### BEGIN {0}".format(marker),
                 stop_at="# ### END {0}".format(marker),
             )
 
         # Other compiler-specific patches:
-        if self.compiler.name == "fj":
+        if self.pkg.compiler.name == "fj":
             x.filter(regex="-nostdlib", repl="", string=True)
             rehead = r"/\S*/"
             for o in [
@@ -365,12 +436,12 @@ def _do_patch_libtool(self):
                 "crtendS.o",
             ]:
                 x.filter(regex=(rehead + o), repl="", string=True)
-        elif self.compiler.name == "dpcpp":
+        elif self.pkg.compiler.name == "dpcpp":
             # Hack to filter out spurious predep_objects when building with Intel dpcpp
             # (see https://github.com/spack/spack/issues/32863):
             x.filter(regex=r"^(predep_objects=.*)/tmp/conftest-[0-9A-Fa-f]+\.o", repl=r"\1")
             x.filter(regex=r"^(predep_objects=.*)/tmp/a-[0-9A-Fa-f]+\.o", repl=r"\1")
-        elif self.compiler.name == "nag":
+        elif self.pkg.compiler.name == "nag":
             for tag in ["fc", "f77"]:
                 marker = markers[tag]
                 start_at = "# ### BEGIN {0}".format(marker)
@@ -446,11 +517,8 @@ def _do_patch_libtool(self):
 
     @property
     def configure_directory(self):
-        """Returns the directory where 'configure' resides.
-
-        :return: directory where to find configure
-        """
-        return self.stage.source_path
+        """Return the directory where 'configure' resides."""
+        return self.pkg.stage.source_path
 
     @property
     def configure_abs_path(self):
@@ -463,34 +531,12 @@ def build_directory(self):
         """Override to provide another place to build the package"""
         return self.configure_directory
 
-    @run_before("autoreconf")
+    @spack.builder.run_before("autoreconf")
     def delete_configure_to_force_update(self):
         if self.force_autoreconf:
-            force_remove(self.configure_abs_path)
+            fs.force_remove(self.configure_abs_path)
 
-    def _require_build_deps(self, pkgs, spec, err):
-        """Require `pkgs` to be direct build dependencies of `spec`. Raises a
-        RuntimeError with a helpful error messages when any dep is missing."""
-
-        build_deps = [d.name for d in spec.dependencies(deptype="build")]
-        missing_deps = [x for x in pkgs if x not in build_deps]
-
-        if not missing_deps:
-            return
-
-        # Raise an exception on missing deps.
-        msg = (
-            "{0}: missing dependencies: {1}.\n\nPlease add "
-            "the following lines to the package:\n\n".format(err, ", ".join(missing_deps))
-        )
-
-        for dep in missing_deps:
-            msg += "    depends_on('{0}', type='build', when='@{1}')\n".format(dep, spec.version)
-
-        msg += "\nUpdate the version (when='@{0}') as needed.".format(spec.version)
-        raise RuntimeError(msg)
-
-    def autoreconf(self, spec, prefix):
+    def autoreconf(self, pkg, spec, prefix):
         """Not needed usually, configure should be already there"""
 
         # If configure exists nothing needs to be done
@@ -498,8 +544,10 @@ def autoreconf(self, spec, prefix):
             return
 
         # Else try to regenerate it, which reuquires a few build dependencies
-        self._require_build_deps(
-            pkgs=["autoconf", "automake", "libtool"], spec=spec, err="Cannot generate configure"
+        ensure_build_dependencies_or_raise(
+            spec=spec,
+            dependencies=["autoconf", "automake", "libtool"],
+            error_msg="Cannot generate configure",
         )
 
         tty.msg("Configure script not found: trying to generate it")
@@ -507,8 +555,8 @@ def autoreconf(self, spec, prefix):
         tty.warn("* If the default procedure fails, consider implementing *")
         tty.warn("*        a custom AUTORECONF phase in the package       *")
         tty.warn("*********************************************************")
-        with working_dir(self.configure_directory):
-            m = inspect.getmodule(self)
+        with fs.working_dir(self.configure_directory):
+            m = inspect.getmodule(self.pkg)
             # This line is what is needed most of the time
             # --install, --verbose, --force
             autoreconf_args = ["-ivf"]
@@ -524,98 +572,66 @@ def autoreconf_search_path_args(self):
         spack dependencies."""
         return _autoreconf_search_path_args(self.spec)
 
-    @run_after("autoreconf")
+    @spack.builder.run_after("autoreconf")
     def set_configure_or_die(self):
-        """Checks the presence of a ``configure`` file after the
-        autoreconf phase. If it is found sets a module attribute
-        appropriately, otherwise raises an error.
+        """Ensure the presence of a "configure" script, or raise. If the "configure"
+        is found, a module level attribute is set.
 
-        :raises RuntimeError: if a configure script is not found in
-            :py:meth:`~AutotoolsPackage.configure_directory`
+        Raises:
+             RuntimeError: if the "configure" script is not found
         """
-        # Check if a configure script is there. If not raise a RuntimeError.
+        # Check if the "configure" script is there. If not raise a RuntimeError.
         if not os.path.exists(self.configure_abs_path):
             msg = "configure script not found in {0}"
             raise RuntimeError(msg.format(self.configure_directory))
 
         # Monkey-patch the configure script in the corresponding module
-        inspect.getmodule(self).configure = Executable(self.configure_abs_path)
+        inspect.getmodule(self.pkg).configure = Executable(self.configure_abs_path)
 
     def configure_args(self):
-        """Produces a list containing all the arguments that must be passed to
-        configure, except ``--prefix`` which will be pre-pended to the list.
-
-        :return: list of arguments for configure
+        """Return the list of all the arguments that must be passed to configure,
+        except ``--prefix`` which will be pre-pended to the list.
         """
         return []
 
-    def flags_to_build_system_args(self, flags):
-        """Produces a list of all command line arguments to pass specified
-        compiler flags to configure."""
-        # Has to be dynamic attribute due to caching.
-        setattr(self, "configure_flag_args", [])
-        for flag, values in flags.items():
-            if values:
-                values_str = "{0}={1}".format(flag.upper(), " ".join(values))
-                self.configure_flag_args.append(values_str)
-        # Spack's fflags are meant for both F77 and FC, therefore we
-        # additionaly set FCFLAGS if required.
-        values = flags.get("fflags", None)
-        if values:
-            values_str = "FCFLAGS={0}".format(" ".join(values))
-            self.configure_flag_args.append(values_str)
-
-    def configure(self, spec, prefix):
-        """Runs configure with the arguments specified in
-        :meth:`~spack.build_systems.autotools.AutotoolsPackage.configure_args`
-        and an appropriately set prefix.
+    def configure(self, pkg, spec, prefix):
+        """Run "configure", with the arguments specified by the builder and an
+        appropriately set prefix.
         """
-        options = getattr(self, "configure_flag_args", [])
+        options = getattr(self.pkg, "configure_flag_args", [])
         options += ["--prefix={0}".format(prefix)]
         options += self.configure_args()
 
-        with working_dir(self.build_directory, create=True):
-            inspect.getmodule(self).configure(*options)
+        with fs.working_dir(self.build_directory, create=True):
+            inspect.getmodule(self.pkg).configure(*options)
 
-    def setup_build_environment(self, env):
-        if self.spec.platform == "darwin" and macos_version() >= Version("11"):
-            # Many configure files rely on matching '10.*' for macOS version
-            # detection and fail to add flags if it shows as version 11.
-            env.set("MACOSX_DEPLOYMENT_TARGET", "10.16")
-
-    def build(self, spec, prefix):
-        """Makes the build targets specified by
-        :py:attr:``~.AutotoolsPackage.build_targets``
-        """
+    def build(self, pkg, spec, prefix):
+        """Run "make" on the build targets specified by the builder."""
         # See https://autotools.io/automake/silent.html
         params = ["V=1"]
         params += self.build_targets
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).make(*params)
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).make(*params)
 
-    def install(self, spec, prefix):
-        """Makes the install targets specified by
-        :py:attr:``~.AutotoolsPackage.install_targets``
-        """
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).make(*self.install_targets)
+    def install(self, pkg, spec, prefix):
+        """Run "make" on the install targets specified by the builder."""
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).make(*self.install_targets)
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def check(self):
-        """Searches the Makefile for targets ``test`` and ``check``
-        and runs them if found.
-        """
-        with working_dir(self.build_directory):
-            self._if_make_target_execute("test")
-            self._if_make_target_execute("check")
+        """Run "make" on the ``test`` and ``check`` targets, if found."""
+        with fs.working_dir(self.build_directory):
+            self.pkg._if_make_target_execute("test")
+            self.pkg._if_make_target_execute("check")
 
     def _activate_or_not(
         self, name, activation_word, deactivation_word, activation_value=None, variant=None
     ):
-        """This function contains the current implementation details of
-        :meth:`~spack.build_systems.autotools.AutotoolsPackage.with_or_without` and
-        :meth:`~spack.build_systems.autotools.AutotoolsPackage.enable_or_disable`.
+        """This function contain the current implementation details of
+        :meth:`~spack.build_systems.autotools.AutotoolsBuilder.with_or_without` and
+        :meth:`~spack.build_systems.autotools.AutotoolsBuilder.enable_or_disable`.
 
         Args:
             name (str): name of the option that is being activated or not
@@ -671,7 +687,7 @@ def _activate_or_not(
         Raises:
             KeyError: if name is not among known variants
         """
-        spec = self.spec
+        spec = self.pkg.spec
         args = []
 
         if activation_value == "prefix":
@@ -681,16 +697,16 @@ def _activate_or_not(
 
         # Defensively look that the name passed as argument is among
         # variants
-        if variant not in self.variants:
+        if variant not in self.pkg.variants:
             msg = '"{0}" is not a variant of "{1}"'
-            raise KeyError(msg.format(variant, self.name))
+            raise KeyError(msg.format(variant, self.pkg.name))
 
         if variant not in spec.variants:
             return []
 
         # Create a list of pairs. Each pair includes a configuration
         # option and whether or not that option is activated
-        variant_desc, _ = self.variants[variant]
+        variant_desc, _ = self.pkg.variants[variant]
         if set(variant_desc.values) == set((True, False)):
             # BoolValuedVariant carry information about a single option.
             # Nonetheless, for uniformity of treatment we'll package them
@@ -718,14 +734,18 @@ def _activate_or_not(
             override_name = "{0}_or_{1}_{2}".format(
                 activation_word, deactivation_word, option_value
             )
-            line_generator = getattr(self, override_name, None)
+            line_generator = getattr(self, override_name, None) or getattr(
+                self.pkg, override_name, None
+            )
             # If not available use a sensible default
             if line_generator is None:
 
                 def _default_generator(is_activated):
                     if is_activated:
                         line = "--{0}-{1}".format(activation_word, option_value)
-                        if activation_value is not None and activation_value(option_value):
+                        if activation_value is not None and activation_value(
+                            option_value
+                        ):  # NOQA=ignore=E501
                             line += "={0}".format(activation_value(option_value))
                         return line
                     return "--{0}-{1}".format(deactivation_word, option_value)
@@ -764,7 +784,7 @@ def with_or_without(self, name, activation_value=None, variant=None):
 
     def enable_or_disable(self, name, activation_value=None, variant=None):
         """Same as
-        :meth:`~spack.build_systems.autotools.AutotoolsPackage.with_or_without`
+        :meth:`~spack.build_systems.autotools.AutotoolsBuilder.with_or_without`
         but substitute ``with`` with ``enable`` and ``without`` with ``disable``.
 
         Args:
@@ -781,19 +801,14 @@ def enable_or_disable(self, name, activation_value=None, variant=None):
         """
         return self._activate_or_not(name, "enable", "disable", activation_value, variant)
 
-    run_after("install")(PackageBase._run_default_install_time_test_callbacks)
+    spack.builder.run_after("install")(execute_install_time_tests)
 
     def installcheck(self):
-        """Searches the Makefile for an ``installcheck`` target
-        and runs it if found.
-        """
-        with working_dir(self.build_directory):
-            self._if_make_target_execute("installcheck")
+        """Run "make" on the ``installcheck`` target, if found."""
+        with fs.working_dir(self.build_directory):
+            self.pkg._if_make_target_execute("installcheck")
 
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
-
-    @run_after("install")
+    @spack.builder.run_after("install")
     def remove_libtool_archives(self):
         """Remove all .la files in prefix sub-folders if the package sets
         ``install_libtool_archives`` to be False.
@@ -803,14 +818,20 @@ def remove_libtool_archives(self):
             return
 
         # Remove the files and create a log of what was removed
-        libtool_files = fs.find(str(self.prefix), "*.la", recursive=True)
+        libtool_files = fs.find(str(self.pkg.prefix), "*.la", recursive=True)
         with fs.safe_remove(*libtool_files):
             fs.mkdirp(os.path.dirname(self._removed_la_files_log))
             with open(self._removed_la_files_log, mode="w") as f:
                 f.write("\n".join(libtool_files))
 
+    def setup_build_environment(self, env):
+        if self.spec.platform == "darwin" and macos_version() >= Version("11"):
+            # Many configure files rely on matching '10.*' for macOS version
+            # detection and fail to add flags if it shows as version 11.
+            env.set("MACOSX_DEPLOYMENT_TARGET", "10.16")
+
     # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
-    run_after("install")(PackageBase.apply_macos_rpath_fixups)
+    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
 
 
 def _autoreconf_search_path_args(spec):

lib/spack/spack/build_systems/bundle.py

@@ -0,0 +1,31 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import spack.builder
+import spack.directives
+import spack.package_base
+
+
+class BundlePackage(spack.package_base.PackageBase):
+    """General purpose bundle, or no-code, package class."""
+
+    #: This attribute is used in UI queries that require to know which
+    #: build-system class we are using
+    build_system_class = "BundlePackage"
+
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "bundle"
+
+    #: Bundle packages do not have associated source or binary code.
+    has_code = False
+
+    spack.directives.build_system("bundle")
+
+
+@spack.builder.builder("bundle")
+class BundleBuilder(spack.builder.Builder):
+    phases = ("install",)
+
+    def install(self, pkg, spec, prefix):
+        pass

lib/spack/spack/build_systems/cached_cmake.py

@@ -3,12 +3,14 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
+from typing import Tuple
 
+import llnl.util.filesystem as fs
 import llnl.util.tty as tty
-from llnl.util.filesystem import install, mkdirp
 
-from spack.build_systems.cmake import CMakePackage
-from spack.package_base import run_after
+import spack.builder
+
+from .cmake import CMakeBuilder, CMakePackage
 
 
 def cmake_cache_path(name, value, comment=""):
@@ -28,44 +30,50 @@ def cmake_cache_option(name, boolean_value, comment=""):
     return 'set({0} {1} CACHE BOOL "{2}")\n'.format(name, value, comment)
 
 
-class CachedCMakePackage(CMakePackage):
-    """Specialized class for packages built using CMake initial cache.
+class CachedCMakeBuilder(CMakeBuilder):
 
-    This feature of CMake allows packages to increase reproducibility,
-    especially between Spack- and manual builds. It also allows packages to
-    sidestep certain parsing bugs in extremely long ``cmake`` commands, and to
-    avoid system limits on the length of the command line."""
+    #: Phases of a Cached CMake package
+    #: Note: the initconfig phase is used for developer builds as a final phase to stop on
+    phases = ("initconfig", "cmake", "build", "install")  # type: Tuple[str, ...]
 
-    phases = ["initconfig", "cmake", "build", "install"]
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = CMakeBuilder.legacy_methods + (
+        "initconfig_compiler_entries",
+        "initconfig_mpi_entries",
+        "initconfig_hardware_entries",
+        "std_initconfig_entries",
+        "initconfig_package_entries",
+    )  # type: Tuple[str, ...]
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = CMakeBuilder.legacy_attributes + (
+        "cache_name",
+        "cache_path",
+    )  # type: Tuple[str, ...]
 
     @property
     def cache_name(self):
         return "{0}-{1}-{2}@{3}.cmake".format(
-            self.name,
-            self.spec.architecture,
-            self.spec.compiler.name,
-            self.spec.compiler.version,
+            self.pkg.name,
+            self.pkg.spec.architecture,
+            self.pkg.spec.compiler.name,
+            self.pkg.spec.compiler.version,
         )
 
     @property
     def cache_path(self):
-        return os.path.join(self.stage.source_path, self.cache_name)
-
-    def flag_handler(self, name, flags):
-        if name in ("cflags", "cxxflags", "cppflags", "fflags"):
-            return (None, None, None)  # handled in the cmake cache
-        return (flags, None, None)
+        return os.path.join(self.pkg.stage.source_path, self.cache_name)
 
     def initconfig_compiler_entries(self):
         # This will tell cmake to use the Spack compiler wrappers when run
         # through Spack, but use the underlying compiler when run outside of
         # Spack
-        spec = self.spec
+        spec = self.pkg.spec
 
         # Fortran compiler is optional
         if "FC" in os.environ:
             spack_fc_entry = cmake_cache_path("CMAKE_Fortran_COMPILER", os.environ["FC"])
-            system_fc_entry = cmake_cache_path("CMAKE_Fortran_COMPILER", self.compiler.fc)
+            system_fc_entry = cmake_cache_path("CMAKE_Fortran_COMPILER", self.pkg.compiler.fc)
         else:
             spack_fc_entry = "# No Fortran compiler defined in spec"
             system_fc_entry = "# No Fortran compiler defined in spec"
@@ -81,8 +89,8 @@ def initconfig_compiler_entries(self):
             "  " + cmake_cache_path("CMAKE_CXX_COMPILER", os.environ["CXX"]),
             "  " + spack_fc_entry,
             "else()\n",
-            "  " + cmake_cache_path("CMAKE_C_COMPILER", self.compiler.cc),
-            "  " + cmake_cache_path("CMAKE_CXX_COMPILER", self.compiler.cxx),
+            "  " + cmake_cache_path("CMAKE_C_COMPILER", self.pkg.compiler.cc),
+            "  " + cmake_cache_path("CMAKE_CXX_COMPILER", self.pkg.compiler.cxx),
             "  " + system_fc_entry,
             "endif()\n",
         ]
@@ -126,7 +134,7 @@ def initconfig_compiler_entries(self):
         return entries
 
     def initconfig_mpi_entries(self):
-        spec = self.spec
+        spec = self.pkg.spec
 
         if not spec.satisfies("^mpi"):
             return []
@@ -160,13 +168,13 @@ def initconfig_mpi_entries(self):
                 mpiexec = os.path.join(spec["mpi"].prefix.bin, "mpiexec")
 
         if not os.path.exists(mpiexec):
-            msg = "Unable to determine MPIEXEC, %s tests may fail" % self.name
+            msg = "Unable to determine MPIEXEC, %s tests may fail" % self.pkg.name
             entries.append("# {0}\n".format(msg))
             tty.warn(msg)
         else:
             # starting with cmake 3.10, FindMPI expects MPIEXEC_EXECUTABLE
             # vs the older versions which expect MPIEXEC
-            if self.spec["cmake"].satisfies("@3.10:"):
+            if self.pkg.spec["cmake"].satisfies("@3.10:"):
                 entries.append(cmake_cache_path("MPIEXEC_EXECUTABLE", mpiexec))
             else:
                 entries.append(cmake_cache_path("MPIEXEC", mpiexec))
@@ -180,7 +188,7 @@ def initconfig_mpi_entries(self):
         return entries
 
     def initconfig_hardware_entries(self):
-        spec = self.spec
+        spec = self.pkg.spec
 
         entries = [
             "#------------------{0}".format("-" * 60),
@@ -197,13 +205,7 @@ def initconfig_hardware_entries(self):
             entries.append(cmake_cache_path("CUDA_TOOLKIT_ROOT_DIR", cudatoolkitdir))
             cudacompiler = "${CUDA_TOOLKIT_ROOT_DIR}/bin/nvcc"
             entries.append(cmake_cache_path("CMAKE_CUDA_COMPILER", cudacompiler))
-
-            if spec.satisfies("^mpi"):
-                entries.append(cmake_cache_path("CMAKE_CUDA_HOST_COMPILER", "${MPI_CXX_COMPILER}"))
-            else:
-                entries.append(
-                    cmake_cache_path("CMAKE_CUDA_HOST_COMPILER", "${CMAKE_CXX_COMPILER}")
-                )
+            entries.append(cmake_cache_path("CMAKE_CUDA_HOST_COMPILER", "${CMAKE_CXX_COMPILER}"))
 
         return entries
 
@@ -212,7 +214,7 @@ def std_initconfig_entries(self):
             "#------------------{0}".format("-" * 60),
             "# !!!! This is a generated file, edit at own risk !!!!",
             "#------------------{0}".format("-" * 60),
-            "# CMake executable path: {0}".format(self.spec["cmake"].command.path),
+            "# CMake executable path: {0}".format(self.pkg.spec["cmake"].command.path),
             "#------------------{0}\n".format("-" * 60),
         ]
 
@@ -220,7 +222,7 @@ def initconfig_package_entries(self):
         """This method is to be overwritten by the package"""
         return []
 
-    def initconfig(self, spec, prefix):
+    def initconfig(self, pkg, spec, prefix):
         cache_entries = (
             self.std_initconfig_entries()
             + self.initconfig_compiler_entries()
@@ -236,11 +238,28 @@ def initconfig(self, spec, prefix):
 
     @property
     def std_cmake_args(self):
-        args = super(CachedCMakePackage, self).std_cmake_args
+        args = super(CachedCMakeBuilder, self).std_cmake_args
         args.extend(["-C", self.cache_path])
         return args
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def install_cmake_cache(self):
-        mkdirp(self.spec.prefix.share.cmake)
-        install(self.cache_path, self.spec.prefix.share.cmake)
+        fs.mkdirp(self.pkg.spec.prefix.share.cmake)
+        fs.install(self.cache_path, self.pkg.spec.prefix.share.cmake)
+
+
+class CachedCMakePackage(CMakePackage):
+    """Specialized class for packages built using CMake initial cache.
+
+    This feature of CMake allows packages to increase reproducibility,
+    especially between Spack- and manual builds. It also allows packages to
+    sidestep certain parsing bugs in extremely long ``cmake`` commands, and to
+    avoid system limits on the length of the command line.
+    """
+
+    CMakeBuilder = CachedCMakeBuilder
+
+    def flag_handler(self, name, flags):
+        if name in ("cflags", "cxxflags", "cppflags", "fflags"):
+            return None, None, None  # handled in the cmake cache
+        return flags, None, None

lib/spack/spack/build_systems/cmake.py

@@ -2,23 +2,26 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 import os
 import platform
 import re
 import sys
-from typing import List
+from typing import List, Tuple
 
 import six
 
+import llnl.util.filesystem as fs
 from llnl.util.compat import Sequence
-from llnl.util.filesystem import working_dir
 
 import spack.build_environment
-from spack.directives import conflicts, depends_on, variant
-from spack.package_base import InstallError, PackageBase, run_after
+import spack.builder
+import spack.package_base
+import spack.util.path
+from spack.directives import build_system, depends_on, variant
+from spack.multimethod import when
+
+from ._checks import BaseBuilder, execute_build_time_tests
 
 # Regex to extract the primary generator from the CMake generator
 # string.
@@ -34,56 +37,141 @@ def _extract_primary_generator(generator):
     return primary_generator
 
 
-class CMakePackage(PackageBase):
+class CMakePackage(spack.package_base.PackageBase):
     """Specialized class for packages built using CMake
 
     For more information on the CMake build system, see:
     https://cmake.org/cmake/help/latest/
+    """
 
-    This class provides three phases that can be overridden:
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "CMakePackage"
 
-        1. :py:meth:`~.CMakePackage.cmake`
-        2. :py:meth:`~.CMakePackage.build`
-        3. :py:meth:`~.CMakePackage.install`
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "cmake"
+
+    build_system("cmake")
+
+    with when("build_system=cmake"):
+        # https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html
+        variant(
+            "build_type",
+            default="RelWithDebInfo",
+            description="CMake build type",
+            values=("Debug", "Release", "RelWithDebInfo", "MinSizeRel"),
+        )
+        # CMAKE_INTERPROCEDURAL_OPTIMIZATION only exists for CMake >= 3.9
+        # https://cmake.org/cmake/help/latest/variable/CMAKE_INTERPROCEDURAL_OPTIMIZATION.html
+        variant(
+            "ipo",
+            default=False,
+            when="^cmake@3.9:",
+            description="CMake interprocedural optimization",
+        )
+        depends_on("cmake", type="build")
+        depends_on("ninja", type="build", when="platform=windows")
+
+    def flags_to_build_system_args(self, flags):
+        """Return a list of all command line arguments to pass the specified
+        compiler flags to cmake. Note CMAKE does not have a cppflags option,
+        so cppflags will be added to cflags, cxxflags, and fflags to mimic the
+        behavior in other tools.
+        """
+        # Has to be dynamic attribute due to caching
+        setattr(self, "cmake_flag_args", [])
+
+        flag_string = "-DCMAKE_{0}_FLAGS={1}"
+        langs = {"C": "c", "CXX": "cxx", "Fortran": "f"}
+
+        # Handle language compiler flags
+        for lang, pre in langs.items():
+            flag = pre + "flags"
+            # cmake has no explicit cppflags support -> add it to all langs
+            lang_flags = " ".join(flags.get(flag, []) + flags.get("cppflags", []))
+            if lang_flags:
+                self.cmake_flag_args.append(flag_string.format(lang, lang_flags))
+
+        # Cmake has different linker arguments for different build types.
+        # We specify for each of them.
+        if flags["ldflags"]:
+            ldflags = " ".join(flags["ldflags"])
+            ld_string = "-DCMAKE_{0}_LINKER_FLAGS={1}"
+            # cmake has separate linker arguments for types of builds.
+            for type in ["EXE", "MODULE", "SHARED", "STATIC"]:
+                self.cmake_flag_args.append(ld_string.format(type, ldflags))
+
+        # CMake has libs options separated by language. Apply ours to each.
+        if flags["ldlibs"]:
+            libs_flags = " ".join(flags["ldlibs"])
+            libs_string = "-DCMAKE_{0}_STANDARD_LIBRARIES={1}"
+            for lang in langs:
+                self.cmake_flag_args.append(libs_string.format(lang, libs_flags))
+
+    # Legacy methods (used by too many packages to change them,
+    # need to forward to the builder)
+    def define(self, *args, **kwargs):
+        return self.builder.define(*args, **kwargs)
+
+    def define_from_variant(self, *args, **kwargs):
+        return self.builder.define_from_variant(*args, **kwargs)
+
+
+@spack.builder.builder("cmake")
+class CMakeBuilder(BaseBuilder):
+    """The cmake builder encodes the default way of building software with CMake. IT
+    has three phases that can be overridden:
+
+        1. :py:meth:`~.CMakeBuilder.cmake`
+        2. :py:meth:`~.CMakeBuilder.build`
+        3. :py:meth:`~.CMakeBuilder.install`
 
     They all have sensible defaults and for many packages the only thing
-    necessary will be to override :py:meth:`~.CMakePackage.cmake_args`.
+    necessary will be to override :py:meth:`~.CMakeBuilder.cmake_args`.
+
     For a finer tuning you may also override:
 
         +-----------------------------------------------+--------------------+
         | **Method**                                    | **Purpose**        |
         +===============================================+====================+
-        | :py:meth:`~.CMakePackage.root_cmakelists_dir` | Location of the    |
+        | :py:meth:`~.CMakeBuilder.root_cmakelists_dir` | Location of the    |
         |                                               | root CMakeLists.txt|
         +-----------------------------------------------+--------------------+
-        | :py:meth:`~.CMakePackage.build_directory`     | Directory where to |
+        | :py:meth:`~.CMakeBuilder.build_directory`     | Directory where to |
         |                                               | build the package  |
         +-----------------------------------------------+--------------------+
 
-
-    The generator used by CMake can be specified by providing the
-    generator attribute. Per
+    The generator used by CMake can be specified by providing the ``generator``
+    attribute. Per
     https://cmake.org/cmake/help/git-master/manual/cmake-generators.7.html,
-    the format is: [<secondary-generator> - ]<primary_generator>. The
-    full list of primary and secondary generators supported by CMake may
-    be found in the documentation for the version of CMake used;
-    however, at this time Spack supports only the primary generators
-    "Unix Makefiles" and "Ninja." Spack's CMake support is agnostic with
-    respect to primary generators. Spack will generate a runtime error
-    if the generator string does not follow the prescribed format, or if
+    the format is: [<secondary-generator> - ]<primary_generator>.
+
+    The full list of primary and secondary generators supported by CMake may be found
+    in the documentation for the version of CMake used; however, at this time Spack
+    supports only the primary generators "Unix Makefiles" and "Ninja." Spack's CMake
+    support is agnostic with respect to primary generators. Spack will generate a
+    runtime error if the generator string does not follow the prescribed format, or if
     the primary generator is not supported.
     """
 
     #: Phases of a CMake package
-    phases = ["cmake", "build", "install"]
-    #: This attribute is used in UI queries that need to know the build
-    #: system base class
-    build_system_class = "CMakePackage"
+    phases = ("cmake", "build", "install")  # type: Tuple[str, ...]
 
-    build_targets = []  # type: List[str]
-    install_targets = ["install"]
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("cmake_args", "check")  # type: Tuple[str, ...]
 
-    build_time_test_callbacks = ["check"]
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "generator",
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "archive_files",
+        "root_cmakelists_dir",
+        "std_cmake_args",
+        "build_dirname",
+        "build_directory",
+    )  # type: Tuple[str, ...]
 
     #: The build system generator to use.
     #:
@@ -93,27 +181,14 @@ class CMakePackage(PackageBase):
     #:
     #: See https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html
     #: for more information.
+    generator = "Ninja" if sys.platform == "win32" else "Unix Makefiles"
 
-    generator = "Unix Makefiles"
-
-    if sys.platform == "win32":
-        generator = "Ninja"
-        depends_on("ninja")
-
-    # https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html
-    variant(
-        "build_type",
-        default="RelWithDebInfo",
-        description="CMake build type",
-        values=("Debug", "Release", "RelWithDebInfo", "MinSizeRel"),
-    )
-
-    # https://cmake.org/cmake/help/latest/variable/CMAKE_INTERPROCEDURAL_OPTIMIZATION.html
-    variant("ipo", default=False, description="CMake interprocedural optimization")
-    # CMAKE_INTERPROCEDURAL_OPTIMIZATION only exists for CMake >= 3.9
-    conflicts("+ipo", when="^cmake@:3.8", msg="+ipo is not supported by CMake < 3.9")
-
-    depends_on("cmake", type="build")
+    #: Targets to be used during the build phase
+    build_targets = []  # type: List[str]
+    #: Targets to be used during the install phase
+    install_targets = ["install"]
+    #: Callback names for build-time test
+    build_time_test_callbacks = ["check"]
 
     @property
     def archive_files(self):
@@ -126,40 +201,30 @@ def root_cmakelists_dir(self):
 
         This path is relative to the root of the extracted tarball,
         not to the ``build_directory``. Defaults to the current directory.
-
-        :return: directory containing CMakeLists.txt
         """
-        return self.stage.source_path
+        return self.pkg.stage.source_path
 
     @property
     def std_cmake_args(self):
         """Standard cmake arguments provided as a property for
         convenience of package writers
-
-        :return: standard cmake arguments
         """
         # standard CMake arguments
-        std_cmake_args = CMakePackage._std_args(self)
-        std_cmake_args += getattr(self, "cmake_flag_args", [])
+        std_cmake_args = CMakeBuilder.std_args(self.pkg, generator=self.generator)
+        std_cmake_args += getattr(self.pkg, "cmake_flag_args", [])
         return std_cmake_args
 
     @staticmethod
-    def _std_args(pkg):
+    def std_args(pkg, generator=None):
         """Computes the standard cmake arguments for a generic package"""
-
-        try:
-            generator = pkg.generator
-        except AttributeError:
-            generator = CMakePackage.generator
-
-        # Make sure a valid generator was chosen
+        generator = generator or "Unix Makefiles"
         valid_primary_generators = ["Unix Makefiles", "Ninja"]
         primary_generator = _extract_primary_generator(generator)
         if primary_generator not in valid_primary_generators:
             msg = "Invalid CMake generator: '{0}'\n".format(generator)
             msg += "CMakePackage currently supports the following "
             msg += "primary generators: '{0}'".format("', '".join(valid_primary_generators))
-            raise InstallError(msg)
+            raise spack.package_base.InstallError(msg)
 
         try:
             build_type = pkg.spec.variants["build_type"].value
@@ -171,7 +236,7 @@ def _std_args(pkg):
         except KeyError:
             ipo = False
 
-        define = CMakePackage.define
+        define = CMakeBuilder.define
         args = [
             "-G",
             generator,
@@ -251,7 +316,7 @@ def define_from_variant(self, cmake_var, variant=None):
         of ``cmake_var``.
 
         This utility function is similar to
-        :meth:`~spack.build_systems.autotools.AutotoolsPackage.with_or_without`.
+        :meth:`~spack.build_systems.autotools.AutotoolsBuilder.with_or_without`.
 
         Examples:
 
@@ -291,122 +356,75 @@ def define_from_variant(self, cmake_var, variant=None):
         if variant is None:
             variant = cmake_var.lower()
 
-        if variant not in self.variants:
-            raise KeyError('"{0}" is not a variant of "{1}"'.format(variant, self.name))
+        if variant not in self.pkg.variants:
+            raise KeyError('"{0}" is not a variant of "{1}"'.format(variant, self.pkg.name))
 
-        if variant not in self.spec.variants:
+        if variant not in self.pkg.spec.variants:
             return ""
 
-        value = self.spec.variants[variant].value
+        value = self.pkg.spec.variants[variant].value
         if isinstance(value, (tuple, list)):
             # Sort multi-valued variants for reproducibility
             value = sorted(value)
 
         return self.define(cmake_var, value)
 
-    def flags_to_build_system_args(self, flags):
-        """Produces a list of all command line arguments to pass the specified
-        compiler flags to cmake. Note CMAKE does not have a cppflags option,
-        so cppflags will be added to cflags, cxxflags, and fflags to mimic the
-        behavior in other tools."""
-        # Has to be dynamic attribute due to caching
-        setattr(self, "cmake_flag_args", [])
-
-        flag_string = "-DCMAKE_{0}_FLAGS={1}"
-        langs = {"C": "c", "CXX": "cxx", "Fortran": "f"}
-
-        # Handle language compiler flags
-        for lang, pre in langs.items():
-            flag = pre + "flags"
-            # cmake has no explicit cppflags support -> add it to all langs
-            lang_flags = " ".join(flags.get(flag, []) + flags.get("cppflags", []))
-            if lang_flags:
-                self.cmake_flag_args.append(flag_string.format(lang, lang_flags))
-
-        # Cmake has different linker arguments for different build types.
-        # We specify for each of them.
-        if flags["ldflags"]:
-            ldflags = " ".join(flags["ldflags"])
-            ld_string = "-DCMAKE_{0}_LINKER_FLAGS={1}"
-            # cmake has separate linker arguments for types of builds.
-            for type in ["EXE", "MODULE", "SHARED", "STATIC"]:
-                self.cmake_flag_args.append(ld_string.format(type, ldflags))
-
-        # CMake has libs options separated by language. Apply ours to each.
-        if flags["ldlibs"]:
-            libs_flags = " ".join(flags["ldlibs"])
-            libs_string = "-DCMAKE_{0}_STANDARD_LIBRARIES={1}"
-            for lang in langs:
-                self.cmake_flag_args.append(libs_string.format(lang, libs_flags))
-
     @property
     def build_dirname(self):
-        """Returns the directory name to use when building the package
-
-        :return: name of the subdirectory for building the package
-        """
-        return "spack-build-%s" % self.spec.dag_hash(7)
+        """Directory name to use when building the package."""
+        return "spack-build-%s" % self.pkg.spec.dag_hash(7)
 
     @property
     def build_directory(self):
-        """Returns the directory to use when building the package
-
-        :return: directory where to build the package
-        """
-        return os.path.join(self.stage.path, self.build_dirname)
+        """Full-path to the directory to use when building the package."""
+        return os.path.join(self.pkg.stage.path, self.build_dirname)
 
     def cmake_args(self):
-        """Produces a list containing all the arguments that must be passed to
-        cmake, except:
+        """List of all the arguments that must be passed to cmake, except:
 
             * CMAKE_INSTALL_PREFIX
             * CMAKE_BUILD_TYPE
             * BUILD_TESTING
 
         which will be set automatically.
-
-        :return: list of arguments for cmake
         """
         return []
 
-    def cmake(self, spec, prefix):
+    def cmake(self, pkg, spec, prefix):
         """Runs ``cmake`` in the build directory"""
         options = self.std_cmake_args
         options += self.cmake_args()
         options.append(os.path.abspath(self.root_cmakelists_dir))
-        with working_dir(self.build_directory, create=True):
-            inspect.getmodule(self).cmake(*options)
+        with fs.working_dir(self.build_directory, create=True):
+            inspect.getmodule(self.pkg).cmake(*options)
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Make the build targets"""
-        with working_dir(self.build_directory):
+        with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
-                inspect.getmodule(self).make(*self.build_targets)
+                inspect.getmodule(self.pkg).make(*self.build_targets)
             elif self.generator == "Ninja":
                 self.build_targets.append("-v")
-                inspect.getmodule(self).ninja(*self.build_targets)
+                inspect.getmodule(self.pkg).ninja(*self.build_targets)
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Make the install targets"""
-        with working_dir(self.build_directory):
+        with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
-                inspect.getmodule(self).make(*self.install_targets)
+                inspect.getmodule(self.pkg).make(*self.install_targets)
             elif self.generator == "Ninja":
-                inspect.getmodule(self).ninja(*self.install_targets)
+                inspect.getmodule(self.pkg).ninja(*self.install_targets)
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def check(self):
-        """Searches the CMake-generated Makefile for the target ``test``
-        and runs it if found.
+        """Search the CMake-generated files for the targets ``test`` and ``check``,
+        and runs them if found.
         """
-        with working_dir(self.build_directory):
+        with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
-                self._if_make_target_execute("test", jobs_env="CTEST_PARALLEL_LEVEL")
-                self._if_make_target_execute("check")
+                self.pkg._if_make_target_execute("test", jobs_env="CTEST_PARALLEL_LEVEL")
+                self.pkg._if_make_target_execute("check")
             elif self.generator == "Ninja":
-                self._if_ninja_target_execute("test", jobs_env="CTEST_PARALLEL_LEVEL")
-                self._if_ninja_target_execute("check")
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+                self.pkg._if_ninja_target_execute("test", jobs_env="CTEST_PARALLEL_LEVEL")
+                self.pkg._if_ninja_target_execute("check")

lib/spack/spack/build_systems/generic.py

@@ -0,0 +1,44 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+from typing import Tuple
+
+import spack.builder
+import spack.directives
+import spack.package_base
+
+from ._checks import BaseBuilder, apply_macos_rpath_fixups
+
+
+class Package(spack.package_base.PackageBase):
+    """General purpose class with a single ``install`` phase that needs to be
+    coded by packagers.
+    """
+
+    #: This attribute is used in UI queries that require to know which
+    #: build-system class we are using
+    build_system_class = "Package"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "generic"
+
+    spack.directives.build_system("generic")
+
+
+@spack.builder.builder("generic")
+class GenericBuilder(BaseBuilder):
+    """A builder for a generic build system, that require packagers
+    to implement an "install" phase.
+    """
+
+    #: A generic package has only the "install" phase
+    phases = ("install",)
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ()  # type: Tuple[str, ...]
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("archive_files",)  # type: Tuple[str, ...]
+
+    # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
+    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)

lib/spack/spack/build_systems/intel.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import glob
 import inspect
 import os
@@ -26,12 +24,14 @@
 
 import spack.error
 from spack.build_environment import dso_suffix
-from spack.package_base import InstallError, PackageBase, run_after
+from spack.package_base import InstallError
 from spack.util.environment import EnvironmentModifications
 from spack.util.executable import Executable
 from spack.util.prefix import Prefix
 from spack.version import Version, ver
 
+from .generic import Package
+
 # A couple of utility functions that might be useful in general. If so, they
 # should really be defined elsewhere, unless deemed heretical.
 # (Or na"ive on my part).
@@ -86,7 +86,7 @@ def _expand_fields(s):
     return s
 
 
-class IntelPackage(PackageBase):
+class IntelPackage(Package):
     """Specialized class for licensed Intel software.
 
     This class provides two phases that can be overridden:
@@ -99,9 +99,6 @@ class IntelPackage(PackageBase):
     to set the appropriate environment variables.
     """
 
-    #: Phases of an Intel package
-    phases = ["configure", "install"]
-
     #: This attribute is used in UI queries that need to know the build
     #: system base class
     build_system_class = "IntelPackage"
@@ -1184,12 +1181,13 @@ def _determine_license_type(self):
         debug_print(license_type)
         return license_type
 
-    def configure(self, spec, prefix):
+    @spack.builder.run_before("install")
+    def configure(self):
         """Generates the silent.cfg file to pass to installer.sh.
 
         See https://software.intel.com/en-us/articles/configuration-file-format
         """
-
+        prefix = self.prefix
         # Both tokens AND values of the configuration file are validated during
         # the run of the underlying binary installer. Any unknown token or
         # unacceptable value will cause that installer to fail.  Notably, this
@@ -1270,7 +1268,7 @@ def install(self, spec, prefix):
         for f in glob.glob("%s/intel*log" % tmpdir):
             install(f, dst)
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def validate_install(self):
         # Sometimes the installer exits with an error but doesn't pass a
         # non-zero exit code to spack. Check for the existence of a 'bin'
@@ -1278,7 +1276,7 @@ def validate_install(self):
         if not os.path.exists(self.prefix.bin):
             raise InstallError("The installer has failed to install anything.")
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def configure_rpath(self):
         if "+rpath" not in self.spec:
             return
@@ -1296,7 +1294,7 @@ def configure_rpath(self):
             with open(compiler_cfg, "w") as fh:
                 fh.write("-Xlinker -rpath={0}\n".format(compilers_lib_dir))
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def configure_auto_dispatch(self):
         if self._has_compilers:
             if "auto_dispatch=none" in self.spec:
@@ -1320,7 +1318,7 @@ def configure_auto_dispatch(self):
                 with open(compiler_cfg, "a") as fh:
                     fh.write("-ax{0}\n".format(",".join(ad)))
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def filter_compiler_wrappers(self):
         if ("+mpi" in self.spec or self.provides("mpi")) and "~newdtags" in self.spec:
             bin_dir = self.component_bin_dir("mpi")
@@ -1328,7 +1326,7 @@ def filter_compiler_wrappers(self):
                 f = os.path.join(bin_dir, f)
                 filter_file("-Xlinker --enable-new-dtags", " ", f, string=True)
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def uninstall_ism(self):
         # The "Intel(R) Software Improvement Program" [ahem] gets installed,
         # apparently regardless of PHONEHOME_SEND_USAGE_DATA.
@@ -1360,7 +1358,7 @@ def base_lib_dir(self):
         debug_print(d)
         return d
 
-    @run_after("install")
+    @spack.builder.run_after("install")
     def modify_LLVMgold_rpath(self):
         """Add libimf.so and other required libraries to the RUNPATH of LLVMgold.so.
 
@@ -1391,6 +1389,3 @@ def modify_LLVMgold_rpath(self):
                     ]
                 )
                 patchelf("--set-rpath", rpath, lib)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/lua.py

@@ -2,59 +2,82 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import os
 
 from llnl.util.filesystem import find
 
-from spack.directives import depends_on, extends
+import spack.builder
+import spack.package_base
+import spack.util.executable
+from spack.directives import build_system, depends_on, extends
 from spack.multimethod import when
-from spack.package_base import PackageBase
-from spack.util.executable import Executable
 
 
-class LuaPackage(PackageBase):
+class LuaPackage(spack.package_base.PackageBase):
     """Specialized class for lua packages"""
 
-    phases = ["unpack", "generate_luarocks_config", "preprocess", "install"]
     #: This attribute is used in UI queries that need to know the build
     #: system base class
     build_system_class = "LuaPackage"
 
-    list_depth = 1  # LuaRocks requires at least one level of spidering to find versions
-    depends_on("lua-lang")
-    extends("lua", when="^lua")
-    with when("^lua-luajit"):
-        extends("lua-luajit")
-        depends_on("luajit")
-        depends_on("lua-luajit+lualinks")
-    with when("^lua-luajit-openresty"):
-        extends("lua-luajit-openresty")
-        depends_on("luajit")
-        depends_on("lua-luajit-openresty+lualinks")
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "lua"
 
-    def unpack(self, spec, prefix):
-        if os.path.splitext(self.stage.archive_file)[1] == ".rock":
-            directory = self.luarocks("unpack", self.stage.archive_file, output=str)
+    list_depth = 1  # LuaRocks requires at least one level of spidering to find versions
+
+    build_system("lua")
+
+    with when("build_system=lua"):
+        depends_on("lua-lang")
+        extends("lua", when="^lua")
+        with when("^lua-luajit"):
+            extends("lua-luajit")
+            depends_on("luajit")
+            depends_on("lua-luajit+lualinks")
+        with when("^lua-luajit-openresty"):
+            extends("lua-luajit-openresty")
+            depends_on("luajit")
+            depends_on("lua-luajit-openresty+lualinks")
+
+    @property
+    def lua(self):
+        return spack.util.executable.Executable(self.spec["lua-lang"].prefix.bin.lua)
+
+    @property
+    def luarocks(self):
+        lr = spack.util.executable.Executable(self.spec["lua-lang"].prefix.bin.luarocks)
+        return lr
+
+
+@spack.builder.builder("lua")
+class LuaBuilder(spack.builder.Builder):
+    phases = ("unpack", "generate_luarocks_config", "preprocess", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("luarocks_args",)
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ()
+
+    def unpack(self, pkg, spec, prefix):
+        if os.path.splitext(pkg.stage.archive_file)[1] == ".rock":
+            directory = pkg.luarocks("unpack", pkg.stage.archive_file, output=str)
             dirlines = directory.split("\n")
             # TODO: figure out how to scope this better
             os.chdir(dirlines[2])
 
-    def _generate_tree_line(self, name, prefix):
+    @staticmethod
+    def _generate_tree_line(name, prefix):
         return """{{ name = "{name}", root = "{prefix}" }};""".format(
             name=name,
             prefix=prefix,
         )
 
-    def _luarocks_config_path(self):
-        return os.path.join(self.stage.source_path, "spack_luarocks.lua")
-
-    def generate_luarocks_config(self, spec, prefix):
-        spec = self.spec
+    def generate_luarocks_config(self, pkg, spec, prefix):
+        spec = self.pkg.spec
         table_entries = []
-        for d in spec.traverse(deptypes=("build", "run"), deptype_query="run"):
-            if d.package.extends(self.extendee_spec):
+        for d in spec.traverse(deptype=("build", "run")):
+            if d.package.extends(self.pkg.extendee_spec):
                 table_entries.append(self._generate_tree_line(d.name, d.prefix))
 
         path = self._luarocks_config_path()
@@ -71,30 +94,24 @@ def generate_luarocks_config(self, spec, prefix):
             )
         return path
 
-    def setup_build_environment(self, env):
-        env.set("LUAROCKS_CONFIG", self._luarocks_config_path())
-
-    def preprocess(self, spec, prefix):
+    def preprocess(self, pkg, spec, prefix):
         """Override this to preprocess source before building with luarocks"""
         pass
 
-    @property
-    def lua(self):
-        return Executable(self.spec["lua-lang"].prefix.bin.lua)
-
-    @property
-    def luarocks(self):
-        lr = Executable(self.spec["lua-lang"].prefix.bin.luarocks)
-        return lr
-
     def luarocks_args(self):
         return []
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         rock = "."
         specs = find(".", "*.rockspec", recursive=False)
         if specs:
             rock = specs[0]
         rocks_args = self.luarocks_args()
         rocks_args.append(rock)
-        self.luarocks("--tree=" + prefix, "make", *rocks_args)
+        self.pkg.luarocks("--tree=" + prefix, "make", *rocks_args)
+
+    def _luarocks_config_path(self):
+        return os.path.join(self.pkg.stage.source_path, "spack_luarocks.lua")
+
+    def setup_build_environment(self, env):
+        env.set("LUAROCKS_CONFIG", self._luarocks_config_path())

lib/spack/spack/build_systems/makefile.py

@@ -2,62 +2,85 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 from typing import List  # novm
 
-import llnl.util.tty as tty
-from llnl.util.filesystem import working_dir
+import llnl.util.filesystem as fs
 
-from spack.directives import conflicts
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, conflicts
+
+from ._checks import (
+    BaseBuilder,
+    apply_macos_rpath_fixups,
+    execute_build_time_tests,
+    execute_install_time_tests,
+)
 
 
-class MakefilePackage(PackageBase):
-    """Specialized class for packages that are built using editable Makefiles
+class MakefilePackage(spack.package_base.PackageBase):
+    """Specialized class for packages built using a Makefiles."""
 
-    This class provides three phases that can be overridden:
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "MakefilePackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "makefile"
 
-        1. :py:meth:`~.MakefilePackage.edit`
-        2. :py:meth:`~.MakefilePackage.build`
-        3. :py:meth:`~.MakefilePackage.install`
+    build_system("makefile")
+    conflicts("platform=windows", when="build_system=makefile")
+
+
+@spack.builder.builder("makefile")
+class MakefileBuilder(BaseBuilder):
+    """The Makefile builder encodes the most common way of building software with
+    Makefiles. It has three phases that can be overridden, if need be:
+
+            1. :py:meth:`~.MakefileBuilder.edit`
+            2. :py:meth:`~.MakefileBuilder.build`
+            3. :py:meth:`~.MakefileBuilder.install`
+
+    It is usually necessary to override the :py:meth:`~.MakefileBuilder.edit`
+    phase (which is by default a no-op), while the other two have sensible defaults.
 
-    It is usually necessary to override the :py:meth:`~.MakefilePackage.edit`
-    phase, while :py:meth:`~.MakefilePackage.build` and
-    :py:meth:`~.MakefilePackage.install` have sensible defaults.
     For a finer tuning you may override:
 
         +-----------------------------------------------+--------------------+
         | **Method**                                    | **Purpose**        |
         +===============================================+====================+
-        | :py:attr:`~.MakefilePackage.build_targets`    | Specify ``make``   |
+        | :py:attr:`~.MakefileBuilder.build_targets`    | Specify ``make``   |
         |                                               | targets for the    |
         |                                               | build phase        |
         +-----------------------------------------------+--------------------+
-        | :py:attr:`~.MakefilePackage.install_targets`  | Specify ``make``   |
+        | :py:attr:`~.MakefileBuilder.install_targets`  | Specify ``make``   |
         |                                               | targets for the    |
         |                                               | install phase      |
         +-----------------------------------------------+--------------------+
-        | :py:meth:`~.MakefilePackage.build_directory`  | Directory where the|
+        | :py:meth:`~.MakefileBuilder.build_directory`  | Directory where the|
         |                                               | Makefile is located|
         +-----------------------------------------------+--------------------+
     """
 
-    #: Phases of a package that is built with an hand-written Makefile
-    phases = ["edit", "build", "install"]
-    #: This attribute is used in UI queries that need to know the build
-    #: system base class
-    build_system_class = "MakefilePackage"
+    phases = ("edit", "build", "install")
 
-    #: Targets for ``make`` during the :py:meth:`~.MakefilePackage.build`
-    #: phase
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("check", "installcheck")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "install_time_test_callbacks",
+        "build_directory",
+    )
+
+    #: Targets for ``make`` during the :py:meth:`~.MakefileBuilder.build` phase
     build_targets = []  # type: List[str]
-    #: Targets for ``make`` during the :py:meth:`~.MakefilePackage.install`
-    #: phase
+    #: Targets for ``make`` during the :py:meth:`~.MakefileBuilder.install` phase
     install_targets = ["install"]
 
-    conflicts("platform=windows")
     #: Callback names for build-time test
     build_time_test_callbacks = ["check"]
 
@@ -66,53 +89,39 @@ class MakefilePackage(PackageBase):
 
     @property
     def build_directory(self):
-        """Returns the directory containing the main Makefile
+        """Return the directory containing the main Makefile."""
+        return self.pkg.stage.source_path
 
-        :return: build directory
-        """
-        return self.stage.source_path
+    def edit(self, pkg, spec, prefix):
+        """Edit the Makefile before calling make. The default is a no-op."""
+        pass
 
-    def edit(self, spec, prefix):
-        """Edits the Makefile before calling make. This phase cannot
-        be defaulted.
-        """
-        tty.msg("Using default implementation: skipping edit phase.")
+    def build(self, pkg, spec, prefix):
+        """Run "make" on the build targets specified by the builder."""
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).make(*self.build_targets)
 
-    def build(self, spec, prefix):
-        """Calls make, passing :py:attr:`~.MakefilePackage.build_targets`
-        as targets.
-        """
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).make(*self.build_targets)
+    def install(self, pkg, spec, prefix):
+        """Run "make" on the install targets specified by the builder."""
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).make(*self.install_targets)
 
-    def install(self, spec, prefix):
-        """Calls make, passing :py:attr:`~.MakefilePackage.install_targets`
-        as targets.
-        """
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).make(*self.install_targets)
-
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def check(self):
-        """Searches the Makefile for targets ``test`` and ``check``
-        and runs them if found.
-        """
-        with working_dir(self.build_directory):
-            self._if_make_target_execute("test")
-            self._if_make_target_execute("check")
+        """Run "make" on the ``test`` and ``check`` targets, if found."""
+        with fs.working_dir(self.build_directory):
+            self.pkg._if_make_target_execute("test")
+            self.pkg._if_make_target_execute("check")
 
-    run_after("install")(PackageBase._run_default_install_time_test_callbacks)
+    spack.builder.run_after("install")(execute_install_time_tests)
 
     def installcheck(self):
         """Searches the Makefile for an ``installcheck`` target
         and runs it if found.
         """
-        with working_dir(self.build_directory):
-            self._if_make_target_execute("installcheck")
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+        with fs.working_dir(self.build_directory):
+            self.pkg._if_make_target_execute("installcheck")
 
     # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
-    run_after("install")(PackageBase.apply_macos_rpath_fixups)
+    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)

lib/spack/spack/build_systems/maven.py

@@ -2,60 +2,73 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import llnl.util.filesystem as fs
 
-
-from llnl.util.filesystem import install_tree, working_dir
-
-from spack.directives import depends_on
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on
+from spack.multimethod import when
 from spack.util.executable import which
 
+from ._checks import BaseBuilder
 
-class MavenPackage(PackageBase):
+
+class MavenPackage(spack.package_base.PackageBase):
     """Specialized class for packages that are built using the
     Maven build system. See https://maven.apache.org/index.html
     for more information.
-
-    This class provides the following phases that can be overridden:
-
-    * build
-    * install
     """
 
-    # Default phases
-    phases = ["build", "install"]
-
     # To be used in UI queries that require to know which
     # build-system class we are using
     build_system_class = "MavenPackage"
 
-    depends_on("java", type=("build", "run"))
-    depends_on("maven", type="build")
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "maven"
+
+    build_system("maven")
+
+    with when("build_system=maven"):
+        depends_on("java", type=("build", "run"))
+        depends_on("maven", type="build")
+
+
+@spack.builder.builder("maven")
+class MavenBuilder(BaseBuilder):
+    """The Maven builder encodes the default way to build software with Maven.
+    It has two phases that can be overridden, if need be:
+
+        1. :py:meth:`~.MavenBuilder.build`
+        2. :py:meth:`~.MavenBuilder.install`
+    """
+
+    phases = ("build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("build_args",)
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("build_directory",)
 
     @property
     def build_directory(self):
         """The directory containing the ``pom.xml`` file."""
-        return self.stage.source_path
+        return self.pkg.stage.source_path
 
     def build_args(self):
         """List of args to pass to build phase."""
         return []
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Compile code and package into a JAR file."""
-
-        with working_dir(self.build_directory):
+        with fs.working_dir(self.build_directory):
             mvn = which("mvn")
-            if self.run_tests:
+            if self.pkg.run_tests:
                 mvn("verify", *self.build_args())
             else:
                 mvn("package", "-DskipTests", *self.build_args())
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Copy to installation prefix."""
-
-        with working_dir(self.build_directory):
-            install_tree(".", prefix)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+        with fs.working_dir(self.build_directory):
+            fs.install_tree(".", prefix)

lib/spack/spack/build_systems/meson.py

@@ -2,76 +2,104 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 import os
 from typing import List  # novm
 
-from llnl.util.filesystem import working_dir
+import llnl.util.filesystem as fs
 
-from spack.directives import depends_on, variant
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on, variant
+from spack.multimethod import when
+
+from ._checks import BaseBuilder, execute_build_time_tests
 
 
-class MesonPackage(PackageBase):
-    """Specialized class for packages built using Meson
+class MesonPackage(spack.package_base.PackageBase):
+    """Specialized class for packages built using Meson. For more information
+    on the Meson build system, see https://mesonbuild.com/
+    """
 
-    For more information on the Meson build system, see:
-    https://mesonbuild.com/
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "MesonPackage"
 
-    This class provides three phases that can be overridden:
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "meson"
 
-        1. :py:meth:`~.MesonPackage.meson`
-        2. :py:meth:`~.MesonPackage.build`
-        3. :py:meth:`~.MesonPackage.install`
+    build_system("meson")
+
+    with when("build_system=meson"):
+        variant(
+            "buildtype",
+            default="debugoptimized",
+            description="Meson build type",
+            values=("plain", "debug", "debugoptimized", "release", "minsize"),
+        )
+        variant(
+            "default_library",
+            default="shared",
+            values=("shared", "static"),
+            multi=True,
+            description="Build shared libs, static libs or both",
+        )
+        variant("strip", default=False, description="Strip targets on install")
+        depends_on("meson", type="build")
+        depends_on("ninja", type="build")
+
+    def flags_to_build_system_args(self, flags):
+        """Produces a list of all command line arguments to pass the specified
+        compiler flags to meson."""
+        # Has to be dynamic attribute due to caching
+        setattr(self, "meson_flag_args", [])
+
+
+@spack.builder.builder("meson")
+class MesonBuilder(BaseBuilder):
+    """The Meson builder encodes the default way to build software with Meson.
+    The builder has three phases that can be overridden, if need be:
+
+            1. :py:meth:`~.MesonBuilder.meson`
+            2. :py:meth:`~.MesonBuilder.build`
+            3. :py:meth:`~.MesonBuilder.install`
 
     They all have sensible defaults and for many packages the only thing
-    necessary will be to override :py:meth:`~.MesonPackage.meson_args`.
+    necessary will be to override :py:meth:`~.MesonBuilder.meson_args`.
+
     For a finer tuning you may also override:
 
         +-----------------------------------------------+--------------------+
         | **Method**                                    | **Purpose**        |
         +===============================================+====================+
-        | :py:meth:`~.MesonPackage.root_mesonlists_dir` | Location of the    |
+        | :py:meth:`~.MesonBuilder.root_mesonlists_dir` | Location of the    |
         |                                               | root MesonLists.txt|
         +-----------------------------------------------+--------------------+
-        | :py:meth:`~.MesonPackage.build_directory`     | Directory where to |
+        | :py:meth:`~.MesonBuilder.build_directory`     | Directory where to |
         |                                               | build the package  |
         +-----------------------------------------------+--------------------+
-
-
     """
 
-    #: Phases of a Meson package
-    phases = ["meson", "build", "install"]
-    #: This attribute is used in UI queries that need to know the build
-    #: system base class
-    build_system_class = "MesonPackage"
+    phases = ("meson", "build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("meson_args", "check")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "root_mesonlists_dir",
+        "std_meson_args",
+        "build_directory",
+    )
 
     build_targets = []  # type: List[str]
     install_targets = ["install"]
 
     build_time_test_callbacks = ["check"]
 
-    variant(
-        "buildtype",
-        default="debugoptimized",
-        description="Meson build type",
-        values=("plain", "debug", "debugoptimized", "release", "minsize"),
-    )
-    variant(
-        "default_library",
-        default="shared",
-        values=("shared", "static"),
-        multi=True,
-        description="Build shared libs, static libs or both",
-    )
-    variant("strip", default=False, description="Strip targets on install")
-
-    depends_on("meson", type="build")
-    depends_on("ninja", type="build")
-
     @property
     def archive_files(self):
         """Files to archive for packages based on Meson"""
@@ -79,31 +107,26 @@ def archive_files(self):
 
     @property
     def root_mesonlists_dir(self):
-        """The relative path to the directory containing meson.build
+        """Relative path to the directory containing meson.build
 
         This path is relative to the root of the extracted tarball,
         not to the ``build_directory``. Defaults to the current directory.
-
-        :return: directory containing meson.build
         """
-        return self.stage.source_path
+        return self.pkg.stage.source_path
 
     @property
     def std_meson_args(self):
-        """Standard meson arguments provided as a property for
-        convenience of package writers
-
-        :return: standard meson arguments
+        """Standard meson arguments provided as a property for convenience
+        of package writers.
         """
         # standard Meson arguments
-        std_meson_args = MesonPackage._std_args(self)
+        std_meson_args = MesonBuilder.std_args(self.pkg)
         std_meson_args += getattr(self, "meson_flag_args", [])
         return std_meson_args
 
     @staticmethod
-    def _std_args(pkg):
-        """Computes the standard meson arguments for a generic package"""
-
+    def std_args(pkg):
+        """Standard meson arguments for a generic package."""
         try:
             build_type = pkg.spec.variants["buildtype"].value
         except KeyError:
@@ -119,44 +142,33 @@ def _std_args(pkg):
             default_library = "shared"
 
         args = [
-            "--prefix={0}".format(pkg.prefix),
+            "-Dprefix={0}".format(pkg.prefix),
             # If we do not specify libdir explicitly, Meson chooses something
             # like lib/x86_64-linux-gnu, which causes problems when trying to
             # find libraries and pkg-config files.
             # See https://github.com/mesonbuild/meson/issues/2197
-            "--libdir={0}".format(pkg.prefix.lib),
+            "-Dlibdir={0}".format(pkg.prefix.lib),
             "-Dbuildtype={0}".format(build_type),
             "-Dstrip={0}".format(strip),
             "-Ddefault_library={0}".format(default_library),
+            # Do not automatically download and install dependencies
+            "-Dwrap_mode=nodownload",
         ]
 
         return args
 
-    def flags_to_build_system_args(self, flags):
-        """Produces a list of all command line arguments to pass the specified
-        compiler flags to meson."""
-        # Has to be dynamic attribute due to caching
-        setattr(self, "meson_flag_args", [])
-
     @property
     def build_dirname(self):
-        """Returns the directory name to use when building the package
-
-        :return: name of the subdirectory for building the package
-        """
-        return "spack-build-%s" % self.spec.dag_hash(7)
+        """Returns the directory name to use when building the package."""
+        return "spack-build-{}".format(self.spec.dag_hash(7))
 
     @property
     def build_directory(self):
-        """Returns the directory to use when building the package
-
-        :return: directory where to build the package
-        """
-        return os.path.join(self.stage.path, self.build_dirname)
+        """Directory to use when building the package."""
+        return os.path.join(self.pkg.stage.path, self.build_dirname)
 
     def meson_args(self):
-        """Produces a list containing all the arguments that must be passed to
-        meson, except:
+        """List of arguments that must be passed to meson, except:
 
         * ``--prefix``
         * ``--libdir``
@@ -165,40 +177,33 @@ def meson_args(self):
         * ``--default_library``
 
         which will be set automatically.
-
-        :return: list of arguments for meson
         """
         return []
 
-    def meson(self, spec, prefix):
-        """Runs ``meson`` in the build directory"""
+    def meson(self, pkg, spec, prefix):
+        """Run ``meson`` in the build directory"""
         options = [os.path.abspath(self.root_mesonlists_dir)]
         options += self.std_meson_args
         options += self.meson_args()
-        with working_dir(self.build_directory, create=True):
-            inspect.getmodule(self).meson(*options)
+        with fs.working_dir(self.build_directory, create=True):
+            inspect.getmodule(self.pkg).meson(*options)
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Make the build targets"""
         options = ["-v"]
         options += self.build_targets
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).ninja(*options)
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).ninja(*options)
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Make the install targets"""
-        with working_dir(self.build_directory):
-            inspect.getmodule(self).ninja(*self.install_targets)
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).ninja(*self.install_targets)
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def check(self):
-        """Searches the Meson-generated file for the target ``test``
-        and runs it if found.
-        """
-        with working_dir(self.build_directory):
+        """Search Meson-generated files for the target ``test`` and run it if found."""
+        with fs.working_dir(self.build_directory):
             self._if_ninja_target_execute("test")
             self._if_ninja_target_execute("check")
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/nmake.py

@@ -0,0 +1,102 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import inspect
+from typing import List  # novm
+
+import llnl.util.filesystem as fs
+
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, conflicts
+
+from ._checks import BaseBuilder
+
+
+class NMakePackage(spack.package_base.PackageBase):
+    """Specialized class for packages built using a Makefiles."""
+
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "NmakePackage"
+
+    build_system("nmake")
+    conflicts("platform=linux", when="build_system=nmake")
+    conflicts("platform=darwin", when="build_system=nmake")
+    conflicts("platform=cray", when="build_system=nmake")
+
+
+@spack.builder.builder("nmake")
+class NMakeBuilder(BaseBuilder):
+    """The NMake builder encodes the most common way of building software with
+    NMake on Windows. It has three phases that can be overridden, if need be:
+
+            1. :py:meth:`~.NMakeBuilder.edit`
+            2. :py:meth:`~.NMakeBuilder.build`
+            3. :py:meth:`~.NMakeBuilder.install`
+
+    It is usually necessary to override the :py:meth:`~.NMakeBuilder.edit`
+    phase (which is by default a no-op), while the other two have sensible defaults.
+
+    For a finer tuning you may override:
+
+            +--------------------------------------------+--------------------+
+            | **Method**                                 | **Purpose**        |
+            +============================================+====================+
+            | :py:attr:`~.NMakeBuilder.build_targets`    | Specify ``nmake``  |
+            |                                            | targets for the    |
+            |                                            | build phase        |
+            +--------------------------------------------+--------------------+
+            | :py:attr:`~.NMakeBuilder.install_targets`  | Specify ``nmake``  |
+            |                                            | targets for the    |
+            |                                            | install phase      |
+            +--------------------------------------------+--------------------+
+            | :py:meth:`~.NMakeBuilder.build_directory`  | Directory where the|
+            |                                            | Makefile is located|
+            +--------------------------------------------+--------------------+
+    """
+
+    phases = ("edit", "build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("check", "installcheck")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "install_time_test_callbacks",
+        "build_directory",
+    )
+
+    #: Targets for ``make`` during the :py:meth:`~.NMakeBuilder.build` phase
+    build_targets = []  # type: List[str]
+    #: Targets for ``make`` during the :py:meth:`~.NMakeBuilder.install` phase
+    install_targets = ["install"]
+
+    #: Callback names for build-time test
+    build_time_test_callbacks = ["check"]
+
+    #: Callback names for install-time test
+    install_time_test_callbacks = ["installcheck"]
+
+    @property
+    def build_directory(self):
+        """Return the directory containing the main Makefile."""
+        return self.pkg.stage.source_path
+
+    def edit(self, pkg, spec, prefix):
+        """Edit the Makefile before calling make. The default is a no-op."""
+        pass
+
+    def build(self, pkg, spec, prefix):
+        """Run "make" on the build targets specified by the builder."""
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).nmake(*self.build_targets)
+
+    def install(self, pkg, spec, prefix):
+        """Run "make" on the install targets specified by the builder."""
+        with fs.working_dir(self.build_directory):
+            inspect.getmodule(self.pkg).nmake(*self.install_targets)

lib/spack/spack/build_systems/octave.py

@@ -2,51 +2,62 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
 import inspect
 
-from spack.directives import extends
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, extends
+from spack.multimethod import when
+
+from ._checks import BaseBuilder
 
 
-class OctavePackage(PackageBase):
+class OctavePackage(spack.package_base.PackageBase):
     """Specialized class for Octave packages. See
     https://www.gnu.org/software/octave/doc/v4.2.0/Installing-and-Removing-Packages.html
     for more information.
-
-    This class provides the following phases that can be overridden:
-
-    1. :py:meth:`~.OctavePackage.install`
-
     """
 
-    # Default phases
-    phases = ["install"]
-
     # To be used in UI queries that require to know which
     # build-system class we are using
     build_system_class = "OctavePackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "octave"
 
-    extends("octave")
+    build_system("octave")
+
+    with when("build_system=octave"):
+        extends("octave")
+
+
+@spack.builder.builder("octave")
+class OctaveBuilder(BaseBuilder):
+    """The octave builder provides the following phases that can be overridden:
+
+    1. :py:meth:`~.OctaveBuilder.install`
+    """
+
+    phases = ("install",)
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ()
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ()
+
+    def install(self, pkg, spec, prefix):
+        """Install the package from the archive file"""
+        inspect.getmodule(self.pkg).octave(
+            "--quiet",
+            "--norc",
+            "--built-in-docstrings-file=/dev/null",
+            "--texi-macros-file=/dev/null",
+            "--eval",
+            "pkg prefix %s; pkg install %s" % (prefix, self.pkg.stage.archive_file),
+        )
 
     def setup_build_environment(self, env):
         # octave does not like those environment variables to be set:
         env.unset("CC")
         env.unset("CXX")
         env.unset("FC")
-
-    def install(self, spec, prefix):
-        """Install the package from the archive file"""
-        inspect.getmodule(self).octave(
-            "--quiet",
-            "--norc",
-            "--built-in-docstrings-file=/dev/null",
-            "--texi-macros-file=/dev/null",
-            "--eval",
-            "pkg prefix %s; pkg install %s" % (prefix, self.stage.archive_file),
-        )
-
-    # Testing
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/oneapi.py

@@ -2,11 +2,7 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-"""Common utilities for managing intel oneapi packages.
-
-"""
-
+"""Common utilities for managing intel oneapi packages."""
 import getpass
 import platform
 import shutil
@@ -14,18 +10,17 @@
 
 from llnl.util.filesystem import find_headers, find_libraries, join_path
 
-from spack.package_base import Package
 from spack.util.environment import EnvironmentModifications
 from spack.util.executable import Executable
 
+from .generic import Package
+
 
 class IntelOneApiPackage(Package):
     """Base class for Intel oneAPI packages."""
 
     homepage = "https://software.intel.com/oneapi"
 
-    phases = ["install"]
-
     # oneAPI license does not allow mirroring outside of the
     # organization (e.g. University/Company).
     redistribute_source = False

lib/spack/spack/build_systems/perl.py

@@ -2,73 +2,87 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 import os
 
 from llnl.util.filesystem import filter_file
 
-from spack.directives import extends
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, extends
+from spack.package_base import PackageBase
 from spack.util.executable import Executable
 
+from ._checks import BaseBuilder, execute_build_time_tests
+
 
 class PerlPackage(PackageBase):
-    """Specialized class for packages that are built using Perl.
+    """Specialized class for packages that are built using Perl."""
 
-    This class provides four phases that can be overridden if required:
+    #: This attribute is used in UI queries that need to know the build
+    #: system base class
+    build_system_class = "PerlPackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "perl"
 
-        1. :py:meth:`~.PerlPackage.configure`
-        2. :py:meth:`~.PerlPackage.build`
-        3. :py:meth:`~.PerlPackage.check`
-        4. :py:meth:`~.PerlPackage.install`
+    build_system("perl")
+
+    extends("perl", when="build_system=perl")
+
+
+@spack.builder.builder("perl")
+class PerlBuilder(BaseBuilder):
+    """The perl builder provides four phases that can be overridden, if required:
+
+        1. :py:meth:`~.PerlBuilder.configure`
+        2. :py:meth:`~.PerlBuilder.build`
+        3. :py:meth:`~.PerlBuilder.check`
+        4. :py:meth:`~.PerlBuilder.install`
 
     The default methods use, in order of preference:
         (1) Makefile.PL,
         (2) Build.PL.
 
-    Some packages may need to override
-    :py:meth:`~.PerlPackage.configure_args`,
-    which produces a list of arguments for
-    :py:meth:`~.PerlPackage.configure`.
+    Some packages may need to override :py:meth:`~.PerlBuilder.configure_args`,
+    which produces a list of arguments for :py:meth:`~.PerlBuilder.configure`.
+
     Arguments should not include the installation base directory.
     """
 
     #: Phases of a Perl package
-    phases = ["configure", "build", "install"]
+    phases = ("configure", "build", "install")
 
-    #: This attribute is used in UI queries that need to know the build
-    #: system base class
-    build_system_class = "PerlPackage"
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("configure_args", "check")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ()
 
     #: Callback names for build-time test
     build_time_test_callbacks = ["check"]
 
-    extends("perl")
-
     def configure_args(self):
-        """Produces a list containing the arguments that must be passed to
-        :py:meth:`~.PerlPackage.configure`. Arguments should not include
-        the installation base directory, which is prepended automatically.
+        """List of arguments passed to :py:meth:`~.PerlBuilder.configure`.
 
-        :return: list of arguments for Makefile.PL or Build.PL
+        Arguments should not include the installation base directory, which
+        is prepended automatically.
         """
         return []
 
-    def configure(self, spec, prefix):
-        """Runs Makefile.PL or Build.PL with arguments consisting of
+    def configure(self, pkg, spec, prefix):
+        """Run Makefile.PL or Build.PL with arguments consisting of
         an appropriate installation base directory followed by the
-        list returned by :py:meth:`~.PerlPackage.configure_args`.
+        list returned by :py:meth:`~.PerlBuilder.configure_args`.
 
-        :raise RuntimeError: if neither Makefile.PL or Build.PL exist
+        Raises:
+            RuntimeError: if neither Makefile.PL nor Build.PL exist
         """
         if os.path.isfile("Makefile.PL"):
             self.build_method = "Makefile.PL"
-            self.build_executable = inspect.getmodule(self).make
+            self.build_executable = inspect.getmodule(self.pkg).make
         elif os.path.isfile("Build.PL"):
             self.build_method = "Build.PL"
-            self.build_executable = Executable(os.path.join(self.stage.source_path, "Build"))
+            self.build_executable = Executable(os.path.join(self.pkg.stage.source_path, "Build"))
         else:
             raise RuntimeError("Unknown build_method for perl package")
 
@@ -78,33 +92,30 @@ def configure(self, spec, prefix):
             options = ["Build.PL", "--install_base", prefix]
         options += self.configure_args()
 
-        inspect.getmodule(self).perl(*options)
+        inspect.getmodule(self.pkg).perl(*options)
 
     # It is possible that the shebang in the Build script that is created from
     # Build.PL may be too long causing the build to fail. Patching the shebang
     # does not happen until after install so set '/usr/bin/env perl' here in
     # the Build script.
-    @run_after("configure")
+    @spack.builder.run_after("configure")
     def fix_shebang(self):
         if self.build_method == "Build.PL":
             pattern = "#!{0}".format(self.spec["perl"].command.path)
             repl = "#!/usr/bin/env perl"
             filter_file(pattern, repl, "Build", backup=False)
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Builds a Perl package."""
         self.build_executable()
 
     # Ensure that tests run after build (if requested):
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def check(self):
         """Runs built-in tests of a Perl package."""
         self.build_executable("test")
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Installs a Perl package."""
         self.build_executable("install")
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/python.py

@@ -8,93 +8,23 @@
 import shutil
 from typing import Optional
 
+import llnl.util.filesystem as fs
+import llnl.util.lang as lang
 import llnl.util.tty as tty
-from llnl.util.filesystem import (
-    filter_file,
-    find,
-    find_all_headers,
-    find_libraries,
-    is_nonsymlink_exe_with_shebang,
-    path_contains_subdirectory,
-    same_path,
-    working_dir,
-)
-from llnl.util.lang import classproperty, match_predicate
 
-from spack.directives import depends_on, extends
+import spack.builder
+import spack.multimethod
+import spack.package_base
+import spack.spec
+from spack.directives import build_system, depends_on, extends
 from spack.error import NoHeadersError, NoLibrariesError, SpecError
-from spack.package_base import PackageBase, run_after
 from spack.version import Version
 
+from ._checks import BaseBuilder, execute_install_time_tests
 
-class PythonPackage(PackageBase):
-    """Specialized class for packages that are built using pip."""
 
-    #: Package name, version, and extension on PyPI
-    pypi = None  # type: Optional[str]
-
-    maintainers = ["adamjstewart", "pradyunsg"]
-
-    # Default phases
-    phases = ["install"]
-
-    # To be used in UI queries that require to know which
-    # build-system class we are using
-    build_system_class = "PythonPackage"
-
-    #: Callback names for install-time test
-    install_time_test_callbacks = ["test"]
-
-    extends("python")
-    depends_on("py-pip", type="build")
-    # FIXME: technically wheel is only needed when building from source, not when
-    # installing a downloaded wheel, but I don't want to add wheel as a dep to every
-    # package manually
-    depends_on("py-wheel", type="build")
-
-    py_namespace = None  # type: Optional[str]
-
-    @staticmethod
-    def _std_args(cls):
-        return [
-            # Verbose
-            "-vvv",
-            # Disable prompting for input
-            "--no-input",
-            # Disable the cache
-            "--no-cache-dir",
-            # Don't check to see if pip is up-to-date
-            "--disable-pip-version-check",
-            # Install packages
-            "install",
-            # Don't install package dependencies
-            "--no-deps",
-            # Overwrite existing packages
-            "--ignore-installed",
-            # Use env vars like PYTHONPATH
-            "--no-build-isolation",
-            # Don't warn that prefix.bin is not in PATH
-            "--no-warn-script-location",
-            # Ignore the PyPI package index
-            "--no-index",
-        ]
-
-    @classproperty
-    def homepage(cls):
-        if cls.pypi:
-            name = cls.pypi.split("/")[0]
-            return "https://pypi.org/project/" + name + "/"
-
-    @classproperty
-    def url(cls):
-        if cls.pypi:
-            return "https://files.pythonhosted.org/packages/source/" + cls.pypi[0] + "/" + cls.pypi
-
-    @classproperty
-    def list_url(cls):
-        if cls.pypi:
-            name = cls.pypi.split("/")[0]
-            return "https://pypi.org/simple/" + name + "/"
+class PythonExtension(spack.package_base.PackageBase):
+    maintainers = ["adamjstewart"]
 
     @property
     def import_modules(self):
@@ -124,7 +54,7 @@ def import_modules(self):
 
             # Some Python libraries are packages: collections of modules
             # distributed in directories containing __init__.py files
-            for path in find(root, "__init__.py", recursive=True):
+            for path in fs.find(root, "__init__.py", recursive=True):
                 modules.append(
                     path.replace(root + os.sep, "", 1)
                     .replace(os.sep + "__init__.py", "")
@@ -133,7 +63,7 @@ def import_modules(self):
 
             # Some Python libraries are modules: individual *.py files
             # found in the site-packages directory
-            for path in find(root, "*.py", recursive=False):
+            for path in fs.find(root, "*.py", recursive=False):
                 modules.append(
                     path.replace(root + os.sep, "", 1).replace(".py", "").replace("/", ".")
                 )
@@ -160,6 +90,229 @@ def skip_modules(self):
         """
         return []
 
+    def view_file_conflicts(self, view, merge_map):
+        """Report all file conflicts, excepting special cases for python.
+        Specifically, this does not report errors for duplicate
+        __init__.py files for packages in the same namespace.
+        """
+        conflicts = list(dst for src, dst in merge_map.items() if os.path.exists(dst))
+
+        if conflicts and self.py_namespace:
+            ext_map = view.extensions_layout.extension_map(self.extendee_spec)
+            namespaces = set(x.package.py_namespace for x in ext_map.values())
+            namespace_re = r"site-packages/{0}/__init__.py".format(self.py_namespace)
+            find_namespace = lang.match_predicate(namespace_re)
+            if self.py_namespace in namespaces:
+                conflicts = list(x for x in conflicts if not find_namespace(x))
+
+        return conflicts
+
+    def add_files_to_view(self, view, merge_map, skip_if_exists=True):
+        bin_dir = self.spec.prefix.bin
+        python_prefix = self.extendee_spec.prefix
+        python_is_external = self.extendee_spec.external
+        global_view = fs.same_path(python_prefix, view.get_projection_for_spec(self.spec))
+        for src, dst in merge_map.items():
+            if os.path.exists(dst):
+                continue
+            elif global_view or not fs.path_contains_subdirectory(src, bin_dir):
+                view.link(src, dst)
+            elif not os.path.islink(src):
+                shutil.copy2(src, dst)
+                is_script = fs.is_nonsymlink_exe_with_shebang(src)
+                if is_script and not python_is_external:
+                    fs.filter_file(
+                        python_prefix,
+                        os.path.abspath(view.get_projection_for_spec(self.spec)),
+                        dst,
+                    )
+            else:
+                orig_link_target = os.path.realpath(src)
+                new_link_target = os.path.abspath(merge_map[orig_link_target])
+                view.link(new_link_target, dst)
+
+    def remove_files_from_view(self, view, merge_map):
+        ignore_namespace = False
+        if self.py_namespace:
+            ext_map = view.extensions_layout.extension_map(self.extendee_spec)
+            remaining_namespaces = set(
+                spec.package.py_namespace for name, spec in ext_map.items() if name != self.name
+            )
+            if self.py_namespace in remaining_namespaces:
+                namespace_init = lang.match_predicate(
+                    r"site-packages/{0}/__init__.py".format(self.py_namespace)
+                )
+                ignore_namespace = True
+
+        bin_dir = self.spec.prefix.bin
+        global_view = self.extendee_spec.prefix == view.get_projection_for_spec(self.spec)
+
+        to_remove = []
+        for src, dst in merge_map.items():
+            if ignore_namespace and namespace_init(dst):
+                continue
+
+            if global_view or not fs.path_contains_subdirectory(src, bin_dir):
+                to_remove.append(dst)
+            else:
+                os.remove(dst)
+
+        view.remove_files(to_remove)
+
+    def test(self):
+        """Attempts to import modules of the installed package."""
+
+        # Make sure we are importing the installed modules,
+        # not the ones in the source directory
+        for module in self.import_modules:
+            self.run_test(
+                inspect.getmodule(self).python.path,
+                ["-c", "import {0}".format(module)],
+                purpose="checking import of {0}".format(module),
+                work_dir="spack-test",
+            )
+
+
+class PythonPackage(PythonExtension):
+    """Specialized class for packages that are built using pip."""
+
+    #: Package name, version, and extension on PyPI
+    pypi = None  # type: Optional[str]
+
+    maintainers = ["adamjstewart", "pradyunsg"]
+
+    # To be used in UI queries that require to know which
+    # build-system class we are using
+    build_system_class = "PythonPackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "python_pip"
+
+    #: Callback names for install-time test
+    install_time_test_callbacks = ["test"]
+
+    build_system("python_pip")
+
+    with spack.multimethod.when("build_system=python_pip"):
+        extends("python")
+        depends_on("py-pip", type="build")
+        # FIXME: technically wheel is only needed when building from source, not when
+        # installing a downloaded wheel, but I don't want to add wheel as a dep to every
+        # package manually
+        depends_on("py-wheel", type="build")
+
+    py_namespace = None  # type: Optional[str]
+
+    @lang.classproperty
+    def homepage(cls):
+        if cls.pypi:
+            name = cls.pypi.split("/")[0]
+            return "https://pypi.org/project/" + name + "/"
+
+    @lang.classproperty
+    def url(cls):
+        if cls.pypi:
+            return "https://files.pythonhosted.org/packages/source/" + cls.pypi[0] + "/" + cls.pypi
+
+    @lang.classproperty
+    def list_url(cls):
+        if cls.pypi:
+            name = cls.pypi.split("/")[0]
+            return "https://pypi.org/simple/" + name + "/"
+
+    def update_external_dependencies(self):
+        """
+        Ensure all external python packages have a python dependency
+
+        If another package in the DAG depends on python, we use that
+        python for the dependency of the external. If not, we assume
+        that the external PythonPackage is installed into the same
+        directory as the python it depends on.
+        """
+        # TODO: Include this in the solve, rather than instantiating post-concretization
+        if "python" not in self.spec:
+            if "python" in self.spec.root:
+                python = self.spec.root["python"]
+            else:
+                python = spack.spec.Spec("python")
+                repo = spack.repo.path.repo_for_pkg(python)
+                python.namespace = repo.namespace
+                python._mark_concrete()
+                python.external_path = self.prefix
+            self.spec.add_dependency_edge(python, ("build", "link", "run"))
+
+    @property
+    def headers(self):
+        """Discover header files in platlib."""
+
+        # Headers may be in either location
+        include = self.prefix.join(self.spec["python"].package.include)
+        platlib = self.prefix.join(self.spec["python"].package.platlib)
+        headers = fs.find_all_headers(include) + fs.find_all_headers(platlib)
+
+        if headers:
+            return headers
+
+        msg = "Unable to locate {} headers in {} or {}"
+        raise NoHeadersError(msg.format(self.spec.name, include, platlib))
+
+    @property
+    def libs(self):
+        """Discover libraries in platlib."""
+
+        # Remove py- prefix in package name
+        library = "lib" + self.spec.name[3:].replace("-", "?")
+        root = self.prefix.join(self.spec["python"].package.platlib)
+
+        for shared in [True, False]:
+            libs = fs.find_libraries(library, root, shared=shared, recursive=True)
+            if libs:
+                return libs
+
+        msg = "Unable to recursively locate {} libraries in {}"
+        raise NoLibrariesError(msg.format(self.spec.name, root))
+
+
+@spack.builder.builder("python_pip")
+class PythonPipBuilder(BaseBuilder):
+    phases = ("install",)
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("test",)
+
+    #: Same as legacy_methods, but the signature is different
+    legacy_long_methods = ("install_options", "global_options", "config_settings")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("build_directory", "install_time_test_callbacks")
+
+    #: Callback names for install-time test
+    install_time_test_callbacks = ["test"]
+
+    @staticmethod
+    def std_args(cls):
+        return [
+            # Verbose
+            "-vvv",
+            # Disable prompting for input
+            "--no-input",
+            # Disable the cache
+            "--no-cache-dir",
+            # Don't check to see if pip is up-to-date
+            "--disable-pip-version-check",
+            # Install packages
+            "install",
+            # Don't install package dependencies
+            "--no-deps",
+            # Overwrite existing packages
+            "--ignore-installed",
+            # Use env vars like PYTHONPATH
+            "--no-build-isolation",
+            # Don't warn that prefix.bin is not in PATH
+            "--no-warn-script-location",
+            # Ignore the PyPI package index
+            "--no-index",
+        ]
+
     @property
     def build_directory(self):
         """The root directory of the Python package.
@@ -170,11 +323,10 @@ def build_directory(self):
         * ``setup.cfg``
         * ``setup.py``
         """
-        return self.stage.source_path
+        return self.pkg.stage.source_path
 
     def config_settings(self, spec, prefix):
         """Configuration settings to be passed to the PEP 517 build backend.
-
         Requires pip 22.1+, which requires Python 3.7+.
 
         Args:
@@ -211,10 +363,10 @@ def global_options(self, spec, prefix):
         """
         return []
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Install everything from build directory."""
 
-        args = PythonPackage._std_args(self) + ["--prefix=" + prefix]
+        args = PythonPipBuilder.std_args(pkg) + ["--prefix=" + prefix]
 
         for key, value in self.config_settings(spec, prefix).items():
             if spec["py-pip"].version < Version("22.1"):
@@ -223,137 +375,21 @@ def install(self, spec, prefix):
                     "pip 22.1+. Add the following line to the package to fix this:\n\n"
                     '    depends_on("py-pip@22.1:", type="build")'.format(spec.name)
                 )
+
             args.append("--config-settings={}={}".format(key, value))
+
         for option in self.install_options(spec, prefix):
             args.append("--install-option=" + option)
         for option in self.global_options(spec, prefix):
             args.append("--global-option=" + option)
 
-        if self.stage.archive_file and self.stage.archive_file.endswith(".whl"):
-            args.append(self.stage.archive_file)
+        if pkg.stage.archive_file and pkg.stage.archive_file.endswith(".whl"):
+            args.append(pkg.stage.archive_file)
         else:
             args.append(".")
 
-        pip = inspect.getmodule(self).pip
-        with working_dir(self.build_directory):
+        pip = inspect.getmodule(pkg).pip
+        with fs.working_dir(self.build_directory):
             pip(*args)
 
-    @property
-    def headers(self):
-        """Discover header files in platlib."""
-
-        # Headers may be in either location
-        include = self.prefix.join(self.spec["python"].package.include)
-        platlib = self.prefix.join(self.spec["python"].package.platlib)
-        headers = find_all_headers(include) + find_all_headers(platlib)
-
-        if headers:
-            return headers
-
-        msg = "Unable to locate {} headers in {} or {}"
-        raise NoHeadersError(msg.format(self.spec.name, include, platlib))
-
-    @property
-    def libs(self):
-        """Discover libraries in platlib."""
-
-        # Remove py- prefix in package name
-        library = "lib" + self.spec.name[3:].replace("-", "?")
-        root = self.prefix.join(self.spec["python"].package.platlib)
-
-        for shared in [True, False]:
-            libs = find_libraries(library, root, shared=shared, recursive=True)
-            if libs:
-                return libs
-
-        msg = "Unable to recursively locate {} libraries in {}"
-        raise NoLibrariesError(msg.format(self.spec.name, root))
-
-    # Testing
-
-    def test(self):
-        """Attempts to import modules of the installed package."""
-
-        # Make sure we are importing the installed modules,
-        # not the ones in the source directory
-        for module in self.import_modules:
-            self.run_test(
-                inspect.getmodule(self).python.path,
-                ["-c", "import {0}".format(module)],
-                purpose="checking import of {0}".format(module),
-                work_dir="spack-test",
-            )
-
-    run_after("install")(PackageBase._run_default_install_time_test_callbacks)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
-
-    def view_file_conflicts(self, view, merge_map):
-        """Report all file conflicts, excepting special cases for python.
-        Specifically, this does not report errors for duplicate
-        __init__.py files for packages in the same namespace.
-        """
-        conflicts = list(dst for src, dst in merge_map.items() if os.path.exists(dst))
-
-        if conflicts and self.py_namespace:
-            ext_map = view.extensions_layout.extension_map(self.extendee_spec)
-            namespaces = set(x.package.py_namespace for x in ext_map.values())
-            namespace_re = r"site-packages/{0}/__init__.py".format(self.py_namespace)
-            find_namespace = match_predicate(namespace_re)
-            if self.py_namespace in namespaces:
-                conflicts = list(x for x in conflicts if not find_namespace(x))
-
-        return conflicts
-
-    def add_files_to_view(self, view, merge_map, skip_if_exists=True):
-        bin_dir = self.spec.prefix.bin
-        python_prefix = self.extendee_spec.prefix
-        python_is_external = self.extendee_spec.external
-        global_view = same_path(python_prefix, view.get_projection_for_spec(self.spec))
-        for src, dst in merge_map.items():
-            if os.path.exists(dst):
-                continue
-            elif global_view or not path_contains_subdirectory(src, bin_dir):
-                view.link(src, dst)
-            elif not os.path.islink(src):
-                shutil.copy2(src, dst)
-                is_script = is_nonsymlink_exe_with_shebang(src)
-                if is_script and not python_is_external:
-                    filter_file(
-                        python_prefix,
-                        os.path.abspath(view.get_projection_for_spec(self.spec)),
-                        dst,
-                    )
-            else:
-                orig_link_target = os.path.realpath(src)
-                new_link_target = os.path.abspath(merge_map[orig_link_target])
-                view.link(new_link_target, dst)
-
-    def remove_files_from_view(self, view, merge_map):
-        ignore_namespace = False
-        if self.py_namespace:
-            ext_map = view.extensions_layout.extension_map(self.extendee_spec)
-            remaining_namespaces = set(
-                spec.package.py_namespace for name, spec in ext_map.items() if name != self.name
-            )
-            if self.py_namespace in remaining_namespaces:
-                namespace_init = match_predicate(
-                    r"site-packages/{0}/__init__.py".format(self.py_namespace)
-                )
-                ignore_namespace = True
-
-        bin_dir = self.spec.prefix.bin
-        global_view = self.extendee_spec.prefix == view.get_projection_for_spec(self.spec)
-
-        to_remove = []
-        for src, dst in merge_map.items():
-            if ignore_namespace and namespace_init(dst):
-                continue
-
-            if global_view or not path_contains_subdirectory(src, bin_dir):
-                to_remove.append(dst)
-            else:
-                os.remove(dst)
-
-        view.remove_files(to_remove)
+    spack.builder.run_after("install")(execute_install_time_tests)

lib/spack/spack/build_systems/qmake.py

@@ -2,82 +2,85 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 
 from llnl.util.filesystem import working_dir
 
-from spack.directives import depends_on
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on
+
+from ._checks import BaseBuilder, execute_build_time_tests
 
 
-class QMakePackage(PackageBase):
+class QMakePackage(spack.package_base.PackageBase):
     """Specialized class for packages built using qmake.
 
     For more information on the qmake build system, see:
     http://doc.qt.io/qt-5/qmake-manual.html
-
-    This class provides three phases that can be overridden:
-
-    1. :py:meth:`~.QMakePackage.qmake`
-    2. :py:meth:`~.QMakePackage.build`
-    3. :py:meth:`~.QMakePackage.install`
-
-    They all have sensible defaults and for many packages the only thing
-    necessary will be to override :py:meth:`~.QMakePackage.qmake_args`.
     """
 
-    #: Phases of a qmake package
-    phases = ["qmake", "build", "install"]
-
     #: This attribute is used in UI queries that need to know the build
     #: system base class
     build_system_class = "QMakePackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "qmake"
+
+    build_system("qmake")
+
+    depends_on("qt", type="build", when="build_system=qmake")
+
+
+@spack.builder.builder("qmake")
+class QMakeBuilder(BaseBuilder):
+    """The qmake builder provides three phases that can be overridden:
+
+    1. :py:meth:`~.QMakeBuilder.qmake`
+    2. :py:meth:`~.QMakeBuilder.build`
+    3. :py:meth:`~.QMakeBuilder.install`
+
+    They all have sensible defaults and for many packages the only thing
+    necessary will be to override :py:meth:`~.QMakeBuilder.qmake_args`.
+    """
+
+    phases = ("qmake", "build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("qmake_args", "check")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("build_directory", "build_time_test_callbacks")
 
     #: Callback names for build-time test
     build_time_test_callbacks = ["check"]
 
-    depends_on("qt", type="build")
-
     @property
     def build_directory(self):
         """The directory containing the ``*.pro`` file."""
         return self.stage.source_path
 
     def qmake_args(self):
-        """Produces a list containing all the arguments that must be passed to
-        qmake
-        """
+        """List of arguments passed to qmake."""
         return []
 
-    def qmake(self, spec, prefix):
+    def qmake(self, pkg, spec, prefix):
         """Run ``qmake`` to configure the project and generate a Makefile."""
-
         with working_dir(self.build_directory):
-            inspect.getmodule(self).qmake(*self.qmake_args())
+            inspect.getmodule(self.pkg).qmake(*self.qmake_args())
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Make the build targets"""
-
         with working_dir(self.build_directory):
-            inspect.getmodule(self).make()
+            inspect.getmodule(self.pkg).make()
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Make the install targets"""
-
         with working_dir(self.build_directory):
-            inspect.getmodule(self).make("install")
-
-    # Tests
+            inspect.getmodule(self.pkg).make("install")
 
     def check(self):
-        """Searches the Makefile for a ``check:`` target and runs it if found."""
-
+        """Search the Makefile for a ``check:`` target and runs it if found."""
         with working_dir(self.build_directory):
             self._if_make_target_execute("check")
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+    spack.builder.run_after("build")(execute_build_time_tests)

lib/spack/spack/build_systems/r.py

@@ -3,30 +3,64 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import inspect
-from typing import Optional
+from typing import Optional, Tuple
 
 import llnl.util.lang as lang
 
 from spack.directives import extends
-from spack.package_base import PackageBase, run_after
+
+from .generic import GenericBuilder, Package
 
 
-class RPackage(PackageBase):
+class RBuilder(GenericBuilder):
+    """The R builder provides a single phase that can be overridden:
+
+        1. :py:meth:`~.RBuilder.install`
+
+    It has sensible defaults, and for many packages the only thing
+    necessary will be to add dependencies.
+    """
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = (
+        "configure_args",
+        "configure_vars",
+    ) + GenericBuilder.legacy_methods  # type: Tuple[str, ...]
+
+    def configure_args(self):
+        """Arguments to pass to install via ``--configure-args``."""
+        return []
+
+    def configure_vars(self):
+        """Arguments to pass to install via ``--configure-vars``."""
+        return []
+
+    def install(self, pkg, spec, prefix):
+        """Installs an R package."""
+
+        config_args = self.configure_args()
+        config_vars = self.configure_vars()
+
+        args = ["--vanilla", "CMD", "INSTALL"]
+
+        if config_args:
+            args.append("--configure-args={0}".format(" ".join(config_args)))
+
+        if config_vars:
+            args.append("--configure-vars={0}".format(" ".join(config_vars)))
+
+        args.extend(["--library={0}".format(self.pkg.module.r_lib_dir), self.stage.source_path])
+
+        inspect.getmodule(self.pkg).R(*args)
+
+
+class RPackage(Package):
     """Specialized class for packages that are built using R.
 
     For more information on the R build system, see:
     https://stat.ethz.ch/R-manual/R-devel/library/utils/html/INSTALL.html
-
-    This class provides a single phase that can be overridden:
-
-        1. :py:meth:`~.RPackage.install`
-
-    It has sensible defaults, and for many packages the only thing
-    necessary will be to add dependencies
     """
 
-    phases = ["install"]
-
     # package attributes that can be expanded to set the homepage, url,
     # list_url, and git values
     # For CRAN packages
@@ -35,6 +69,8 @@ class RPackage(PackageBase):
     # For Bioconductor packages
     bioc = None  # type: Optional[str]
 
+    GenericBuilder = RBuilder
+
     maintainers = ["glennpj"]
 
     #: This attribute is used in UI queries that need to know the build
@@ -70,32 +106,3 @@ def list_url(cls):
     def git(self):
         if self.bioc:
             return "https://git.bioconductor.org/packages/" + self.bioc
-
-    def configure_args(self):
-        """Arguments to pass to install via ``--configure-args``."""
-        return []
-
-    def configure_vars(self):
-        """Arguments to pass to install via ``--configure-vars``."""
-        return []
-
-    def install(self, spec, prefix):
-        """Installs an R package."""
-
-        config_args = self.configure_args()
-        config_vars = self.configure_vars()
-
-        args = ["--vanilla", "CMD", "INSTALL"]
-
-        if config_args:
-            args.append("--configure-args={0}".format(" ".join(config_args)))
-
-        if config_vars:
-            args.append("--configure-vars={0}".format(" ".join(config_vars)))
-
-        args.extend(["--library={0}".format(self.module.r_lib_dir), self.stage.source_path])
-
-        inspect.getmodule(self).R(*args)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/racket.py

@@ -3,14 +3,15 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
-from typing import Optional
+from typing import Optional, Tuple
 
+import llnl.util.filesystem as fs
 import llnl.util.lang as lang
 import llnl.util.tty as tty
-from llnl.util.filesystem import working_dir
 
+import spack.builder
 from spack.build_environment import SPACK_NO_PARALLEL_MAKE, determine_number_of_jobs
-from spack.directives import extends
+from spack.directives import build_system, extends
 from spack.package_base import PackageBase
 from spack.util.environment import env_flag
 from spack.util.executable import Executable, ProcessError
@@ -19,34 +20,52 @@
 class RacketPackage(PackageBase):
     """Specialized class for packages that are built using Racket's
     `raco pkg install` and `raco setup` commands.
-
-    This class provides the following phases that can be overridden:
-
-    * install
-    * setup
     """
 
     #: Package name, version, and extension on PyPI
     maintainers = ["elfprince13"]
-
-    # Default phases
-    phases = ["install"]
-
     # To be used in UI queries that require to know which
     # build-system class we are using
     build_system_class = "RacketPackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "racket"
 
-    extends("racket")
+    build_system("racket")
+
+    extends("racket", when="build_system=racket")
 
-    pkgs = False
-    subdirectory = None  # type: Optional[str]
     racket_name = None  # type: Optional[str]
     parallel = True
 
     @lang.classproperty
     def homepage(cls):
-        if cls.pkgs:
+        if cls.racket_name:
             return "https://pkgs.racket-lang.org/package/{0}".format(cls.racket_name)
+        return None
+
+
+@spack.builder.builder("racket")
+class RacketBuilder(spack.builder.Builder):
+    """The Racket builder provides an ``install`` phase that can be overridden."""
+
+    phases = ("install",)
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = tuple()  # type: Tuple[str, ...]
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("build_directory", "build_time_test_callbacks", "subdirectory")
+
+    #: Callback names for build-time test
+    build_time_test_callbacks = ["check"]
+
+    racket_name = None  # type: Optional[str]
+
+    @property
+    def subdirectory(self):
+        if self.racket_name:
+            return "pkgs/{0}".format(self.pkg.racket_name)
+        return None
 
     @property
     def build_directory(self):
@@ -55,25 +74,25 @@ def build_directory(self):
             ret = os.path.join(ret, self.subdirectory)
         return ret
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Install everything from build directory."""
         raco = Executable("raco")
-        with working_dir(self.build_directory):
-            allow_parallel = self.parallel and (not env_flag(SPACK_NO_PARALLEL_MAKE))
+        with fs.working_dir(self.build_directory):
+            parallel = self.pkg.parallel and (not env_flag(SPACK_NO_PARALLEL_MAKE))
             args = [
                 "pkg",
                 "install",
                 "-t",
                 "dir",
                 "-n",
-                self.racket_name,
+                self.pkg.racket_name,
                 "--deps",
                 "fail",
                 "--ignore-implies",
                 "--copy",
                 "-i",
                 "-j",
-                str(determine_number_of_jobs(allow_parallel)),
+                str(determine_number_of_jobs(parallel)),
                 "--",
                 os.getcwd(),
             ]
@@ -82,9 +101,8 @@ def install(self, spec, prefix):
             except ProcessError:
                 args.insert(-2, "--skip-installed")
                 raco(*args)
-                tty.warn(
-                    (
-                        "Racket package {0} was already installed, uninstalling via "
-                        "Spack may make someone unhappy!"
-                    ).format(self.racket_name)
+                msg = (
+                    "Racket package {0} was already installed, uninstalling via "
+                    "Spack may make someone unhappy!"
                 )
+                tty.warn(msg.format(self.pkg.racket_name))

lib/spack/spack/build_systems/ruby.py

@@ -2,35 +2,49 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
 import glob
 import inspect
 
-from spack.directives import extends
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, extends
+
+from ._checks import BaseBuilder
 
 
-class RubyPackage(PackageBase):
-    """Specialized class for building Ruby gems.
-
-    This class provides two phases that can be overridden if required:
-
-    #. :py:meth:`~.RubyPackage.build`
-    #. :py:meth:`~.RubyPackage.install`
-    """
+class RubyPackage(spack.package_base.PackageBase):
+    """Specialized class for building Ruby gems."""
 
     maintainers = ["Kerilk"]
 
-    #: Phases of a Ruby package
-    phases = ["build", "install"]
-
     #: This attribute is used in UI queries that need to know the build
     #: system base class
     build_system_class = "RubyPackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "ruby"
 
-    extends("ruby")
+    build_system("ruby")
 
-    def build(self, spec, prefix):
+    extends("ruby", when="build_system=ruby")
+
+
+@spack.builder.builder("ruby")
+class RubyBuilder(BaseBuilder):
+    """The Ruby builder provides two phases that can be overridden if required:
+
+    #. :py:meth:`~.RubyBuilder.build`
+    #. :py:meth:`~.RubyBuilder.install`
+    """
+
+    phases = ("build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ()
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ()
+
+    def build(self, pkg, spec, prefix):
         """Build a Ruby gem."""
 
         # ruby-rake provides both rake.gemspec and Rakefile, but only
@@ -38,15 +52,15 @@ def build(self, spec, prefix):
         gemspecs = glob.glob("*.gemspec")
         rakefiles = glob.glob("Rakefile")
         if gemspecs:
-            inspect.getmodule(self).gem("build", "--norc", gemspecs[0])
+            inspect.getmodule(self.pkg).gem("build", "--norc", gemspecs[0])
         elif rakefiles:
-            jobs = inspect.getmodule(self).make_jobs
-            inspect.getmodule(self).rake("package", "-j{0}".format(jobs))
+            jobs = inspect.getmodule(self.pkg).make_jobs
+            inspect.getmodule(self.pkg).rake("package", "-j{0}".format(jobs))
         else:
             # Some Ruby packages only ship `*.gem` files, so nothing to build
             pass
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Install a Ruby gem.
 
         The ruby package sets ``GEM_HOME`` to tell gem where to install to."""
@@ -56,9 +70,6 @@ def install(self, spec, prefix):
             # if --install-dir is not used, GEM_PATH is deleted from the
             # environement, and Gems required to build native extensions will
             # not be found. Those extensions are built during `gem install`.
-            inspect.getmodule(self).gem(
+            inspect.getmodule(self.pkg).gem(
                 "install", "--norc", "--ignore-dependencies", "--install-dir", prefix, gems[0]
             )
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)

lib/spack/spack/build_systems/scons.py

@@ -2,63 +2,79 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 
-from spack.directives import depends_on
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on
+
+from ._checks import BaseBuilder, execute_build_time_tests
 
 
-class SConsPackage(PackageBase):
+class SConsPackage(spack.package_base.PackageBase):
     """Specialized class for packages built using SCons.
 
     See http://scons.org/documentation.html for more information.
-
-    This class provides the following phases that can be overridden:
-
-    1. :py:meth:`~.SConsPackage.build`
-    2. :py:meth:`~.SConsPackage.install`
-
-    Packages that use SCons as a build system are less uniform than packages
-    that use other build systems. Developers can add custom subcommands or
-    variables that control the build. You will likely need to override
-    :py:meth:`~.SConsPackage.build_args` to pass the appropriate variables.
     """
 
-    #: Phases of a SCons package
-    phases = ["build", "install"]
-
     #: To be used in UI queries that require to know which
     #: build-system class we are using
     build_system_class = "SConsPackage"
 
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "scons"
+
+    build_system("scons")
+
+    depends_on("scons", type="build", when="build_system=scons")
+
+
+@spack.builder.builder("scons")
+class SConsBuilder(BaseBuilder):
+    """The Scons builder provides the following phases that can be overridden:
+
+    1. :py:meth:`~.SConsBuilder.build`
+    2. :py:meth:`~.SConsBuilder.install`
+
+    Packages that use SCons as a build system are less uniform than packages that use
+    other build systems. Developers can add custom subcommands or variables that
+    control the build. You will likely need to override
+    :py:meth:`~.SConsBuilder.build_args` to pass the appropriate variables.
+    """
+
+    #: Phases of a SCons package
+    phases = ("build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("install_args", "build_test")
+
+    #: Same as legacy_methods, but the signature is different
+    legacy_long_methods = ("build_args",)
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = ("build_time_test_callbacks",)
+
     #: Callback names for build-time test
     build_time_test_callbacks = ["build_test"]
 
-    depends_on("scons", type="build")
-
     def build_args(self, spec, prefix):
         """Arguments to pass to build."""
         return []
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Build the package."""
         args = self.build_args(spec, prefix)
+        inspect.getmodule(self.pkg).scons(*args)
 
-        inspect.getmodule(self).scons(*args)
-
-    def install_args(self, spec, prefix):
+    def install_args(self):
         """Arguments to pass to install."""
         return []
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Install the package."""
-        args = self.install_args(spec, prefix)
+        args = self.install_args()
 
-        inspect.getmodule(self).scons("install", *args)
-
-    # Testing
+        inspect.getmodule(self.pkg).scons("install", *args)
 
     def build_test(self):
         """Run unit tests after build.
@@ -68,7 +84,4 @@ def build_test(self):
         """
         pass
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+    spack.builder.run_after("build")(execute_build_time_tests)

lib/spack/spack/build_systems/sip.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
 import inspect
 import os
 import re
@@ -10,28 +9,20 @@
 import llnl.util.tty as tty
 from llnl.util.filesystem import find, join_path, working_dir
 
-from spack.directives import depends_on, extends
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on, extends
+from spack.multimethod import when
+
+from ._checks import BaseBuilder, execute_install_time_tests
 
 
-class SIPPackage(PackageBase):
+class SIPPackage(spack.package_base.PackageBase):
     """Specialized class for packages that are built using the
     SIP build system. See https://www.riverbankcomputing.com/software/sip/intro
     for more information.
-
-    This class provides the following phases that can be overridden:
-
-    * configure
-    * build
-    * install
-
-    The configure phase already adds a set of default flags. To see more
-    options, run ``python configure.py --help``.
     """
 
-    # Default phases
-    phases = ["configure", "build", "install"]
-
     # To be used in UI queries that require to know which
     # build-system class we are using
     build_system_class = "SIPPackage"
@@ -41,11 +32,15 @@ class SIPPackage(PackageBase):
 
     #: Callback names for install-time test
     install_time_test_callbacks = ["test"]
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "sip"
 
-    extends("python")
+    build_system("sip")
 
-    depends_on("qt")
-    depends_on("py-sip")
+    with when("build_system=sip"):
+        extends("python")
+        depends_on("qt")
+        depends_on("py-sip")
 
     @property
     def import_modules(self):
@@ -95,11 +90,51 @@ def python(self, *args, **kwargs):
         """The python ``Executable``."""
         inspect.getmodule(self).python(*args, **kwargs)
 
+    def test(self):
+        """Attempts to import modules of the installed package."""
+
+        # Make sure we are importing the installed modules,
+        # not the ones in the source directory
+        for module in self.import_modules:
+            self.run_test(
+                inspect.getmodule(self).python.path,
+                ["-c", "import {0}".format(module)],
+                purpose="checking import of {0}".format(module),
+                work_dir="spack-test",
+            )
+
+
+@spack.builder.builder("sip")
+class SIPBuilder(BaseBuilder):
+    """The SIP builder provides the following phases that can be overridden:
+
+    * configure
+    * build
+    * install
+
+    The configure phase already adds a set of default flags. To see more
+    options, run ``python configure.py --help``.
+    """
+
+    phases = ("configure", "build", "install")
+
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = ("configure_file", "configure_args", "build_args", "install_args")
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "build_targets",
+        "install_targets",
+        "build_time_test_callbacks",
+        "install_time_test_callbacks",
+        "build_directory",
+    )
+
     def configure_file(self):
         """Returns the name of the configure file to use."""
         return "configure.py"
 
-    def configure(self, spec, prefix):
+    def configure(self, pkg, spec, prefix):
         """Configure the package."""
         configure = self.configure_file()
 
@@ -118,7 +153,7 @@ def configure(self, spec, prefix):
                 "--bindir",
                 prefix.bin,
                 "--destdir",
-                inspect.getmodule(self).python_platlib,
+                inspect.getmodule(self.pkg).python_platlib,
             ]
         )
 
@@ -128,53 +163,35 @@ def configure_args(self):
         """Arguments to pass to configure."""
         return []
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Build the package."""
         args = self.build_args()
 
-        inspect.getmodule(self).make(*args)
+        inspect.getmodule(self.pkg).make(*args)
 
     def build_args(self):
         """Arguments to pass to build."""
         return []
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Install the package."""
         args = self.install_args()
 
-        inspect.getmodule(self).make("install", parallel=False, *args)
+        inspect.getmodule(self.pkg).make("install", parallel=False, *args)
 
     def install_args(self):
         """Arguments to pass to install."""
         return []
 
-    # Testing
+    spack.builder.run_after("install")(execute_install_time_tests)
 
-    def test(self):
-        """Attempts to import modules of the installed package."""
-
-        # Make sure we are importing the installed modules,
-        # not the ones in the source directory
-        for module in self.import_modules:
-            self.run_test(
-                inspect.getmodule(self).python.path,
-                ["-c", "import {0}".format(module)],
-                purpose="checking import of {0}".format(module),
-                work_dir="spack-test",
-            )
-
-    run_after("install")(PackageBase._run_default_install_time_test_callbacks)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
-
-    @run_after("install")
+    @spack.builder.run_after("install")
     def extend_path_setup(self):
         # See github issue #14121 and PR #15297
-        module = self.spec["py-sip"].variants["module"].value
+        module = self.pkg.spec["py-sip"].variants["module"].value
         if module != "sip":
             module = module.split(".")[0]
-            with working_dir(inspect.getmodule(self).python_platlib):
+            with working_dir(inspect.getmodule(self.pkg).python_platlib):
                 with open(os.path.join(module, "__init__.py"), "a") as f:
                     f.write("from pkgutil import extend_path\n")
                     f.write("__path__ = extend_path(__path__, __name__)\n")

lib/spack/spack/build_systems/waf.py

@@ -2,21 +2,38 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 import inspect
 
 from llnl.util.filesystem import working_dir
 
-from spack.directives import depends_on
-from spack.package_base import PackageBase, run_after
+import spack.builder
+import spack.package_base
+from spack.directives import build_system, depends_on
+
+from ._checks import BaseBuilder, execute_build_time_tests, execute_install_time_tests
 
 
-class WafPackage(PackageBase):
+class WafPackage(spack.package_base.PackageBase):
     """Specialized class for packages that are built using the
     Waf build system. See https://waf.io/book/ for more information.
+    """
 
-    This class provides the following phases that can be overridden:
+    # To be used in UI queries that require to know which
+    # build-system class we are using
+    build_system_class = "WafPackage"
+    #: Legacy buildsystem attribute used to deserialize and install old specs
+    legacy_buildsystem = "waf"
+
+    build_system("waf")
+    # Much like AutotoolsPackage does not require automake and autoconf
+    # to build, WafPackage does not require waf to build. It only requires
+    # python to run the waf build script.
+    depends_on("python@2.5:", type="build", when="build_system=waf")
+
+
+@spack.builder.builder("waf")
+class WafBuilder(BaseBuilder):
+    """The WAF builder provides the following phases that can be overridden:
 
     * configure
     * build
@@ -40,12 +57,25 @@ class WafPackage(PackageBase):
     function, which passes ``--prefix=/path/to/installation/prefix``.
     """
 
-    # Default phases
-    phases = ["configure", "build", "install"]
+    phases = ("configure", "build", "install")
 
-    # To be used in UI queries that require to know which
-    # build-system class we are using
-    build_system_class = "WafPackage"
+    #: Names associated with package methods in the old build-system format
+    legacy_methods = (
+        "build_test",
+        "install_test",
+        "configure_args",
+        "build_args",
+        "install_args",
+        "build_test",
+        "install_test",
+    )
+
+    #: Names associated with package attributes in the old build-system format
+    legacy_attributes = (
+        "build_time_test_callbacks",
+        "build_time_test_callbacks",
+        "build_directory",
+    )
 
     # Callback names for build-time test
     build_time_test_callbacks = ["build_test"]
@@ -53,11 +83,6 @@ class WafPackage(PackageBase):
     # Callback names for install-time test
     install_time_test_callbacks = ["install_test"]
 
-    # Much like AutotoolsPackage does not require automake and autoconf
-    # to build, WafPackage does not require waf to build. It only requires
-    # python to run the waf build script.
-    depends_on("python@2.5:", type="build")
-
     @property
     def build_directory(self):
         """The directory containing the ``waf`` file."""
@@ -65,18 +90,18 @@ def build_directory(self):
 
     def python(self, *args, **kwargs):
         """The python ``Executable``."""
-        inspect.getmodule(self).python(*args, **kwargs)
+        inspect.getmodule(self.pkg).python(*args, **kwargs)
 
     def waf(self, *args, **kwargs):
         """Runs the waf ``Executable``."""
-        jobs = inspect.getmodule(self).make_jobs
+        jobs = inspect.getmodule(self.pkg).make_jobs
 
         with working_dir(self.build_directory):
             self.python("waf", "-j{0}".format(jobs), *args, **kwargs)
 
-    def configure(self, spec, prefix):
+    def configure(self, pkg, spec, prefix):
         """Configures the project."""
-        args = ["--prefix={0}".format(self.prefix)]
+        args = ["--prefix={0}".format(self.pkg.prefix)]
         args += self.configure_args()
 
         self.waf("configure", *args)
@@ -85,7 +110,7 @@ def configure_args(self):
         """Arguments to pass to configure."""
         return []
 
-    def build(self, spec, prefix):
+    def build(self, pkg, spec, prefix):
         """Executes the build."""
         args = self.build_args()
 
@@ -95,7 +120,7 @@ def build_args(self):
         """Arguments to pass to build."""
         return []
 
-    def install(self, spec, prefix):
+    def install(self, pkg, spec, prefix):
         """Installs the targets on the system."""
         args = self.install_args()
 
@@ -105,8 +130,6 @@ def install_args(self):
         """Arguments to pass to install."""
         return []
 
-    # Testing
-
     def build_test(self):
         """Run unit tests after build.
 
@@ -115,7 +138,7 @@ def build_test(self):
         """
         pass
 
-    run_after("build")(PackageBase._run_default_build_time_test_callbacks)
+    spack.builder.run_after("build")(execute_build_time_tests)
 
     def install_test(self):
         """Run unit tests after install.
@@ -125,7 +148,4 @@ def install_test(self):
         """
         pass
 
-    run_after("install")(PackageBase._run_default_install_time_test_callbacks)
-
-    # Check that self.prefix is there after installation
-    run_after("install")(PackageBase.sanity_check_prefix)
+    spack.builder.run_after("install")(execute_install_time_tests)

lib/spack/spack/builder.py

@@ -0,0 +1,574 @@
+# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import collections
+import copy
+import functools
+import inspect
+from typing import List, Optional, Tuple
+
+import six
+
+import llnl.util.compat
+
+import spack.build_environment
+
+#: Builder classes, as registered by the "builder" decorator
+BUILDER_CLS = {}
+
+#: An object of this kind is a shared global state used to collect callbacks during
+#: class definition time, and is flushed when the class object is created at the end
+#: of the class definition
+#:
+#: Args:
+#:    attribute_name (str): name of the attribute that will be attached to the builder
+#:    callbacks (list): container used to temporarily aggregate the callbacks
+CallbackTemporaryStage = collections.namedtuple(
+    "CallbackTemporaryStage", ["attribute_name", "callbacks"]
+)
+
+#: Shared global state to aggregate "@run_before" callbacks
+_RUN_BEFORE = CallbackTemporaryStage(attribute_name="run_before_callbacks", callbacks=[])
+#: Shared global state to aggregate "@run_after" callbacks
+_RUN_AFTER = CallbackTemporaryStage(attribute_name="run_after_callbacks", callbacks=[])
+
+#: Map id(pkg) to a builder, to avoid creating multiple
+#: builders for the same package object.
+_BUILDERS = {}
+
+
+def builder(build_system_name):
+    """Class decorator used to register the default builder
+    for a given build-system.
+
+    Args:
+        build_system_name (str): name of the build-system
+    """
+
+    def _decorator(cls):
+        cls.build_system = build_system_name
+        BUILDER_CLS[build_system_name] = cls
+        return cls
+
+    return _decorator
+
+
+def create(pkg):
+    """Given a package object with an associated concrete spec,
+    return the builder object that can install it.
+
+    Args:
+         pkg (spack.package_base.PackageBase): package for which we want the builder
+    """
+    if id(pkg) not in _BUILDERS:
+        _BUILDERS[id(pkg)] = _create(pkg)
+    return _BUILDERS[id(pkg)]
+
+
+class _PhaseAdapter(object):
+    def __init__(self, builder, phase_fn):
+        self.builder = builder
+        self.phase_fn = phase_fn
+
+    def __call__(self, spec, prefix):
+        return self.phase_fn(self.builder.pkg, spec, prefix)
+
+
+def _create(pkg):
+    """Return a new builder object for the package object being passed as argument.
+
+    The function inspects the build-system used by the package object and try to:
+
+    1. Return a custom builder, if any is defined in the same ``package.py`` file.
+    2. Return a customization of more generic builders, if any is defined in the
+       class hierarchy (look at AspellDictPackage for an example of that)
+    3. Return a run-time generated adapter builder otherwise
+
+    The run-time generated adapter builder is capable of adapting an old-style package
+    to the new architecture, where the installation procedure has been extracted from
+    the ``*Package`` hierarchy into a ``*Builder`` hierarchy. This means that the
+    adapter looks for attribute or method overrides preferably in the ``*Package``
+    before using the default builder implementation.
+
+    Note that in case a builder is explicitly coded in ``package.py``, no attempt is made
+    to look for build-related methods in the ``*Package``.
+
+    Args:
+        pkg (spack.package_base.PackageBase): package object for which we need a builder
+    """
+    package_module = inspect.getmodule(pkg)
+    package_buildsystem = buildsystem_name(pkg)
+    default_builder_cls = BUILDER_CLS[package_buildsystem]
+    builder_cls_name = default_builder_cls.__name__
+    builder_cls = getattr(package_module, builder_cls_name, None)
+    if builder_cls:
+        return builder_cls(pkg)
+
+    # Specialized version of a given buildsystem can subclass some
+    # base classes and specialize certain phases or methods or attributes.
+    # In that case they can store their builder class as a class level attribute.
+    # See e.g. AspellDictPackage as an example.
+    base_cls = getattr(pkg, builder_cls_name, default_builder_cls)
+
+    # From here on we define classes to construct a special builder that adapts to the
+    # old, single class, package format. The adapter forwards any call or access to an
+    # attribute related to the installation procedure to a package object wrapped in
+    # a class that falls-back on calling the base builder if no override is found on the
+    # package. The semantic should be the same as the method in the base builder were still
+    # present in the base class of the package.
+
+    class _ForwardToBaseBuilder(object):
+        def __init__(self, wrapped_pkg_object, root_builder):
+            self.wrapped_package_object = wrapped_pkg_object
+            self.root_builder = root_builder
+
+            package_cls = type(wrapped_pkg_object)
+            wrapper_cls = type(self)
+            bases = (package_cls, wrapper_cls)
+            new_cls_name = package_cls.__name__ + "Wrapper"
+            new_cls = type(new_cls_name, bases, {})
+            new_cls.__module__ = package_cls.__module__
+            self.__class__ = new_cls
+            self.__dict__.update(wrapped_pkg_object.__dict__)
+
+        def __getattr__(self, item):
+            result = getattr(super(type(self.root_builder), self.root_builder), item)
+            if item in super(type(self.root_builder), self.root_builder).phases:
+                result = _PhaseAdapter(self.root_builder, result)
+            return result
+
+    def forward_method_to_getattr(fn_name):
+        def __forward(self, *args, **kwargs):
+            return self.__getattr__(fn_name)(*args, **kwargs)
+
+        return __forward
+
+    # Add fallback methods for the Package object to refer to the builder. If a method
+    # with the same name is defined in the Package, it will override this definition
+    # (when _ForwardToBaseBuilder is initialized)
+    for method_name in (
+        base_cls.phases
+        + base_cls.legacy_methods
+        + getattr(base_cls, "legacy_long_methods", tuple())
+        + ("setup_build_environment", "setup_dependent_build_environment")
+    ):
+        setattr(_ForwardToBaseBuilder, method_name, forward_method_to_getattr(method_name))
+
+    def forward_property_to_getattr(property_name):
+        def __forward(self):
+            return self.__getattr__(property_name)
+
+        return __forward
+
+    for attribute_name in base_cls.legacy_attributes:
+        setattr(
+            _ForwardToBaseBuilder,
+            attribute_name,
+            property(forward_property_to_getattr(attribute_name)),
+        )
+
+    class Adapter(six.with_metaclass(_PackageAdapterMeta, base_cls)):
+        def __init__(self, pkg):
+            # Deal with custom phases in packages here
+            if hasattr(pkg, "phases"):
+                self.phases = pkg.phases
+                for phase in self.phases:
+                    setattr(Adapter, phase, _PackageAdapterMeta.phase_method_adapter(phase))
+
+            # Attribute containing the package wrapped in dispatcher with a `__getattr__`
+            # method that will forward certain calls to the default builder.
+            self.pkg_with_dispatcher = _ForwardToBaseBuilder(pkg, root_builder=self)
+            super(Adapter, self).__init__(pkg)
+
+        # These two methods don't follow the (self, spec, prefix) signature of phases nor
+        # the (self) signature of methods, so they are added explicitly to avoid using a
+        # catch-all (*args, **kwargs)
+        def setup_build_environment(self, env):
+            return self.pkg_with_dispatcher.setup_build_environment(env)
+
+        def setup_dependent_build_environment(self, env, dependent_spec):
+            return self.pkg_with_dispatcher.setup_dependent_build_environment(env, dependent_spec)
+
+    return Adapter(pkg)
+
+
+def buildsystem_name(pkg):
+    """Given a package object with an associated concrete spec,
+    return the name of its build system.
+
+    Args:
+         pkg (spack.package_base.PackageBase): package for which we want
+            the build system name
+    """
+    try:
+        return pkg.spec.variants["build_system"].value
+    except KeyError:
+        # We are reading an old spec without the build_system variant
+        return pkg.legacy_buildsystem
+
+
+class PhaseCallbacksMeta(type):
+    """Permit to register arbitrary functions during class definition and run them
+    later, before or after a given install phase.
+
+    Each method decorated with ``run_before`` or ``run_after`` gets temporarily
+    stored in a global shared state when a class being defined is parsed by the Python
+    interpreter. At class definition time that temporary storage gets flushed and a list
+    of callbacks is attached to the class being defined.
+    """
+
+    def __new__(mcs, name, bases, attr_dict):
+        for temporary_stage in (_RUN_BEFORE, _RUN_AFTER):
+            staged_callbacks = temporary_stage.callbacks
+
+            # We don't have callbacks in this class, move on
+            if not staged_callbacks:
+                continue
+
+            # If we are here we have callbacks. To get a complete list, get first what
+            # was attached to parent classes, then prepend what we have registered here.
+            #
+            # The order should be:
+            # 1. Callbacks are registered in order within the same class
+            # 2. Callbacks defined in derived classes precede those defined in base
+            #    classes
+            for base in bases:
+                callbacks_from_base = getattr(base, temporary_stage.attribute_name, None)
+                if callbacks_from_base:
+                    break
+            callbacks_from_base = callbacks_from_base or []
+
+            # Set the callbacks in this class and flush the temporary stage
+            attr_dict[temporary_stage.attribute_name] = staged_callbacks[:] + callbacks_from_base
+            del temporary_stage.callbacks[:]
+
+        return super(PhaseCallbacksMeta, mcs).__new__(mcs, name, bases, attr_dict)
+
+    @staticmethod
+    def run_after(phase, when=None):
+        """Decorator to register a function for running after a given phase.
+
+        Args:
+            phase (str): phase after which the function must run.
+            when (str): condition under which the function is run (if None, it is always run).
+        """
+
+        def _decorator(fn):
+            key = (phase, when)
+            item = (key, fn)
+            _RUN_AFTER.callbacks.append(item)
+            return fn
+
+        return _decorator
+
+    @staticmethod
+    def run_before(phase, when=None):
+        """Decorator to register a function for running before a given phase.
+
+        Args:
+           phase (str): phase before which the function must run.
+           when (str): condition under which the function is run (if None, it is always run).
+        """
+
+        def _decorator(fn):
+            key = (phase, when)
+            item = (key, fn)
+            _RUN_BEFORE.callbacks.append(item)
+            return fn
+
+        return _decorator
+
+
+class BuilderMeta(PhaseCallbacksMeta, type(llnl.util.compat.Sequence)):  # type: ignore
+    pass
+
+
+class _PackageAdapterMeta(BuilderMeta):
+    """Metaclass to adapt old-style packages to the new architecture based on builders
+    for the installation phase.
+
+    This class does the necessary mangling to function argument so that a call to a
+    builder object can delegate to a package object.
+    """
+
+    @staticmethod
+    def phase_method_adapter(phase_name):
+        def _adapter(self, pkg, spec, prefix):
+            phase_fn = getattr(self.pkg_with_dispatcher, phase_name)
+            return phase_fn(spec, prefix)
+
+        return _adapter
+
+    @staticmethod
+    def legacy_long_method_adapter(method_name):
+        def _adapter(self, spec, prefix):
+            bind_method = getattr(self.pkg_with_dispatcher, method_name)
+            return bind_method(spec, prefix)
+
+        return _adapter
+
+    @staticmethod
+    def legacy_method_adapter(method_name):
+        def _adapter(self):
+            bind_method = getattr(self.pkg_with_dispatcher, method_name)
+            return bind_method()
+
+        return _adapter
+
+    @staticmethod
+    def legacy_attribute_adapter(attribute_name):
+        def _adapter(self):
+            return getattr(self.pkg_with_dispatcher, attribute_name)
+
+        return property(_adapter)
+
+    @staticmethod
+    def combine_callbacks(pipeline_attribute_name):
+        """This function combines callbacks from old-style packages with callbacks that might
+        be registered for the default builder.
+
+        It works by:
+        1. Extracting the callbacks from the old-style package
+        2. Transforming those callbacks by adding an adapter that receives a builder as argument
+           and calls the wrapped function with ``builder.pkg``
+        3. Combining the list of transformed callbacks with those that might be present in the
+           default builder
+        """
+
+        def _adapter(self):
+            def unwrap_pkg(fn):
+                @functools.wraps(fn)
+                def _wrapped(builder):
+                    return fn(builder.pkg_with_dispatcher)
+
+                return _wrapped
+
+            # Concatenate the current list with the one from package
+            callbacks_from_package = getattr(self.pkg, pipeline_attribute_name, [])
+            callbacks_from_package = [(key, unwrap_pkg(x)) for key, x in callbacks_from_package]
+            callbacks_from_builder = getattr(super(type(self), self), pipeline_attribute_name, [])
+            return callbacks_from_package + callbacks_from_builder
+
+        return property(_adapter)
+
+    def __new__(mcs, name, bases, attr_dict):
+        # Add ways to intercept methods and attribute calls and dispatch
+        # them first to a package object
+        default_builder_cls = bases[0]
+        for phase_name in default_builder_cls.phases:
+            attr_dict[phase_name] = _PackageAdapterMeta.phase_method_adapter(phase_name)
+
+        for method_name in default_builder_cls.legacy_methods:
+            attr_dict[method_name] = _PackageAdapterMeta.legacy_method_adapter(method_name)
+
+        # These exist e.g. for Python, see discussion in https://github.com/spack/spack/pull/32068
+        for method_name in getattr(default_builder_cls, "legacy_long_methods", []):
+            attr_dict[method_name] = _PackageAdapterMeta.legacy_long_method_adapter(method_name)
+
+        for attribute_name in default_builder_cls.legacy_attributes:
+            attr_dict[attribute_name] = _PackageAdapterMeta.legacy_attribute_adapter(
+                attribute_name
+            )
+
+        combine_callbacks = _PackageAdapterMeta.combine_callbacks
+        attr_dict[_RUN_BEFORE.attribute_name] = combine_callbacks(_RUN_BEFORE.attribute_name)
+        attr_dict[_RUN_AFTER.attribute_name] = combine_callbacks(_RUN_AFTER.attribute_name)
+
+        return super(_PackageAdapterMeta, mcs).__new__(mcs, name, bases, attr_dict)
+
+
+class InstallationPhase(object):
+    """Manages a single phase of the installation.
+
+    This descriptor stores at creation time the name of the method it should
+    search for execution. The method is retrieved at __get__ time, so that
+    it can be overridden by subclasses of whatever class declared the phases.
+
+    It also provides hooks to execute arbitrary callbacks before and after
+    the phase.
+    """
+
+    def __init__(self, name, builder):
+        self.name = name
+        self.builder = builder
+        self.phase_fn = self._select_phase_fn()
+        self.run_before = self._make_callbacks(_RUN_BEFORE.attribute_name)
+        self.run_after = self._make_callbacks(_RUN_AFTER.attribute_name)
+
+    def _make_callbacks(self, callbacks_attribute):
+        result = []
+        callbacks = getattr(self.builder, callbacks_attribute, [])
+        for (phase, condition), fn in callbacks:
+            # Same if it is for another phase
+            if phase != self.name:
+                continue
+
+            # If we have no condition or the callback satisfies a condition, register it
+            if condition is None or self.builder.pkg.spec.satisfies(condition):
+                result.append(fn)
+        return result
+
+    def __str__(self):
+        msg = '{0}: executing "{1}" phase'
+        return msg.format(self.builder, self.name)
+
+    def execute(self):
+        pkg = self.builder.pkg
+        self._on_phase_start(pkg)
+
+        for callback in self.run_before:
+            callback(self.builder)
+
+        self.phase_fn(pkg, pkg.spec, pkg.prefix)
+
+        for callback in self.run_after:
+            callback(self.builder)
+
+        self._on_phase_exit(pkg)
+
+    def _select_phase_fn(self):
+        phase_fn = getattr(self.builder, self.name, None)
+
+        if not phase_fn:
+            msg = (
+                'unexpected error: package "{0.fullname}" must implement an '
+                '"{1}" phase for the "{2}" build system'
+            )
+            raise RuntimeError(msg.format(self.builder.pkg, self.name, self.builder.build_system))
+
+        return phase_fn
+
+    def _on_phase_start(self, instance):
+        # If a phase has a matching stop_before_phase attribute,
+        # stop the installation process raising a StopPhase
+        if getattr(instance, "stop_before_phase", None) == self.name:
+            raise spack.build_environment.StopPhase(
+                "Stopping before '{0}' phase".format(self.name)
+            )
+
+    def _on_phase_exit(self, instance):
+        # If a phase has a matching last_phase attribute,
+        # stop the installation process raising a StopPhase
+        if getattr(instance, "last_phase", None) == self.name:
+            raise spack.build_environment.StopPhase("Stopping at '{0}' phase".format(self.name))
+
+    def copy(self):
+        return copy.deepcopy(self)
+
+
+class Builder(six.with_metaclass(BuilderMeta, llnl.util.compat.Sequence)):
+    """A builder is a class that, given a package object (i.e. associated with
+    concrete spec), knows how to install it.
+
+    The builder behaves like a sequence, and when iterated over return the
+    "phases" of the installation in the correct order.
+
+    Args:
+        pkg (spack.package_base.PackageBase): package object to be built
+    """
+
+    #: Sequence of phases. Must be defined in derived classes
+    phases = ()  # type: Tuple[str, ...]
+    #: Build system name. Must also be defined in derived classes.
+    build_system = None  # type: Optional[str]
+
+    legacy_methods = ()  # type: Tuple[str, ...]
+    legacy_attributes = ()  # type: Tuple[str, ...]
+
+    #: List of glob expressions. Each expression must either be
+    #: absolute or relative to the package source path.
+    #: Matching artifacts found at the end of the build process will be
+    #: copied in the same directory tree as _spack_build_logfile and
+    #: _spack_build_envfile.
+    archive_files = []  # type: List[str]
+
+    def __init__(self, pkg):
+        self.pkg = pkg
+        self.callbacks = {}
+        for phase in self.phases:
+            self.callbacks[phase] = InstallationPhase(phase, self)
+
+    @property
+    def spec(self):
+        return self.pkg.spec
+
+    @property
+    def stage(self):
+        return self.pkg.stage
+
+    @property
+    def prefix(self):
+        return self.pkg.prefix
+
+    def test(self):
+        # Defer tests to virtual and concrete packages
+        pass
+
+    def setup_build_environment(self, env):
+        """Sets up the build environment for a package.
+
+        This method will be called before the current package prefix exists in
+        Spack's store.
+
+        Args:
+            env (spack.util.environment.EnvironmentModifications): environment
+                modifications to be applied when the package is built. Package authors
+                can call methods on it to alter the build environment.
+        """
+        if not hasattr(super(Builder, self), "setup_build_environment"):
+            return
+        super(Builder, self).setup_build_environment(env)
+
+    def setup_dependent_build_environment(self, env, dependent_spec):
+        """Sets up the build environment of packages that depend on this one.
+
+        This is similar to ``setup_build_environment``, but it is used to
+        modify the build environments of packages that *depend* on this one.
+
+        This gives packages like Python and others that follow the extension
+        model a way to implement common environment or compile-time settings
+        for dependencies.
+
+        This method will be called before the dependent package prefix exists
+        in Spack's store.
+
+        Examples:
+            1. Installing python modules generally requires ``PYTHONPATH``
+            to point to the ``lib/pythonX.Y/site-packages`` directory in the
+            module's install prefix. This method could be used to set that
+            variable.
+
+        Args:
+            env (spack.util.environment.EnvironmentModifications): environment
+                modifications to be applied when the dependent package is built.
+                Package authors can call methods on it to alter the build environment.
+
+            dependent_spec (spack.spec.Spec): the spec of the dependent package
+                about to be built. This allows the extendee (self) to query
+                the dependent's state. Note that *this* package's spec is
+                available as ``self.spec``
+        """
+        if not hasattr(super(Builder, self), "setup_dependent_build_environment"):
+            return
+        super(Builder, self).setup_dependent_build_environment(env, dependent_spec)
+
+    def __getitem__(self, idx):
+        key = self.phases[idx]
+        return self.callbacks[key]
+
+    def __len__(self):
+        return len(self.phases)
+
+    def __repr__(self):
+        msg = "{0}({1})"
+        return msg.format(type(self).__name__, self.pkg.spec.format("{name}/{hash:7}"))
+
+    def __str__(self):
+        msg = '"{0}" builder for "{1}"'
+        return msg.format(type(self).build_system, self.pkg.spec.format("{name}/{hash:7}"))
+
+
+# Export these names as standalone to be used in packages
+run_after = PhaseCallbacksMeta.run_after
+run_before = PhaseCallbacksMeta.run_before