cmake.py: include transitive run deps in CMAKE_PREFIX_PATH

- Run deps often need to be located during the build
- In cases like python-venv and python, where there's a direct build dep
  on both, but python-venv has a run dep on python, meaning we'd rather
  see python-venv in path before python topologically.

.github/workflows/build-containers.yml

@@ -57,7 +57,13 @@ jobs:
       - name: Checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
 
-      - uses: docker/metadata-action@8e5442c4ef9f78752691e2d8f8d19755c6f78e81
+      - name: Determine latest release tag
+        id: latest
+        run: |
+          git fetch --quiet --tags
+          echo "tag=$(git tag --list --sort=-v:refname | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$' | head -n 1)" | tee -a $GITHUB_OUTPUT
+
+      - uses: docker/metadata-action@369eb591f429131d6889c46b94e711f089e6ca96
         id: docker_meta
         with:
           images: |
@@ -71,6 +77,7 @@ jobs:
               type=semver,pattern={{major}}
               type=ref,event=branch
               type=ref,event=pr
+              type=raw,value=latest,enable=${{ github.ref == format('refs/tags/{0}', steps.latest.outputs.tag) }}
 
       - name: Generate the Dockerfile
         env:
@@ -113,7 +120,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build & Deploy ${{ matrix.dockerfile[0] }}
-        uses: docker/build-push-action@4f58ea79222b3b9dc2c8bbdd6debcef730109a75
+        uses: docker/build-push-action@48aba3b46d1b1fec4febb7c5d0c644b249a11355
         with:
           context: dockerfiles/${{ matrix.dockerfile[0] }}
           platforms: ${{ matrix.dockerfile[1] }}

.github/workflows/ci.yaml

@@ -83,10 +83,17 @@ jobs:
 
   all-prechecks:
     needs: [ prechecks ]
+    if: ${{ always() }}
     runs-on: ubuntu-latest
     steps:
     - name: Success
-      run: "true"
+      run: |
+        if [ "${{ needs.prechecks.result }}" == "failure" ] || [ "${{ needs.prechecks.result }}" == "canceled" ]; then
+          echo "Unit tests failed." 
+          exit 1
+        else
+          exit 0
+        fi
 
   coverage:
     needs: [ unit-tests, prechecks ]
@@ -94,8 +101,19 @@ jobs:
     secrets: inherit
 
   all:
-    needs: [ coverage, bootstrap ]
+    needs: [ unit-tests, coverage, bootstrap ]
+    if: ${{ always() }}
     runs-on: ubuntu-latest
+    # See https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#needs-context
     steps:
-    - name: Success
-      run: "true"
+    - name: Status summary
+      run: |
+        if [ "${{ needs.unit-tests.result }}" == "failure" ] || [ "${{ needs.unit-tests.result }}" == "canceled" ]; then
+          echo "Unit tests failed." 
+          exit 1
+        elif [ "${{ needs.bootstrap.result }}" == "failure" ] || [ "${{ needs.bootstrap.result }}" == "canceled" ]; then
+          echo "Bootstrap tests failed." 
+          exit 1
+        else
+          exit 0
+        fi

.github/workflows/coverage.yml

@@ -29,6 +29,6 @@ jobs:
     - run: coverage xml
 
     - name: "Upload coverage report to CodeCov"
-      uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238
+      uses: codecov/codecov-action@05f5a9cfad807516dbbef9929c4a42df3eb78766
       with:
         verbose: true

.github/workflows/requirements/style/requirements.txt

@@ -3,5 +3,5 @@ clingo==5.7.1
 flake8==7.1.1
 isort==5.13.2
 mypy==1.8.0
-types-six==1.16.21.20241009
+types-six==1.16.21.20241105
 vermin==1.6.0

.github/workflows/unit_tests.yaml

@@ -174,7 +174,7 @@ jobs:
         spack bootstrap disable github-actions-v0.6
         spack bootstrap status
         spack solve zlib
-        spack unit-test --verbose --cov --cov-config=pyproject.toml --cov-report=xml:coverage.xml lib/spack/spack/test/concretize.py
+        spack unit-test --verbose --cov --cov-config=pyproject.toml --cov-report=xml:coverage.xml lib/spack/spack/test/concretization/core.py
     - uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882
       with:
         name: coverage-clingo-cffi

README.md

@@ -70,7 +70,7 @@ Tutorial
 ----------------
 
 We maintain a
-[**hands-on tutorial**](https://spack.readthedocs.io/en/latest/tutorial.html).
+[**hands-on tutorial**](https://spack-tutorial.readthedocs.io/).
 It covers basic to advanced usage, packaging, developer features, and large HPC
 deployments.  You can do all of the exercises on your own laptop using a
 Docker container.

etc/spack/defaults/concretizer.yaml

@@ -39,7 +39,8 @@ concretizer:
   # Option to deal with possible duplicate nodes (i.e. different nodes from the same package) in the DAG.
   duplicates:
     # "none": allows a single node for any package in the DAG.
-    # "minimal": allows the duplication of 'build-tools' nodes only (e.g. py-setuptools, cmake etc.)
+    # "minimal": allows the duplication of 'build-tools' nodes only
+    # (e.g. py-setuptools, cmake etc.)
     # "full" (experimental): allows separation of the entire build-tool stack (e.g. the entire "cmake" subDAG)
     strategy: minimal
   # Option to specify compatibility between operating systems for reuse of compilers and packages
@@ -47,3 +48,18 @@ concretizer:
   # it can reuse. Note this is a directional compatibility so mutual compatibility between two OS's
   # requires two entries i.e. os_compatible: {sonoma: [monterey], monterey: [sonoma]}
   os_compatible: {}
+
+  # Option to specify whether to support splicing. Splicing allows for
+  # the relinking of concrete package dependencies in order to better
+  # reuse already built packages with ABI compatible dependencies
+  splice:
+    explicit: []
+    automatic: false
+  # Maximum time, in seconds, allowed for the 'solve' phase. If set to 0, there is no time limit.
+  timeout: 0
+  # If set to true, exceeding the timeout will always result in a concretization error. If false,
+  # the best (suboptimal) model computed before the timeout is used.
+  #
+  # Setting this to false yields unreproducible results, so we advise to use that value only
+  # for debugging purposes (e.g. check which constraints can help Spack concretize faster).
+  error_on_timeout: true

lib/spack/docs/basic_usage.rst

@@ -1359,6 +1359,10 @@ For example, for the ``stackstart`` variant:
     mpileaks stackstart==4   # variant will be propagated to dependencies
     mpileaks stackstart=4    # only mpileaks will have this variant value
 
+Spack also allows variants to be propagated from a package that does
+not have that variant.
+
+
 ^^^^^^^^^^^^^^
 Compiler Flags
 ^^^^^^^^^^^^^^

lib/spack/docs/build_settings.rst

@@ -237,3 +237,35 @@ is optional -- by default, splices will be transitive.
    ``mpich/abcdef`` instead of ``mvapich2`` as the MPI provider. Spack
    will warn the user in this case, but will not fail the
    concretization.
+
+.. _automatic_splicing:
+
+^^^^^^^^^^^^^^^^^^
+Automatic Splicing
+^^^^^^^^^^^^^^^^^^
+
+The Spack solver can be configured to do automatic splicing for
+ABI-compatible packages. Automatic splices are enabled in the concretizer
+config section
+
+.. code-block:: yaml
+
+   concretizer:
+     splice:
+       automatic: True
+
+Packages can include ABI-compatibility information using the
+``can_splice`` directive. See :ref:`the packaging
+guide<abi_compatibility>` for instructions on specifying ABI
+compatibility using the ``can_splice`` directive.
+
+.. note::
+
+   The ``can_splice`` directive is experimental and may be changed in
+   future versions.
+
+When automatic splicing is enabled, the concretizer will combine any
+number of ABI-compatible specs if possible to reuse installed packages
+and packages available from binary caches. The end result of these
+specs is equivalent to a series of transitive/intransitive splices,
+but the series may be non-obvious.

lib/spack/docs/conf.py

@@ -210,16 +210,18 @@ 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"),
+    ("py:class", "spack.build_systems._checks.BuilderWithDefaults"),
     # Spack classes that intersphinx is unable to resolve
     ("py:class", "spack.version.StandardVersion"),
     ("py:class", "spack.spec.DependencySpec"),
+    ("py:class", "spack.spec.ArchSpec"),
     ("py:class", "spack.spec.InstallStatus"),
     ("py:class", "spack.spec.SpecfileReaderBase"),
     ("py:class", "spack.install_test.Pb"),
     ("py:class", "spack.filesystem_view.SimpleFilesystemView"),
     ("py:class", "spack.traverse.EdgeAndDepth"),
     ("py:class", "archspec.cpu.microarchitecture.Microarchitecture"),
+    ("py:class", "spack.compiler.CompilerCache"),
     # TypeVar that is not handled correctly
     ("py:class", "llnl.util.lang.T"),
 ]

lib/spack/docs/environments.rst

@@ -1042,7 +1042,7 @@ file snippet we define a view named ``mpis``, rooted at
 ``/path/to/view`` in which all projections use the package name,
 version, and compiler name to determine the path for a given
 package. This view selects all packages that depend on MPI, and
-excludes those built with the PGI compiler at version 18.5.
+excludes those built with the GCC compiler at version 18.5.
 The root specs with their (transitive) link and run type dependencies
 will be put in the view due to the  ``link: all`` option,
 and the files in the view will be symlinks to the spack install
@@ -1056,7 +1056,7 @@ directories.
        mpis:
          root: /path/to/view
          select: [^mpi]
-         exclude: ['%pgi@18.5']
+         exclude: ['%gcc@18.5']
          projections:
            all: '{name}/{version}-{compiler.name}'
          link: all

lib/spack/docs/getting_started.rst

@@ -35,7 +35,7 @@ A build matrix showing which packages are working on which systems is shown belo
       .. code-block:: console
 
          apt update
-         apt install build-essential ca-certificates coreutils curl environment-modules gfortran git gpg lsb-release python3 python3-distutils python3-venv unzip zip
+         apt install bzip2 ca-certificates file g++ gcc gfortran git gzip lsb-release patch python3 tar unzip xz-utils zstd
 
    .. tab-item:: RHEL
 
@@ -43,14 +43,14 @@ A build matrix showing which packages are working on which systems is shown belo
 
          dnf install epel-release
          dnf group install "Development Tools"
-         dnf install curl findutils gcc-gfortran gnupg2 hostname iproute redhat-lsb-core python3 python3-pip python3-setuptools unzip python3-boto3
+         dnf install gcc-gfortran redhat-lsb-core python3 unzip
 
    .. tab-item:: macOS Brew
 
       .. code-block:: console
 
          brew update
-         brew install curl gcc git gnupg zip
+         brew install gcc git zip
 
 ------------
 Installation
@@ -283,10 +283,6 @@ compilers`` or ``spack compiler list``:
        intel@14.0.1  intel@13.0.1  intel@12.1.2  intel@10.1
    -- clang -------------------------------------------------------
        clang@3.4  clang@3.3  clang@3.2  clang@3.1
-   -- pgi ---------------------------------------------------------
-       pgi@14.3-0   pgi@13.2-0  pgi@12.1-0   pgi@10.9-0  pgi@8.0-1
-       pgi@13.10-0  pgi@13.1-1  pgi@11.10-0  pgi@10.2-0  pgi@7.1-3
-       pgi@13.6-0   pgi@12.8-0  pgi@11.1-0   pgi@9.0-4   pgi@7.0-6
 
 Any of these compilers can be used to build Spack packages.  More on
 how this is done is in :ref:`sec-specs`.
@@ -806,65 +802,6 @@ flags to the ``icc`` command:
            spec: intel@15.0.24.4.9.3
 
 
-^^^
-PGI
-^^^
-
-PGI comes with two sets of compilers for C++ and Fortran,
-distinguishable by their names.  "Old" compilers:
-
-.. code-block:: yaml
-
-    cc:  /soft/pgi/15.10/linux86-64/15.10/bin/pgcc
-    cxx: /soft/pgi/15.10/linux86-64/15.10/bin/pgCC
-    f77: /soft/pgi/15.10/linux86-64/15.10/bin/pgf77
-    fc:  /soft/pgi/15.10/linux86-64/15.10/bin/pgf90
-
-"New" compilers:
-
-.. code-block:: yaml
-
-    cc:  /soft/pgi/15.10/linux86-64/15.10/bin/pgcc
-    cxx: /soft/pgi/15.10/linux86-64/15.10/bin/pgc++
-    f77: /soft/pgi/15.10/linux86-64/15.10/bin/pgfortran
-    fc:  /soft/pgi/15.10/linux86-64/15.10/bin/pgfortran
-
-Older installations of PGI contains just the old compilers; whereas
-newer installations contain the old and the new.  The new compiler is
-considered preferable, as some packages
-(``hdf``) will not build with the old compiler.
-
-When auto-detecting a PGI compiler, there are cases where Spack will
-find the old compilers, when you really want it to find the new
-compilers.  It is best to check this ``compilers.yaml``; and if the old
-compilers are being used, change ``pgf77`` and ``pgf90`` to
-``pgfortran``.
-
-Other issues:
-
-* There are reports that some packages will not build with PGI,
-  including ``libpciaccess`` and ``openssl``.  A workaround is to
-  build these packages with another compiler and then use them as
-  dependencies for PGI-build packages.  For example:
-
-  .. code-block:: console
-
-     $ spack install openmpi%pgi ^libpciaccess%gcc
-
-
-* PGI requires a license to use; see :ref:`licensed-compilers` for more
-  information on installation.
-
-.. note::
-
-   It is believed the problem with HDF 4 is that everything is
-   compiled with the ``F77`` compiler, but at some point some Fortran
-   90 code slipped in there. So compilers that can handle both FORTRAN
-   77 and Fortran 90 (``gfortran``, ``pgfortran``, etc) are fine.  But
-   compilers specific to one or the other (``pgf77``, ``pgf90``) won't
-   work.
-
-
 ^^^
 NAG
 ^^^
@@ -1389,6 +1326,7 @@ Required:
 * Microsoft Visual Studio
 * Python
 * Git
+* 7z
 
 Optional:
 * Intel Fortran (needed for some packages)
@@ -1454,6 +1392,13 @@ as the project providing Git support on Windows. This is additionally the recomm
 for installing Git on Windows, a link to which can be found above. Spack requires the
 utilities vendored by this project.
 
+"""
+7zip
+"""
+
+A tool for extracting ``.xz`` files is required for extracting source tarballs. The latest 7zip
+can be located at https://sourceforge.net/projects/sevenzip/.
+
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Step 2: Install and setup Spack
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

lib/spack/docs/packaging_guide.rst

@@ -1267,7 +1267,7 @@ Git fetching supports the following parameters to ``version``:
   This feature requires ``git`` to be version ``2.25.0`` or later but is useful for
   large repositories that have separate portions that can be built independently.
   If paths provided are directories then all the subdirectories and associated files
-  will also be cloned. 
+  will also be cloned.
 
 Only one of ``tag``, ``branch``, or ``commit`` can be used at a time.
 
@@ -1367,8 +1367,8 @@ Submodules
   git-submodule``.
 
 Sparse-Checkout
-  You can supply ``git_sparse_paths`` at the package or version level to utilize git's 
-  sparse-checkout feature. This will only clone the paths that are specified in the 
+  You can supply ``git_sparse_paths`` at the package or version level to utilize git's
+  sparse-checkout feature. This will only clone the paths that are specified in the
   ``git_sparse_paths`` attribute for the package along with the files in the top level directory.
   This feature allows you to only clone what you need from a large repository.
   Note that this is a newer feature in git and requries git ``2.25.0`` or greater.
@@ -1928,71 +1928,29 @@ to the empty list.
 String. A URL pointing to license setup instructions for the software.
 Defaults to the empty string.
 
-For example, let's take a look at the package for the PGI compilers.
+For example, let's take a look at the Arm Forge package.
 
 .. code-block:: python
 
    # Licensing
    license_required = True
-   license_comment  = "#"
-   license_files    = ["license.dat"]
-   license_vars     = ["PGROUPD_LICENSE_FILE", "LM_LICENSE_FILE"]
-   license_url      = "http://www.pgroup.com/doc/pgiinstall.pdf"
+   license_comment = "#"
+   license_files = ["licences/Licence"]
+   license_vars = [
+       "ALLINEA_LICENSE_DIR",
+       "ALLINEA_LICENCE_DIR",
+       "ALLINEA_LICENSE_FILE",
+       "ALLINEA_LICENCE_FILE",
+   ]
+   license_url = "https://developer.arm.com/documentation/101169/latest/Use-Arm-Licence-Server"
 
-As you can see, PGI requires a license. Its license manager, FlexNet, uses
-the ``#`` symbol to denote a comment. It expects the license file to be
-named ``license.dat`` and to be located directly in the installation prefix.
-If you would like the installation file to be located elsewhere, simply set
-``PGROUPD_LICENSE_FILE`` or ``LM_LICENSE_FILE`` after installation. For
-further instructions on installation and licensing, see the URL provided.
+Arm Forge requires a license. Its license manager uses the ``#`` symbol to denote a comment.
+It expects the license file to be named ``License`` and to be located in a ``licenses`` directory
+in the installation prefix.
 
-Let's walk through a sample PGI installation to see exactly what Spack is
-and isn't capable of. Since PGI does not provide a download URL, it must
-be downloaded manually. It can either be added to a mirror or located in
-the current directory when ``spack install pgi`` is run. See :ref:`mirrors`
-for instructions on setting up a mirror.
-
-After running ``spack install pgi``, the first thing that will happen is
-Spack will create a global license file located at
-``$SPACK_ROOT/etc/spack/licenses/pgi/license.dat``. It will then open up the
-file using :ref:`your favorite editor <controlling-the-editor>`. It will look like
-this:
-
-.. code-block:: sh
-
-   # A license is required to use pgi.
-   #
-   # The recommended solution is to store your license key in this global
-   # license file. After installation, the following symlink(s) will be
-   # added to point to this file (relative to the installation prefix):
-   #
-   #   license.dat
-   #
-   # Alternatively, use one of the following environment variable(s):
-   #
-   #   PGROUPD_LICENSE_FILE
-   #   LM_LICENSE_FILE
-   #
-   # If you choose to store your license in a non-standard location, you may
-   # set one of these variable(s) to the full pathname to the license file, or
-   # port@host if you store your license keys on a dedicated license server.
-   # You will likely want to set this variable in a module file so that it
-   # gets loaded every time someone tries to use pgi.
-   #
-   # For further information on how to acquire a license, please refer to:
-   #
-   #   http://www.pgroup.com/doc/pgiinstall.pdf
-   #
-   # You may enter your license below.
-
-You can add your license directly to this file, or tell FlexNet to use a
-license stored on a separate license server. Here is an example that
-points to a license server called licman1:
-
-.. code-block:: none
-
-   SERVER licman1.mcs.anl.gov 00163eb7fba5 27200
-   USE_SERVER
+If you would like the installation file to be located elsewhere, simply set ``ALLINEA_LICENSE_DIR`` or
+one of the other license variables after installation. For further instructions on installation and
+licensing, see the URL provided.
 
 If your package requires the license to install, you can reference the
 location of this global license using ``self.global_license_file``.
@@ -2392,7 +2350,7 @@ by the ``--jobs`` option:
 .. code-block:: python
    :emphasize-lines: 7, 11
    :linenos:
- 
+
    class Xios(Package):
       ...
       def install(self, spec, prefix):
@@ -2503,15 +2461,14 @@ with. For example, suppose that in the ``libdwarf`` package you write:
 
    depends_on("libelf@0.8")
 
-Now ``libdwarf`` will require ``libelf`` at *exactly* version ``0.8``.
-You can also specify a requirement for a particular variant or for
-specific compiler flags:
+Now ``libdwarf`` will require ``libelf`` in the range ``0.8``, which
+includes patch versions ``0.8.1``, ``0.8.2``, etc. Apart from version
+restrictions, you can also specify variants if this package requires
+optional features of the dependency.
 
 .. code-block:: python
 
-   depends_on("libelf@0.8+debug")
-   depends_on("libelf debug=True")
-   depends_on("libelf cppflags='-fPIC'")
+   depends_on("libelf@0.8 +parser +pic")
 
 Both users *and* package authors can use the same spec syntax to refer
 to different package configurations. Users use the spec syntax on the
@@ -2519,46 +2476,82 @@ command line to find installed packages or to install packages with
 particular constraints, and package authors can use specs to describe
 relationships between packages.
 
-^^^^^^^^^^^^^^
-Version ranges
-^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Specifying backward and forward compatibility
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Although some packages require a specific version for their dependencies,
-most can be built with a range of versions. For example, if you are
-writing a package for a legacy Python module that only works with Python
-2.4 through 2.6, this would look like:
+Packages are often compatible with a range of versions of their
+dependencies. This is typically referred to as backward and forward
+compatibility. Spack allows you to specify this in the ``depends_on``
+directive using version ranges.
+
+**Backwards compatibility** means that the package requires at least a
+certain version of its dependency:
 
 .. code-block:: python
 
-   depends_on("python@2.4:2.6")
+   depends_on("python@3.10:")
 
-Version ranges in Spack are *inclusive*, so ``2.4:2.6`` means any version
-greater than or equal to ``2.4`` and up to and including any ``2.6.x``. If
-you want to specify that a package works with any version of Python 3 (or
-higher), this would look like:
+In this case, the package requires Python 3.10 or newer.
+
+Commonly, packages drop support for older versions of a dependency as
+they release new versions. In Spack you can conveniently add every
+backward compatibility rule as a separate line:
 
 .. code-block:: python
 
-   depends_on("python@3:")
+   # backward compatibility with Python
+   depends_on("python@3.8:")
+   depends_on("python@3.9:", when="@1.2:")
+   depends_on("python@3.10:", when="@1.4:")
 
-Here we leave out the upper bound. If you want to say that a package
-requires Python 2, you can similarly leave out the lower bound:
+This means that in general we need Python 3.8 or newer; from version
+1.2 onwards we need Python 3.9 or newer; from version 1.4 onwards we
+need Python 3.10 or newer. Notice that it's fine to have overlapping
+ranges in the ``when`` clauses.
+
+**Forward compatibility** means that the package requires at most a
+certain version of its dependency. Forward compatibility rules are
+necessary when there are breaking changes in the dependency that the
+package cannot handle. In Spack we often add forward compatibility
+bounds only at the time a new, breaking version of a dependency is
+released. As with backward compatibility, it is typical to see a list
+of forward compatibility bounds in a package file as seperate lines:
 
 .. code-block:: python
 
-   depends_on("python@:2")
+   # forward compatibility with Python
+   depends_on("python@:3.12", when="@:1.10")
+   depends_on("python@:3.13", when="@:1.12")
 
-Notice that we didn't use ``@:3``. Version ranges are *inclusive*, so
-``@:3`` means "up to and including any 3.x version".
+Notice how the ``:`` now appears before the version number both in the
+dependency and in the ``when`` clause. This tells Spack that in general
+we need Python 3.13 or older up to version ``1.12.x``, and up to version
+``1.10.x`` we need Python 3.12 or older. Said differently, forward compatibility
+with Python 3.13 was added in version 1.11, while version 1.13 added forward
+compatibility with Python 3.14.
 
-You can also simply write
+Notice that a version range ``@:3.12`` includes *any* patch version
+number ``3.12.x``, which is often useful when specifying forward compatibility
+bounds.
+
+So far we have seen open-ended version ranges, which is by far the most
+common use case. It is also possible to specify both a lower and an upper bound
+on the version of a dependency, like this:
 
 .. code-block:: python
 
-   depends_on("python@2.7")
+   depends_on("python@3.10:3.12")
 
-to tell Spack that the package needs Python 2.7.x. This is equivalent to
-``@2.7:2.7``.
+There is short syntax to specify that a package is compatible with say any
+``3.x`` version:
+
+.. code-block:: python
+
+   depends_on("python@3")
+
+The above is equivalent to ``depends_on("python@3:3")``, which means at least
+Python version 3 and at most any version ``3.x.y``.
 
 In very rare cases, you may need to specify an exact version, for example
 if you need to distinguish between ``3.2`` and ``3.2.1``:
@@ -2932,9 +2925,9 @@ make sense during the build phase may not be needed at runtime, and vice versa.
 it makes sense to let a dependency set the environment variables for its dependents. To allow all
 this, Spack provides four different methods that can be overridden in a package:
 
-1. :meth:`setup_build_environment <spack.builder.Builder.setup_build_environment>`
+1. :meth:`setup_build_environment <spack.builder.BaseBuilder.setup_build_environment>`
 2. :meth:`setup_run_environment <spack.package_base.PackageBase.setup_run_environment>`
-3. :meth:`setup_dependent_build_environment <spack.builder.Builder.setup_dependent_build_environment>`
+3. :meth:`setup_dependent_build_environment <spack.builder.BaseBuilder.setup_dependent_build_environment>`
 4. :meth:`setup_dependent_run_environment <spack.package_base.PackageBase.setup_dependent_run_environment>`
 
 The Qt package, for instance, uses this call:
@@ -5385,7 +5378,7 @@ by build recipes. Examples of checking :ref:`variant settings <variants>` and
     determine whether it needs to also set up build dependencies (see
     :ref:`test-build-tests`).
 
-The ``MyPackage`` package below provides two basic test examples: 
+The ``MyPackage`` package below provides two basic test examples:
 ``test_example`` and ``test_example2``.  The first runs the installed
 ``example`` and ensures its output contains an expected string. The second
 runs ``example2`` without checking output so is only concerned with confirming
@@ -5702,7 +5695,7 @@ subdirectory of the installation prefix. They are automatically copied to
 the appropriate relative paths under the test stage directory prior to
 executing stand-alone tests.
 
-.. tip:: 
+.. tip::
 
     *Perform test-related conversions once when copying files.*
 
@@ -7078,6 +7071,46 @@ might write:
    CXXFLAGS += -I$DWARF_PREFIX/include
    CXXFLAGS += -L$DWARF_PREFIX/lib
 
+.. _abi_compatibility:
+
+----------------------------
+Specifying ABI Compatibility
+----------------------------
+
+Packages can include ABI-compatibility information using the
+``can_splice`` directive. For example, if ``Foo`` version 1.1 can
+always replace version 1.0, then the package could have:
+
+.. code-block:: python
+
+   can_splice("foo@1.0", when="@1.1")
+
+For virtual packages, packages can also specify ABI-compabitiliby with
+other packages providing the same virtual. For example, ``zlib-ng``
+could specify:
+
+.. code-block:: python
+
+   can_splice("zlib@1.3.1", when="@2.2+compat")
+
+Some packages have ABI-compatibility that is dependent on matching
+variant values, either for all variants or for some set of
+ABI-relevant variants. In those cases, it is not necessary to specify
+the full combinatorial explosion. The ``match_variants`` keyword can
+cover all single-value variants.
+
+.. code-block:: python
+
+   can_splice("foo@1.1", when="@1.2", match_variants=["bar"])  # any value for bar as long as they're the same
+   can_splice("foo@1.2", when="@1.3", match_variants="*")  # any variant values if all single-value variants match
+
+The concretizer will use ABI compatibility to determine automatic
+splices when :ref:`automatic splicing<automatic_splicing>` is enabled.
+
+.. note::
+
+   The ``can_splice`` directive is experimental, and may be replaced
+   by a higher-level interface in future versions of Spack.
 
 .. _package_class_structure:
 

lib/spack/docs/requirements.txt

@@ -1,7 +1,7 @@
 sphinx==8.1.3
 sphinxcontrib-programoutput==0.17
 sphinx_design==0.6.1
-sphinx-rtd-theme==3.0.1
+sphinx-rtd-theme==3.0.2
 python-levenshtein==0.26.1
 docutils==0.21.2
 pygments==2.18.0

lib/spack/env/cc

@@ -101,10 +101,9 @@ setsep() {
     esac
 }
 
-# prepend LISTNAME ELEMENT [SEP]
+# prepend LISTNAME ELEMENT
 #
-# Prepend ELEMENT to the list stored in the variable LISTNAME,
-# assuming the list is separated by SEP.
+# Prepend ELEMENT to the list stored in the variable LISTNAME.
 # Handles empty lists and single-element lists.
 prepend() {
     varname="$1"
@@ -238,6 +237,36 @@ esac
 }
 "
 
+# path_list functions. Path_lists have 3 parts: spack_store_<list>, <list> and system_<list>,
+# which are used to prioritize paths when assembling the final command line.
+
+# init_path_lists LISTNAME
+# Set <LISTNAME>, spack_store_<LISTNAME>, and system_<LISTNAME> to "".
+init_path_lists() {
+    eval "spack_store_$1=\"\""
+    eval "$1=\"\""
+    eval "system_$1=\"\""
+}
+
+# assign_path_lists LISTNAME1 LISTNAME2
+# Copy contents of LISTNAME2 into LISTNAME1, for each path_list prefix.
+assign_path_lists() {
+    eval "spack_store_$1=\"\${spack_store_$2}\""
+    eval "$1=\"\${$2}\""
+    eval "system_$1=\"\${system_$2}\""
+}
+
+# append_path_lists LISTNAME ELT
+# Append the provided ELT to the appropriate list, based on the result of path_order().
+append_path_lists() {
+    path_order "$2"
+    case $? in
+        0) eval "append spack_store_$1 \"\$2\"" ;;
+        1) eval "append $1 \"\$2\"" ;;
+        2) eval "append system_$1 \"\$2\"" ;;
+    esac
+}
+
 # Check if optional parameters are defined
 # If we aren't asking for debug flags, don't add them
 if [ -z "${SPACK_ADD_DEBUG_FLAGS:-}" ]; then
@@ -470,12 +499,7 @@ input_command="$*"
 parse_Wl() {
     while [ $# -ne 0 ]; do
     if [ "$wl_expect_rpath" = yes ]; then
-        path_order "$1"
-        case $? in
-            0) append return_spack_store_rpath_dirs_list "$1" ;;
-            1) append return_rpath_dirs_list "$1" ;;
-            2) append return_system_rpath_dirs_list "$1" ;;
-        esac
+        append_path_lists return_rpath_dirs_list "$1"
         wl_expect_rpath=no
     else
         case "$1" in
@@ -484,24 +508,14 @@ parse_Wl() {
                 if [ -z "$arg" ]; then
                     shift; continue
                 fi
-                path_order "$arg"
-                case $? in
-                    0) append return_spack_store_rpath_dirs_list "$arg" ;;
-                    1) append return_rpath_dirs_list "$arg" ;;
-                    2) append return_system_rpath_dirs_list "$arg" ;;
-                esac
+                append_path_lists return_rpath_dirs_list "$arg"
                 ;;
             --rpath=*)
                 arg="${1#--rpath=}"
                 if [ -z "$arg" ]; then
                     shift; continue
                 fi
-                path_order "$arg"
-                case $? in
-                    0) append return_spack_store_rpath_dirs_list "$arg" ;;
-                    1) append return_rpath_dirs_list "$arg" ;;
-                    2) append return_system_rpath_dirs_list "$arg" ;;
-                esac
+                append_path_lists return_rpath_dirs_list "$arg"
                 ;;
             -rpath|--rpath)
                 wl_expect_rpath=yes
@@ -509,8 +523,7 @@ parse_Wl() {
             "$dtags_to_strip")
                 ;;
             -Wl)
-                # Nested -Wl,-Wl means we're in NAG compiler territory, we don't support
-                # it.
+                # Nested -Wl,-Wl means we're in NAG compiler territory. We don't support it.
                 return 1
                 ;;
             *)
@@ -529,21 +542,10 @@ categorize_arguments() {
     return_other_args_list=""
     return_isystem_was_used=""
 
-    return_isystem_spack_store_include_dirs_list=""
-    return_isystem_system_include_dirs_list=""
-    return_isystem_include_dirs_list=""
-
-    return_spack_store_include_dirs_list=""
-    return_system_include_dirs_list=""
-    return_include_dirs_list=""
-
-    return_spack_store_lib_dirs_list=""
-    return_system_lib_dirs_list=""
-    return_lib_dirs_list=""
-
-    return_spack_store_rpath_dirs_list=""
-    return_system_rpath_dirs_list=""
-    return_rpath_dirs_list=""
+    init_path_lists return_isystem_include_dirs_list
+    init_path_lists return_include_dirs_list
+    init_path_lists return_lib_dirs_list
+    init_path_lists return_rpath_dirs_list
 
     # Global state for keeping track of -Wl,-rpath -Wl,/path
     wl_expect_rpath=no
@@ -609,32 +611,17 @@ categorize_arguments() {
                 arg="${1#-isystem}"
                 return_isystem_was_used=true
                 if [ -z "$arg" ]; then shift; arg="$1"; fi
-                path_order "$arg"
-                case $? in
-                    0) append return_isystem_spack_store_include_dirs_list "$arg" ;;
-                    1) append return_isystem_include_dirs_list "$arg" ;;
-                    2) append return_isystem_system_include_dirs_list "$arg" ;;
-                esac
+                append_path_lists return_isystem_include_dirs_list "$arg"
                 ;;
             -I*)
                 arg="${1#-I}"
                 if [ -z "$arg" ]; then shift; arg="$1"; fi
-                path_order "$arg"
-                case $? in
-                    0) append return_spack_store_include_dirs_list "$arg" ;;
-                    1) append return_include_dirs_list "$arg" ;;
-                    2) append return_system_include_dirs_list "$arg" ;;
-                esac
+                append_path_lists return_include_dirs_list "$arg"
                 ;;
             -L*)
                 arg="${1#-L}"
                 if [ -z "$arg" ]; then shift; arg="$1"; fi
-                path_order "$arg"
-                case $? in
-                    0) append return_spack_store_lib_dirs_list "$arg" ;;
-                    1) append return_lib_dirs_list "$arg" ;;
-                    2) append return_system_lib_dirs_list "$arg" ;;
-                esac
+                append_path_lists return_lib_dirs_list "$arg"
                 ;;
             -l*)
                 # -loopopt=0 is generated erroneously in autoconf <= 2.69,
@@ -667,32 +654,17 @@ categorize_arguments() {
                     break
                 elif [ "$xlinker_expect_rpath" = yes ]; then
                     # Register the path of -Xlinker -rpath <other args> -Xlinker <path>
-                    path_order "$1"
-                    case $? in
-                        0) append return_spack_store_rpath_dirs_list "$1" ;;
-                        1) append return_rpath_dirs_list "$1" ;;
-                        2) append return_system_rpath_dirs_list "$1" ;;
-                    esac
+                    append_path_lists return_rpath_dirs_list "$1"
                     xlinker_expect_rpath=no
                 else
                     case "$1" in
                         -rpath=*)
                             arg="${1#-rpath=}"
-                            path_order "$arg"
-                            case $? in
-                                0) append return_spack_store_rpath_dirs_list "$arg" ;;
-                                1) append return_rpath_dirs_list "$arg" ;;
-                                2) append return_system_rpath_dirs_list "$arg" ;;
-                            esac
+                            append_path_lists return_rpath_dirs_list "$arg"
                             ;;
                         --rpath=*)
                             arg="${1#--rpath=}"
-                            path_order "$arg"
-                            case $? in
-                                0) append return_spack_store_rpath_dirs_list "$arg" ;;
-                                1) append return_rpath_dirs_list "$arg" ;;
-                                2) append return_system_rpath_dirs_list "$arg" ;;
-                            esac
+                            append_path_lists return_rpath_dirs_list "$arg"
                             ;;
                         -rpath|--rpath)
                             xlinker_expect_rpath=yes
@@ -709,7 +681,36 @@ categorize_arguments() {
             "$dtags_to_strip")
                 ;;
             *)
-                append return_other_args_list "$1"
+                # if mode is not ld, we can just add to other args
+                if [ "$mode" != "ld" ]; then
+                    append return_other_args_list "$1"
+                    shift
+                    continue
+                fi
+
+                # if we're in linker mode, we need to parse raw RPATH args
+                case "$1" in
+                    -rpath=*)
+                        arg="${1#-rpath=}"
+                        append_path_lists return_rpath_dirs_list "$arg"
+                        ;;
+                    --rpath=*)
+                        arg="${1#--rpath=}"
+                        append_path_lists return_rpath_dirs_list "$arg"
+                        ;;
+                    -rpath|--rpath)
+                        if [ $# -eq 1 ]; then
+                            # -rpath without value: let the linker raise an error.
+                            append return_other_args_list "$1"
+                            break
+                        fi
+                        shift
+                        append_path_lists return_rpath_dirs_list "$1"
+                        ;;
+                    *)
+                        append return_other_args_list "$1"
+                        ;;
+                esac
                 ;;
         esac
         shift
@@ -731,21 +732,10 @@ categorize_arguments() {
 
 categorize_arguments "$@"
 
-spack_store_include_dirs_list="$return_spack_store_include_dirs_list"
-system_include_dirs_list="$return_system_include_dirs_list"
-include_dirs_list="$return_include_dirs_list"
-
-spack_store_lib_dirs_list="$return_spack_store_lib_dirs_list"
-system_lib_dirs_list="$return_system_lib_dirs_list"
-lib_dirs_list="$return_lib_dirs_list"
-
-spack_store_rpath_dirs_list="$return_spack_store_rpath_dirs_list"
-system_rpath_dirs_list="$return_system_rpath_dirs_list"
-rpath_dirs_list="$return_rpath_dirs_list"
-
-isystem_spack_store_include_dirs_list="$return_isystem_spack_store_include_dirs_list"
-isystem_system_include_dirs_list="$return_isystem_system_include_dirs_list"
-isystem_include_dirs_list="$return_isystem_include_dirs_list"
+assign_path_lists isystem_include_dirs_list return_isystem_include_dirs_list
+assign_path_lists include_dirs_list return_include_dirs_list
+assign_path_lists lib_dirs_list return_lib_dirs_list
+assign_path_lists rpath_dirs_list return_rpath_dirs_list
 
 isystem_was_used="$return_isystem_was_used"
 other_args_list="$return_other_args_list"
@@ -821,21 +811,10 @@ IFS="$lsep"
     categorize_arguments $spack_flags_list
 unset IFS
 
-spack_flags_isystem_spack_store_include_dirs_list="$return_isystem_spack_store_include_dirs_list"
-spack_flags_isystem_system_include_dirs_list="$return_isystem_system_include_dirs_list"
-spack_flags_isystem_include_dirs_list="$return_isystem_include_dirs_list"
-
-spack_flags_spack_store_include_dirs_list="$return_spack_store_include_dirs_list"
-spack_flags_system_include_dirs_list="$return_system_include_dirs_list"
-spack_flags_include_dirs_list="$return_include_dirs_list"
-
-spack_flags_spack_store_lib_dirs_list="$return_spack_store_lib_dirs_list"
-spack_flags_system_lib_dirs_list="$return_system_lib_dirs_list"
-spack_flags_lib_dirs_list="$return_lib_dirs_list"
-
-spack_flags_spack_store_rpath_dirs_list="$return_spack_store_rpath_dirs_list"
-spack_flags_system_rpath_dirs_list="$return_system_rpath_dirs_list"
-spack_flags_rpath_dirs_list="$return_rpath_dirs_list"
+assign_path_lists spack_flags_isystem_include_dirs_list return_isystem_include_dirs_list
+assign_path_lists spack_flags_include_dirs_list return_include_dirs_list
+assign_path_lists spack_flags_lib_dirs_list return_lib_dirs_list
+assign_path_lists spack_flags_rpath_dirs_list return_rpath_dirs_list
 
 spack_flags_isystem_was_used="$return_isystem_was_used"
 spack_flags_other_args_list="$return_other_args_list"
@@ -894,7 +873,7 @@ esac
 case "$mode" in
     cpp|cc|as|ccld)
         if [ "$spack_flags_isystem_was_used" = "true" ] || [ "$isystem_was_used" = "true" ]; then
-            extend isystem_spack_store_include_dirs_list SPACK_STORE_INCLUDE_DIRS
+            extend spack_store_isystem_include_dirs_list SPACK_STORE_INCLUDE_DIRS
             extend isystem_include_dirs_list SPACK_INCLUDE_DIRS
         else
             extend spack_store_include_dirs_list SPACK_STORE_INCLUDE_DIRS
@@ -910,64 +889,63 @@ args_list="$flags_list"
 
 # Include search paths partitioned by (in store, non-sytem, system)
 # NOTE: adding ${lsep} to the prefix here turns every added element into two
-extend args_list spack_flags_spack_store_include_dirs_list -I
+extend args_list spack_store_spack_flags_include_dirs_list -I
 extend args_list spack_store_include_dirs_list -I
 
 extend args_list spack_flags_include_dirs_list -I
 extend args_list include_dirs_list -I
 
-extend args_list spack_flags_isystem_spack_store_include_dirs_list "-isystem${lsep}"
-extend args_list isystem_spack_store_include_dirs_list "-isystem${lsep}"
+extend args_list spack_store_spack_flags_isystem_include_dirs_list "-isystem${lsep}"
+extend args_list spack_store_isystem_include_dirs_list "-isystem${lsep}"
 
 extend args_list spack_flags_isystem_include_dirs_list "-isystem${lsep}"
 extend args_list isystem_include_dirs_list "-isystem${lsep}"
 
-extend args_list spack_flags_system_include_dirs_list -I
+extend args_list system_spack_flags_include_dirs_list -I
 extend args_list system_include_dirs_list -I
 
-extend args_list spack_flags_isystem_system_include_dirs_list "-isystem${lsep}"
-extend args_list isystem_system_include_dirs_list "-isystem${lsep}"
+extend args_list system_spack_flags_isystem_include_dirs_list "-isystem${lsep}"
+extend args_list system_isystem_include_dirs_list "-isystem${lsep}"
 
 # Library search paths partitioned by (in store, non-sytem, system)
-extend args_list spack_flags_spack_store_lib_dirs_list "-L"
+extend args_list spack_store_spack_flags_lib_dirs_list "-L"
 extend args_list spack_store_lib_dirs_list "-L"
 
 extend args_list spack_flags_lib_dirs_list "-L"
 extend args_list lib_dirs_list "-L"
 
-extend args_list spack_flags_system_lib_dirs_list "-L"
+extend args_list system_spack_flags_lib_dirs_list "-L"
 extend args_list system_lib_dirs_list "-L"
 
 # RPATHs arguments
+rpath_prefix=""
 case "$mode" in
     ccld)
         if [ -n "$dtags_to_add" ] ; then
             append args_list "$linker_arg$dtags_to_add"
         fi
-        extend args_list spack_flags_spack_store_rpath_dirs_list "$rpath"
-        extend args_list spack_store_rpath_dirs_list "$rpath"
-
-        extend args_list spack_flags_rpath_dirs_list "$rpath"
-        extend args_list rpath_dirs_list "$rpath"
-
-        extend args_list spack_flags_system_rpath_dirs_list "$rpath"
-        extend args_list system_rpath_dirs_list "$rpath"
+        rpath_prefix="$rpath"
         ;;
     ld)
         if [ -n "$dtags_to_add" ] ; then
             append args_list "$dtags_to_add"
         fi
-        extend args_list spack_flags_spack_store_rpath_dirs_list "-rpath${lsep}"
-        extend args_list spack_store_rpath_dirs_list "-rpath${lsep}"
-
-        extend args_list spack_flags_rpath_dirs_list "-rpath${lsep}"
-        extend args_list rpath_dirs_list "-rpath${lsep}"
-
-        extend args_list spack_flags_system_rpath_dirs_list "-rpath${lsep}"
-        extend args_list system_rpath_dirs_list "-rpath${lsep}"
+        rpath_prefix="-rpath${lsep}"
         ;;
 esac
 
+# if mode is ccld or ld, extend RPATH lists with the prefix determined above
+if [ -n "$rpath_prefix" ]; then
+    extend args_list spack_store_spack_flags_rpath_dirs_list "$rpath_prefix"
+    extend args_list spack_store_rpath_dirs_list "$rpath_prefix"
+
+    extend args_list spack_flags_rpath_dirs_list "$rpath_prefix"
+    extend args_list rpath_dirs_list "$rpath_prefix"
+
+    extend args_list system_spack_flags_rpath_dirs_list "$rpath_prefix"
+    extend args_list system_rpath_dirs_list "$rpath_prefix"
+fi
+
 # Other arguments from the input command
 extend args_list other_args_list
 extend args_list spack_flags_other_args_list

lib/spack/llnl/util/filesystem.py

@@ -20,11 +20,24 @@
 import tempfile
 from contextlib import contextmanager
 from itertools import accumulate
-from typing import Callable, Iterable, List, Match, Optional, Tuple, Union
+from typing import (
+    Callable,
+    Deque,
+    Dict,
+    Generator,
+    Iterable,
+    List,
+    Match,
+    Optional,
+    Sequence,
+    Set,
+    Tuple,
+    Union,
+)
 
 import llnl.util.symlink
 from llnl.util import tty
-from llnl.util.lang import dedupe, memoized
+from llnl.util.lang import dedupe, fnmatch_translate_multiple, memoized
 from llnl.util.symlink import islink, readlink, resolve_link_target_relative_to_the_link, symlink
 
 from ..path import path_to_os_path, system_path_filter
@@ -85,6 +98,8 @@
     "visit_directory_tree",
 ]
 
+Path = Union[str, pathlib.Path]
+
 if sys.version_info < (3, 7, 4):
     # monkeypatch shutil.copystat to fix PermissionError when copying read-only
     # files on Lustre when using Python < 3.7.4
@@ -1673,105 +1688,203 @@ def find_first(root: str, files: Union[Iterable[str], str], bfs_depth: int = 2)
     return FindFirstFile(root, *files, bfs_depth=bfs_depth).find()
 
 
-def find(root, files, recursive=True):
-    """Search for ``files`` starting from the ``root`` directory.
-
-    Like GNU/BSD find but written entirely in Python.
-
-    Examples:
-
-    .. code-block:: console
-
-       $ find /usr -name python
-
-    is equivalent to:
-
-    >>> find('/usr', 'python')
-
-    .. code-block:: console
-
-       $ find /usr/local/bin -maxdepth 1 -name python
-
-    is equivalent to:
-
-    >>> find('/usr/local/bin', 'python', recursive=False)
+def find(
+    root: Union[Path, Sequence[Path]],
+    files: Union[str, Sequence[str]],
+    recursive: bool = True,
+    max_depth: Optional[int] = None,
+) -> List[str]:
+    """Finds all files matching the patterns from ``files`` starting from ``root``. This function
+    returns a deterministic result for the same input and directory structure when run multiple
+    times. Symlinked directories are followed, and unique directories are searched only once. Each
+    matching file is returned only once at lowest depth in case multiple paths exist due to
+    symlinked directories.
 
     Accepts any glob characters accepted by fnmatch:
 
     ==========  ====================================
     Pattern     Meaning
     ==========  ====================================
-    ``*``       matches everything
+    ``*``       matches one or more characters
     ``?``       matches any single character
     ``[seq]``   matches any character in ``seq``
     ``[!seq]``  matches any character not in ``seq``
     ==========  ====================================
 
-    Parameters:
-        root (str): The root directory to start searching from
-        files (str or collections.abc.Sequence): Library name(s) to search for
-        recursive (bool): if False search only root folder,
-            if True descends top-down from the root. Defaults to True.
+    Examples:
 
-    Returns:
-        list: The files that have been found
+    >>> find("/usr", "*.txt", recursive=True, max_depth=2)
+
+    finds all files with the extension ``.txt`` in the directory ``/usr`` and subdirectories up to
+    depth 2.
+
+    >>> find(["/usr", "/var"], ["*.txt", "*.log"], recursive=True)
+
+    finds all files with the extension ``.txt`` or ``.log`` in the directories ``/usr`` and
+    ``/var`` at any depth.
+
+    >>> find("/usr", "GL/*.h", recursive=True)
+
+    finds all header files in a directory GL at any depth in the directory ``/usr``.
+
+    Parameters:
+        root: One or more root directories to start searching from
+        files: One or more filename patterns to search for
+        recursive: if False search only root, if True descends from roots. Defaults to True.
+        max_depth: if set, don't search below this depth. Cannot be set if recursive is False
+
+    Returns a list of absolute, matching file paths.
     """
+    if isinstance(root, (str, pathlib.Path)):
+        root = [root]
+    elif not isinstance(root, collections.abc.Sequence):
+        raise TypeError(f"'root' arg must be a path or a sequence of paths, not '{type(root)}']")
+
     if isinstance(files, str):
         files = [files]
+    elif not isinstance(files, collections.abc.Sequence):
+        raise TypeError(f"'files' arg must be str or a sequence of str, not '{type(files)}']")
 
-    if recursive:
-        tty.debug(f"Find (recursive): {root} {str(files)}")
-        result = _find_recursive(root, files)
-    else:
-        tty.debug(f"Find (not recursive): {root} {str(files)}")
-        result = _find_non_recursive(root, files)
+    # If recursive is false, max_depth can only be None or 0
+    if max_depth and not recursive:
+        raise ValueError(f"max_depth ({max_depth}) cannot be set if recursive is False")
 
-    tty.debug(f"Find complete: {root} {str(files)}")
+    tty.debug(f"Find (max depth = {max_depth}): {root} {files}")
+    if not recursive:
+        max_depth = 0
+    elif max_depth is None:
+        max_depth = sys.maxsize
+    result = _find_max_depth(root, files, max_depth)
+    tty.debug(f"Find complete: {root} {files}")
     return result
 
 
-@system_path_filter
-def _find_recursive(root, search_files):
-    # The variable here is **on purpose** a defaultdict. The idea is that
-    # we want to poke the filesystem as little as possible, but still maintain
-    # stability in the order of the answer. Thus we are recording each library
-    # found in a key, and reconstructing the stable order later.
-    found_files = collections.defaultdict(list)
-
-    # Make the path absolute to have os.walk also return an absolute path
-    root = os.path.abspath(root)
-    for path, _, list_files in os.walk(root):
-        for search_file in search_files:
-            matches = glob.glob(os.path.join(path, search_file))
-            matches = [os.path.join(path, x) for x in matches]
-            found_files[search_file].extend(matches)
-
-    answer = []
-    for search_file in search_files:
-        answer.extend(found_files[search_file])
-
-    return answer
+def _log_file_access_issue(e: OSError, path: str) -> None:
+    errno_name = errno.errorcode.get(e.errno, "UNKNOWN")
+    tty.debug(f"find must skip {path}: {errno_name} {e}")
 
 
-@system_path_filter
-def _find_non_recursive(root, search_files):
-    # The variable here is **on purpose** a defaultdict as os.list_dir
-    # can return files in any order (does not preserve stability)
-    found_files = collections.defaultdict(list)
+def _file_id(s: os.stat_result) -> Tuple[int, int]:
+    # Note: on windows, st_ino is the file index and st_dev is the volume serial number. See
+    # https://github.com/python/cpython/blob/3.9/Python/fileutils.c
+    return (s.st_ino, s.st_dev)
 
-    # Make the path absolute to have absolute path returned
-    root = os.path.abspath(root)
 
-    for search_file in search_files:
-        matches = glob.glob(os.path.join(root, search_file))
-        matches = [os.path.join(root, x) for x in matches]
-        found_files[search_file].extend(matches)
+def _dedupe_files(paths: List[str]) -> List[str]:
+    """Deduplicate files by inode and device, dropping files that cannot be accessed."""
+    unique_files: List[str] = []
+    # tuple of (inode, device) for each file without following symlinks
+    visited: Set[Tuple[int, int]] = set()
+    for path in paths:
+        try:
+            stat_info = os.lstat(path)
+        except OSError as e:
+            _log_file_access_issue(e, path)
+            continue
+        file_id = _file_id(stat_info)
+        if file_id not in visited:
+            unique_files.append(path)
+            visited.add(file_id)
+    return unique_files
 
-    answer = []
-    for search_file in search_files:
-        answer.extend(found_files[search_file])
 
-    return answer
+def _find_max_depth(
+    roots: Sequence[Path], globs: Sequence[str], max_depth: int = sys.maxsize
+) -> List[str]:
+    """See ``find`` for the public API."""
+    # We optimize for the common case of simple filename only patterns: a single, combined regex
+    # is used. For complex patterns that include path components, we use a slower glob call from
+    # every directory we visit within max_depth.
+    filename_only_patterns = {
+        f"pattern_{i}": os.path.normcase(x) for i, x in enumerate(globs) if "/" not in x
+    }
+    complex_patterns = {f"pattern_{i}": x for i, x in enumerate(globs) if "/" in x}
+    regex = re.compile(fnmatch_translate_multiple(filename_only_patterns))
+    # Ordered dictionary that keeps track of what pattern found which files
+    matched_paths: Dict[str, List[str]] = {f"pattern_{i}": [] for i, _ in enumerate(globs)}
+    # Ensure returned paths are always absolute
+    roots = [os.path.abspath(r) for r in roots]
+    # Breadth-first search queue. Each element is a tuple of (depth, dir)
+    dir_queue: Deque[Tuple[int, str]] = collections.deque()
+    # Set of visited directories. Each element is a tuple of (inode, device)
+    visited_dirs: Set[Tuple[int, int]] = set()
+
+    for root in roots:
+        try:
+            stat_root = os.stat(root)
+        except OSError as e:
+            _log_file_access_issue(e, root)
+            continue
+        dir_id = _file_id(stat_root)
+        if dir_id not in visited_dirs:
+            dir_queue.appendleft((0, root))
+            visited_dirs.add(dir_id)
+
+    while dir_queue:
+        depth, curr_dir = dir_queue.pop()
+        try:
+            dir_iter = os.scandir(curr_dir)
+        except OSError as e:
+            _log_file_access_issue(e, curr_dir)
+            continue
+
+        # Use glob.glob for complex patterns.
+        for pattern_name, pattern in complex_patterns.items():
+            matched_paths[pattern_name].extend(
+                path for path in glob.glob(os.path.join(curr_dir, pattern))
+            )
+
+        # List of subdirectories by path and (inode, device) tuple
+        subdirs: List[Tuple[str, Tuple[int, int]]] = []
+
+        with dir_iter:
+            for dir_entry in dir_iter:
+
+                # Match filename only patterns
+                if filename_only_patterns:
+                    m = regex.match(os.path.normcase(dir_entry.name))
+                    if m:
+                        for pattern_name in filename_only_patterns:
+                            if m.group(pattern_name):
+                                matched_paths[pattern_name].append(dir_entry.path)
+                                break
+
+                # Collect subdirectories
+                if depth >= max_depth:
+                    continue
+
+                try:
+                    if not dir_entry.is_dir(follow_symlinks=True):
+                        continue
+                    if sys.platform == "win32":
+                        # Note: st_ino/st_dev on DirEntry.stat are not set on Windows, so we have
+                        # to call os.stat
+                        stat_info = os.stat(dir_entry.path, follow_symlinks=True)
+                    else:
+                        stat_info = dir_entry.stat(follow_symlinks=True)
+                except OSError as e:
+                    # Possible permission issue, or a symlink that cannot be resolved (ELOOP).
+                    _log_file_access_issue(e, dir_entry.path)
+                    continue
+
+                subdirs.append((dir_entry.path, _file_id(stat_info)))
+
+        # Enqueue subdirectories in a deterministic order
+        if subdirs:
+            subdirs.sort(key=lambda s: os.path.basename(s[0]))
+            for subdir, subdir_id in subdirs:
+                if subdir_id not in visited_dirs:
+                    dir_queue.appendleft((depth + 1, subdir))
+                    visited_dirs.add(subdir_id)
+
+    # Sort the matched paths for deterministic output
+    for paths in matched_paths.values():
+        paths.sort()
+    all_matching_paths = [path for paths in matched_paths.values() for path in paths]
+
+    # We only dedupe files if we have any complex patterns, since only they can match the same file
+    # multiple times
+    return _dedupe_files(all_matching_paths) if complex_patterns else all_matching_paths
 
 
 # Utilities for libraries and headers
@@ -2210,7 +2323,9 @@ def find_system_libraries(libraries, shared=True):
     return libraries_found
 
 
-def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
+def find_libraries(
+    libraries, root, shared=True, recursive=False, runtime=True, max_depth: Optional[int] = None
+):
     """Returns an iterable of full paths to libraries found in a root dir.
 
     Accepts any glob characters accepted by fnmatch:
@@ -2231,6 +2346,8 @@ def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
             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.
+        max_depth (int): if set, don't search below this depth. Cannot be set
+            if recursive is 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.
@@ -2239,6 +2356,7 @@ def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
     Returns:
         LibraryList: The libraries that have been found
     """
+
     if isinstance(libraries, str):
         libraries = [libraries]
     elif not isinstance(libraries, collections.abc.Sequence):
@@ -2271,8 +2389,10 @@ def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
     libraries = ["{0}.{1}".format(lib, suffix) for lib in libraries for suffix in suffixes]
 
     if not recursive:
+        if max_depth:
+            raise ValueError(f"max_depth ({max_depth}) cannot be set if recursive is False")
         # If not recursive, look for the libraries directly in root
-        return LibraryList(find(root, libraries, False))
+        return LibraryList(find(root, libraries, recursive=False))
 
     # To speedup the search for external packages configured e.g. in /usr,
     # perform first non-recursive search in root/lib then in root/lib64 and
@@ -2290,7 +2410,7 @@ def find_libraries(libraries, root, shared=True, recursive=False, runtime=True):
         if found_libs:
             break
     else:
-        found_libs = find(root, libraries, True)
+        found_libs = find(root, libraries, recursive=True, max_depth=max_depth)
 
     return LibraryList(found_libs)
 
@@ -2719,6 +2839,25 @@ def temporary_dir(
         remove_directory_contents(tmp_dir)
 
 
+@contextmanager
+def edit_in_place_through_temporary_file(file_path: str) -> Generator[str, None, None]:
+    """Context manager for modifying ``file_path`` in place, preserving its inode and hardlinks,
+    for functions or external tools that do not support in-place editing. Notice that this function
+    is unsafe in that it works with paths instead of a file descriptors, but this is by design,
+    since we assume the call site will create a new inode at the same path."""
+    tmp_fd, tmp_path = tempfile.mkstemp(
+        dir=os.path.dirname(file_path), prefix=f"{os.path.basename(file_path)}."
+    )
+    # windows cannot replace a file with open fds, so close since the call site needs to replace.
+    os.close(tmp_fd)
+    try:
+        shutil.copyfile(file_path, tmp_path, follow_symlinks=True)
+        yield tmp_path
+        shutil.copyfile(tmp_path, file_path, follow_symlinks=True)
+    finally:
+        os.unlink(tmp_path)
+
+
 def filesummary(path, print_bytes=16) -> Tuple[int, bytes]:
     """Create a small summary of the given file. Does not error
     when file does not exist.

lib/spack/llnl/util/lang.py

@@ -5,15 +5,17 @@
 
 import collections.abc
 import contextlib
+import fnmatch
 import functools
 import itertools
 import os
 import re
 import sys
 import traceback
+import typing
 import warnings
 from datetime import datetime, timedelta
-from typing import Callable, Iterable, List, Tuple, TypeVar
+from typing import Callable, Dict, Iterable, List, Tuple, TypeVar
 
 # Ignore emacs backups when listing modules
 ignore_modules = r"^\.#|~$"
@@ -859,6 +861,19 @@ def elide_list(line_list: List[str], max_num: int = 10) -> List[str]:
     return line_list
 
 
+if sys.version_info >= (3, 9):
+    PatternStr = re.Pattern[str]
+else:
+    PatternStr = typing.Pattern[str]
+
+
+def fnmatch_translate_multiple(named_patterns: Dict[str, str]) -> str:
+    """Similar to ``fnmatch.translate``, but takes an ordered dictionary where keys are pattern
+    names, and values are filename patterns. The output is a regex that matches any of the
+    patterns in order, and named capture groups are used to identify which pattern matched."""
+    return "|".join(f"(?P<{n}>{fnmatch.translate(p)})" for n, p in named_patterns.items())
+
+
 @contextlib.contextmanager
 def nullcontext(*args, **kwargs):
     """Empty context manager.

lib/spack/spack/__init__.py

@@ -11,7 +11,7 @@
 import spack.util.git
 
 #: PEP440 canonical <major>.<minor>.<micro>.<devN> string
-__version__ = "0.23.0.dev0"
+__version__ = "0.24.0.dev0"
 spack_version = __version__
 
 

lib/spack/spack/audit.py

@@ -571,8 +571,13 @@ def _search_for_deprecated_package_methods(pkgs, error_cls):
 @package_properties
 def _ensure_all_package_names_are_lowercase(pkgs, error_cls):
     """Ensure package names are lowercase and consistent"""
+    reserved_names = ("all",)
     badname_regex, errors = re.compile(r"[_A-Z]"), []
     for pkg_name in pkgs:
+        if pkg_name in reserved_names:
+            error_msg = f"The name '{pkg_name}' is reserved, and cannot be used for packages"
+            errors.append(error_cls(error_msg, []))
+
         if badname_regex.search(pkg_name):
             error_msg = f"Package name '{pkg_name}' should be lowercase and must not contain '_'"
             errors.append(error_cls(error_msg, []))
@@ -714,9 +719,9 @@ def _ensure_env_methods_are_ported_to_builders(pkgs, error_cls):
     for pkg_name in pkgs:
         pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
 
-        # values are either Value objects (for conditional values) or the values themselves
+        # values are either ConditionalValue objects or the values themselves
         build_system_names = set(
-            v.value if isinstance(v, spack.variant.Value) else v
+            v.value if isinstance(v, spack.variant.ConditionalValue) else v
             for _, variant in pkg_cls.variant_definitions("build_system")
             for v in variant.values
         )

lib/spack/spack/binary_distribution.py

@@ -87,6 +87,8 @@
 from spack.stage import Stage
 from spack.util.executable import which
 
+from .enums import InstallRecordStatus
+
 BUILD_CACHE_RELATIVE_PATH = "build_cache"
 BUILD_CACHE_KEYS_RELATIVE_PATH = "_pgp"
 
@@ -252,7 +254,7 @@ def _associate_built_specs_with_mirror(self, cache_key, mirror_url):
 
             spec_list = [
                 s
-                for s in db.query_local(installed=any)
+                for s in db.query_local(installed=InstallRecordStatus.ANY)
                 if s.external or db.query_local_by_spec_hash(s.dag_hash()).in_buildcache
             ]
 
@@ -1182,6 +1184,9 @@ def __init__(self, mirror: spack.mirror.Mirror, force: bool, update_index: bool)
         self.tmpdir: str
         self.executor: concurrent.futures.Executor
 
+        # Verify if the mirror meets the requirements to push
+        self.mirror.ensure_mirror_usable("push")
+
     def __enter__(self):
         self._tmpdir = tempfile.TemporaryDirectory(dir=spack.stage.get_stage_root())
         self._executor = spack.util.parallel.make_concurrent_executor()
@@ -2329,7 +2334,9 @@ def is_backup_file(file):
             if not codesign:
                 return
             for binary in changed_files:
-                codesign("-fs-", binary)
+                # preserve the original inode by running codesign on a copy
+                with fsys.edit_in_place_through_temporary_file(binary) as tmp_binary:
+                    codesign("-fs-", tmp_binary)
 
     # If we are installing back to the same location
     # relocate the sbang location if the spack directory changed

lib/spack/spack/build_environment.py

@@ -56,7 +56,6 @@
 from llnl.util.symlink import symlink
 from llnl.util.tty.color import cescape, colorize
 
-import spack.build_systems._checks
 import spack.build_systems.cmake
 import spack.build_systems.meson
 import spack.build_systems.python
@@ -883,6 +882,9 @@ def __init__(self, *roots: spack.spec.Spec, context: Context):
         elif context == Context.RUN:
             self.root_depflag = dt.RUN | dt.LINK
 
+    def accept(self, item):
+        return True
+
     def neighbors(self, item):
         spec = item.edge.spec
         if spec.dag_hash() in self.root_hashes:
@@ -920,19 +922,19 @@ def effective_deptypes(
     a flag specifying in what way they do so. The list is ordered topologically
     from root to leaf, meaning that environment modifications should be applied
     in reverse so that dependents override dependencies, not the other way around."""
-    visitor = traverse.TopoVisitor(
-        EnvironmentVisitor(*specs, context=context),
-        key=lambda x: x.dag_hash(),
+    topo_sorted_edges = traverse.traverse_topo_edges_generator(
+        traverse.with_artificial_edges(specs),
+        visitor=EnvironmentVisitor(*specs, context=context),
+        key=traverse.by_dag_hash,
         root=True,
         all_edges=True,
     )
-    traverse.traverse_depth_first_with_visitor(traverse.with_artificial_edges(specs), visitor)
 
     # Dictionary with "no mode" as default value, so it's easy to write modes[x] |= flag.
     use_modes = defaultdict(lambda: UseMode(0))
     nodes_with_type = []
 
-    for edge in visitor.edges:
+    for edge in topo_sorted_edges:
         parent, child, depflag = edge.parent, edge.spec, edge.depflag
 
         # Mark the starting point
@@ -1375,7 +1377,7 @@ def exitcode_msg(p):
     return child_result
 
 
-CONTEXT_BASES = (spack.package_base.PackageBase, spack.build_systems._checks.BaseBuilder)
+CONTEXT_BASES = (spack.package_base.PackageBase, spack.builder.Builder)
 
 
 def get_package_context(traceback, context=3):

lib/spack/spack/build_systems/_checks.py

@@ -9,6 +9,7 @@
 
 import spack.builder
 import spack.error
+import spack.phase_callbacks
 import spack.relocate
 import spack.spec
 import spack.store
@@ -63,7 +64,7 @@ def apply_macos_rpath_fixups(builder: spack.builder.Builder):
 
 
 def ensure_build_dependencies_or_raise(
-    spec: spack.spec.Spec, dependencies: List[spack.spec.Spec], error_msg: str
+    spec: spack.spec.Spec, dependencies: List[str], error_msg: str
 ):
     """Ensure that some build dependencies are present in the concrete spec.
 
@@ -71,7 +72,7 @@ def ensure_build_dependencies_or_raise(
 
     Args:
         spec: concrete spec to be checked.
-        dependencies: list of abstract specs to be satisfied
+        dependencies: list of package names of required build dependencies
         error_msg: brief error message to be prepended to a longer description
 
     Raises:
@@ -127,8 +128,8 @@ def execute_install_time_tests(builder: spack.builder.Builder):
     builder.pkg.tester.phase_tests(builder, "install", builder.install_time_test_callbacks)
 
 
-class BaseBuilder(spack.builder.Builder):
-    """Base class for builders to register common checks"""
+class BuilderWithDefaults(spack.builder.Builder):
+    """Base class for all specific builders with common callbacks registered."""
 
     # Check that self.prefix is there after installation
-    spack.builder.run_after("install")(sanity_check_prefix)
+    spack.phase_callbacks.run_after("install")(sanity_check_prefix)

lib/spack/spack/build_systems/autotools.py

@@ -6,7 +6,7 @@
 import os.path
 import stat
 import subprocess
-from typing import List
+from typing import Callable, List, Optional, Set, Tuple, Union
 
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
@@ -15,6 +15,9 @@
 import spack.builder
 import spack.error
 import spack.package_base
+import spack.phase_callbacks
+import spack.spec
+import spack.util.prefix
 from spack.directives import build_system, conflicts, depends_on
 from spack.multimethod import when
 from spack.operating_systems.mac_os import macos_version
@@ -22,7 +25,7 @@
 from spack.version import Version
 
 from ._checks import (
-    BaseBuilder,
+    BuilderWithDefaults,
     apply_macos_rpath_fixups,
     ensure_build_dependencies_or_raise,
     execute_build_time_tests,
@@ -69,14 +72,14 @@ def flags_to_build_system_args(self, flags):
     # 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)
+        return spack.builder.create(self).enable_or_disable(*args, **kwargs)
 
     def with_or_without(self, *args, **kwargs):
-        return self.builder.with_or_without(*args, **kwargs)
+        return spack.builder.create(self).with_or_without(*args, **kwargs)
 
 
 @spack.builder.builder("autotools")
-class AutotoolsBuilder(BaseBuilder):
+class AutotoolsBuilder(BuilderWithDefaults):
     """The autotools builder encodes the default way of installing software built
     with autotools. It has four phases that can be overridden, if need be:
 
@@ -157,7 +160,7 @@ class AutotoolsBuilder(BaseBuilder):
     install_libtool_archives = False
 
     @property
-    def patch_config_files(self):
+    def patch_config_files(self) -> bool:
         """Whether to update old ``config.guess`` and ``config.sub`` files
         distributed with the tarball.
 
@@ -177,7 +180,7 @@ def patch_config_files(self):
         )
 
     @property
-    def _removed_la_files_log(self):
+    def _removed_la_files_log(self) -> str:
         """File containing the list of removed libtool archives"""
         build_dir = self.build_directory
         if not os.path.isabs(self.build_directory):
@@ -185,15 +188,15 @@ def _removed_la_files_log(self):
         return os.path.join(build_dir, "removed_la_files.txt")
 
     @property
-    def archive_files(self):
+    def archive_files(self) -> List[str]:
         """Files to archive for packages based on autotools"""
         files = [os.path.join(self.build_directory, "config.log")]
         if not self.install_libtool_archives:
             files.append(self._removed_la_files_log)
         return files
 
-    @spack.builder.run_after("autoreconf")
-    def _do_patch_config_files(self):
+    @spack.phase_callbacks.run_after("autoreconf")
+    def _do_patch_config_files(self) -> None:
         """Some packages ship with older config.guess/config.sub files and need to
         have these updated when installed on a newer architecture.
 
@@ -294,7 +297,7 @@ def runs_ok(script_abs_path):
    and set the prefix to the directory containing the `config.guess` and
    `config.sub` files.
 """
-            raise spack.error.InstallError(msg.format(", ".join(to_be_found), self.name))
+            raise spack.error.InstallError(msg.format(", ".join(to_be_found), self.pkg.name))
 
         # Copy the good files over the bad ones
         for abs_path in to_be_patched:
@@ -304,8 +307,8 @@ def runs_ok(script_abs_path):
             fs.copy(substitutes[name], abs_path)
             os.chmod(abs_path, mode)
 
-    @spack.builder.run_before("configure")
-    def _patch_usr_bin_file(self):
+    @spack.phase_callbacks.run_before("configure")
+    def _patch_usr_bin_file(self) -> None:
         """On NixOS file is not available in /usr/bin/file. Patch configure
         scripts to use file from path."""
 
@@ -316,8 +319,8 @@ def _patch_usr_bin_file(self):
             with fs.keep_modification_time(*x.filenames):
                 x.filter(regex="/usr/bin/file", repl="file", string=True)
 
-    @spack.builder.run_before("configure")
-    def _set_autotools_environment_variables(self):
+    @spack.phase_callbacks.run_before("configure")
+    def _set_autotools_environment_variables(self) -> None:
         """Many autotools builds use a version of mknod.m4 that fails when
         running as root unless FORCE_UNSAFE_CONFIGURE is set to 1.
 
@@ -330,8 +333,8 @@ def _set_autotools_environment_variables(self):
         """
         os.environ["FORCE_UNSAFE_CONFIGURE"] = "1"
 
-    @spack.builder.run_before("configure")
-    def _do_patch_libtool_configure(self):
+    @spack.phase_callbacks.run_before("configure")
+    def _do_patch_libtool_configure(self) -> None:
         """Patch bugs that propagate from libtool macros into "configure" and
         further into "libtool". Note that patches that can be fixed by patching
         "libtool" directly should be implemented in the _do_patch_libtool method
@@ -358,8 +361,8 @@ 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')
 
-    @spack.builder.run_after("configure")
-    def _do_patch_libtool(self):
+    @spack.phase_callbacks.run_after("configure")
+    def _do_patch_libtool(self) -> None:
         """If configure generates a "libtool" script that does not correctly
         detect the compiler (and patch_libtool is set), patch in the correct
         values for libtool variables.
@@ -507,27 +510,64 @@ def _do_patch_libtool(self):
             )
 
     @property
-    def configure_directory(self):
+    def configure_directory(self) -> str:
         """Return the directory where 'configure' resides."""
         return self.pkg.stage.source_path
 
     @property
-    def configure_abs_path(self):
+    def configure_abs_path(self) -> str:
         # Absolute path to configure
         configure_abs_path = os.path.join(os.path.abspath(self.configure_directory), "configure")
         return configure_abs_path
 
     @property
-    def build_directory(self):
+    def build_directory(self) -> str:
         """Override to provide another place to build the package"""
         return self.configure_directory
 
-    @spack.builder.run_before("autoreconf")
-    def delete_configure_to_force_update(self):
+    @spack.phase_callbacks.run_before("autoreconf")
+    def delete_configure_to_force_update(self) -> None:
         if self.force_autoreconf:
             fs.force_remove(self.configure_abs_path)
 
-    def autoreconf(self, pkg, spec, prefix):
+    @property
+    def autoreconf_search_path_args(self) -> List[str]:
+        """Search path includes for autoreconf. Add an -I flag for all `aclocal` dirs
+        of build deps, skips the default path of automake, move external include
+        flags to the back, since they might pull in unrelated m4 files shadowing
+        spack dependencies."""
+        return _autoreconf_search_path_args(self.spec)
+
+    @spack.phase_callbacks.run_after("autoreconf")
+    def set_configure_or_die(self) -> None:
+        """Ensure the presence of a "configure" script, or raise. If the "configure"
+        is found, a module level attribute is set.
+
+        Raises:
+             RuntimeError: if the "configure" script is not found
+        """
+        # 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
+        globals_for_pkg = spack.build_environment.ModuleChangePropagator(self.pkg)
+        globals_for_pkg.configure = Executable(self.configure_abs_path)
+        globals_for_pkg.propagate_changes_to_mro()
+
+    def configure_args(self) -> List[str]:
+        """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 autoreconf(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Not needed usually, configure should be already there"""
 
         # If configure exists nothing needs to be done
@@ -554,39 +594,12 @@ def autoreconf(self, pkg, spec, prefix):
             autoreconf_args += self.autoreconf_extra_args
             self.pkg.module.autoreconf(*autoreconf_args)
 
-    @property
-    def autoreconf_search_path_args(self):
-        """Search path includes for autoreconf. Add an -I flag for all `aclocal` dirs
-        of build deps, skips the default path of automake, move external include
-        flags to the back, since they might pull in unrelated m4 files shadowing
-        spack dependencies."""
-        return _autoreconf_search_path_args(self.spec)
-
-    @spack.builder.run_after("autoreconf")
-    def set_configure_or_die(self):
-        """Ensure the presence of a "configure" script, or raise. If the "configure"
-        is found, a module level attribute is set.
-
-        Raises:
-             RuntimeError: if the "configure" script is not found
-        """
-        # 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
-        globals_for_pkg = spack.build_environment.ModuleChangePropagator(self.pkg)
-        globals_for_pkg.configure = Executable(self.configure_abs_path)
-        globals_for_pkg.propagate_changes_to_mro()
-
-    def configure_args(self):
-        """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 configure(self, pkg, spec, prefix):
+    def configure(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run "configure", with the arguments specified by the builder and an
         appropriately set prefix.
         """
@@ -597,7 +610,12 @@ def configure(self, pkg, spec, prefix):
         with fs.working_dir(self.build_directory, create=True):
             pkg.module.configure(*options)
 
-    def build(self, pkg, spec, prefix):
+    def build(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run "make" on the build targets specified by the builder."""
         # See https://autotools.io/automake/silent.html
         params = ["V=1"]
@@ -605,41 +623,49 @@ def build(self, pkg, spec, prefix):
         with fs.working_dir(self.build_directory):
             pkg.module.make(*params)
 
-    def install(self, pkg, spec, prefix):
+    def install(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run "make" on the install targets specified by the builder."""
         with fs.working_dir(self.build_directory):
             pkg.module.make(*self.install_targets)
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
-    def check(self):
+    def check(self) -> None:
         """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
-    ):
+        self,
+        name: str,
+        activation_word: str,
+        deactivation_word: str,
+        activation_value: Optional[Union[Callable, str]] = None,
+        variant=None,
+    ) -> List[str]:
         """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
-            activation_word (str): the default activation word ('with' in the
-                case of ``with_or_without``)
-            deactivation_word (str): the default deactivation word ('without'
-                in the case of ``with_or_without``)
-            activation_value (typing.Callable): callable that accepts a single
-                value. This value is either one of the allowed values for a
-                multi-valued variant or the name of a bool-valued variant.
+            name: name of the option that is being activated or not
+            activation_word: the default activation word ('with' in the case of
+                ``with_or_without``)
+            deactivation_word: the default deactivation word ('without' in the case of
+                ``with_or_without``)
+            activation_value: callable that accepts a single value. This value is either one of the
+                allowed values for a multi-valued variant or the name of a bool-valued variant.
                 Returns the parameter to be used when the value is activated.
 
-                The special value 'prefix' can also be assigned and will return
+                The special value "prefix" can also be assigned and will return
                 ``spec[name].prefix`` as activation parameter.
-            variant (str): name of the variant that is being processed
-                           (if different from option name)
+            variant: name of the variant that is being processed (if different from option name)
 
         Examples:
 
@@ -647,19 +673,19 @@ def _activate_or_not(
 
             .. code-block:: python
 
-                variant('foo', values=('x', 'y'), description='')
-                variant('bar', default=True, description='')
-                variant('ba_z', default=True, description='')
+                variant("foo", values=("x", "y"), description=")
+                variant("bar", default=True, description=")
+                variant("ba_z", default=True, description=")
 
             calling this function like:
 
             .. code-block:: python
 
                 _activate_or_not(
-                    'foo', 'with', 'without', activation_value='prefix'
+                    "foo", "with", "without", activation_value="prefix"
                 )
-                _activate_or_not('bar', 'with', 'without')
-                _activate_or_not('ba-z', 'with', 'without', variant='ba_z')
+                _activate_or_not("bar", "with", "without")
+                _activate_or_not("ba-z", "with", "without", variant="ba_z")
 
             will generate the following configuration options:
 
@@ -679,8 +705,8 @@ def _activate_or_not(
         Raises:
             KeyError: if name is not among known variants
         """
-        spec = self.pkg.spec
-        args = []
+        spec: spack.spec.Spec = self.pkg.spec
+        args: List[str] = []
 
         if activation_value == "prefix":
             activation_value = lambda x: spec[x].prefix
@@ -698,7 +724,7 @@ def _activate_or_not(
         # Create a list of pairs. Each pair includes a configuration
         # option and whether or not that option is activated
         vdef = self.pkg.get_variant(variant)
-        if set(vdef.values) == set((True, False)):
+        if set(vdef.values) == set((True, False)):  # type: ignore
             # BoolValuedVariant carry information about a single option.
             # Nonetheless, for uniformity of treatment we'll package them
             # in an iterable of one element.
@@ -709,14 +735,12 @@ def _activate_or_not(
             # package's build system. It excludes values which have special
             # meanings and do not correspond to features (e.g. "none")
             feature_values = getattr(vdef.values, "feature_values", None) or vdef.values
-            options = [(value, f"{variant}={value}" in spec) for value in feature_values]
+            options = [(v, f"{variant}={v}" in spec) for v in feature_values]  # type: ignore
 
         # For each allowed value in the list of values
         for option_value, activated in options:
             # Search for an override in the package for this value
-            override_name = "{0}_or_{1}_{2}".format(
-                activation_word, deactivation_word, option_value
-            )
+            override_name = f"{activation_word}_or_{deactivation_word}_{option_value}"
             line_generator = getattr(self, override_name, None) or getattr(
                 self.pkg, override_name, None
             )
@@ -725,19 +749,24 @@ def _activate_or_not(
 
                 def _default_generator(is_activated):
                     if is_activated:
-                        line = "--{0}-{1}".format(activation_word, option_value)
+                        line = f"--{activation_word}-{option_value}"
                         if activation_value is not None and activation_value(
                             option_value
                         ):  # NOQA=ignore=E501
-                            line += "={0}".format(activation_value(option_value))
+                            line = f"{line}={activation_value(option_value)}"
                         return line
-                    return "--{0}-{1}".format(deactivation_word, option_value)
+                    return f"--{deactivation_word}-{option_value}"
 
                 line_generator = _default_generator
             args.append(line_generator(activated))
         return args
 
-    def with_or_without(self, name, activation_value=None, variant=None):
+    def with_or_without(
+        self,
+        name: str,
+        activation_value: Optional[Union[Callable, str]] = None,
+        variant: Optional[str] = None,
+    ) -> List[str]:
         """Inspects a variant and returns the arguments that activate
         or deactivate the selected feature(s) for the configure options.
 
@@ -752,12 +781,11 @@ def with_or_without(self, name, activation_value=None, variant=None):
         ``variant=value`` is in the spec.
 
         Args:
-            name (str): name of a valid multi-valued variant
-            activation_value (typing.Callable): callable that accepts a single
-                value and returns the parameter to be used leading to an entry
-                of the type ``--with-{name}={parameter}``.
+            name: name of a valid multi-valued variant
+            activation_value: callable that accepts a single value and returns the parameter to be
+                used leading to an entry of the type ``--with-{name}={parameter}``.
 
-                The special value 'prefix' can also be assigned and will return
+                The special value "prefix" can also be assigned and will return
                 ``spec[name].prefix`` as activation parameter.
 
         Returns:
@@ -765,18 +793,22 @@ def with_or_without(self, name, activation_value=None, variant=None):
         """
         return self._activate_or_not(name, "with", "without", activation_value, variant)
 
-    def enable_or_disable(self, name, activation_value=None, variant=None):
+    def enable_or_disable(
+        self,
+        name: str,
+        activation_value: Optional[Union[Callable, str]] = None,
+        variant: Optional[str] = None,
+    ) -> List[str]:
         """Same as
         :meth:`~spack.build_systems.autotools.AutotoolsBuilder.with_or_without`
         but substitute ``with`` with ``enable`` and ``without`` with ``disable``.
 
         Args:
-            name (str): name of a valid multi-valued variant
-            activation_value (typing.Callable): if present accepts a single value
-                and returns the parameter to be used leading to an entry of the
-                type ``--enable-{name}={parameter}``
+            name: name of a valid multi-valued variant
+            activation_value: if present accepts a single value and returns the parameter to be
+                used leading to an entry of the type ``--enable-{name}={parameter}``
 
-                The special value 'prefix' can also be assigned and will return
+                The special value "prefix" can also be assigned and will return
                 ``spec[name].prefix`` as activation parameter.
 
         Returns:
@@ -784,15 +816,15 @@ def enable_or_disable(self, name, activation_value=None, variant=None):
         """
         return self._activate_or_not(name, "enable", "disable", activation_value, variant)
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)
 
-    def installcheck(self):
+    def installcheck(self) -> None:
         """Run "make" on the ``installcheck`` target, if found."""
         with fs.working_dir(self.build_directory):
             self.pkg._if_make_target_execute("installcheck")
 
-    @spack.builder.run_after("install")
-    def remove_libtool_archives(self):
+    @spack.phase_callbacks.run_after("install")
+    def remove_libtool_archives(self) -> None:
         """Remove all .la files in prefix sub-folders if the package sets
         ``install_libtool_archives`` to be False.
         """
@@ -814,12 +846,13 @@ def setup_build_environment(self, env):
             env.set("MACOSX_DEPLOYMENT_TARGET", "10.16")
 
     # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
-    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
+    spack.phase_callbacks.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
 
 
-def _autoreconf_search_path_args(spec):
-    dirs_seen = set()
-    flags_spack, flags_external = [], []
+def _autoreconf_search_path_args(spec: spack.spec.Spec) -> List[str]:
+    dirs_seen: Set[Tuple[int, int]] = set()
+    flags_spack: List[str] = []
+    flags_external: List[str] = []
 
     # We don't want to add an include flag for automake's default search path.
     for automake in spec.dependencies(name="automake", deptype="build"):

lib/spack/spack/build_systems/cached_cmake.py

@@ -10,7 +10,7 @@
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
 
-import spack.builder
+import spack.phase_callbacks
 
 from .cmake import CMakeBuilder, CMakePackage
 
@@ -192,7 +192,10 @@ def initconfig_mpi_entries(self):
 
         entries.append(cmake_cache_path("MPI_C_COMPILER", spec["mpi"].mpicc))
         entries.append(cmake_cache_path("MPI_CXX_COMPILER", spec["mpi"].mpicxx))
-        entries.append(cmake_cache_path("MPI_Fortran_COMPILER", spec["mpi"].mpifc))
+
+        # not all MPIs have Fortran wrappers
+        if hasattr(spec["mpi"], "mpifc"):
+            entries.append(cmake_cache_path("MPI_Fortran_COMPILER", spec["mpi"].mpifc))
 
         # Check for slurm
         using_slurm = False
@@ -332,7 +335,7 @@ def std_cmake_args(self):
         args.extend(["-C", self.cache_path])
         return args
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.run_after("install")
     def install_cmake_cache(self):
         fs.mkdirp(self.pkg.spec.prefix.share.cmake)
         fs.install(self.cache_path, self.pkg.spec.prefix.share.cmake)

lib/spack/spack/build_systems/cargo.py

@@ -7,10 +7,11 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, depends_on
 from spack.multimethod import when
 
-from ._checks import BaseBuilder, execute_install_time_tests
+from ._checks import BuilderWithDefaults, execute_install_time_tests
 
 
 class CargoPackage(spack.package_base.PackageBase):
@@ -27,7 +28,7 @@ class CargoPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("cargo")
-class CargoBuilder(BaseBuilder):
+class CargoBuilder(BuilderWithDefaults):
     """The Cargo builder encodes the most common way of building software with
     a rust Cargo.toml file. It has two phases that can be overridden, if need be:
 
@@ -77,7 +78,7 @@ def install(self, pkg, spec, prefix):
         with fs.working_dir(self.build_directory):
             fs.install_tree("out", prefix)
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)
 
     def check(self):
         """Run "cargo test"."""

lib/spack/spack/build_systems/cmake.py

@@ -9,7 +9,7 @@
 import re
 import sys
 from itertools import chain
-from typing import List, Optional, Set, Tuple
+from typing import Any, List, Optional, Tuple
 
 import llnl.util.filesystem as fs
 from llnl.util.lang import stable_partition
@@ -18,11 +18,15 @@
 import spack.deptypes as dt
 import spack.error
 import spack.package_base
+import spack.phase_callbacks
+import spack.spec
+import spack.util.prefix
+from spack import traverse
 from spack.directives import build_system, conflicts, depends_on, variant
 from spack.multimethod import when
 from spack.util.environment import filter_system_paths
 
-from ._checks import BaseBuilder, execute_build_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests
 
 # Regex to extract the primary generator from the CMake generator
 # string.
@@ -48,9 +52,9 @@ def _maybe_set_python_hints(pkg: spack.package_base.PackageBase, args: List[str]
     python_executable = pkg.spec["python"].command.path
     args.extend(
         [
-            CMakeBuilder.define("PYTHON_EXECUTABLE", python_executable),
-            CMakeBuilder.define("Python_EXECUTABLE", python_executable),
-            CMakeBuilder.define("Python3_EXECUTABLE", python_executable),
+            define("PYTHON_EXECUTABLE", python_executable),
+            define("Python_EXECUTABLE", python_executable),
+            define("Python3_EXECUTABLE", python_executable),
         ]
     )
 
@@ -85,7 +89,7 @@ def _conditional_cmake_defaults(pkg: spack.package_base.PackageBase, args: List[
         ipo = False
 
     if cmake.satisfies("@3.9:"):
-        args.append(CMakeBuilder.define("CMAKE_INTERPROCEDURAL_OPTIMIZATION", ipo))
+        args.append(define("CMAKE_INTERPROCEDURAL_OPTIMIZATION", ipo))
 
     # Disable Package Registry: export(PACKAGE) may put files in the user's home directory, and
     # find_package may search there. This is not what we want.
@@ -93,30 +97,36 @@ def _conditional_cmake_defaults(pkg: spack.package_base.PackageBase, args: List[
     # Do not populate CMake User Package Registry
     if cmake.satisfies("@3.15:"):
         # see https://cmake.org/cmake/help/latest/policy/CMP0090.html
-        args.append(CMakeBuilder.define("CMAKE_POLICY_DEFAULT_CMP0090", "NEW"))
+        args.append(define("CMAKE_POLICY_DEFAULT_CMP0090", "NEW"))
     elif cmake.satisfies("@3.1:"):
         # see https://cmake.org/cmake/help/latest/variable/CMAKE_EXPORT_NO_PACKAGE_REGISTRY.html
-        args.append(CMakeBuilder.define("CMAKE_EXPORT_NO_PACKAGE_REGISTRY", True))
+        args.append(define("CMAKE_EXPORT_NO_PACKAGE_REGISTRY", True))
 
     # Do not use CMake User/System Package Registry
     # https://cmake.org/cmake/help/latest/manual/cmake-packages.7.html#disabling-the-package-registry
     if cmake.satisfies("@3.16:"):
-        args.append(CMakeBuilder.define("CMAKE_FIND_USE_PACKAGE_REGISTRY", False))
+        args.append(define("CMAKE_FIND_USE_PACKAGE_REGISTRY", False))
     elif cmake.satisfies("@3.1:3.15"):
-        args.append(CMakeBuilder.define("CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY", False))
-        args.append(CMakeBuilder.define("CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY", False))
+        args.append(define("CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY", False))
+        args.append(define("CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY", False))
 
     # Export a compilation database if supported.
     if _supports_compilation_databases(pkg):
-        args.append(CMakeBuilder.define("CMAKE_EXPORT_COMPILE_COMMANDS", True))
+        args.append(define("CMAKE_EXPORT_COMPILE_COMMANDS", True))
 
     # Enable MACOSX_RPATH by default when cmake_minimum_required < 3
     # https://cmake.org/cmake/help/latest/policy/CMP0042.html
     if pkg.spec.satisfies("platform=darwin") and cmake.satisfies("@3:"):
-        args.append(CMakeBuilder.define("CMAKE_POLICY_DEFAULT_CMP0042", "NEW"))
+        args.append(define("CMAKE_POLICY_DEFAULT_CMP0042", "NEW"))
+
+    # Disable find package's config mode for versions of Boost that
+    # didn't provide it. See https://github.com/spack/spack/issues/20169
+    # and https://cmake.org/cmake/help/latest/module/FindBoost.html
+    if pkg.spec.satisfies("^boost@:1.69.0"):
+        args.append(define("Boost_NO_BOOST_CMAKE", True))
 
 
-def generator(*names: str, default: Optional[str] = None):
+def generator(*names: str, default: Optional[str] = None) -> None:
     """The build system generator to use.
 
     See ``cmake --help`` for a list of valid generators.
@@ -157,15 +167,18 @@ def _values(x):
 def get_cmake_prefix_path(pkg: spack.package_base.PackageBase) -> List[str]:
     """Obtain the CMAKE_PREFIX_PATH entries for a package, based on the cmake_prefix_path package
     attribute of direct build/test and transitive link dependencies."""
-    # Add direct build/test deps
-    selected: Set[str] = {s.dag_hash() for s in pkg.spec.dependencies(deptype=dt.BUILD | dt.TEST)}
-    # Add transitive link deps
-    selected.update(s.dag_hash() for s in pkg.spec.traverse(root=False, deptype=dt.LINK))
-    # Separate out externals so they do not shadow Spack prefixes
-    externals, spack_built = stable_partition(
-        (s for s in pkg.spec.traverse(root=False, order="topo") if s.dag_hash() in selected),
-        lambda x: x.external,
+    edges = traverse.traverse_topo_edges_generator(
+        traverse.with_artificial_edges([pkg.spec]),
+        visitor=traverse.MixedDepthVisitor(
+            direct=dt.BUILD | dt.TEST, transitive=dt.LINK | dt.RUN, key=traverse.by_dag_hash
+        ),
+        key=traverse.by_dag_hash,
+        root=False,
+        all_edges=False,  # cover all nodes, not all edges
     )
+    ordered_specs = [edge.spec for edge in edges]
+    # Separate out externals so they do not shadow Spack prefixes
+    externals, spack_built = stable_partition((s for s in ordered_specs), lambda x: x.external)
 
     return filter_system_paths(
         path for spec in chain(spack_built, externals) for path in spec.package.cmake_prefix_paths
@@ -263,15 +276,15 @@ def flags_to_build_system_args(self, 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(self, cmake_var: str, value: Any) -> str:
+        return define(cmake_var, value)
 
-    def define_from_variant(self, *args, **kwargs):
-        return self.builder.define_from_variant(*args, **kwargs)
+    def define_from_variant(self, cmake_var: str, variant: Optional[str] = None) -> str:
+        return define_from_variant(self, cmake_var, variant)
 
 
 @spack.builder.builder("cmake")
-class CMakeBuilder(BaseBuilder):
+class CMakeBuilder(BuilderWithDefaults):
     """The cmake builder encodes the default way of building software with CMake. IT
     has three phases that can be overridden:
 
@@ -321,15 +334,15 @@ class CMakeBuilder(BaseBuilder):
     build_time_test_callbacks = ["check"]
 
     @property
-    def archive_files(self):
+    def archive_files(self) -> List[str]:
         """Files to archive for packages based on CMake"""
         files = [os.path.join(self.build_directory, "CMakeCache.txt")]
-        if _supports_compilation_databases(self):
+        if _supports_compilation_databases(self.pkg):
             files.append(os.path.join(self.build_directory, "compile_commands.json"))
         return files
 
     @property
-    def root_cmakelists_dir(self):
+    def root_cmakelists_dir(self) -> str:
         """The relative path to the directory containing CMakeLists.txt
 
         This path is relative to the root of the extracted tarball,
@@ -338,16 +351,17 @@ def root_cmakelists_dir(self):
         return self.pkg.stage.source_path
 
     @property
-    def generator(self):
+    def generator(self) -> str:
         if self.spec.satisfies("generator=make"):
             return "Unix Makefiles"
         if self.spec.satisfies("generator=ninja"):
             return "Ninja"
-        msg = f'{self.spec.format()} has an unsupported value for the "generator" variant'
-        raise ValueError(msg)
+        raise ValueError(
+            f'{self.spec.format()} has an unsupported value for the "generator" variant'
+        )
 
     @property
-    def std_cmake_args(self):
+    def std_cmake_args(self) -> List[str]:
         """Standard cmake arguments provided as a property for
         convenience of package writers
         """
@@ -356,7 +370,9 @@ def std_cmake_args(self):
         return args
 
     @staticmethod
-    def std_args(pkg, generator=None):
+    def std_args(
+        pkg: spack.package_base.PackageBase, generator: Optional[str] = None
+    ) -> List[str]:
         """Computes the standard cmake arguments for a generic package"""
         default_generator = "Ninja" if sys.platform == "win32" else "Unix Makefiles"
         generator = generator or default_generator
@@ -373,7 +389,6 @@ def std_args(pkg, generator=None):
         except KeyError:
             build_type = "RelWithDebInfo"
 
-        define = CMakeBuilder.define
         args = [
             "-G",
             generator,
@@ -405,152 +420,31 @@ def std_args(pkg, generator=None):
         return args
 
     @staticmethod
-    def define_cuda_architectures(pkg):
-        """Returns the str ``-DCMAKE_CUDA_ARCHITECTURES:STRING=(expanded cuda_arch)``.
-
-        ``cuda_arch`` is variant composed of a list of target CUDA architectures and
-        it is declared in the cuda package.
-
-        This method is no-op for cmake<3.18 and when ``cuda_arch`` variant is not set.
-
-        """
-        cmake_flag = str()
-        if "cuda_arch" in pkg.spec.variants and pkg.spec.satisfies("^cmake@3.18:"):
-            cmake_flag = CMakeBuilder.define(
-                "CMAKE_CUDA_ARCHITECTURES", pkg.spec.variants["cuda_arch"].value
-            )
-
-        return cmake_flag
+    def define_cuda_architectures(pkg: spack.package_base.PackageBase) -> str:
+        return define_cuda_architectures(pkg)
 
     @staticmethod
-    def define_hip_architectures(pkg):
-        """Returns the str ``-DCMAKE_HIP_ARCHITECTURES:STRING=(expanded amdgpu_target)``.
-
-        ``amdgpu_target`` is variant composed of a list of the target HIP
-        architectures and it is declared in the rocm package.
-
-        This method is no-op for cmake<3.18 and when ``amdgpu_target`` variant is
-        not set.
-
-        """
-        cmake_flag = str()
-        if "amdgpu_target" in pkg.spec.variants and pkg.spec.satisfies("^cmake@3.21:"):
-            cmake_flag = CMakeBuilder.define(
-                "CMAKE_HIP_ARCHITECTURES", pkg.spec.variants["amdgpu_target"].value
-            )
-
-        return cmake_flag
+    def define_hip_architectures(pkg: spack.package_base.PackageBase) -> str:
+        return define_hip_architectures(pkg)
 
     @staticmethod
-    def define(cmake_var, value):
-        """Return a CMake command line argument that defines a variable.
+    def define(cmake_var: str, value: Any) -> str:
+        return define(cmake_var, value)
 
-        The resulting argument will convert boolean values to OFF/ON
-        and lists/tuples to CMake semicolon-separated string lists. All other
-        values will be interpreted as strings.
-
-        Examples:
-
-            .. code-block:: python
-
-                [define('BUILD_SHARED_LIBS', True),
-                 define('CMAKE_CXX_STANDARD', 14),
-                 define('swr', ['avx', 'avx2'])]
-
-            will generate the following configuration options:
-
-            .. code-block:: console
-
-                ["-DBUILD_SHARED_LIBS:BOOL=ON",
-                 "-DCMAKE_CXX_STANDARD:STRING=14",
-                 "-DSWR:STRING=avx;avx2]
-
-        """
-        # Create a list of pairs. Each pair includes a configuration
-        # option and whether or not that option is activated
-        if isinstance(value, bool):
-            kind = "BOOL"
-            value = "ON" if value else "OFF"
-        else:
-            kind = "STRING"
-            if isinstance(value, collections.abc.Sequence) and not isinstance(value, str):
-                value = ";".join(str(v) for v in value)
-            else:
-                value = str(value)
-
-        return "".join(["-D", cmake_var, ":", kind, "=", value])
-
-    def define_from_variant(self, cmake_var, variant=None):
-        """Return a CMake command line argument from the given variant's value.
-
-        The optional ``variant`` argument defaults to the lower-case transform
-        of ``cmake_var``.
-
-        This utility function is similar to
-        :meth:`~spack.build_systems.autotools.AutotoolsBuilder.with_or_without`.
-
-        Examples:
-
-            Given a package with:
-
-            .. code-block:: python
-
-                variant('cxxstd', default='11', values=('11', '14'),
-                        multi=False, description='')
-                variant('shared', default=True, description='')
-                variant('swr', values=any_combination_of('avx', 'avx2'),
-                        description='')
-
-            calling this function like:
-
-            .. code-block:: python
-
-                [self.define_from_variant('BUILD_SHARED_LIBS', 'shared'),
-                 self.define_from_variant('CMAKE_CXX_STANDARD', 'cxxstd'),
-                 self.define_from_variant('SWR')]
-
-            will generate the following configuration options:
-
-            .. code-block:: console
-
-                ["-DBUILD_SHARED_LIBS:BOOL=ON",
-                 "-DCMAKE_CXX_STANDARD:STRING=14",
-                 "-DSWR:STRING=avx;avx2]
-
-            for ``<spec-name> cxxstd=14 +shared swr=avx,avx2``
-
-        Note: if the provided variant is conditional, and the condition is not met,
-                this function returns an empty string. CMake discards empty strings
-                provided on the command line.
-        """
-
-        if variant is None:
-            variant = cmake_var.lower()
-
-        if not self.pkg.has_variant(variant):
-            raise KeyError('"{0}" is not a variant of "{1}"'.format(variant, self.pkg.name))
-
-        if variant not in self.pkg.spec.variants:
-            return ""
-
-        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 define_from_variant(self, cmake_var: str, variant: Optional[str] = None) -> str:
+        return define_from_variant(self.pkg, cmake_var, variant)
 
     @property
-    def build_dirname(self):
+    def build_dirname(self) -> str:
         """Directory name to use when building the package."""
-        return "spack-build-%s" % self.pkg.spec.dag_hash(7)
+        return f"spack-build-{self.pkg.spec.dag_hash(7)}"
 
     @property
-    def build_directory(self):
+    def build_directory(self) -> str:
         """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):
+    def cmake_args(self) -> List[str]:
         """List of all the arguments that must be passed to cmake, except:
 
             * CMAKE_INSTALL_PREFIX
@@ -560,7 +454,12 @@ def cmake_args(self):
         """
         return []
 
-    def cmake(self, pkg, spec, prefix):
+    def cmake(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Runs ``cmake`` in the build directory"""
 
         # skip cmake phase if it is an incremental develop build
@@ -575,7 +474,12 @@ def cmake(self, pkg, spec, prefix):
         with fs.working_dir(self.build_directory, create=True):
             pkg.module.cmake(*options)
 
-    def build(self, pkg, spec, prefix):
+    def build(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Make the build targets"""
         with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
@@ -584,7 +488,12 @@ def build(self, pkg, spec, prefix):
                 self.build_targets.append("-v")
                 pkg.module.ninja(*self.build_targets)
 
-    def install(self, pkg, spec, prefix):
+    def install(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Make the install targets"""
         with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
@@ -592,9 +501,9 @@ def install(self, pkg, spec, prefix):
             elif self.generator == "Ninja":
                 pkg.module.ninja(*self.install_targets)
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
-    def check(self):
+    def check(self) -> None:
         """Search the CMake-generated files for the targets ``test`` and ``check``,
         and runs them if found.
         """
@@ -605,3 +514,133 @@ def check(self):
             elif self.generator == "Ninja":
                 self.pkg._if_ninja_target_execute("test", jobs_env="CTEST_PARALLEL_LEVEL")
                 self.pkg._if_ninja_target_execute("check")
+
+
+def define(cmake_var: str, value: Any) -> str:
+    """Return a CMake command line argument that defines a variable.
+
+    The resulting argument will convert boolean values to OFF/ON and lists/tuples to CMake
+    semicolon-separated string lists. All other values will be interpreted as strings.
+
+    Examples:
+
+        .. code-block:: python
+
+            [define("BUILD_SHARED_LIBS", True),
+                define("CMAKE_CXX_STANDARD", 14),
+                define("swr", ["avx", "avx2"])]
+
+        will generate the following configuration options:
+
+        .. code-block:: console
+
+            ["-DBUILD_SHARED_LIBS:BOOL=ON",
+                "-DCMAKE_CXX_STANDARD:STRING=14",
+                "-DSWR:STRING=avx;avx2]
+
+    """
+    # Create a list of pairs. Each pair includes a configuration
+    # option and whether or not that option is activated
+    if isinstance(value, bool):
+        kind = "BOOL"
+        value = "ON" if value else "OFF"
+    else:
+        kind = "STRING"
+        if isinstance(value, collections.abc.Sequence) and not isinstance(value, str):
+            value = ";".join(str(v) for v in value)
+        else:
+            value = str(value)
+
+    return "".join(["-D", cmake_var, ":", kind, "=", value])
+
+
+def define_from_variant(
+    pkg: spack.package_base.PackageBase, cmake_var: str, variant: Optional[str] = None
+) -> str:
+    """Return a CMake command line argument from the given variant's value.
+
+    The optional ``variant`` argument defaults to the lower-case transform
+    of ``cmake_var``.
+
+    Examples:
+
+        Given a package with:
+
+        .. code-block:: python
+
+            variant("cxxstd", default="11", values=("11", "14"),
+                    multi=False, description="")
+            variant("shared", default=True, description="")
+            variant("swr", values=any_combination_of("avx", "avx2"),
+                    description="")
+
+        calling this function like:
+
+        .. code-block:: python
+
+            [
+                self.define_from_variant("BUILD_SHARED_LIBS", "shared"),
+                self.define_from_variant("CMAKE_CXX_STANDARD", "cxxstd"),
+                self.define_from_variant("SWR"),
+            ]
+
+        will generate the following configuration options:
+
+        .. code-block:: console
+
+            [
+                "-DBUILD_SHARED_LIBS:BOOL=ON",
+                "-DCMAKE_CXX_STANDARD:STRING=14",
+                "-DSWR:STRING=avx;avx2",
+            ]
+
+        for ``<spec-name> cxxstd=14 +shared swr=avx,avx2``
+
+    Note: if the provided variant is conditional, and the condition is not met, this function
+        returns an empty string. CMake discards empty strings provided on the command line.
+    """
+    if variant is None:
+        variant = cmake_var.lower()
+
+    if not pkg.has_variant(variant):
+        raise KeyError('"{0}" is not a variant of "{1}"'.format(variant, pkg.name))
+
+    if variant not in pkg.spec.variants:
+        return ""
+
+    value = pkg.spec.variants[variant].value
+    if isinstance(value, (tuple, list)):
+        # Sort multi-valued variants for reproducibility
+        value = sorted(value)
+
+    return define(cmake_var, value)
+
+
+def define_hip_architectures(pkg: spack.package_base.PackageBase) -> str:
+    """Returns the str ``-DCMAKE_HIP_ARCHITECTURES:STRING=(expanded amdgpu_target)``.
+
+    ``amdgpu_target`` is variant composed of a list of the target HIP
+    architectures and it is declared in the rocm package.
+
+    This method is no-op for cmake<3.18 and when ``amdgpu_target`` variant is
+    not set.
+
+    """
+    if "amdgpu_target" in pkg.spec.variants and pkg.spec.satisfies("^cmake@3.21:"):
+        return define("CMAKE_HIP_ARCHITECTURES", pkg.spec.variants["amdgpu_target"].value)
+
+    return ""
+
+
+def define_cuda_architectures(pkg: spack.package_base.PackageBase) -> str:
+    """Returns the str ``-DCMAKE_CUDA_ARCHITECTURES:STRING=(expanded cuda_arch)``.
+
+    ``cuda_arch`` is variant composed of a list of target CUDA architectures and
+    it is declared in the cuda package.
+
+    This method is no-op for cmake<3.18 and when ``cuda_arch`` variant is not set.
+
+    """
+    if "cuda_arch" in pkg.spec.variants and pkg.spec.satisfies("^cmake@3.18:"):
+        return define("CMAKE_CUDA_ARCHITECTURES", pkg.spec.variants["cuda_arch"].value)
+    return ""

lib/spack/spack/build_systems/cuda.py

@@ -180,13 +180,6 @@ def compute_capabilities(arch_list: Iterable[str]) -> List[str]:
         conflicts("%gcc@7:", when="+cuda ^cuda@:9.1 target=x86_64:")
         conflicts("%gcc@8:", when="+cuda ^cuda@:10.0.130 target=x86_64:")
         conflicts("%gcc@9:", when="+cuda ^cuda@:10.2.89 target=x86_64:")
-        conflicts("%pgi@:14.8", when="+cuda ^cuda@:7.0.27 target=x86_64:")
-        conflicts("%pgi@:15.3,15.5:", when="+cuda ^cuda@7.5 target=x86_64:")
-        conflicts("%pgi@:16.2,16.0:16.3", when="+cuda ^cuda@8 target=x86_64:")
-        conflicts("%pgi@:15,18:", when="+cuda ^cuda@9.0:9.1 target=x86_64:")
-        conflicts("%pgi@:16,19:", when="+cuda ^cuda@9.2.88:10.0 target=x86_64:")
-        conflicts("%pgi@:17,20:", when="+cuda ^cuda@10.1.105:10.2.89 target=x86_64:")
-        conflicts("%pgi@:17,21:", when="+cuda ^cuda@11.0.2:11.1.0 target=x86_64:")
         conflicts("%clang@:3.4", when="+cuda ^cuda@:7.5 target=x86_64:")
         conflicts("%clang@:3.7,4:", when="+cuda ^cuda@8.0:9.0 target=x86_64:")
         conflicts("%clang@:3.7,4.1:", when="+cuda ^cuda@9.1 target=x86_64:")
@@ -212,9 +205,6 @@ def compute_capabilities(arch_list: Iterable[str]) -> List[str]:
         conflicts("%gcc@8:", when="+cuda ^cuda@:10.0.130 target=ppc64le:")
         conflicts("%gcc@9:", when="+cuda ^cuda@:10.1.243 target=ppc64le:")
         # officially, CUDA 11.0.2 only supports the system GCC 8.3 on ppc64le
-        conflicts("%pgi", when="+cuda ^cuda@:8 target=ppc64le:")
-        conflicts("%pgi@:16", when="+cuda ^cuda@:9.1.185 target=ppc64le:")
-        conflicts("%pgi@:17", when="+cuda ^cuda@:10 target=ppc64le:")
         conflicts("%clang@4:", when="+cuda ^cuda@:9.0.176 target=ppc64le:")
         conflicts("%clang@5:", when="+cuda ^cuda@:9.1 target=ppc64le:")
         conflicts("%clang@6:", when="+cuda ^cuda@:9.2 target=ppc64le:")

lib/spack/spack/build_systems/generic.py

@@ -7,8 +7,9 @@
 import spack.builder
 import spack.directives
 import spack.package_base
+import spack.phase_callbacks
 
-from ._checks import BaseBuilder, apply_macos_rpath_fixups, execute_install_time_tests
+from ._checks import BuilderWithDefaults, apply_macos_rpath_fixups, execute_install_time_tests
 
 
 class Package(spack.package_base.PackageBase):
@@ -26,7 +27,7 @@ class Package(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("generic")
-class GenericBuilder(BaseBuilder):
+class GenericBuilder(BuilderWithDefaults):
     """A builder for a generic build system, that require packagers
     to implement an "install" phase.
     """
@@ -44,7 +45,7 @@ class GenericBuilder(BaseBuilder):
     install_time_test_callbacks = []
 
     # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
-    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
+    spack.phase_callbacks.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
 
     # unconditionally perform any post-install phase tests
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)

lib/spack/spack/build_systems/go.py

@@ -7,10 +7,11 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, extends
 from spack.multimethod import when
 
-from ._checks import BaseBuilder, execute_install_time_tests
+from ._checks import BuilderWithDefaults, execute_install_time_tests
 
 
 class GoPackage(spack.package_base.PackageBase):
@@ -32,7 +33,7 @@ class GoPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("go")
-class GoBuilder(BaseBuilder):
+class GoBuilder(BuilderWithDefaults):
     """The Go builder encodes the most common way of building software with
     a golang go.mod file. It has two phases that can be overridden, if need be:
 
@@ -99,7 +100,7 @@ def install(self, pkg, spec, prefix):
             fs.mkdirp(prefix.bin)
             fs.install(pkg.name, prefix.bin)
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)
 
     def check(self):
         """Run ``go test .`` in the source directory"""

lib/spack/spack/build_systems/intel.py

@@ -22,8 +22,8 @@
     install,
 )
 
-import spack.builder
 import spack.error
+import spack.phase_callbacks
 from spack.build_environment import dso_suffix
 from spack.error import InstallError
 from spack.util.environment import EnvironmentModifications
@@ -1163,7 +1163,7 @@ def _determine_license_type(self):
         debug_print(license_type)
         return license_type
 
-    @spack.builder.run_before("install")
+    @spack.phase_callbacks.run_before("install")
     def configure(self):
         """Generates the silent.cfg file to pass to installer.sh.
 
@@ -1250,7 +1250,7 @@ def install(self, spec, prefix):
         for f in glob.glob("%s/intel*log" % tmpdir):
             install(f, dst)
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.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'
@@ -1258,7 +1258,7 @@ def validate_install(self):
         if not os.path.exists(self.prefix.bin):
             raise InstallError("The installer has failed to install anything.")
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.run_after("install")
     def configure_rpath(self):
         if "+rpath" not in self.spec:
             return
@@ -1276,7 +1276,7 @@ def configure_rpath(self):
             with open(compiler_cfg, "w") as fh:
                 fh.write("-Xlinker -rpath={0}\n".format(compilers_lib_dir))
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.run_after("install")
     def configure_auto_dispatch(self):
         if self._has_compilers:
             if "auto_dispatch=none" in self.spec:
@@ -1300,7 +1300,7 @@ def configure_auto_dispatch(self):
                 with open(compiler_cfg, "a") as fh:
                     fh.write("-ax{0}\n".format(",".join(ad)))
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.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")
@@ -1308,7 +1308,7 @@ def filter_compiler_wrappers(self):
                 f = os.path.join(bin_dir, f)
                 filter_file("-Xlinker --enable-new-dtags", " ", f, string=True)
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.run_after("install")
     def uninstall_ism(self):
         # The "Intel(R) Software Improvement Program" [ahem] gets installed,
         # apparently regardless of PHONEHOME_SEND_USAGE_DATA.
@@ -1340,7 +1340,7 @@ def base_lib_dir(self):
         debug_print(d)
         return d
 
-    @spack.builder.run_after("install")
+    @spack.phase_callbacks.run_after("install")
     def modify_LLVMgold_rpath(self):
         """Add libimf.so and other required libraries to the RUNPATH of LLVMgold.so.
 

lib/spack/spack/build_systems/makefile.py

@@ -8,11 +8,14 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
+import spack.spec
+import spack.util.prefix
 from spack.directives import build_system, conflicts, depends_on
 from spack.multimethod import when
 
 from ._checks import (
-    BaseBuilder,
+    BuilderWithDefaults,
     apply_macos_rpath_fixups,
     execute_build_time_tests,
     execute_install_time_tests,
@@ -36,7 +39,7 @@ class MakefilePackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("makefile")
-class MakefileBuilder(BaseBuilder):
+class MakefileBuilder(BuilderWithDefaults):
     """The Makefile builder encodes the most common way of building software with
     Makefiles. It has three phases that can be overridden, if need be:
 
@@ -91,35 +94,50 @@ class MakefileBuilder(BaseBuilder):
     install_time_test_callbacks = ["installcheck"]
 
     @property
-    def build_directory(self):
+    def build_directory(self) -> str:
         """Return the directory containing the main Makefile."""
         return self.pkg.stage.source_path
 
-    def edit(self, pkg, spec, prefix):
+    def edit(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Edit the Makefile before calling make. The default is a no-op."""
         pass
 
-    def build(self, pkg, spec, prefix):
+    def build(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run "make" on the build targets specified by the builder."""
         with fs.working_dir(self.build_directory):
             pkg.module.make(*self.build_targets)
 
-    def install(self, pkg, spec, prefix):
+    def install(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run "make" on the install targets specified by the builder."""
         with fs.working_dir(self.build_directory):
             pkg.module.make(*self.install_targets)
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
-    def check(self):
+    def check(self) -> None:
         """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")
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)
 
-    def installcheck(self):
+    def installcheck(self) -> None:
         """Searches the Makefile for an ``installcheck`` target
         and runs it if found.
         """
@@ -127,4 +145,4 @@ def installcheck(self):
             self.pkg._if_make_target_execute("installcheck")
 
     # On macOS, force rpaths for shared library IDs and remove duplicate rpaths
-    spack.builder.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)
+    spack.phase_callbacks.run_after("install", when="platform=darwin")(apply_macos_rpath_fixups)

lib/spack/spack/build_systems/maven.py

@@ -10,7 +10,7 @@
 from spack.multimethod import when
 from spack.util.executable import which
 
-from ._checks import BaseBuilder
+from ._checks import BuilderWithDefaults
 
 
 class MavenPackage(spack.package_base.PackageBase):
@@ -34,7 +34,7 @@ class MavenPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("maven")
-class MavenBuilder(BaseBuilder):
+class MavenBuilder(BuilderWithDefaults):
     """The Maven builder encodes the default way to build software with Maven.
     It has two phases that can be overridden, if need be:
 

lib/spack/spack/build_systems/meson.py

@@ -9,10 +9,13 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
+import spack.spec
+import spack.util.prefix
 from spack.directives import build_system, conflicts, depends_on, variant
 from spack.multimethod import when
 
-from ._checks import BaseBuilder, execute_build_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests
 
 
 class MesonPackage(spack.package_base.PackageBase):
@@ -62,7 +65,7 @@ def flags_to_build_system_args(self, flags):
 
 
 @spack.builder.builder("meson")
-class MesonBuilder(BaseBuilder):
+class MesonBuilder(BuilderWithDefaults):
     """The Meson builder encodes the default way to build software with Meson.
     The builder has three phases that can be overridden, if need be:
 
@@ -112,7 +115,7 @@ def archive_files(self):
         return [os.path.join(self.build_directory, "meson-logs", "meson-log.txt")]
 
     @property
-    def root_mesonlists_dir(self):
+    def root_mesonlists_dir(self) -> str:
         """Relative path to the directory containing meson.build
 
         This path is relative to the root of the extracted tarball,
@@ -121,7 +124,7 @@ def root_mesonlists_dir(self):
         return self.pkg.stage.source_path
 
     @property
-    def std_meson_args(self):
+    def std_meson_args(self) -> List[str]:
         """Standard meson arguments provided as a property for convenience
         of package writers.
         """
@@ -132,7 +135,7 @@ def std_meson_args(self):
         return std_meson_args
 
     @staticmethod
-    def std_args(pkg):
+    def std_args(pkg) -> List[str]:
         """Standard meson arguments for a generic package."""
         try:
             build_type = pkg.spec.variants["buildtype"].value
@@ -172,7 +175,7 @@ def build_directory(self):
         """Directory to use when building the package."""
         return os.path.join(self.pkg.stage.path, self.build_dirname)
 
-    def meson_args(self):
+    def meson_args(self) -> List[str]:
         """List of arguments that must be passed to meson, except:
 
         * ``--prefix``
@@ -185,7 +188,12 @@ def meson_args(self):
         """
         return []
 
-    def meson(self, pkg, spec, prefix):
+    def meson(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Run ``meson`` in the build directory"""
         options = []
         if self.spec["meson"].satisfies("@0.64:"):
@@ -196,21 +204,31 @@ def meson(self, pkg, spec, prefix):
         with fs.working_dir(self.build_directory, create=True):
             pkg.module.meson(*options)
 
-    def build(self, pkg, spec, prefix):
+    def build(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Make the build targets"""
         options = ["-v"]
         options += self.build_targets
         with fs.working_dir(self.build_directory):
             pkg.module.ninja(*options)
 
-    def install(self, pkg, spec, prefix):
+    def install(
+        self,
+        pkg: spack.package_base.PackageBase,
+        spec: spack.spec.Spec,
+        prefix: spack.util.prefix.Prefix,
+    ) -> None:
         """Make the install targets"""
         with fs.working_dir(self.build_directory):
             pkg.module.ninja(*self.install_targets)
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
-    def check(self):
+    def check(self) -> None:
         """Search Meson-generated files for the target ``test`` and run it if found."""
         with fs.working_dir(self.build_directory):
             self.pkg._if_ninja_target_execute("test")

lib/spack/spack/build_systems/msbuild.py

@@ -10,7 +10,7 @@
 import spack.package_base
 from spack.directives import build_system, conflicts
 
-from ._checks import BaseBuilder
+from ._checks import BuilderWithDefaults
 
 
 class MSBuildPackage(spack.package_base.PackageBase):
@@ -26,7 +26,7 @@ class MSBuildPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("msbuild")
-class MSBuildBuilder(BaseBuilder):
+class MSBuildBuilder(BuilderWithDefaults):
     """The MSBuild builder encodes the most common way of building software with
     Mircosoft's MSBuild tool. It has two phases that can be overridden, if need be:
 

lib/spack/spack/build_systems/nmake.py

@@ -10,7 +10,7 @@
 import spack.package_base
 from spack.directives import build_system, conflicts
 
-from ._checks import BaseBuilder
+from ._checks import BuilderWithDefaults
 
 
 class NMakePackage(spack.package_base.PackageBase):
@@ -26,7 +26,7 @@ class NMakePackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("nmake")
-class NMakeBuilder(BaseBuilder):
+class NMakeBuilder(BuilderWithDefaults):
     """The NMake builder encodes the most common way of building software with
     Mircosoft's NMake tool. It has two phases that can be overridden, if need be:
 

lib/spack/spack/build_systems/octave.py

@@ -7,7 +7,7 @@
 from spack.directives import build_system, extends
 from spack.multimethod import when
 
-from ._checks import BaseBuilder
+from ._checks import BuilderWithDefaults
 
 
 class OctavePackage(spack.package_base.PackageBase):
@@ -29,7 +29,7 @@ class OctavePackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("octave")
-class OctaveBuilder(BaseBuilder):
+class OctaveBuilder(BuilderWithDefaults):
     """The octave builder provides the following phases that can be overridden:
 
     1. :py:meth:`~.OctaveBuilder.install`

lib/spack/spack/build_systems/oneapi.py

@@ -255,7 +255,7 @@ def libs(self):
         return find_libraries("*", root=self.component_prefix.lib, recursive=not self.v2_layout)
 
 
-class IntelOneApiLibraryPackageWithSdk(IntelOneApiPackage):
+class IntelOneApiLibraryPackageWithSdk(IntelOneApiLibraryPackage):
     """Base class for Intel oneAPI library packages with SDK components.
 
     Contains some convenient default implementations for libraries

lib/spack/spack/build_systems/perl.py

@@ -10,11 +10,12 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, extends
 from spack.install_test import SkipTest, test_part
 from spack.util.executable import Executable
 
-from ._checks import BaseBuilder, execute_build_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests
 
 
 class PerlPackage(spack.package_base.PackageBase):
@@ -84,7 +85,7 @@ def test_use(self):
 
 
 @spack.builder.builder("perl")
-class PerlBuilder(BaseBuilder):
+class PerlBuilder(BuilderWithDefaults):
     """The perl builder provides four phases that can be overridden, if required:
 
         1. :py:meth:`~.PerlBuilder.configure`
@@ -163,7 +164,7 @@ def configure(self, pkg, spec, prefix):
     # 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.
-    @spack.builder.run_after("configure")
+    @spack.phase_callbacks.run_after("configure")
     def fix_shebang(self):
         if self.build_method == "Build.PL":
             pattern = "#!{0}".format(self.spec["perl"].command.path)
@@ -175,7 +176,7 @@ def build(self, pkg, spec, prefix):
         self.build_executable()
 
     # Ensure that tests run after build (if requested):
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
     def check(self):
         """Runs built-in tests of a Perl package."""

lib/spack/spack/build_systems/python.py

@@ -24,6 +24,7 @@
 import spack.detection
 import spack.multimethod
 import spack.package_base
+import spack.phase_callbacks
 import spack.platforms
 import spack.repo
 import spack.spec
@@ -34,7 +35,7 @@
 from spack.spec import Spec
 from spack.util.prefix import Prefix
 
-from ._checks import BaseBuilder, execute_install_time_tests
+from ._checks import BuilderWithDefaults, execute_install_time_tests
 
 
 def _flatten_dict(dictionary: Mapping[str, object]) -> Iterable[str]:
@@ -374,7 +375,7 @@ def list_url(cls) -> Optional[str]:  # type: ignore[override]
         return None
 
     @property
-    def python_spec(self):
+    def python_spec(self) -> Spec:
         """Get python-venv if it exists or python otherwise."""
         python, *_ = self.spec.dependencies("python-venv") or self.spec.dependencies("python")
         return python
@@ -425,7 +426,7 @@ def libs(self) -> LibraryList:
 
 
 @spack.builder.builder("python_pip")
-class PythonPipBuilder(BaseBuilder):
+class PythonPipBuilder(BuilderWithDefaults):
     phases = ("install",)
 
     #: Names associated with package methods in the old build-system format
@@ -543,4 +544,4 @@ def install(self, pkg: PythonPackage, spec: Spec, prefix: Prefix) -> None:
         with fs.working_dir(self.build_directory):
             pip(*args)
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)

lib/spack/spack/build_systems/qmake.py

@@ -6,9 +6,10 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, depends_on
 
-from ._checks import BaseBuilder, execute_build_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests
 
 
 class QMakePackage(spack.package_base.PackageBase):
@@ -30,7 +31,7 @@ class QMakePackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("qmake")
-class QMakeBuilder(BaseBuilder):
+class QMakeBuilder(BuilderWithDefaults):
     """The qmake builder provides three phases that can be overridden:
 
     1. :py:meth:`~.QMakeBuilder.qmake`
@@ -81,4 +82,4 @@ def check(self):
         with working_dir(self.build_directory):
             self.pkg._if_make_target_execute("check")
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)

lib/spack/spack/build_systems/ruby.py

@@ -8,7 +8,7 @@
 import spack.package_base
 from spack.directives import build_system, extends, maintainers
 
-from ._checks import BaseBuilder
+from ._checks import BuilderWithDefaults
 
 
 class RubyPackage(spack.package_base.PackageBase):
@@ -28,7 +28,7 @@ class RubyPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("ruby")
-class RubyBuilder(BaseBuilder):
+class RubyBuilder(BuilderWithDefaults):
     """The Ruby builder provides two phases that can be overridden if required:
 
     #. :py:meth:`~.RubyBuilder.build`

lib/spack/spack/build_systems/scons.py

@@ -4,9 +4,10 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, depends_on
 
-from ._checks import BaseBuilder, execute_build_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests
 
 
 class SConsPackage(spack.package_base.PackageBase):
@@ -28,7 +29,7 @@ class SConsPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("scons")
-class SConsBuilder(BaseBuilder):
+class SConsBuilder(BuilderWithDefaults):
     """The Scons builder provides the following phases that can be overridden:
 
     1. :py:meth:`~.SConsBuilder.build`
@@ -79,4 +80,4 @@ def build_test(self):
         """
         pass
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)

lib/spack/spack/build_systems/sip.py

@@ -11,11 +11,12 @@
 import spack.builder
 import spack.install_test
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, depends_on, extends
 from spack.multimethod import when
 from spack.util.executable import Executable
 
-from ._checks import BaseBuilder, execute_install_time_tests
+from ._checks import BuilderWithDefaults, execute_install_time_tests
 
 
 class SIPPackage(spack.package_base.PackageBase):
@@ -103,7 +104,7 @@ def test_imports(self):
 
 
 @spack.builder.builder("sip")
-class SIPBuilder(BaseBuilder):
+class SIPBuilder(BuilderWithDefaults):
     """The SIP builder provides the following phases that can be overridden:
 
     * configure
@@ -170,4 +171,4 @@ def install_args(self):
         """Arguments to pass to install."""
         return []
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)

lib/spack/spack/build_systems/waf.py

@@ -6,9 +6,10 @@
 
 import spack.builder
 import spack.package_base
+import spack.phase_callbacks
 from spack.directives import build_system, depends_on
 
-from ._checks import BaseBuilder, execute_build_time_tests, execute_install_time_tests
+from ._checks import BuilderWithDefaults, execute_build_time_tests, execute_install_time_tests
 
 
 class WafPackage(spack.package_base.PackageBase):
@@ -30,7 +31,7 @@ class WafPackage(spack.package_base.PackageBase):
 
 
 @spack.builder.builder("waf")
-class WafBuilder(BaseBuilder):
+class WafBuilder(BuilderWithDefaults):
     """The WAF builder provides the following phases that can be overridden:
 
     * configure
@@ -136,7 +137,7 @@ def build_test(self):
         """
         pass
 
-    spack.builder.run_after("build")(execute_build_time_tests)
+    spack.phase_callbacks.run_after("build")(execute_build_time_tests)
 
     def install_test(self):
         """Run unit tests after install.
@@ -146,4 +147,4 @@ def install_test(self):
         """
         pass
 
-    spack.builder.run_after("install")(execute_install_time_tests)
+    spack.phase_callbacks.run_after("install")(execute_install_time_tests)

lib/spack/spack/builder.py

@@ -6,44 +6,30 @@
 import collections.abc
 import copy
 import functools
-from typing import List, Optional, Tuple
-
-from llnl.util import lang
+from typing import Dict, List, Optional, Tuple, Type
 
 import spack.error
 import spack.multimethod
+import spack.package_base
+import spack.phase_callbacks
 import spack.repo
+import spack.spec
+import spack.util.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=[])
+BUILDER_CLS: Dict[str, Type["Builder"]] = {}
 
 #: Map id(pkg) to a builder, to avoid creating multiple
 #: builders for the same package object.
-_BUILDERS = {}
+_BUILDERS: Dict[int, "Builder"] = {}
 
 
-def builder(build_system_name):
+def builder(build_system_name: str):
     """Class decorator used to register the default builder
     for a given build-system.
 
     Args:
-        build_system_name (str): name of the build-system
+        build_system_name: name of the build-system
     """
 
     def _decorator(cls):
@@ -54,13 +40,9 @@ def _decorator(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
-    """
+def create(pkg: spack.package_base.PackageBase) -> "Builder":
+    """Given a package object with an associated concrete spec, return the builder object that can
+    install it."""
     if id(pkg) not in _BUILDERS:
         _BUILDERS[id(pkg)] = _create(pkg)
     return _BUILDERS[id(pkg)]
@@ -75,7 +57,7 @@ def __call__(self, spec, prefix):
         return self.phase_fn(self.builder.pkg, spec, prefix)
 
 
-def get_builder_class(pkg, name: str) -> Optional[type]:
+def get_builder_class(pkg, name: str) -> Optional[Type["Builder"]]:
     """Return the builder class if a package module defines it."""
     cls = getattr(pkg.module, name, None)
     if cls and cls.__module__.startswith(spack.repo.ROOT_PYTHON_NAMESPACE):
@@ -83,7 +65,7 @@ def get_builder_class(pkg, name: str) -> Optional[type]:
     return None
 
 
-def _create(pkg):
+def _create(pkg: spack.package_base.PackageBase) -> "Builder":
     """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:
@@ -103,7 +85,7 @@ class hierarchy (look at AspellDictPackage for an example of that)
     to look for build-related methods in the ``*Package``.
 
     Args:
-        pkg (spack.package_base.PackageBase): package object for which we need a builder
+        pkg: package object for which we need a builder
     """
     package_buildsystem = buildsystem_name(pkg)
     default_builder_cls = BUILDER_CLS[package_buildsystem]
@@ -168,8 +150,8 @@ def __forward(self, *args, **kwargs):
     # 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
+        base_cls.phases  # type: ignore
+        + base_cls.legacy_methods  # type: ignore
         + getattr(base_cls, "legacy_long_methods", tuple())
         + ("setup_build_environment", "setup_dependent_build_environment")
     ):
@@ -181,14 +163,14 @@ def __forward(self):
 
         return __forward
 
-    for attribute_name in base_cls.legacy_attributes:
+    for attribute_name in base_cls.legacy_attributes:  # type: ignore
         setattr(
             _ForwardToBaseBuilder,
             attribute_name,
             property(forward_property_to_getattr(attribute_name)),
         )
 
-    class Adapter(base_cls, metaclass=_PackageAdapterMeta):
+    class Adapter(base_cls, metaclass=_PackageAdapterMeta):  # type: ignore
         def __init__(self, pkg):
             # Deal with custom phases in packages here
             if hasattr(pkg, "phases"):
@@ -213,99 +195,18 @@ def setup_dependent_build_environment(self, env, dependent_spec):
     return Adapter(pkg)
 
 
-def buildsystem_name(pkg):
+def buildsystem_name(pkg: spack.package_base.PackageBase) -> str:
     """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
-    """
+    return the name of its build system."""
     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
-
-            # Here we have an adapter from an old-style package. This means there is no
-            # hierarchy of builders, and every callback that had to be combined between
-            # *Package and *Builder has been combined already by _PackageAdapterMeta
-            if name == "Adapter":
-                continue
-
-            # If we are here we have callbacks. To get a complete list, we accumulate all the
-            # callbacks from base classes, we deduplicate them, 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
-            callbacks_from_base = []
-            for base in bases:
-                current_callbacks = getattr(base, temporary_stage.attribute_name, None)
-                if not current_callbacks:
-                    continue
-                callbacks_from_base.extend(current_callbacks)
-            callbacks_from_base = list(lang.dedupe(callbacks_from_base))
-            # 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
+        return pkg.legacy_buildsystem  # type: ignore
 
 
 class BuilderMeta(
-    PhaseCallbacksMeta,
+    spack.phase_callbacks.PhaseCallbacksMeta,
     spack.multimethod.MultiMethodMeta,
     type(collections.abc.Sequence),  # type: ignore
 ):
@@ -400,8 +301,12 @@ def __new__(mcs, name, bases, attr_dict):
             )
 
         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)
+        attr_dict[spack.phase_callbacks._RUN_BEFORE.attribute_name] = combine_callbacks(
+            spack.phase_callbacks._RUN_BEFORE.attribute_name
+        )
+        attr_dict[spack.phase_callbacks._RUN_AFTER.attribute_name] = combine_callbacks(
+            spack.phase_callbacks._RUN_AFTER.attribute_name
+        )
 
         return super(_PackageAdapterMeta, mcs).__new__(mcs, name, bases, attr_dict)
 
@@ -421,8 +326,8 @@ 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)
+        self.run_before = self._make_callbacks(spack.phase_callbacks._RUN_BEFORE.attribute_name)
+        self.run_after = self._make_callbacks(spack.phase_callbacks._RUN_AFTER.attribute_name)
 
     def _make_callbacks(self, callbacks_attribute):
         result = []
@@ -483,15 +388,103 @@ def copy(self):
         return copy.deepcopy(self)
 
 
-class Builder(collections.abc.Sequence, metaclass=BuilderMeta):
-    """A builder is a class that, given a package object (i.e. associated with
-    concrete spec), knows how to install it.
+class BaseBuilder(metaclass=BuilderMeta):
+    """An interface for builders, without any phases defined. This class is exposed in the package
+    API, so that packagers can create a single class to define ``setup_build_environment`` and
+    ``@run_before`` and ``@run_after`` callbacks that can be shared among different builders.
 
-    The builder behaves like a sequence, and when iterated over return the
-    "phases" of the installation in the correct order.
+    Example:
 
-    Args:
-        pkg (spack.package_base.PackageBase): package object to be built
+    .. code-block:: python
+
+       class AnyBuilder(BaseBuilder):
+           @run_after("install")
+           def fixup_install(self):
+                # do something after the package is installed
+                pass
+
+           def setup_build_environment(self, env):
+                env.set("MY_ENV_VAR", "my_value")
+
+        class CMakeBuilder(cmake.CMakeBuilder, AnyBuilder):
+            pass
+
+        class AutotoolsBuilder(autotools.AutotoolsBuilder, AnyBuilder):
+            pass
+    """
+
+    def __init__(self, pkg: spack.package_base.PackageBase) -> None:
+        self.pkg = pkg
+
+    @property
+    def spec(self) -> spack.spec.Spec:
+        return self.pkg.spec
+
+    @property
+    def stage(self):
+        return self.pkg.stage
+
+    @property
+    def prefix(self):
+        return self.pkg.prefix
+
+    def setup_build_environment(
+        self, env: spack.util.environment.EnvironmentModifications
+    ) -> None:
+        """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: 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(), "setup_build_environment"):
+            return
+        super().setup_build_environment(env)  # type: ignore
+
+    def setup_dependent_build_environment(
+        self, env: spack.util.environment.EnvironmentModifications, dependent_spec: spack.spec.Spec
+    ) -> None:
+        """Sets up the build environment of a package that depends on this one.
+
+        This is similar to ``setup_build_environment``, but it is used to modify the build
+        environment of a package that *depends* on this one.
+
+        This gives packages the ability to set environment variables for the build of the
+        dependent, which can be useful to provide search hints for headers or libraries if they are
+        not in standard locations.
+
+        This method will be called before the dependent package prefix exists in Spack's store.
+
+        Args:
+            env: 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: 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(), "setup_dependent_build_environment"):
+            return
+        super().setup_dependent_build_environment(env, dependent_spec)  # type: ignore
+
+    def __repr__(self):
+        fmt = "{name}{/hash:7}"
+        return f"{self.__class__.__name__}({self.spec.format(fmt)})"
+
+    def __str__(self):
+        fmt = "{name}{/hash:7}"
+        return f'"{self.__class__.__name__}" builder for "{self.spec.format(fmt)}"'
+
+
+class Builder(BaseBuilder, collections.abc.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.
     """
 
     #: Sequence of phases. Must be defined in derived classes
@@ -506,95 +499,22 @@ class Builder(collections.abc.Sequence, metaclass=BuilderMeta):
     build_time_test_callbacks: List[str]
     install_time_test_callbacks: List[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: List[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.
+    @property
+    def archive_files(self) -> List[str]:
+        return []
 
-    def __init__(self, pkg):
-        self.pkg = pkg
+    def __init__(self, pkg: spack.package_base.PackageBase) -> None:
+        super().__init__(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 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(), "setup_build_environment"):
-            return
-        super().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(), "setup_dependent_build_environment"):
-            return
-        super().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

lib/spack/spack/ci.py

@@ -32,12 +32,12 @@
 
 import spack
 import spack.binary_distribution as bindist
+import spack.builder
 import spack.concretize
 import spack.config as cfg
 import spack.error
 import spack.main
 import spack.mirror
-import spack.package_base
 import spack.paths
 import spack.repo
 import spack.spec
@@ -265,22 +265,14 @@ def _format_job_needs(dep_jobs, build_group, prune_dag, rebuild_decisions):
 def get_change_revisions():
     """If this is a git repo get the revisions to use when checking
     for changed packages and spack core modules."""
-    rev1 = None
-    rev2 = None
-
-    # Note: git_dir may be a file in a worktree. If it exists, attempt to use git
-    #       to determine if there is a revision
     git_dir = os.path.join(spack.paths.prefix, ".git")
-    if os.path.exists(git_dir):
-        # The default will only find changed packages from the last
-        # commit. When the commit is a merge commit, this is will return all of the
-        # changes on the topic.
-        # TODO: Handle the case where the clone is not shallow clone of a merge commit
-        #       using `git merge-base`
-        rev1 = "HEAD^"
-        rev2 = "HEAD"
-
-    return rev1, rev2
+    if os.path.exists(git_dir) and os.path.isdir(git_dir):
+        # TODO: This will only find changed packages from the last
+        # TODO: commit.  While this may work for single merge commits
+        # TODO: when merging the topic branch into the base, it will
+        # TODO: require more thought outside of that narrow case.
+        return "HEAD^", "HEAD"
+    return None, None
 
 
 def get_stack_changed(env_path, rev1="HEAD^", rev2="HEAD"):
@@ -399,7 +391,7 @@ class SpackCI:
     used by the CI generator(s).
     """
 
-    def __init__(self, ci_config, spec_labels=None, stages=None):
+    def __init__(self, ci_config, spec_labels, stages):
         """Given the information from the ci section of the config
         and the staged jobs, set up meta data needed for generating Spack
         CI IR.
@@ -417,9 +409,8 @@ def __init__(self, ci_config, spec_labels=None, stages=None):
         }
         jobs = self.ir["jobs"]
 
-        if spec_labels and stages:
-            for spec, dag_hash in _build_jobs(spec_labels, stages):
-                jobs[dag_hash] = self.__init_job(spec)
+        for spec, dag_hash in _build_jobs(spec_labels, stages):
+            jobs[dag_hash] = self.__init_job(spec)
 
         for name in self.named_jobs:
             # Skip the special named jobs
@@ -715,53 +706,14 @@ def generate_gitlab_ci_yaml(
             files (spack.yaml, spack.lock), etc should be written.  GitLab
             requires this to be within the project directory.
     """
-    rev1, rev2 = get_change_revisions()
-    tty.debug(f"Got following revisions: rev1={rev1}, rev2={rev2}")
-
-    # Get the joined "ci" config with all of the current scopes resolved
-    ci_config = cfg.get("ci")
-    spack_prune_untouched = os.environ.get("SPACK_PRUNE_UNTOUCHED", None)
-
-    changed = rev1 and rev2
-    affected_pkgs = None
-    if spack_prune_untouched and changed:
-        affected_pkgs = compute_affected_packages(rev1, rev2)
-        tty.debug("affected pkgs:")
-        if affected_pkgs:
-            for p in affected_pkgs:
-                tty.debug(f"  {p}")
-        else:
-            tty.debug("  no affected packages...")
-
-        possible_builds = spack.package_base.possible_dependencies(*env.user_specs)
-        changed = any((spec in p for p in possible_builds.values()) for spec in affected_pkgs)
-
-        if not changed:
-            spack_ci = SpackCI(ci_config)
-            spack_ci_ir = spack_ci.generate_ir()
-
-            # No jobs should be generated.
-            noop_job = spack_ci_ir["jobs"]["noop"]["attributes"]
-            # If this job fails ignore the status and carry on
-            noop_job["retry"] = 0
-            noop_job["allow_failure"] = True
-
-            tty.msg("Skipping concretization, generating no-op job")
-            output_object = {"no-specs-to-rebuild": noop_job}
-
-            # Ensure the child pipeline always runs
-            output_object["workflow"] = {"rules": [{"when": "always"}]}
-
-            with open(output_file, "w") as f:
-                ruamel.yaml.YAML().dump(output_object, f)
-
-            return
-
     with spack.concretize.disable_compiler_existence_check():
         with env.write_transaction():
             env.concretize()
             env.write()
 
+    # Get the joined "ci" config with all of the current scopes resolved
+    ci_config = cfg.get("ci")
+
     if not ci_config:
         raise SpackCIError("Environment does not have a `ci` configuration")
 
@@ -786,13 +738,20 @@ def generate_gitlab_ci_yaml(
             dependent_depth = None
 
     prune_untouched_packages = False
+    spack_prune_untouched = os.environ.get("SPACK_PRUNE_UNTOUCHED", None)
     if spack_prune_untouched is not None and spack_prune_untouched.lower() == "true":
         # Requested to prune untouched packages, but assume we won't do that
         # unless we're actually in a git repo.
-        if changed:
+        rev1, rev2 = get_change_revisions()
+        tty.debug(f"Got following revisions: rev1={rev1}, rev2={rev2}")
+        if rev1 and rev2:
             # If the stack file itself did not change, proceed with pruning
             if not get_stack_changed(env.manifest_path, rev1, rev2):
                 prune_untouched_packages = True
+                affected_pkgs = compute_affected_packages(rev1, rev2)
+                tty.debug("affected pkgs:")
+                for p in affected_pkgs:
+                    tty.debug(f"  {p}")
                 affected_specs = get_spec_filter_list(
                     env, affected_pkgs, dependent_traverse_depth=dependent_depth
                 )
@@ -1140,6 +1099,11 @@ def main_script_replacements(cmd):
         # warn only if there was actually a CDash configuration.
         tty.warn("Unable to populate buildgroup without CDash credentials")
 
+    service_job_retries = {
+        "max": 2,
+        "when": ["runner_system_failure", "stuck_or_timeout_failure", "script_failure"],
+    }
+
     if copy_only_pipeline:
         stage_names.append("copy")
         sync_job = copy.deepcopy(spack_ci_ir["jobs"]["copy"]["attributes"])
@@ -1199,10 +1163,7 @@ def main_script_replacements(cmd):
             )
 
             final_job["when"] = "always"
-            final_job["retry"] = {
-                "max": 2,
-                "when": ["runner_system_failure", "stuck_or_timeout_failure", "script_failure"],
-            }
+            final_job["retry"] = service_job_retries
             final_job["interruptible"] = True
             final_job["dependencies"] = []
 
@@ -1427,7 +1388,11 @@ def copy_stage_logs_to_artifacts(job_spec: spack.spec.Spec, job_log_dir: str) ->
 
     stage_dir = job_pkg.stage.path
     tty.debug(f"stage dir: {stage_dir}")
-    for file in [job_pkg.log_path, job_pkg.env_mods_path, *job_pkg.builder.archive_files]:
+    for file in [
+        job_pkg.log_path,
+        job_pkg.env_mods_path,
+        *spack.builder.create(job_pkg).archive_files,
+    ]:
         copy_files_to_artifacts(file, job_log_dir)
 
 

lib/spack/spack/cmd/__init__.py

@@ -8,7 +8,8 @@
 import os
 import re
 import sys
-from typing import List, Union
+from collections import Counter
+from typing import List, Optional, Union
 
 import llnl.string
 import llnl.util.tty as tty
@@ -17,12 +18,14 @@
 from llnl.util.tty.colify import colify
 from llnl.util.tty.color import colorize
 
+import spack.concretize
 import spack.config  # breaks a cycle.
 import spack.environment as ev
 import spack.error
 import spack.extensions
 import spack.parser
 import spack.paths
+import spack.repo
 import spack.spec
 import spack.store
 import spack.traverse as traverse
@@ -30,6 +33,8 @@
 import spack.util.spack_json as sjson
 import spack.util.spack_yaml as syaml
 
+from ..enums import InstallRecordStatus
+
 # cmd has a submodule called "list" so preserve the python list module
 python_list = list
 
@@ -188,13 +193,50 @@ def _concretize_spec_pairs(to_concretize, tests=False):
     rules from config."""
     unify = spack.config.get("concretizer:unify", False)
 
+    # Special case for concretizing a single spec
+    if len(to_concretize) == 1:
+        abstract, concrete = to_concretize[0]
+        return [concrete or abstract.concretized()]
+
+    # Special case if every spec is either concrete or has an abstract hash
+    if all(
+        concrete or abstract.concrete or abstract.abstract_hash
+        for abstract, concrete in to_concretize
+    ):
+        # Get all the concrete specs
+        ret = [
+            concrete or (abstract if abstract.concrete else abstract.lookup_hash())
+            for abstract, concrete in to_concretize
+        ]
+
+        # If unify: true, check that specs don't conflict
+        # Since all concrete, "when_possible" is not relevant
+        if unify is True:  # True, "when_possible", False are possible values
+            runtimes = spack.repo.PATH.packages_with_tags("runtime")
+            specs_per_name = Counter(
+                spec.name
+                for spec in traverse.traverse_nodes(
+                    ret, deptype=("link", "run"), key=traverse.by_dag_hash
+                )
+                if spec.name not in runtimes  # runtimes are allowed multiple times
+            )
+
+            conflicts = sorted(name for name, count in specs_per_name.items() if count > 1)
+            if conflicts:
+                raise spack.error.SpecError(
+                    "Specs conflict and `concretizer:unify` is configured true.",
+                    f"    specs depend on multiple versions of {', '.join(conflicts)}",
+                )
+        return ret
+
+    # Standard case
     concretize_method = spack.concretize.concretize_separately  # unify: false
     if unify is True:
         concretize_method = spack.concretize.concretize_together
     elif unify == "when_possible":
         concretize_method = spack.concretize.concretize_together_when_possible
 
-    concretized = concretize_method(*to_concretize, tests=tests)
+    concretized = concretize_method(to_concretize, tests=tests)
     return [concrete for _, concrete in concretized]
 
 
@@ -227,39 +269,48 @@ def matching_specs_from_env(specs):
     return _concretize_spec_pairs(spec_pairs + additional_concrete_specs)[: len(spec_pairs)]
 
 
-def disambiguate_spec(spec, env, local=False, installed=True, first=False):
+def disambiguate_spec(
+    spec: spack.spec.Spec,
+    env: Optional[ev.Environment],
+    local: bool = False,
+    installed: Union[bool, InstallRecordStatus] = True,
+    first: bool = False,
+) -> spack.spec.Spec:
     """Given a spec, figure out which installed package it refers to.
 
-    Arguments:
-        spec (spack.spec.Spec): a spec to disambiguate
-        env (spack.environment.Environment): a spack environment,
-            if one is active, or None if no environment is active
-        local (bool): do not search chained spack instances
-        installed (bool or spack.database.InstallStatus or typing.Iterable):
-            install status argument passed to database query.
-            See ``spack.database.Database._query`` for details.
+    Args:
+        spec: a spec to disambiguate
+        env: a spack environment, if one is active, or None if no environment is active
+        local: do not search chained spack instances
+        installed: install status argument passed to database query.
+        first: returns the first matching spec, even if more than one match is found
     """
     hashes = env.all_hashes() if env else None
     return disambiguate_spec_from_hashes(spec, hashes, local, installed, first)
 
 
-def disambiguate_spec_from_hashes(spec, hashes, local=False, installed=True, first=False):
+def disambiguate_spec_from_hashes(
+    spec: spack.spec.Spec,
+    hashes: List[str],
+    local: bool = False,
+    installed: Union[bool, InstallRecordStatus] = True,
+    first: bool = False,
+) -> spack.spec.Spec:
     """Given a spec and a list of hashes, get concrete spec the spec refers to.
 
     Arguments:
-        spec (spack.spec.Spec): a spec to disambiguate
-        hashes (typing.Iterable): a set of hashes of specs among which to disambiguate
-        local (bool): do not search chained spack instances
-        installed (bool or spack.database.InstallStatus or typing.Iterable):
-            install status argument passed to database query.
-            See ``spack.database.Database._query`` for details.
+        spec: a spec to disambiguate
+        hashes: a set of hashes of specs among which to disambiguate
+        local: if True, do not search chained spack instances
+        installed: install status argument passed to database query.
+        first: returns the first matching spec, even if more than one match is found
     """
     if local:
         matching_specs = spack.store.STORE.db.query_local(spec, hashes=hashes, installed=installed)
     else:
         matching_specs = spack.store.STORE.db.query(spec, hashes=hashes, installed=installed)
     if not matching_specs:
-        tty.die("Spec '%s' matches no installed packages." % spec)
+        tty.die(f"Spec '{spec}' matches no installed packages.")
 
     elif first:
         return matching_specs[0]
@@ -544,6 +595,18 @@ def __init__(self, name):
         super().__init__("{0} is not a permissible Spack command name.".format(name))
 
 
+class MultipleSpecsMatch(Exception):
+    """Raised when multiple specs match a constraint, in a context where
+    this is not allowed.
+    """
+
+
+class NoSpecMatches(Exception):
+    """Raised when no spec matches a constraint, in a context where
+    this is not allowed.
+    """
+
+
 ########################################
 # argparse types for argument validation
 ########################################

lib/spack/spack/cmd/buildcache.py

@@ -34,6 +34,8 @@
 from spack.cmd.common import arguments
 from spack.spec import Spec, save_dependency_specfiles
 
+from ..enums import InstallRecordStatus
+
 description = "create, download and install binary packages"
 section = "packaging"
 level = "long"
@@ -308,7 +310,10 @@ def setup_parser(subparser: argparse.ArgumentParser):
 
 def _matching_specs(specs: List[Spec]) -> List[Spec]:
     """Disambiguate specs and return a list of matching specs"""
-    return [spack.cmd.disambiguate_spec(s, ev.active_environment(), installed=any) for s in specs]
+    return [
+        spack.cmd.disambiguate_spec(s, ev.active_environment(), installed=InstallRecordStatus.ANY)
+        for s in specs
+    ]
 
 
 def _format_spec(spec: Spec) -> str:

lib/spack/spack/cmd/common/arguments.py

@@ -581,23 +581,51 @@ def add_concretizer_args(subparser):
 
 
 def add_connection_args(subparser, add_help):
-    subparser.add_argument(
-        "--s3-access-key-id", help="ID string to use to connect to this S3 mirror"
+    def add_argument_string_or_variable(parser, arg: str, *, deprecate_str: bool = True, **kwargs):
+        group = parser.add_mutually_exclusive_group()
+        group.add_argument(arg, **kwargs)
+        # Update help string
+        if "help" in kwargs:
+            kwargs["help"] = "environment variable containing " + kwargs["help"]
+        group.add_argument(arg + "-variable", **kwargs)
+
+    s3_connection_parser = subparser.add_argument_group("S3 Connection")
+
+    add_argument_string_or_variable(
+        s3_connection_parser,
+        "--s3-access-key-id",
+        help="ID string to use to connect to this S3 mirror",
     )
-    subparser.add_argument(
-        "--s3-access-key-secret", help="secret string to use to connect to this S3 mirror"
+    add_argument_string_or_variable(
+        s3_connection_parser,
+        "--s3-access-key-secret",
+        help="secret string to use to connect to this S3 mirror",
     )
-    subparser.add_argument(
-        "--s3-access-token", help="access token to use to connect to this S3 mirror"
+    add_argument_string_or_variable(
+        s3_connection_parser,
+        "--s3-access-token",
+        help="access token to use to connect to this S3 mirror",
     )
-    subparser.add_argument(
+    s3_connection_parser.add_argument(
         "--s3-profile", help="S3 profile name to use to connect to this S3 mirror", default=None
     )
-    subparser.add_argument(
+    s3_connection_parser.add_argument(
         "--s3-endpoint-url", help="endpoint URL to use to connect to this S3 mirror"
     )
-    subparser.add_argument("--oci-username", help="username to use to connect to this OCI mirror")
-    subparser.add_argument("--oci-password", help="password to use to connect to this OCI mirror")
+
+    oci_connection_parser = subparser.add_argument_group("OCI Connection")
+
+    add_argument_string_or_variable(
+        oci_connection_parser,
+        "--oci-username",
+        deprecate_str=False,
+        help="username to use to connect to this OCI mirror",
+    )
+    add_argument_string_or_variable(
+        oci_connection_parser,
+        "--oci-password",
+        help="password to use to connect to this OCI mirror",
+    )
 
 
 def use_buildcache(cli_arg_value):

lib/spack/spack/cmd/deprecate.py

@@ -23,9 +23,10 @@
 import spack.installer
 import spack.store
 from spack.cmd.common import arguments
-from spack.database import InstallStatuses
 from spack.error import SpackError
 
+from ..enums import InstallRecordStatus
+
 description = "replace one package with another via symlinks"
 section = "admin"
 level = "long"
@@ -95,8 +96,12 @@ def deprecate(parser, args):
     if len(specs) != 2:
         raise SpackError("spack deprecate requires exactly two specs")
 
-    install_query = [InstallStatuses.INSTALLED, InstallStatuses.DEPRECATED]
-    deprecate = spack.cmd.disambiguate_spec(specs[0], env, local=True, installed=install_query)
+    deprecate = spack.cmd.disambiguate_spec(
+        specs[0],
+        env,
+        local=True,
+        installed=(InstallRecordStatus.INSTALLED | InstallRecordStatus.DEPRECATED),
+    )
 
     if args.install:
         deprecator = specs[1].concretized()

lib/spack/spack/cmd/env.py

@@ -10,11 +10,12 @@
 import sys
 import tempfile
 from pathlib import Path
-from typing import List, Optional
+from typing import List, Optional, Set
 
 import llnl.string as string
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
+from llnl.util.symlink import islink, symlink
 from llnl.util.tty.colify import colify
 from llnl.util.tty.color import cescape, colorize
 
@@ -50,6 +51,8 @@
     "update",
     "revert",
     "depfile",
+    "track",
+    "untrack",
 ]
 
 
@@ -446,6 +449,193 @@ def env_deactivate(args):
     sys.stdout.write(cmds)
 
 
+#
+# env track
+#
+def env_track_setup_parser(subparser):
+    """track an environment from a directory in Spack"""
+    subparser.add_argument("-n", "--name", help="custom environment name")
+    subparser.add_argument("dir", help="path to environment")
+    arguments.add_common_arguments(subparser, ["yes_to_all"])
+
+
+def env_track(args):
+    src_path = os.path.abspath(args.dir)
+    if not ev.is_env_dir(src_path):
+        tty.die("Cannot track environment. Path doesn't contain an environment")
+
+    if args.name:
+        name = args.name
+    else:
+        name = os.path.basename(src_path)
+
+    try:
+        dst_path = ev.environment_dir_from_name(name, exists_ok=False)
+    except ev.SpackEnvironmentError:
+        tty.die(
+            f"An environment named {name} already exists. Set a name with:"
+            "\n\n"
+            f"        spack env track --name NAME {src_path}\n"
+        )
+
+    symlink(src_path, dst_path)
+
+    tty.msg(f"Tracking environment in {src_path}")
+    tty.msg(
+        "You can now activate this environment with the following command:\n\n"
+        f"        spack env activate {name}\n"
+    )
+
+
+#
+# env remove & untrack helpers
+#
+def filter_managed_env_names(env_names: Set[str]) -> Set[str]:
+    tracked_env_names = {e for e in env_names if islink(ev.environment_dir_from_name(e))}
+    managed_env_names = env_names - set(tracked_env_names)
+
+    num_managed_envs = len(managed_env_names)
+    managed_envs_str = " ".join(managed_env_names)
+    if num_managed_envs >= 2:
+        tty.error(
+            f"The following are not tracked environments. "
+            "To remove them completely run,"
+            "\n\n"
+            f"        spack env rm {managed_envs_str}\n"
+        )
+
+    elif num_managed_envs > 0:
+        tty.error(
+            f"'{managed_envs_str}' is not a tracked env. "
+            "To remove it completely run,"
+            "\n\n"
+            f"        spack env rm {managed_envs_str}\n"
+        )
+
+    return tracked_env_names
+
+
+def get_valid_envs(env_names: Set[str]) -> Set[ev.Environment]:
+    valid_envs = set()
+    for env_name in env_names:
+        try:
+            env = ev.read(env_name)
+            valid_envs.add(env)
+
+        except (spack.config.ConfigFormatError, ev.SpackEnvironmentConfigError):
+            pass
+
+    return valid_envs
+
+
+def _env_untrack_or_remove(
+    env_names: List[str], remove: bool = False, force: bool = False, yes_to_all: bool = False
+):
+    all_env_names = set(ev.all_environment_names())
+    known_env_names = set(env_names).intersection(all_env_names)
+    unknown_env_names = set(env_names) - known_env_names
+
+    # print error for unknown environments
+    for env_name in unknown_env_names:
+        tty.error(f"Environment '{env_name}' does not exist")
+
+    # if only unlinking is allowed, remove all environments
+    # which do not point internally at symlinks
+    if not remove:
+        env_names_to_remove = filter_managed_env_names(known_env_names)
+    else:
+        env_names_to_remove = known_env_names
+
+    # initalize all environments with valid spack.yaml configs
+    all_valid_envs = get_valid_envs(all_env_names)
+
+    # build a task list of environments and bad env names to remove
+    envs_to_remove = [e for e in all_valid_envs if e.name in env_names_to_remove]
+    bad_env_names_to_remove = env_names_to_remove - {e.name for e in envs_to_remove}
+    for remove_env in envs_to_remove:
+        for env in all_valid_envs:
+            # don't check if an environment is included to itself
+            if env.name == remove_env.name:
+                continue
+
+            # check if an environment is included un another
+            if remove_env.path in env.included_concrete_envs:
+                msg = f"Environment '{remove_env.name}' is used by environment '{env.name}'"
+                if force:
+                    tty.warn(msg)
+                else:
+                    tty.error(msg)
+                    envs_to_remove.remove(remove_env)
+
+    # ask the user if they really want to remove the known environments
+    # force should do the same as yes to all here following the symantics of rm
+    if not (yes_to_all or force) and (envs_to_remove or bad_env_names_to_remove):
+        environments = string.plural(len(env_names_to_remove), "environment", show_n=False)
+        envs = string.comma_and(list(env_names_to_remove))
+        answer = tty.get_yes_or_no(
+            f"Really {'remove' if remove else 'untrack'} {environments} {envs}?", default=False
+        )
+        if not answer:
+            tty.die("Will not remove any environments")
+
+    # keep track of the environments we remove for later printing the exit code
+    removed_env_names = []
+    for env in envs_to_remove:
+        name = env.name
+        if not force and env.active:
+            tty.error(
+                f"Environment '{name}' can't be "
+                f"{'removed' if remove else 'untracked'} while activated."
+            )
+            continue
+        # Get path to check if environment is a tracked / symlinked environment
+        if islink(env.path):
+            real_env_path = os.path.realpath(env.path)
+            os.unlink(env.path)
+            tty.msg(
+                f"Sucessfully untracked environment '{name}', "
+                "but it can still be found at:\n\n"
+                f"        {real_env_path}\n"
+            )
+        else:
+            env.destroy()
+            tty.msg(f"Successfully removed environment '{name}'")
+
+        removed_env_names.append(env.name)
+
+    for bad_env_name in bad_env_names_to_remove:
+        shutil.rmtree(
+            spack.environment.environment.environment_dir_from_name(bad_env_name, exists_ok=True)
+        )
+        tty.msg(f"Successfully removed environment '{bad_env_name}'")
+        removed_env_names.append(env.name)
+
+    # Following the design of linux rm we should exit with a status of 1
+    # anytime we cannot delete every environment the user asks for.
+    # However, we should still process all the environments we know about
+    # and delete them instead of failing on the first unknown enviornment.
+    if len(removed_env_names) < len(known_env_names):
+        sys.exit(1)
+
+
+#
+# env untrack
+#
+def env_untrack_setup_parser(subparser):
+    """track an environment from a directory in Spack"""
+    subparser.add_argument("env", nargs="+", help="tracked environment name")
+    subparser.add_argument(
+        "-f", "--force", action="store_true", help="force unlink even when environment is active"
+    )
+    arguments.add_common_arguments(subparser, ["yes_to_all"])
+
+
+def env_untrack(args):
+    _env_untrack_or_remove(
+        env_names=args.env, force=args.force, yes_to_all=args.yes_to_all, remove=False
+    )
+
+
 #
 # env remove
 #
@@ -471,54 +661,9 @@ def env_remove_setup_parser(subparser):
 
 def env_remove(args):
     """remove existing environment(s)"""
-    remove_envs = []
-    valid_envs = []
-    bad_envs = []
-
-    for env_name in ev.all_environment_names():
-        try:
-            env = ev.read(env_name)
-            valid_envs.append(env)
-
-            if env_name in args.rm_env:
-                remove_envs.append(env)
-        except (spack.config.ConfigFormatError, ev.SpackEnvironmentConfigError):
-            if env_name in args.rm_env:
-                bad_envs.append(env_name)
-
-    # Check if remove_env is included from another env before trying to remove
-    for env in valid_envs:
-        for remove_env in remove_envs:
-            # don't check if environment is included to itself
-            if env.name == remove_env.name:
-                continue
-
-            if remove_env.path in env.included_concrete_envs:
-                msg = f'Environment "{remove_env.name}" is being used by environment "{env.name}"'
-                if args.force:
-                    tty.warn(msg)
-                else:
-                    tty.die(msg)
-
-    if not args.yes_to_all:
-        environments = string.plural(len(args.rm_env), "environment", show_n=False)
-        envs = string.comma_and(args.rm_env)
-        answer = tty.get_yes_or_no(f"Really remove {environments} {envs}?", default=False)
-        if not answer:
-            tty.die("Will not remove any environments")
-
-    for env in remove_envs:
-        name = env.name
-        if env.active:
-            tty.die(f"Environment {name} can't be removed while activated.")
-        env.destroy()
-        tty.msg(f"Successfully removed environment '{name}'")
-
-    for bad_env_name in bad_envs:
-        shutil.rmtree(
-            spack.environment.environment.environment_dir_from_name(bad_env_name, exists_ok=True)
-        )
-        tty.msg(f"Successfully removed environment '{bad_env_name}'")
+    _env_untrack_or_remove(
+        env_names=args.rm_env, remove=True, force=args.force, yes_to_all=args.yes_to_all
+    )
 
 
 #

lib/spack/spack/cmd/find.py

@@ -17,7 +17,8 @@
 import spack.spec
 import spack.store
 from spack.cmd.common import arguments
-from spack.database import InstallStatuses
+
+from ..enums import InstallRecordStatus
 
 description = "list and search installed packages"
 section = "basic"
@@ -137,21 +138,22 @@ def setup_parser(subparser):
     subparser.add_argument(
         "--loaded", action="store_true", help="show only packages loaded in the user environment"
     )
-    subparser.add_argument(
+    only_missing_or_deprecated = subparser.add_mutually_exclusive_group()
+    only_missing_or_deprecated.add_argument(
         "-M",
         "--only-missing",
         action="store_true",
         dest="only_missing",
         help="show only missing dependencies",
     )
+    only_missing_or_deprecated.add_argument(
+        "--only-deprecated", action="store_true", help="show only deprecated packages"
+    )
     subparser.add_argument(
         "--deprecated",
         action="store_true",
         help="show deprecated packages as well as installed specs",
     )
-    subparser.add_argument(
-        "--only-deprecated", action="store_true", help="show only deprecated packages"
-    )
     subparser.add_argument(
         "--install-tree",
         action="store",
@@ -165,14 +167,23 @@ def setup_parser(subparser):
 
 
 def query_arguments(args):
-    # Set up query arguments.
-    installed = []
-    if not (args.only_missing or args.only_deprecated):
-        installed.append(InstallStatuses.INSTALLED)
-    if (args.deprecated or args.only_deprecated) and not args.only_missing:
-        installed.append(InstallStatuses.DEPRECATED)
-    if (args.missing or args.only_missing) and not args.only_deprecated:
-        installed.append(InstallStatuses.MISSING)
+    if args.only_missing and (args.deprecated or args.missing):
+        raise RuntimeError("cannot use --only-missing with --deprecated, or --missing")
+
+    if args.only_deprecated and (args.deprecated or args.missing):
+        raise RuntimeError("cannot use --only-deprecated with --deprecated, or --missing")
+
+    installed = InstallRecordStatus.INSTALLED
+    if args.only_missing:
+        installed = InstallRecordStatus.MISSING
+    elif args.only_deprecated:
+        installed = InstallRecordStatus.DEPRECATED
+
+    if args.missing:
+        installed |= InstallRecordStatus.MISSING
+
+    if args.deprecated:
+        installed |= InstallRecordStatus.DEPRECATED
 
     predicate_fn = None
     if args.unknown:
@@ -222,11 +233,9 @@ def decorator(spec, fmt):
 def display_env(env, args, decorator, results):
     """Display extra find output when running in an environment.
 
-    Find in an environment outputs 2 or 3 sections:
-
-    1. Root specs
-    2. Concretized roots (if asked for with -c)
-    3. Installed specs
+    In an environment, `spack find` outputs a preliminary section
+    showing the root specs of the environment (this is in addition
+    to the section listing out specs matching the query parameters).
 
     """
     tty.msg("In environment %s" % env.name)
@@ -299,6 +308,56 @@ def root_decorator(spec, string):
         print()
 
 
+def _find_query(args, env):
+    q_args = query_arguments(args)
+    concretized_but_not_installed = list()
+    if env:
+        all_env_specs = env.all_specs()
+        if args.constraint:
+            init_specs = cmd.parse_specs(args.constraint)
+            env_specs = env.all_matching_specs(*init_specs)
+        else:
+            env_specs = all_env_specs
+
+        spec_hashes = set(x.dag_hash() for x in env_specs)
+        specs_meeting_q_args = set(spack.store.STORE.db.query(hashes=spec_hashes, **q_args))
+
+        results = list()
+        with spack.store.STORE.db.read_transaction():
+            for spec in env_specs:
+                if not spec.installed:
+                    concretized_but_not_installed.append(spec)
+                if spec in specs_meeting_q_args:
+                    results.append(spec)
+    else:
+        results = args.specs(**q_args)
+
+    # use groups by default except with format.
+    if args.groups is None:
+        args.groups = not args.format
+
+    # Exit early with an error code if no package matches the constraint
+    if concretized_but_not_installed and args.show_concretized:
+        pass
+    elif results:
+        pass
+    elif args.constraint:
+        raise cmd.NoSpecMatches()
+
+    # If tags have been specified on the command line, filter by tags
+    if args.tags:
+        packages_with_tags = spack.repo.PATH.packages_with_tags(*args.tags)
+        results = [x for x in results if x.name in packages_with_tags]
+        concretized_but_not_installed = [
+            x for x in concretized_but_not_installed if x.name in packages_with_tags
+        ]
+
+    if args.loaded:
+        results = cmd.filter_loaded_specs(results)
+
+    return results, concretized_but_not_installed
+
+
 def find(parser, args):
     env = ev.active_environment()
 
@@ -307,34 +366,12 @@ def find(parser, args):
     if not env and args.show_concretized:
         tty.die("-c / --show-concretized requires an active environment")
 
-    if env:
-        if args.constraint:
-            init_specs = spack.cmd.parse_specs(args.constraint)
-            results = env.all_matching_specs(*init_specs)
-        else:
-            results = env.all_specs()
-    else:
-        q_args = query_arguments(args)
-        results = args.specs(**q_args)
-
-    decorator = make_env_decorator(env) if env else lambda s, f: f
-
-    # use groups by default except with format.
-    if args.groups is None:
-        args.groups = not args.format
-
-    # Exit early with an error code if no package matches the constraint
-    if not results and args.constraint:
-        constraint_str = " ".join(str(s) for s in args.constraint_specs)
-        tty.die(f"No package matches the query: {constraint_str}")
-
-    # If tags have been specified on the command line, filter by tags
-    if args.tags:
-        packages_with_tags = spack.repo.PATH.packages_with_tags(*args.tags)
-        results = [x for x in results if x.name in packages_with_tags]
-
-    if args.loaded:
-        results = spack.cmd.filter_loaded_specs(results)
+    try:
+        results, concretized_but_not_installed = _find_query(args, env)
+    except cmd.NoSpecMatches:
+        # Note: this uses args.constraint vs. args.constraint_specs because
+        # the latter only exists if you call args.specs()
+        tty.die(f"No package matches the query: {' '.join(args.constraint)}")
 
     if args.install_status or args.show_concretized:
         status_fn = spack.spec.Spec.install_status
@@ -345,14 +382,16 @@ def find(parser, args):
     if args.json:
         cmd.display_specs_as_json(results, deps=args.deps)
     else:
+        decorator = make_env_decorator(env) if env else lambda s, f: f
+
         if not args.format:
             if env:
                 display_env(env, args, decorator, results)
 
         if not args.only_roots:
-            display_results = results
-            if not args.show_concretized:
-                display_results = list(x for x in results if x.installed)
+            display_results = list(results)
+            if args.show_concretized:
+                display_results += concretized_but_not_installed
             cmd.display_specs(
                 display_results, args, decorator=decorator, all_headers=True, status_fn=status_fn
             )
@@ -370,13 +409,9 @@ def find(parser, args):
                     concretized_suffix += " (show with `spack find -c`)"
 
             pkg_type = "loaded" if args.loaded else "installed"
-            spack.cmd.print_how_many_pkgs(
-                list(x for x in results if x.installed), pkg_type, suffix=installed_suffix
-            )
+            cmd.print_how_many_pkgs(results, pkg_type, suffix=installed_suffix)
 
             if env:
-                spack.cmd.print_how_many_pkgs(
-                    list(x for x in results if not x.installed),
-                    "concretized",
-                    suffix=concretized_suffix,
+                cmd.print_how_many_pkgs(
+                    concretized_but_not_installed, "concretized", suffix=concretized_suffix
                 )

lib/spack/spack/cmd/help.py

@@ -78,8 +78,8 @@
       boxlib @B{dim=2}                  boxlib built for 2 dimensions
       libdwarf @g{%intel} ^libelf@g{%gcc}
           libdwarf, built with intel compiler, linked to libelf built with gcc
-      mvapich2 @g{%pgi} @B{fabrics=psm,mrail,sock}
-          mvapich2, built with pgi compiler, with support for multiple fabrics
+      mvapich2 @g{%gcc} @B{fabrics=psm,mrail,sock}
+          mvapich2, built with gcc compiler, with support for multiple fabrics
 """
 
 

lib/spack/spack/cmd/info.py

@@ -11,6 +11,7 @@
 import llnl.util.tty.color as color
 from llnl.util.tty.colify import colify
 
+import spack.builder
 import spack.deptypes as dt
 import spack.fetch_strategy as fs
 import spack.install_test
@@ -202,11 +203,13 @@ def print_namespace(pkg, args):
 def print_phases(pkg, args):
     """output installation phases"""
 
-    if hasattr(pkg.builder, "phases") and pkg.builder.phases:
+    builder = spack.builder.create(pkg)
+
+    if hasattr(builder, "phases") and builder.phases:
         color.cprint("")
         color.cprint(section_title("Installation Phases:"))
         phase_str = ""
-        for phase in pkg.builder.phases:
+        for phase in builder.phases:
             phase_str += "    {0}".format(phase)
         color.cprint(phase_str)
 

lib/spack/spack/cmd/mark.py

@@ -10,7 +10,8 @@
 import spack.cmd
 import spack.store
 from spack.cmd.common import arguments
-from spack.database import InstallStatuses
+
+from ..enums import InstallRecordStatus
 
 description = "mark packages as explicitly or implicitly installed"
 section = "admin"
@@ -67,8 +68,7 @@ def find_matching_specs(specs, allow_multiple_matches=False):
     has_errors = False
 
     for spec in specs:
-        install_query = [InstallStatuses.INSTALLED]
-        matching = spack.store.STORE.db.query_local(spec, installed=install_query)
+        matching = spack.store.STORE.db.query_local(spec, installed=InstallRecordStatus.INSTALLED)
         # For each spec provided, make sure it refers to only one package.
         # Fail and ask user to be unambiguous if it doesn't
         if not allow_multiple_matches and len(matching) > 1:

lib/spack/spack/cmd/mirror.py

@@ -231,31 +231,133 @@ def setup_parser(subparser):
     )
 
 
+def _configure_access_pair(
+    args, id_tok, id_variable_tok, secret_tok, secret_variable_tok, default=None
+):
+    """Configure the access_pair options"""
+
+    # Check if any of the arguments are set to update this access_pair.
+    # If none are set, then skip computing the new access pair
+    args_id = getattr(args, id_tok)
+    args_id_variable = getattr(args, id_variable_tok)
+    args_secret = getattr(args, secret_tok)
+    args_secret_variable = getattr(args, secret_variable_tok)
+    if not any([args_id, args_id_variable, args_secret, args_secret_variable]):
+        return None
+
+    def _default_value(id_):
+        if isinstance(default, list):
+            return default[0] if id_ == "id" else default[1]
+        elif isinstance(default, dict):
+            return default.get(id_)
+        else:
+            return None
+
+    def _default_variable(id_):
+        if isinstance(default, dict):
+            return default.get(id_ + "_variable")
+        else:
+            return None
+
+    id_ = None
+    id_variable = None
+    secret = None
+    secret_variable = None
+
+    # Get the value/default value if the argument of the inverse
+    if not args_id_variable:
+        id_ = getattr(args, id_tok) or _default_value("id")
+    if not args_id:
+        id_variable = getattr(args, id_variable_tok) or _default_variable("id")
+    if not args_secret_variable:
+        secret = getattr(args, secret_tok) or _default_value("secret")
+    if not args_secret:
+        secret_variable = getattr(args, secret_variable_tok) or _default_variable("secret")
+
+    if (id_ or id_variable) and (secret or secret_variable):
+        if secret:
+            if not id_:
+                raise SpackError("Cannot add mirror with a variable id and text secret")
+
+            return [id_, secret]
+        else:
+            return dict(
+                [
+                    (("id", id_) if id_ else ("id_variable", id_variable)),
+                    ("secret_variable", secret_variable),
+                ]
+            )
+    else:
+        if id_ or id_variable or secret or secret_variable is not None:
+            id_arg_tok = id_tok.replace("_", "-")
+            secret_arg_tok = secret_tok.replace("_", "-")
+            tty.warn(
+                "Expected both parts of the access pair to be specified. "
+                f"(i.e. --{id_arg_tok} and --{secret_arg_tok})"
+            )
+
+        return None
+
+
 def mirror_add(args):
     """add a mirror to Spack"""
     if (
         args.s3_access_key_id
         or args.s3_access_key_secret
         or args.s3_access_token
+        or args.s3_access_key_id_variable
+        or args.s3_access_key_secret_variable
+        or args.s3_access_token_variable
         or args.s3_profile
         or args.s3_endpoint_url
         or args.type
         or args.oci_username
         or args.oci_password
+        or args.oci_username_variable
+        or args.oci_password_variable
         or args.autopush
         or args.signed is not None
     ):
         connection = {"url": args.url}
-        if args.s3_access_key_id and args.s3_access_key_secret:
-            connection["access_pair"] = [args.s3_access_key_id, args.s3_access_key_secret]
+        # S3 Connection
+        if args.s3_access_key_secret:
+            tty.warn(
+                "Configuring mirror secrets as plain text with --s3-access-key-secret is "
+                "deprecated. Use --s3-access-key-secret-variable instead"
+            )
+        if args.oci_password:
+            tty.warn(
+                "Configuring mirror secrets as plain text with --oci-password is deprecated. "
+                "Use --oci-password-variable instead"
+            )
+        access_pair = _configure_access_pair(
+            args,
+            "s3_access_key_id",
+            "s3_access_key_id_variable",
+            "s3_access_key_secret",
+            "s3_access_key_secret_variable",
+        )
+        if access_pair:
+            connection["access_pair"] = access_pair
+
         if args.s3_access_token:
             connection["access_token"] = args.s3_access_token
+        elif args.s3_access_token_variable:
+            connection["access_token_variable"] = args.s3_access_token_variable
+
         if args.s3_profile:
             connection["profile"] = args.s3_profile
+
         if args.s3_endpoint_url:
             connection["endpoint_url"] = args.s3_endpoint_url
-        if args.oci_username and args.oci_password:
-            connection["access_pair"] = [args.oci_username, args.oci_password]
+
+        # OCI Connection
+        access_pair = _configure_access_pair(
+            args, "oci_username", "oci_username_variable", "oci_password", "oci_password_variable"
+        )
+        if access_pair:
+            connection["access_pair"] = access_pair
+
         if args.type:
             connection["binary"] = "binary" in args.type
             connection["source"] = "source" in args.type
@@ -285,16 +387,35 @@ def _configure_mirror(args):
     changes = {}
     if args.url:
         changes["url"] = args.url
-    if args.s3_access_key_id and args.s3_access_key_secret:
-        changes["access_pair"] = [args.s3_access_key_id, args.s3_access_key_secret]
+
+    default_access_pair = entry._get_value("access_pair", direction or "fetch")
+    # TODO: Init access_pair args with the fetch/push/base values in the current mirror state
+    access_pair = _configure_access_pair(
+        args,
+        "s3_access_key_id",
+        "s3_access_key_id_variable",
+        "s3_access_key_secret",
+        "s3_access_key_secret_variable",
+        default=default_access_pair,
+    )
+    if access_pair:
+        changes["access_pair"] = access_pair
     if args.s3_access_token:
         changes["access_token"] = args.s3_access_token
     if args.s3_profile:
         changes["profile"] = args.s3_profile
     if args.s3_endpoint_url:
         changes["endpoint_url"] = args.s3_endpoint_url
-    if args.oci_username and args.oci_password:
-        changes["access_pair"] = [args.oci_username, args.oci_password]
+    access_pair = _configure_access_pair(
+        args,
+        "oci_username",
+        "oci_username_variable",
+        "oci_password",
+        "oci_password_variable",
+        default=default_access_pair,
+    )
+    if access_pair:
+        changes["access_pair"] = access_pair
     if getattr(args, "signed", None) is not None:
         changes["signed"] = args.signed
     if getattr(args, "autopush", None) is not None:

lib/spack/spack/cmd/modules/__init__.py

@@ -19,6 +19,7 @@
 import spack.modules
 import spack.modules.common
 import spack.repo
+from spack.cmd import MultipleSpecsMatch, NoSpecMatches
 from spack.cmd.common import arguments
 
 description = "manipulate module files"
@@ -91,18 +92,6 @@ def add_loads_arguments(subparser):
     arguments.add_common_arguments(subparser, ["recurse_dependencies"])
 
 
-class MultipleSpecsMatch(Exception):
-    """Raised when multiple specs match a constraint, in a context where
-    this is not allowed.
-    """
-
-
-class NoSpecMatches(Exception):
-    """Raised when no spec matches a constraint, in a context where
-    this is not allowed.
-    """
-
-
 def one_spec_or_raise(specs):
     """Ensures exactly one spec has been selected, or raises the appropriate
     exception.

lib/spack/spack/cmd/modules/lmod.py

@@ -8,6 +8,7 @@
 import spack.cmd.common.arguments
 import spack.cmd.modules
 import spack.config
+import spack.modules
 import spack.modules.lmod
 
 

lib/spack/spack/cmd/modules/tcl.py

@@ -7,6 +7,7 @@
 import spack.cmd.common.arguments
 import spack.cmd.modules
 import spack.config
+import spack.modules
 import spack.modules.tcl
 
 

lib/spack/spack/cmd/spec.py

@@ -82,14 +82,6 @@ def spec(parser, args):
     if args.namespaces:
         fmt = "{namespace}." + fmt
 
-    tree_kwargs = {
-        "cover": args.cover,
-        "format": fmt,
-        "hashlen": None if args.very_long else 7,
-        "show_types": args.types,
-        "status_fn": install_status_fn if args.install_status else None,
-    }
-
     # use a read transaction if we are getting install status for every
     # spec in the DAG.  This avoids repeatedly querying the DB.
     tree_context = lang.nullcontext
@@ -99,46 +91,35 @@ def spec(parser, args):
     env = ev.active_environment()
 
     if args.specs:
-        input_specs = spack.cmd.parse_specs(args.specs)
-        concretized_specs = spack.cmd.parse_specs(args.specs, concretize=True)
-        specs = list(zip(input_specs, concretized_specs))
+        concrete_specs = spack.cmd.parse_specs(args.specs, concretize=True)
     elif env:
         env.concretize()
-        specs = env.concretized_specs()
-
-        if not args.format:
-            # environments are printed together in a combined tree() invocation,
-            # except when using --yaml or --json, which we print spec by spec below.
-            tree_kwargs["key"] = spack.traverse.by_dag_hash
-            tree_kwargs["hashes"] = args.long or args.very_long
-            print(spack.spec.tree([concrete for _, concrete in specs], **tree_kwargs))
-            return
+        concrete_specs = env.concrete_roots()
     else:
         tty.die("spack spec requires at least one spec or an active environment")
 
-    for input, output in specs:
-        # With --yaml or --json, just print the raw specs to output
-        if args.format:
+    # With --yaml, --json, or --format, just print the raw specs to output
+    if args.format:
+        for spec in concrete_specs:
             if args.format == "yaml":
                 # use write because to_yaml already has a newline.
-                sys.stdout.write(output.to_yaml(hash=ht.dag_hash))
+                sys.stdout.write(spec.to_yaml(hash=ht.dag_hash))
             elif args.format == "json":
-                print(output.to_json(hash=ht.dag_hash))
+                print(spec.to_json(hash=ht.dag_hash))
             else:
-                print(output.format(args.format))
-            continue
+                print(spec.format(args.format))
+        return
 
-        with tree_context():
-            # Only show the headers for input specs that are not concrete to avoid
-            # repeated output. This happens because parse_specs outputs concrete
-            # specs for `/hash` inputs.
-            if not input.concrete:
-                tree_kwargs["hashes"] = False  # Always False for input spec
-                print("Input spec")
-                print("--------------------------------")
-                print(input.tree(**tree_kwargs))
-                print("Concretized")
-                print("--------------------------------")
-
-            tree_kwargs["hashes"] = args.long or args.very_long
-            print(output.tree(**tree_kwargs))
+    with tree_context():
+        print(
+            spack.spec.tree(
+                concrete_specs,
+                cover=args.cover,
+                format=fmt,
+                hashlen=None if args.very_long else 7,
+                show_types=args.types,
+                status_fn=install_status_fn if args.install_status else None,
+                hashes=args.long or args.very_long,
+                key=spack.traverse.by_dag_hash,
+            )
+        )

lib/spack/spack/cmd/style.py

@@ -3,18 +3,21 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import argparse
+import ast
 import os
 import re
 import sys
 from itertools import zip_longest
+from typing import Dict, List, Optional
 
 import llnl.util.tty as tty
 import llnl.util.tty.color as color
 from llnl.util.filesystem import working_dir
 
 import spack.paths
+import spack.repo
 import spack.util.git
-from spack.util.executable import which
+from spack.util.executable import Executable, which
 
 description = "runs source code style checks on spack"
 section = "developer"
@@ -36,10 +39,7 @@ def grouper(iterable, n, fillvalue=None):
 #: double-check the results of other tools (if, e.g., --fix was provided)
 #: The list maps an executable name to a method to ensure the tool is
 #: bootstrapped or present in the environment.
-tool_names = ["isort", "black", "flake8", "mypy"]
-
-#: tools we run in spack style
-tools = {}
+tool_names = ["import", "isort", "black", "flake8", "mypy"]
 
 #: warnings to ignore in mypy
 mypy_ignores = [
@@ -61,14 +61,28 @@ def is_package(f):
 
 #: decorator for adding tools to the list
 class tool:
-    def __init__(self, name, required=False):
+    def __init__(self, name: str, required: bool = False, external: bool = True) -> None:
         self.name = name
+        self.external = external
         self.required = required
 
     def __call__(self, fun):
-        tools[self.name] = (fun, self.required)
+        self.fun = fun
+        tools[self.name] = self
         return fun
 
+    @property
+    def installed(self) -> bool:
+        return bool(which(self.name)) if self.external else True
+
+    @property
+    def executable(self) -> Optional[Executable]:
+        return which(self.name) if self.external else None
+
+
+#: tools we run in spack style
+tools: Dict[str, tool] = {}
+
 
 def changed_files(base="develop", untracked=True, all_files=False, root=None):
     """Get list of changed files in the Spack repository.
@@ -176,22 +190,22 @@ def setup_parser(subparser):
         "-t",
         "--tool",
         action="append",
-        help="specify which tools to run (default: %s)" % ",".join(tool_names),
+        help="specify which tools to run (default: %s)" % ", ".join(tool_names),
     )
     tool_group.add_argument(
         "-s",
         "--skip",
         metavar="TOOL",
         action="append",
-        help="specify tools to skip (choose from %s)" % ",".join(tool_names),
+        help="specify tools to skip (choose from %s)" % ", ".join(tool_names),
     )
 
     subparser.add_argument("files", nargs=argparse.REMAINDER, help="specific files to check")
 
 
-def cwd_relative(path, args):
+def cwd_relative(path, root, initial_working_dir):
     """Translate prefix-relative path to current working directory-relative."""
-    return os.path.relpath(os.path.join(args.root, path), args.initial_working_dir)
+    return os.path.relpath(os.path.join(root, path), initial_working_dir)
 
 
 def rewrite_and_print_output(
@@ -201,7 +215,10 @@ def rewrite_and_print_output(
 
     # print results relative to current working directory
     def translate(match):
-        return replacement.format(cwd_relative(match.group(1), args), *list(match.groups()[1:]))
+        return replacement.format(
+            cwd_relative(match.group(1), args.root, args.initial_working_dir),
+            *list(match.groups()[1:]),
+        )
 
     for line in output.split("\n"):
         if not line:
@@ -220,7 +237,7 @@ def print_style_header(file_list, args, tools_to_run):
     # translate modified paths to cwd_relative if needed
     paths = [filename.strip() for filename in file_list]
     if not args.root_relative:
-        paths = [cwd_relative(filename, args) for filename in paths]
+        paths = [cwd_relative(filename, args.root, args.initial_working_dir) for filename in paths]
 
     tty.msg("Modified files", *paths)
     sys.stdout.flush()
@@ -352,17 +369,137 @@ def run_black(black_cmd, file_list, args):
     return returncode
 
 
+def _module_part(root: str, expr: str):
+    parts = expr.split(".")
+    # spack.pkg is for repositories, don't try to resolve it here.
+    if ".".join(parts[:2]) == spack.repo.ROOT_PYTHON_NAMESPACE:
+        return None
+    while parts:
+        f1 = os.path.join(root, "lib", "spack", *parts) + ".py"
+        f2 = os.path.join(root, "lib", "spack", *parts, "__init__.py")
+
+        if (
+            os.path.exists(f1)
+            # ensure case sensitive match
+            and f"{parts[-1]}.py" in os.listdir(os.path.dirname(f1))
+            or os.path.exists(f2)
+        ):
+            return ".".join(parts)
+        parts.pop()
+    return None
+
+
+def _run_import_check(
+    file_list: List[str],
+    *,
+    fix: bool,
+    root_relative: bool,
+    root=spack.paths.prefix,
+    working_dir=spack.paths.prefix,
+    out=sys.stdout,
+):
+    if sys.version_info < (3, 9):
+        print("import check requires Python 3.9 or later")
+        return 0
+
+    is_use = re.compile(r"(?<!from )(?<!import )(?:llnl|spack)\.[a-zA-Z0-9_\.]+")
+
+    # redundant imports followed by a `# comment` are ignored, cause there can be legimitate reason
+    # to import a module: execute module scope init code, or to deal with circular imports.
+    is_abs_import = re.compile(r"^import ((?:llnl|spack)\.[a-zA-Z0-9_\.]+)$", re.MULTILINE)
+
+    exit_code = 0
+
+    for file in file_list:
+        to_add = set()
+        to_remove = []
+
+        pretty_path = file if root_relative else cwd_relative(file, root, working_dir)
+
+        try:
+            with open(file, "r") as f:
+                contents = open(file, "r").read()
+            parsed = ast.parse(contents)
+        except Exception:
+            exit_code = 1
+            print(f"{pretty_path}: could not parse", file=out)
+            continue
+
+        for m in is_abs_import.finditer(contents):
+            if contents.count(m.group(1)) == 1:
+                to_remove.append(m.group(0))
+                exit_code = 1
+                print(f"{pretty_path}: redundant import: {m.group(1)}", file=out)
+
+        # Clear all strings to avoid matching comments/strings etc.
+        for node in ast.walk(parsed):
+            if isinstance(node, ast.Constant) and isinstance(node.value, str):
+                node.value = ""
+
+        filtered_contents = ast.unparse(parsed)  # novermin
+        for m in is_use.finditer(filtered_contents):
+            module = _module_part(root, m.group(0))
+            if not module or module in to_add:
+                continue
+            if re.search(rf"import {re.escape(module)}\b(?!\.)", contents):
+                continue
+            to_add.add(module)
+            exit_code = 1
+            print(f"{pretty_path}: missing import: {module} ({m.group(0)})", file=out)
+
+        if not fix or not to_add and not to_remove:
+            continue
+
+        with open(file, "r") as f:
+            lines = f.readlines()
+
+        if to_add:
+            # insert missing imports before the first import, delegate ordering to isort
+            for node in parsed.body:
+                if isinstance(node, (ast.Import, ast.ImportFrom)):
+                    first_line = node.lineno
+                    break
+            else:
+                print(f"{pretty_path}: could not fix", file=out)
+                continue
+            lines.insert(first_line, "\n".join(f"import {x}" for x in to_add) + "\n")
+
+        new_contents = "".join(lines)
+
+        # remove redundant imports
+        for statement in to_remove:
+            new_contents = new_contents.replace(f"{statement}\n", "")
+
+        with open(file, "w") as f:
+            f.write(new_contents)
+
+    return exit_code
+
+
+@tool("import", external=False)
+def run_import_check(import_check_cmd, file_list, args):
+    exit_code = _run_import_check(
+        file_list,
+        fix=args.fix,
+        root_relative=args.root_relative,
+        root=args.root,
+        working_dir=args.initial_working_dir,
+    )
+    print_tool_result("import", exit_code)
+    return exit_code
+
+
 def validate_toolset(arg_value):
     """Validate --tool and --skip arguments (sets of optionally comma-separated tools)."""
     tools = set(",".join(arg_value).split(","))  # allow args like 'isort,flake8'
     for tool in tools:
         if tool not in tool_names:
-            tty.die("Invaild tool: '%s'" % tool, "Choose from: %s" % ", ".join(tool_names))
+            tty.die("Invalid tool: '%s'" % tool, "Choose from: %s" % ", ".join(tool_names))
     return tools
 
 
-def missing_tools(tools_to_run):
-    return [t for t in tools_to_run if which(t) is None]
+def missing_tools(tools_to_run: List[str]) -> List[str]:
+    return [t for t in tools_to_run if not tools[t].installed]
 
 
 def _bootstrap_dev_dependencies():
@@ -417,9 +554,9 @@ def prefix_relative(path):
 
         print_style_header(file_list, args, tools_to_run)
         for tool_name in tools_to_run:
-            run_function, required = tools[tool_name]
+            tool = tools[tool_name]
             print_tool_header(tool_name)
-            return_code |= run_function(which(tool_name), file_list, args)
+            return_code |= tool.fun(tool.executable, file_list, args)
 
     if return_code == 0:
         tty.msg(color.colorize("@*{spack style checks were clean}"))

lib/spack/spack/cmd/tutorial.py

@@ -24,7 +24,7 @@
 
 
 # tutorial configuration parameters
-tutorial_branch = "releases/v0.22"
+tutorial_branch = "releases/v0.23"
 tutorial_mirror = "file:///mirror"
 tutorial_key = os.path.join(spack.paths.share_path, "keys", "tutorial.pub")
 

lib/spack/spack/cmd/uninstall.py

@@ -17,7 +17,8 @@
 import spack.store
 import spack.traverse as traverse
 from spack.cmd.common import arguments
-from spack.database import InstallStatuses
+
+from ..enums import InstallRecordStatus
 
 description = "remove installed packages"
 section = "build"
@@ -99,12 +100,14 @@ def find_matching_specs(
     hashes = env.all_hashes() if env else None
 
     # List of specs that match expressions given via command line
-    specs_from_cli: List["spack.spec.Spec"] = []
+    specs_from_cli: List[spack.spec.Spec] = []
     has_errors = False
     for spec in specs:
-        install_query = [InstallStatuses.INSTALLED, InstallStatuses.DEPRECATED]
         matching = spack.store.STORE.db.query_local(
-            spec, hashes=hashes, installed=install_query, origin=origin
+            spec,
+            hashes=hashes,
+            installed=(InstallRecordStatus.INSTALLED | InstallRecordStatus.DEPRECATED),
+            origin=origin,
         )
         # For each spec provided, make sure it refers to only one package.
         # Fail and ask user to be unambiguous if it doesn't

lib/spack/spack/compiler.py

@@ -4,20 +4,23 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import contextlib
+import hashlib
 import itertools
+import json
 import os
 import platform
 import re
 import shutil
 import sys
 import tempfile
-from typing import List, Optional, Sequence
+from typing import Dict, List, Optional, Sequence
 
 import llnl.path
 import llnl.util.lang
 import llnl.util.tty as tty
 from llnl.util.filesystem import path_contains_subdirectory, paths_containing_libs
 
+import spack.caches
 import spack.error
 import spack.schema.environment
 import spack.spec
@@ -26,6 +29,7 @@
 import spack.util.module_cmd
 import spack.version
 from spack.util.environment import filter_system_paths
+from spack.util.file_cache import FileCache
 
 __all__ = ["Compiler"]
 
@@ -34,7 +38,7 @@
 
 
 @llnl.util.lang.memoized
-def _get_compiler_version_output(compiler_path, version_arg, ignore_errors=()):
+def _get_compiler_version_output(compiler_path, version_arg, ignore_errors=()) -> str:
     """Invokes the compiler at a given path passing a single
     version argument and returns the output.
 
@@ -57,7 +61,7 @@ def _get_compiler_version_output(compiler_path, version_arg, ignore_errors=()):
     return output
 
 
-def get_compiler_version_output(compiler_path, *args, **kwargs):
+def get_compiler_version_output(compiler_path, *args, **kwargs) -> str:
     """Wrapper for _get_compiler_version_output()."""
     # This ensures that we memoize compiler output by *absolute path*,
     # not just executable name. If we don't do this, and the path changes
@@ -290,6 +294,7 @@ def __init__(
         self.environment = environment or {}
         self.extra_rpaths = extra_rpaths or []
         self.enable_implicit_rpaths = enable_implicit_rpaths
+        self.cache = COMPILER_CACHE
 
         self.cc = paths[0]
         self.cxx = paths[1]
@@ -390,15 +395,11 @@ def real_version(self):
 
         E.g. C++11 flag checks.
         """
-        if not self._real_version:
-            try:
-                real_version = spack.version.Version(self.get_real_version())
-                if real_version == spack.version.Version("unknown"):
-                    return self.version
-                self._real_version = real_version
-            except spack.util.executable.ProcessError:
-                self._real_version = self.version
-        return self._real_version
+        real_version_str = self.cache.get(self).real_version
+        if not real_version_str or real_version_str == "unknown":
+            return self.version
+
+        return spack.version.StandardVersion.from_string(real_version_str)
 
     def implicit_rpaths(self) -> List[str]:
         if self.enable_implicit_rpaths is False:
@@ -427,6 +428,11 @@ def default_dynamic_linker(self) -> Optional[str]:
     @property
     def default_libc(self) -> Optional["spack.spec.Spec"]:
         """Determine libc targeted by the compiler from link line"""
+        # technically this should be testing the target platform of the compiler, but we don't have
+        # that, so stick to host platform for now.
+        if sys.platform in ("darwin", "win32"):
+            return None
+
         dynamic_linker = self.default_dynamic_linker
 
         if not dynamic_linker:
@@ -445,19 +451,23 @@ def required_libs(self):
     @property
     def compiler_verbose_output(self) -> Optional[str]:
         """Verbose output from compiling a dummy C source file. Output is cached."""
-        if not hasattr(self, "_compile_c_source_output"):
-            self._compile_c_source_output = self._compile_dummy_c_source()
-        return self._compile_c_source_output
+        return self.cache.get(self).c_compiler_output
 
     def _compile_dummy_c_source(self) -> Optional[str]:
-        cc = self.cc if self.cc else self.cxx
+        if self.cc:
+            cc = self.cc
+            ext = "c"
+        else:
+            cc = self.cxx
+            ext = "cc"
+
         if not cc or not self.verbose_flag:
             return None
 
         try:
             tmpdir = tempfile.mkdtemp(prefix="spack-implicit-link-info")
             fout = os.path.join(tmpdir, "output")
-            fin = os.path.join(tmpdir, "main.c")
+            fin = os.path.join(tmpdir, f"main.{ext}")
 
             with open(fin, "w") as csource:
                 csource.write(
@@ -559,7 +569,7 @@ def fc_pic_flag(self):
     # Note: This is not a class method. The class methods are used to detect
     # compilers on PATH based systems, and do not set up the run environment of
     # the compiler. This method can be called on `module` based systems as well
-    def get_real_version(self):
+    def get_real_version(self) -> str:
         """Query the compiler for its version.
 
         This is the "real" compiler version, regardless of what is in the
@@ -569,14 +579,17 @@ def get_real_version(self):
         modifications) to enable the compiler to run properly on any platform.
         """
         cc = spack.util.executable.Executable(self.cc)
-        with self.compiler_environment():
-            output = cc(
-                self.version_argument,
-                output=str,
-                error=str,
-                ignore_errors=tuple(self.ignore_version_errors),
-            )
-            return self.extract_version_from_output(output)
+        try:
+            with self.compiler_environment():
+                output = cc(
+                    self.version_argument,
+                    output=str,
+                    error=str,
+                    ignore_errors=tuple(self.ignore_version_errors),
+                )
+                return self.extract_version_from_output(output)
+        except spack.util.executable.ProcessError:
+            return "unknown"
 
     @property
     def prefix(self):
@@ -603,7 +616,7 @@ def default_version(cls, cc):
 
     @classmethod
     @llnl.util.lang.memoized
-    def extract_version_from_output(cls, output):
+    def extract_version_from_output(cls, output: str) -> str:
         """Extracts the version from compiler's output."""
         match = re.search(cls.version_regex, output)
         return match.group(1) if match else "unknown"
@@ -732,3 +745,106 @@ def __init__(self, compiler, feature, flag_name, ver_string=None):
             )
             + " implement the {0} property and submit a pull request or issue.".format(flag_name),
         )
+
+
+class CompilerCacheEntry:
+    """Deserialized cache entry for a compiler"""
+
+    __slots__ = ["c_compiler_output", "real_version"]
+
+    def __init__(self, c_compiler_output: Optional[str], real_version: str):
+        self.c_compiler_output = c_compiler_output
+        self.real_version = real_version
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Optional[str]]):
+        if not isinstance(data, dict):
+            raise ValueError(f"Invalid {cls.__name__} data")
+        c_compiler_output = data.get("c_compiler_output")
+        real_version = data.get("real_version")
+        if not isinstance(real_version, str) or not isinstance(
+            c_compiler_output, (str, type(None))
+        ):
+            raise ValueError(f"Invalid {cls.__name__} data")
+        return cls(c_compiler_output, real_version)
+
+
+class CompilerCache:
+    """Base class for compiler output cache. Default implementation does not cache anything."""
+
+    def value(self, compiler: Compiler) -> Dict[str, Optional[str]]:
+        return {
+            "c_compiler_output": compiler._compile_dummy_c_source(),
+            "real_version": compiler.get_real_version(),
+        }
+
+    def get(self, compiler: Compiler) -> CompilerCacheEntry:
+        return CompilerCacheEntry.from_dict(self.value(compiler))
+
+
+class FileCompilerCache(CompilerCache):
+    """Cache for compiler output, which is used to determine implicit link paths, the default libc
+    version, and the compiler version."""
+
+    name = os.path.join("compilers", "compilers.json")
+
+    def __init__(self, cache: "FileCache") -> None:
+        self.cache = cache
+        self.cache.init_entry(self.name)
+        self._data: Dict[str, Dict[str, Optional[str]]] = {}
+
+    def _get_entry(self, key: str) -> Optional[CompilerCacheEntry]:
+        try:
+            return CompilerCacheEntry.from_dict(self._data[key])
+        except ValueError:
+            del self._data[key]
+        except KeyError:
+            pass
+        return None
+
+    def get(self, compiler: Compiler) -> CompilerCacheEntry:
+        # Cache hit
+        try:
+            with self.cache.read_transaction(self.name) as f:
+                assert f is not None
+                self._data = json.loads(f.read())
+                assert isinstance(self._data, dict)
+        except (json.JSONDecodeError, AssertionError):
+            self._data = {}
+
+        key = self._key(compiler)
+        value = self._get_entry(key)
+        if value is not None:
+            return value
+
+        # Cache miss
+        with self.cache.write_transaction(self.name) as (old, new):
+            try:
+                assert old is not None
+                self._data = json.loads(old.read())
+                assert isinstance(self._data, dict)
+            except (json.JSONDecodeError, AssertionError):
+                self._data = {}
+
+            # Use cache entry that may have been created by another process in the meantime.
+            entry = self._get_entry(key)
+
+            # Finally compute the cache entry
+            if entry is None:
+                self._data[key] = self.value(compiler)
+                entry = CompilerCacheEntry.from_dict(self._data[key])
+
+            new.write(json.dumps(self._data, separators=(",", ":")))
+
+            return entry
+
+    def _key(self, compiler: Compiler) -> str:
+        as_bytes = json.dumps(compiler.to_dict(), separators=(",", ":")).encode("utf-8")
+        return hashlib.sha256(as_bytes).hexdigest()
+
+
+def _make_compiler_cache():
+    return FileCompilerCache(spack.caches.MISC_CACHE)
+
+
+COMPILER_CACHE: CompilerCache = llnl.util.lang.Singleton(_make_compiler_cache)  # type: ignore

lib/spack/spack/compilers/aocc.py

@@ -116,5 +116,5 @@ def fflags(self):
     def _handle_default_flag_addtions(self):
         # This is a known issue for AOCC 3.0 see:
         # https://developer.amd.com/wp-content/resources/AOCC-3.0-Install-Guide.pdf
-        if self.real_version.satisfies(ver("3.0.0")):
+        if self.version.satisfies(ver("3.0.0")):
             return "-Wno-unused-command-line-argument " "-mllvm -eliminate-similar-expr=false"

lib/spack/spack/compilers/clang.py

@@ -16,7 +16,6 @@
     ("gfortran", os.path.join("clang", "gfortran")),
     ("xlf_r", os.path.join("xl_r", "xlf_r")),
     ("xlf", os.path.join("xl", "xlf")),
-    ("pgfortran", os.path.join("pgi", "pgfortran")),
     ("ifort", os.path.join("intel", "ifort")),
 ]
 
@@ -25,7 +24,6 @@
     ("gfortran", os.path.join("clang", "gfortran")),
     ("xlf90_r", os.path.join("xl_r", "xlf90_r")),
     ("xlf90", os.path.join("xl", "xlf90")),
-    ("pgfortran", os.path.join("pgi", "pgfortran")),
     ("ifort", os.path.join("intel", "ifort")),
 ]
 

lib/spack/spack/compilers/intel.py

@@ -124,8 +124,8 @@ def setup_custom_environment(self, pkg, env):
         # Edge cases for Intel's oneAPI compilers when using the legacy classic compilers:
         # Always pass flags to disable deprecation warnings, since these warnings can
         # confuse tools that parse the output of compiler commands (e.g. version checks).
-        if self.real_version >= Version("2021") and self.real_version <= Version("2023"):
+        if self.real_version >= Version("2021") and self.real_version < Version("2024"):
             env.append_flags("SPACK_ALWAYS_CFLAGS", "-diag-disable=10441")
             env.append_flags("SPACK_ALWAYS_CXXFLAGS", "-diag-disable=10441")
-        if self.real_version >= Version("2021") and self.real_version <= Version("2024"):
+        if self.real_version >= Version("2021") and self.real_version < Version("2025"):
             env.append_flags("SPACK_ALWAYS_FFLAGS", "-diag-disable=10448")

lib/spack/spack/compilers/oneapi.py

@@ -155,10 +155,10 @@ def setup_custom_environment(self, pkg, env):
         # icx+icpx+ifx or icx+icpx+ifort. But to be on the safe side (some users may
         # want to try to swap icpx against icpc, for example), and since the Intel LLVM
         # compilers accept these diag-disable flags, we apply them for all compilers.
-        if self.real_version >= Version("2021") and self.real_version <= Version("2023"):
+        if self.real_version >= Version("2021") and self.real_version < Version("2024"):
             env.append_flags("SPACK_ALWAYS_CFLAGS", "-diag-disable=10441")
             env.append_flags("SPACK_ALWAYS_CXXFLAGS", "-diag-disable=10441")
-        if self.real_version >= Version("2021") and self.real_version <= Version("2024"):
+        if self.real_version >= Version("2021") and self.real_version < Version("2025"):
             env.append_flags("SPACK_ALWAYS_FFLAGS", "-diag-disable=10448")
 
         # 2024 release bumped the libsycl version because of an ABI

lib/spack/spack/compilers/pgi.py

@@ -1,77 +0,0 @@
-# Copyright 2013-2024 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
-
-from spack.compiler import Compiler, UnsupportedCompilerFlag
-from spack.version import Version
-
-
-class Pgi(Compiler):
-    # Named wrapper links within build_env_path
-    link_paths = {
-        "cc": os.path.join("pgi", "pgcc"),
-        "cxx": os.path.join("pgi", "pgc++"),
-        "f77": os.path.join("pgi", "pgfortran"),
-        "fc": os.path.join("pgi", "pgfortran"),
-    }
-
-    version_argument = "-V"
-    ignore_version_errors = [2]  # `pgcc -V` on PowerPC annoyingly returns 2
-    version_regex = r"pg[^ ]* ([0-9.]+)-[0-9]+ (LLVM )?[^ ]+ target on "
-
-    @property
-    def verbose_flag(self):
-        return "-v"
-
-    @property
-    def debug_flags(self):
-        return ["-g", "-gopt"]
-
-    @property
-    def opt_flags(self):
-        return ["-O", "-O0", "-O1", "-O2", "-O3", "-O4"]
-
-    @property
-    def openmp_flag(self):
-        return "-mp"
-
-    @property
-    def cxx11_flag(self):
-        return "-std=c++11"
-
-    @property
-    def cc_pic_flag(self):
-        return "-fpic"
-
-    @property
-    def cxx_pic_flag(self):
-        return "-fpic"
-
-    @property
-    def f77_pic_flag(self):
-        return "-fpic"
-
-    @property
-    def fc_pic_flag(self):
-        return "-fpic"
-
-    required_libs = ["libpgc", "libpgf90"]
-
-    @property
-    def c99_flag(self):
-        if self.real_version >= Version("12.10"):
-            return "-c99"
-        raise UnsupportedCompilerFlag(self, "the C99 standard", "c99_flag", "< 12.10")
-
-    @property
-    def c11_flag(self):
-        if self.real_version >= Version("15.3"):
-            return "-c11"
-        raise UnsupportedCompilerFlag(self, "the C11 standard", "c11_flag", "< 15.3")
-
-    @property
-    def stdcxx_libs(self):
-        return ("-pgc++libs",)

lib/spack/spack/concretize.py

@@ -2,20 +2,20 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-"""
-(DEPRECATED) Used to contain the code for the original concretizer
-"""
+"""High-level functions to concretize list of specs"""
 import sys
 import time
 from contextlib import contextmanager
-from itertools import chain
-from typing import Tuple
+from typing import Iterable, Optional, Sequence, Tuple, Union
 
 import llnl.util.tty as tty
 
+import spack.compilers
 import spack.config
 import spack.error
-from spack.spec import Spec
+import spack.repo
+import spack.util.parallel
+from spack.spec import ArchSpec, CompilerSpec, Spec
 
 CHECK_COMPILER_EXISTENCE = True
 
@@ -36,92 +36,62 @@ def enable_compiler_existence_check():
     CHECK_COMPILER_EXISTENCE = saved
 
 
-def find_spec(spec, condition, default=None):
-    """Searches the dag from spec in an intelligent order and looks
-    for a spec that matches a condition"""
-    # First search parents, then search children
-    deptype = ("build", "link")
-    dagiter = chain(
-        spec.traverse(direction="parents", deptype=deptype, root=False),
-        spec.traverse(direction="children", deptype=deptype, root=False),
-    )
-    visited = set()
-    for relative in dagiter:
-        if condition(relative):
-            return relative
-        visited.add(id(relative))
-
-    # Then search all other relatives in the DAG *except* spec
-    for relative in spec.root.traverse(deptype="all"):
-        if relative is spec:
-            continue
-        if id(relative) in visited:
-            continue
-        if condition(relative):
-            return relative
-
-    # Finally search spec itself.
-    if condition(spec):
-        return spec
-
-    return default  # Nothing matched the condition; return default.
+SpecPair = Tuple[Spec, Spec]
+SpecLike = Union[Spec, str]
+TestsType = Union[bool, Iterable[str]]
 
 
-def concretize_specs_together(*abstract_specs, **kwargs):
+def concretize_specs_together(
+    abstract_specs: Sequence[SpecLike], tests: TestsType = False
+) -> Sequence[Spec]:
     """Given a number of specs as input, tries to concretize them together.
 
     Args:
-        tests (bool or list or set): False to run no tests, True to test
-            all packages, or a list of package names to run tests for some
-        *abstract_specs: abstract specs to be concretized, given either
-            as Specs or strings
-
-    Returns:
-        List of concretized specs
+        abstract_specs: abstract specs to be concretized
+        tests: list of package names for which to consider tests dependencies. If True, all nodes
+            will have test dependencies. If False, test dependencies will be disregarded.
     """
     import spack.solver.asp
 
     allow_deprecated = spack.config.get("config:deprecated", False)
     solver = spack.solver.asp.Solver()
-    result = solver.solve(
-        abstract_specs, tests=kwargs.get("tests", False), allow_deprecated=allow_deprecated
-    )
+    result = solver.solve(abstract_specs, tests=tests, allow_deprecated=allow_deprecated)
     return [s.copy() for s in result.specs]
 
 
-def concretize_together(*spec_list, **kwargs):
+def concretize_together(
+    spec_list: Sequence[SpecPair], tests: TestsType = False
+) -> Sequence[SpecPair]:
     """Given a number of specs as input, tries to concretize them together.
 
     Args:
-        tests (bool or list or set): False to run no tests, True to test
-            all packages, or a list of package names to run tests for some
-        *spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
+        spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
             already concrete spec or None if not yet concretized
-
-    Returns:
-        List of tuples of abstract and concretized specs
+        tests: list of package names for which to consider tests dependencies. If True, all nodes
+            will have test dependencies. If False, test dependencies will be disregarded.
     """
     to_concretize = [concrete if concrete else abstract for abstract, concrete in spec_list]
     abstract_specs = [abstract for abstract, _ in spec_list]
-    concrete_specs = concretize_specs_together(*to_concretize, **kwargs)
+    concrete_specs = concretize_specs_together(to_concretize, tests=tests)
     return list(zip(abstract_specs, concrete_specs))
 
 
-def concretize_together_when_possible(*spec_list, **kwargs):
+def concretize_together_when_possible(
+    spec_list: Sequence[SpecPair], tests: TestsType = False
+) -> Sequence[SpecPair]:
     """Given a number of specs as input, tries to concretize them together to the extent possible.
 
     See documentation for ``unify: when_possible`` concretization for the precise definition of
     "to the extent possible".
 
     Args:
-        tests (bool or list or set): False to run no tests, True to test
-            all packages, or a list of package names to run tests for some
-        *spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
+        spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
             already concrete spec or None if not yet concretized
-
-    Returns:
-        List of tuples of abstract and concretized specs
+        tests: list of package names for which to consider tests dependencies. If True, all nodes
+            will have test dependencies. If False, test dependencies will be disregarded.
     """
+    import spack.solver.asp
+
     to_concretize = [concrete if concrete else abstract for abstract, concrete in spec_list]
     old_concrete_to_abstract = {
         concrete: abstract for (abstract, concrete) in spec_list if concrete
@@ -131,7 +101,7 @@ def concretize_together_when_possible(*spec_list, **kwargs):
     solver = spack.solver.asp.Solver()
     allow_deprecated = spack.config.get("config:deprecated", False)
     for result in solver.solve_in_rounds(
-        to_concretize, tests=kwargs.get("tests", False), allow_deprecated=allow_deprecated
+        to_concretize, tests=tests, allow_deprecated=allow_deprecated
     ):
         result_by_user_spec.update(result.specs_by_input)
 
@@ -143,19 +113,19 @@ def concretize_together_when_possible(*spec_list, **kwargs):
     ]
 
 
-def concretize_separately(*spec_list, **kwargs):
-    """Given a number of specs as input, tries to concretize them together.
+def concretize_separately(
+    spec_list: Sequence[SpecPair], tests: TestsType = False
+) -> Sequence[SpecPair]:
+    """Concretizes the input specs separately from each other.
 
     Args:
-        tests (bool or list or set): False to run no tests, True to test
-            all packages, or a list of package names to run tests for some
-        *spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
+        spec_list: list of tuples to concretize. First entry is abstract spec, second entry is
             already concrete spec or None if not yet concretized
-
-    Returns:
-        List of tuples of abstract and concretized specs
+        tests: list of package names for which to consider tests dependencies. If True, all nodes
+            will have test dependencies. If False, test dependencies will be disregarded.
     """
-    tests = kwargs.get("tests", False)
+    import spack.bootstrap
+
     to_concretize = [abstract for abstract, concrete in spec_list if not concrete]
     args = [
         (i, str(abstract), tests)
@@ -190,13 +160,14 @@ def concretize_separately(*spec_list, **kwargs):
     # TODO: support parallel concretization on macOS and Windows
     num_procs = min(len(args), spack.config.determine_number_of_jobs(parallel=True))
 
+    msg = "Starting concretization"
+    if sys.platform not in ("darwin", "win32") and num_procs > 1:
+        msg += f" pool with {num_procs} processes"
+    tty.msg(msg)
+
     for j, (i, concrete, duration) in enumerate(
         spack.util.parallel.imap_unordered(
-            spack.concretize._concretize_task,
-            args,
-            processes=num_procs,
-            debug=tty.is_debug(),
-            maxtaskperchild=1,
+            _concretize_task, args, processes=num_procs, debug=tty.is_debug(), maxtaskperchild=1
         )
     ):
         ret.append((i, concrete))
@@ -215,7 +186,7 @@ def concretize_separately(*spec_list, **kwargs):
     ]
 
 
-def _concretize_task(packed_arguments) -> Tuple[int, Spec, float]:
+def _concretize_task(packed_arguments: Tuple[int, str, TestsType]) -> Tuple[int, Spec, float]:
     index, spec_str, tests = packed_arguments
     with tty.SuppressOutput(msg_enabled=False):
         start = time.time()
@@ -227,10 +198,10 @@ class UnavailableCompilerVersionError(spack.error.SpackError):
     """Raised when there is no available compiler that satisfies a
     compiler spec."""
 
-    def __init__(self, compiler_spec, arch=None):
-        err_msg = "No compilers with spec {0} found".format(compiler_spec)
+    def __init__(self, compiler_spec: CompilerSpec, arch: Optional[ArchSpec] = None) -> None:
+        err_msg = f"No compilers with spec {compiler_spec} found"
         if arch:
-            err_msg += " for operating system {0} and target {1}.".format(arch.os, arch.target)
+            err_msg += f" for operating system {arch.os} and target {arch.target}."
 
         super().__init__(
             err_msg,

lib/spack/spack/config.py

@@ -427,6 +427,10 @@ def __init__(self, *scopes: ConfigScope) -> None:
             self.push_scope(scope)
         self.format_updates: Dict[str, List[ConfigScope]] = collections.defaultdict(list)
 
+    def ensure_unwrapped(self) -> "Configuration":
+        """Ensure we unwrap this object from any dynamic wrapper (like Singleton)"""
+        return self
+
     @_config_mutator
     def push_scope(self, scope: ConfigScope) -> None:
         """Add a higher precedence scope to the Configuration."""
@@ -752,10 +756,6 @@ def override(
         assert scope is overrides
 
 
-#: configuration scopes added on the command line set by ``spack.main.main()``
-COMMAND_LINE_SCOPES: List[str] = []
-
-
 def _add_platform_scope(cfg: Configuration, name: str, path: str, writable: bool = True) -> None:
     """Add a platform-specific subdirectory for the current platform."""
     platform = spack.platforms.host().name
@@ -860,13 +860,6 @@ def create() -> Configuration:
         # Each scope can have per-platfom overrides in subdirectories
         _add_platform_scope(cfg, name, path)
 
-    # add command-line scopes
-    _add_command_line_scopes(cfg, COMMAND_LINE_SCOPES)
-
-    # we make a special scope for spack commands so that they can
-    # override configuration options.
-    cfg.push_scope(InternalConfigScope("command_line"))
-
     return cfg
 
 

lib/spack/spack/database.py

@@ -69,6 +69,8 @@
 from spack.error import SpackError
 from spack.util.crypto import bit_length
 
+from .enums import InstallRecordStatus
+
 # TODO: Provide an API automatically retyring a build after detecting and
 # TODO: clearing a failure.
 
@@ -160,36 +162,12 @@ def converter(self, spec_like, *args, **kwargs):
     return converter
 
 
-class InstallStatus(str):
-    pass
-
-
-class InstallStatuses:
-    INSTALLED = InstallStatus("installed")
-    DEPRECATED = InstallStatus("deprecated")
-    MISSING = InstallStatus("missing")
-
-    @classmethod
-    def canonicalize(cls, query_arg):
-        if query_arg is True:
-            return [cls.INSTALLED]
-        if query_arg is False:
-            return [cls.MISSING]
-        if query_arg is any:
-            return [cls.INSTALLED, cls.DEPRECATED, cls.MISSING]
-        if isinstance(query_arg, InstallStatus):
-            return [query_arg]
-        try:
-            statuses = list(query_arg)
-            if all(isinstance(x, InstallStatus) for x in statuses):
-                return statuses
-        except TypeError:
-            pass
-
-        raise TypeError(
-            "installation query must be `any`, boolean, "
-            "InstallStatus, or iterable of InstallStatus"
-        )
+def normalize_query(installed: Union[bool, InstallRecordStatus]) -> InstallRecordStatus:
+    if installed is True:
+        installed = InstallRecordStatus.INSTALLED
+    elif installed is False:
+        installed = InstallRecordStatus.MISSING
+    return installed
 
 
 class InstallRecord:
@@ -227,8 +205,8 @@ def __init__(
         installation_time: Optional[float] = None,
         deprecated_for: Optional[str] = None,
         in_buildcache: bool = False,
-        origin=None,
-    ):
+        origin: Optional[str] = None,
+    ) -> None:
         self.spec = spec
         self.path = str(path) if path else None
         self.installed = bool(installed)
@@ -239,14 +217,12 @@ def __init__(
         self.in_buildcache = in_buildcache
         self.origin = origin
 
-    def install_type_matches(self, installed):
-        installed = InstallStatuses.canonicalize(installed)
+    def install_type_matches(self, installed: InstallRecordStatus) -> bool:
         if self.installed:
-            return InstallStatuses.INSTALLED in installed
+            return InstallRecordStatus.INSTALLED in installed
         elif self.deprecated_for:
-            return InstallStatuses.DEPRECATED in installed
-        else:
-            return InstallStatuses.MISSING in installed
+            return InstallRecordStatus.DEPRECATED in installed
+        return InstallRecordStatus.MISSING in installed
 
     def to_dict(self, include_fields=DEFAULT_INSTALL_RECORD_FIELDS):
         rec_dict = {}
@@ -1396,7 +1372,13 @@ def installed_extensions_for(self, extendee_spec: "spack.spec.Spec"):
             if spec.package.extends(extendee_spec):
                 yield spec.package
 
-    def _get_by_hash_local(self, dag_hash, default=None, installed=any):
+    def _get_by_hash_local(
+        self,
+        dag_hash: str,
+        default: Optional[List["spack.spec.Spec"]] = None,
+        installed: Union[bool, InstallRecordStatus] = InstallRecordStatus.ANY,
+    ) -> Optional[List["spack.spec.Spec"]]:
+        installed = normalize_query(installed)
         # hash is a full hash and is in the data somewhere
         if dag_hash in self._data:
             rec = self._data[dag_hash]
@@ -1405,8 +1387,7 @@ def _get_by_hash_local(self, dag_hash, default=None, installed=any):
             else:
                 return default
 
-        # check if hash is a prefix of some installed (or previously
-        # installed) spec.
+        # check if hash is a prefix of some installed (or previously installed) spec.
         matches = [
             record.spec
             for h, record in self._data.items()
@@ -1418,52 +1399,43 @@ def _get_by_hash_local(self, dag_hash, default=None, installed=any):
         # nothing found
         return default
 
-    def get_by_hash_local(self, dag_hash, default=None, installed=any):
+    def get_by_hash_local(
+        self,
+        dag_hash: str,
+        default: Optional[List["spack.spec.Spec"]] = None,
+        installed: Union[bool, InstallRecordStatus] = InstallRecordStatus.ANY,
+    ) -> Optional[List["spack.spec.Spec"]]:
         """Look up a spec in *this DB* by DAG hash, or by a DAG hash prefix.
 
-        Arguments:
-            dag_hash (str): hash (or hash prefix) to look up
-            default (object or None): default value to return if dag_hash is
-                not in the DB (default: None)
-            installed (bool or InstallStatus or typing.Iterable or None):
-                if ``True``, includes only installed
-                specs in the search; if ``False`` only missing specs, and if
-                ``any``, all specs in database. If an InstallStatus or iterable
-                of InstallStatus, returns specs whose install status
-                (installed, deprecated, or missing) matches (one of) the
-                InstallStatus. (default: any)
+        Args:
+            dag_hash: hash (or hash prefix) to look up
+            default: default value to return if dag_hash is not in the DB
+            installed: if ``True``, includes only installed specs in the search; if ``False``
+                only missing specs. Otherwise, a InstallRecordStatus flag.
 
-        ``installed`` defaults to ``any`` so that we can refer to any
-        known hash.  Note that ``query()`` and ``query_one()`` differ in
-        that they only return installed specs by default.
-
-        Returns:
-            (list): a list of specs matching the hash or hash prefix
+        ``installed`` defaults to ``InstallRecordStatus.ANY`` so we can refer to any known hash.
 
+        ``query()`` and ``query_one()`` differ in that they only return installed specs by default.
         """
         with self.read_transaction():
             return self._get_by_hash_local(dag_hash, default=default, installed=installed)
 
-    def get_by_hash(self, dag_hash, default=None, installed=any):
+    def get_by_hash(
+        self,
+        dag_hash: str,
+        default: Optional[List["spack.spec.Spec"]] = None,
+        installed: Union[bool, InstallRecordStatus] = InstallRecordStatus.ANY,
+    ) -> Optional[List["spack.spec.Spec"]]:
         """Look up a spec by DAG hash, or by a DAG hash prefix.
 
-        Arguments:
-            dag_hash (str): hash (or hash prefix) to look up
-            default (object or None): default value to return if dag_hash is
-                not in the DB (default: None)
-            installed (bool or InstallStatus or typing.Iterable or None):
-                if ``True``, includes only installed specs in the search; if ``False``
-                only missing specs, and if ``any``, all specs in database. If an
-                InstallStatus or iterable of InstallStatus, returns specs whose install
-                status (installed, deprecated, or missing) matches (one of) the
-                InstallStatus. (default: any)
+        Args:
+            dag_hash: hash (or hash prefix) to look up
+            default: default value to return if dag_hash is not in the DB
+            installed: if ``True``, includes only installed specs in the search; if ``False``
+                only missing specs. Otherwise, a InstallRecordStatus flag.
 
-        ``installed`` defaults to ``any`` so that we can refer to any
-        known hash.  Note that ``query()`` and ``query_one()`` differ in
-        that they only return installed specs by default.
-
-        Returns:
-            (list): a list of specs matching the hash or hash prefix
+        ``installed`` defaults to ``InstallRecordStatus.ANY`` so we can refer to any known hash.
+        ``query()`` and ``query_one()`` differ in that they only return installed specs by default.
 
         """
 
@@ -1483,7 +1455,7 @@ def _query(
         query_spec: Optional[Union[str, "spack.spec.Spec"]] = None,
         *,
         predicate_fn: Optional[SelectType] = None,
-        installed: Union[bool, InstallStatus, List[InstallStatus]] = True,
+        installed: Union[bool, InstallRecordStatus] = True,
         explicit: Optional[bool] = None,
         start_date: Optional[datetime.datetime] = None,
         end_date: Optional[datetime.datetime] = None,
@@ -1491,6 +1463,7 @@ def _query(
         in_buildcache: Optional[bool] = None,
         origin: Optional[str] = None,
     ) -> List["spack.spec.Spec"]:
+        installed = normalize_query(installed)
 
         # Restrict the set of records over which we iterate first
         matching_hashes = self._data
@@ -1560,7 +1533,7 @@ def query_local(
         query_spec: Optional[Union[str, "spack.spec.Spec"]] = None,
         *,
         predicate_fn: Optional[SelectType] = None,
-        installed: Union[bool, InstallStatus, List[InstallStatus]] = True,
+        installed: Union[bool, InstallRecordStatus] = True,
         explicit: Optional[bool] = None,
         start_date: Optional[datetime.datetime] = None,
         end_date: Optional[datetime.datetime] = None,
@@ -1620,7 +1593,7 @@ def query(
         query_spec: Optional[Union[str, "spack.spec.Spec"]] = None,
         *,
         predicate_fn: Optional[SelectType] = None,
-        installed: Union[bool, InstallStatus, List[InstallStatus]] = True,
+        installed: Union[bool, InstallRecordStatus] = True,
         explicit: Optional[bool] = None,
         start_date: Optional[datetime.datetime] = None,
         end_date: Optional[datetime.datetime] = None,
@@ -1628,7 +1601,7 @@ def query(
         hashes: Optional[List[str]] = None,
         origin: Optional[str] = None,
         install_tree: str = "all",
-    ):
+    ) -> List["spack.spec.Spec"]:
         """Queries the Spack database including all upstream databases.
 
         Args:
@@ -1709,13 +1682,14 @@ def query(
             )
 
         results = list(local_results) + list(x for x in upstream_results if x not in local_results)
-        return sorted(results)
+        results.sort()
+        return results
 
     def query_one(
         self,
         query_spec: Optional[Union[str, "spack.spec.Spec"]],
         predicate_fn: Optional[SelectType] = None,
-        installed: Union[bool, InstallStatus, List[InstallStatus]] = True,
+        installed: Union[bool, InstallRecordStatus] = True,
     ) -> Optional["spack.spec.Spec"]:
         """Query for exactly one spec that matches the query spec.
 

lib/spack/spack/directives.py

@@ -34,12 +34,12 @@ class OpenMpi(Package):
 import collections.abc
 import os.path
 import re
-from typing import TYPE_CHECKING, Any, Callable, List, Optional, Tuple, Union
+from typing import Any, Callable, List, Optional, Tuple, Union
 
-import llnl.util.lang
 import llnl.util.tty.color
 
 import spack.deptypes as dt
+import spack.package_base
 import spack.patch
 import spack.spec
 import spack.util.crypto
@@ -56,14 +56,10 @@ class OpenMpi(Package):
     VersionLookupError,
 )
 
-if TYPE_CHECKING:
-    import spack.package_base
-
 __all__ = [
     "DirectiveError",
-    "DirectiveMeta",
-    "DisableRedistribute",
     "version",
+    "conditional",
     "conflicts",
     "depends_on",
     "extends",
@@ -76,6 +72,7 @@ class OpenMpi(Package):
     "build_system",
     "requires",
     "redistribute",
+    "can_splice",
 ]
 
 _patch_order_index = 0
@@ -83,15 +80,15 @@ class OpenMpi(Package):
 
 SpecType = str
 DepType = Union[Tuple[str, ...], str]
-WhenType = Optional[Union["spack.spec.Spec", str, bool]]
-Patcher = Callable[[Union["spack.package_base.PackageBase", Dependency]], None]
+WhenType = Optional[Union[spack.spec.Spec, str, bool]]
+Patcher = Callable[[Union[spack.package_base.PackageBase, Dependency]], None]
 PatchesType = Optional[Union[Patcher, str, List[Union[Patcher, str]]]]
 
 
 SUPPORTED_LANGUAGES = ("fortran", "cxx", "c")
 
 
-def _make_when_spec(value: WhenType) -> Optional["spack.spec.Spec"]:
+def _make_when_spec(value: WhenType) -> Optional[spack.spec.Spec]:
     """Create a ``Spec`` that indicates when a directive should be applied.
 
     Directives with ``when`` specs, e.g.:
@@ -136,7 +133,7 @@ def _make_when_spec(value: WhenType) -> Optional["spack.spec.Spec"]:
     return spack.spec.Spec(value)
 
 
-SubmoduleCallback = Callable[["spack.package_base.PackageBase"], Union[str, List[str], bool]]
+SubmoduleCallback = Callable[[spack.package_base.PackageBase], Union[str, List[str], bool]]
 directive = DirectiveMeta.directive
 
 
@@ -252,8 +249,8 @@ def _execute_version(pkg, ver, **kwargs):
 
 
 def _depends_on(
-    pkg: "spack.package_base.PackageBase",
-    spec: "spack.spec.Spec",
+    pkg: spack.package_base.PackageBase,
+    spec: spack.spec.Spec,
     *,
     when: WhenType = None,
     type: DepType = dt.DEFAULT_TYPES,
@@ -332,7 +329,7 @@ def conflicts(conflict_spec: SpecType, when: WhenType = None, msg: Optional[str]
         msg (str): optional user defined message
     """
 
-    def _execute_conflicts(pkg: "spack.package_base.PackageBase"):
+    def _execute_conflicts(pkg: spack.package_base.PackageBase):
         # If when is not specified the conflict always holds
         when_spec = _make_when_spec(when)
         if not when_spec:
@@ -373,19 +370,12 @@ def depends_on(
         assert type == "build", "languages must be of 'build' type"
         return _language(lang_spec_str=spec, when=when)
 
-    def _execute_depends_on(pkg: "spack.package_base.PackageBase"):
+    def _execute_depends_on(pkg: spack.package_base.PackageBase):
         _depends_on(pkg, dep_spec, when=when, type=type, patches=patches)
 
     return _execute_depends_on
 
 
-#: Store whether a given Spec source/binary should not be redistributed.
-class DisableRedistribute:
-    def __init__(self, source, binary):
-        self.source = source
-        self.binary = binary
-
-
 @directive("disable_redistribute")
 def redistribute(source=None, binary=None, when: WhenType = None):
     """Can be used inside a Package definition to declare that
@@ -402,7 +392,7 @@ def redistribute(source=None, binary=None, when: WhenType = None):
 
 
 def _execute_redistribute(
-    pkg: "spack.package_base.PackageBase", source=None, binary=None, when: WhenType = None
+    pkg: spack.package_base.PackageBase, source=None, binary=None, when: WhenType = None
 ):
     if source is None and binary is None:
         return
@@ -432,7 +422,7 @@ def _execute_redistribute(
         if not binary:
             disable.binary = True
     else:
-        pkg.disable_redistribute[when_spec] = DisableRedistribute(
+        pkg.disable_redistribute[when_spec] = spack.package_base.DisableRedistribute(
             source=not source, binary=not binary
         )
 
@@ -478,7 +468,7 @@ def provides(*specs: SpecType, when: WhenType = None):
         when: condition when this provides clause needs to be considered
     """
 
-    def _execute_provides(pkg: "spack.package_base.PackageBase"):
+    def _execute_provides(pkg: spack.package_base.PackageBase):
         import spack.parser  # Avoid circular dependency
 
         when_spec = _make_when_spec(when)
@@ -504,6 +494,43 @@ def _execute_provides(pkg: "spack.package_base.PackageBase"):
     return _execute_provides
 
 
+@directive("splice_specs")
+def can_splice(
+    target: SpecType, *, when: SpecType, match_variants: Union[None, str, List[str]] = None
+):
+    """Packages can declare whether they are ABI-compatible with another package
+    and thus can be spliced into concrete versions of that package.
+
+    Args:
+        target: The spec that the current package is ABI-compatible with.
+
+        when: An anonymous spec constraining current package for when it is
+            ABI-compatible with target.
+
+        match_variants: A list of variants that must match
+            between target spec and current package, with special value '*'
+            which matches all variants. Example: a variant is defined on both
+            packages called json, and they are ABI-compatible whenever they agree on
+            the json variant (regardless of whether it is turned on or off).  Note
+            that this cannot be applied to multi-valued variants and multi-valued
+            variants will be skipped by '*'.
+    """
+
+    def _execute_can_splice(pkg: spack.package_base.PackageBase):
+        when_spec = _make_when_spec(when)
+        if isinstance(match_variants, str) and match_variants != "*":
+            raise ValueError(
+                "* is the only valid string for match_variants "
+                "if looking to provide a single variant, use "
+                f"[{match_variants}] instead"
+            )
+        if when_spec is None:
+            return
+        pkg.splice_specs[when_spec] = (spack.spec.Spec(target), match_variants)
+
+    return _execute_can_splice
+
+
 @directive("patches")
 def patch(
     url_or_filename: str,
@@ -530,7 +557,7 @@ def patch(
             compressed URL patches)
     """
 
-    def _execute_patch(pkg_or_dep: Union["spack.package_base.PackageBase", Dependency]):
+    def _execute_patch(pkg_or_dep: Union[spack.package_base.PackageBase, Dependency]):
         pkg = pkg_or_dep
         if isinstance(pkg, Dependency):
             pkg = pkg.pkg
@@ -577,6 +604,15 @@ def _execute_patch(pkg_or_dep: Union["spack.package_base.PackageBase", Dependenc
     return _execute_patch
 
 
+def conditional(*values: List[Any], when: Optional[WhenType] = None):
+    """Conditional values that can be used in variant declarations."""
+    # _make_when_spec returns None when the condition is statically false.
+    when = _make_when_spec(when)
+    return spack.variant.ConditionalVariantValues(
+        spack.variant.ConditionalValue(x, when=when) for x in values
+    )
+
+
 @directive("variants")
 def variant(
     name: str,
@@ -845,7 +881,7 @@ def requires(*requirement_specs: str, policy="one_of", when=None, msg=None):
         msg: optional user defined message
     """
 
-    def _execute_requires(pkg: "spack.package_base.PackageBase"):
+    def _execute_requires(pkg: spack.package_base.PackageBase):
         if policy not in ("one_of", "any_of"):
             err_msg = (
                 f"the 'policy' argument of the 'requires' directive in {pkg.name} is set "
@@ -870,7 +906,7 @@ def _execute_requires(pkg: "spack.package_base.PackageBase"):
 def _language(lang_spec_str: str, *, when: Optional[Union[str, bool]] = None):
     """Temporary implementation of language virtuals, until compilers are proper dependencies."""
 
-    def _execute_languages(pkg: "spack.package_base.PackageBase"):
+    def _execute_languages(pkg: spack.package_base.PackageBase):
         when_spec = _make_when_spec(when)
         if not when_spec:
             return

lib/spack/spack/enums.py

@@ -0,0 +1,15 @@
+# Copyright 2013-2024 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)
+"""Enumerations used throughout Spack"""
+import enum
+
+
+class InstallRecordStatus(enum.Flag):
+    """Enum flag to facilitate querying status from the DB"""
+
+    INSTALLED = enum.auto()
+    DEPRECATED = enum.auto()
+    MISSING = enum.auto()
+    ANY = INSTALLED | DEPRECATED | MISSING

lib/spack/spack/environment/environment.py

@@ -14,17 +14,16 @@
 import urllib.parse
 import urllib.request
 import warnings
-from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
+from typing import Any, Dict, Iterable, List, Optional, Sequence, Tuple, Union
 
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
 import llnl.util.tty.color as clr
 from llnl.util.link_tree import ConflictingSpecsError
-from llnl.util.symlink import readlink, symlink
+from llnl.util.symlink import islink, readlink, symlink
 
 import spack
 import spack.caches
-import spack.compilers
 import spack.concretize
 import spack.config
 import spack.deptypes as dt
@@ -43,7 +42,6 @@
 import spack.util.environment
 import spack.util.hash
 import spack.util.lock as lk
-import spack.util.parallel
 import spack.util.path
 import spack.util.spack_json as sjson
 import spack.util.spack_yaml as syaml
@@ -55,7 +53,7 @@
 from spack.spec_list import SpecList
 from spack.util.path import substitute_path_variables
 
-SpecPair = Tuple[spack.spec.Spec, spack.spec.Spec]
+SpecPair = spack.concretize.SpecPair
 
 #: environment variable used to indicate the active environment
 spack_env_var = "SPACK_ENV"
@@ -670,7 +668,7 @@ def from_dict(base_path, d):
 
     @property
     def _current_root(self):
-        if not os.path.islink(self.root):
+        if not islink(self.root):
             return None
 
         root = readlink(self.root)
@@ -1533,9 +1531,7 @@ def _get_specs_to_concretize(
         ]
         return new_user_specs, kept_user_specs, specs_to_concretize
 
-    def _concretize_together_where_possible(
-        self, tests: bool = False
-    ) -> List[Tuple[spack.spec.Spec, spack.spec.Spec]]:
+    def _concretize_together_where_possible(self, tests: bool = False) -> Sequence[SpecPair]:
         # Avoid cyclic dependency
         import spack.solver.asp
 
@@ -1550,7 +1546,7 @@ def _concretize_together_where_possible(
 
         ret = []
         result = spack.concretize.concretize_together_when_possible(
-            *specs_to_concretize, tests=tests
+            specs_to_concretize, tests=tests
         )
         for abstract, concrete in result:
             # Only add to the environment if it's from this environment (not included in)
@@ -1563,7 +1559,7 @@ def _concretize_together_where_possible(
 
         return ret
 
-    def _concretize_together(self, tests: bool = False) -> List[SpecPair]:
+    def _concretize_together(self, tests: bool = False) -> Sequence[SpecPair]:
         """Concretization strategy that concretizes all the specs
         in the same DAG.
         """
@@ -1577,8 +1573,8 @@ def _concretize_together(self, tests: bool = False) -> List[SpecPair]:
         self.specs_by_hash = {}
 
         try:
-            concretized_specs: List[SpecPair] = spack.concretize.concretize_together(
-                *specs_to_concretize, tests=tests
+            concretized_specs = spack.concretize.concretize_together(
+                specs_to_concretize, tests=tests
             )
         except spack.error.UnsatisfiableSpecError as e:
             # "Enhance" the error message for multiple root specs, suggest a less strict
@@ -1627,7 +1623,7 @@ def _concretize_separately(self, tests=False):
         to_concretize = [
             (root, None) for root in self.user_specs if root not in old_concretized_user_specs
         ]
-        concretized_specs = spack.concretize.concretize_separately(*to_concretize, tests=tests)
+        concretized_specs = spack.concretize.concretize_separately(to_concretize, tests=tests)
 
         by_hash = {}
         for abstract, concrete in concretized_specs:

lib/spack/spack/graph.py

@@ -325,12 +325,7 @@ def write(self, spec, color=None, out=None):
         self._out = llnl.util.tty.color.ColorStream(out, color=color)
 
         # We'll traverse the spec in topological order as we graph it.
-        nodes_in_topological_order = [
-            edge.spec
-            for edge in spack.traverse.traverse_edges_topo(
-                [spec], direction="children", deptype=self.depflag
-            )
-        ]
+        nodes_in_topological_order = list(spec.traverse(order="topo", deptype=self.depflag))
         nodes_in_topological_order.reverse()
 
         # Work on a copy to be nondestructive

lib/spack/spack/install_test.py

@@ -23,7 +23,6 @@
 from llnl.util.tty.color import colorize
 
 import spack.build_environment
-import spack.builder
 import spack.config
 import spack.error
 import spack.package_base
@@ -353,9 +352,7 @@ def status(self, name: str, status: "TestStatus", msg: Optional[str] = None):
         self.test_parts[part_name] = status
         self.counts[status] += 1
 
-    def phase_tests(
-        self, builder: spack.builder.Builder, phase_name: str, method_names: List[str]
-    ):
+    def phase_tests(self, builder, phase_name: str, method_names: List[str]):
         """Execute the builder's package phase-time tests.
 
         Args:
@@ -378,23 +375,16 @@ def phase_tests(
 
             for name in method_names:
                 try:
-                    # Prefer the method in the package over the builder's.
-                    # We need this primarily to pick up arbitrarily named test
-                    # methods but also some build-time checks.
-                    fn = getattr(builder.pkg, name, getattr(builder, name))
-
-                    msg = f"RUN-TESTS: {phase_name}-time tests [{name}]"
-                    print_message(logger, msg, verbose)
-
-                    fn()
-
+                    fn = getattr(builder, name, None) or getattr(builder.pkg, name)
                 except AttributeError as e:
-                    msg = f"RUN-TESTS: method not implemented [{name}]"
-                    print_message(logger, msg, verbose)
-
-                    self.add_failure(e, msg)
+                    print_message(logger, f"RUN-TESTS: method not implemented [{name}]", verbose)
+                    self.add_failure(e, f"RUN-TESTS: method not implemented [{name}]")
                     if fail_fast:
                         break
+                    continue
+
+                print_message(logger, f"RUN-TESTS: {phase_name}-time tests [{name}]", verbose)
+                fn()
 
             if have_tests:
                 print_message(logger, "Completed testing", verbose)
@@ -764,7 +754,7 @@ def virtuals(pkg):
 
     # hack for compilers that are not dependencies (yet)
     # TODO: this all eventually goes away
-    c_names = ("gcc", "intel", "intel-parallel-studio", "pgi")
+    c_names = ("gcc", "intel", "intel-parallel-studio")
     if pkg.name in c_names:
         v_names.extend(["c", "cxx", "fortran"])
     if pkg.spec.satisfies("llvm+clang"):

lib/spack/spack/installer.py

@@ -50,6 +50,7 @@
 
 import spack.binary_distribution as binary_distribution
 import spack.build_environment
+import spack.builder
 import spack.config
 import spack.database
 import spack.deptypes as dt
@@ -212,7 +213,7 @@ def _check_last_phase(pkg: "spack.package_base.PackageBase") -> None:
     Raises:
         ``BadInstallPhase`` if stop_before or last phase is invalid
     """
-    phases = pkg.builder.phases  # type: ignore[attr-defined]
+    phases = spack.builder.create(pkg).phases  # type: ignore[attr-defined]
     if pkg.stop_before_phase and pkg.stop_before_phase not in phases:  # type: ignore[attr-defined]
         raise BadInstallPhase(pkg.name, pkg.stop_before_phase)  # type: ignore[attr-defined]
 
@@ -661,7 +662,7 @@ def log(pkg: "spack.package_base.PackageBase") -> None:
             spack.store.STORE.layout.metadata_path(pkg.spec), "archived-files"
         )
 
-        for glob_expr in pkg.builder.archive_files:
+        for glob_expr in spack.builder.create(pkg).archive_files:
             # Check that we are trying to copy things that are
             # in the stage tree (not arbitrary files)
             abs_expr = os.path.realpath(glob_expr)
@@ -2394,7 +2395,6 @@ def _install_source(self) -> None:
         fs.install_tree(pkg.stage.source_path, src_target)
 
     def _real_install(self) -> None:
-        import spack.builder
 
         pkg = self.pkg
 

lib/spack/spack/main.py

@@ -911,13 +911,6 @@ def _main(argv=None):
     # Make spack load / env activate work on macOS
     restore_macos_dyld_vars()
 
-    # make spack.config aware of any command line configuration scopes
-    if args.config_scopes:
-        spack.config.COMMAND_LINE_SCOPES = args.config_scopes
-
-    # ensure options on spack command come before everything
-    setup_main_options(args)
-
     # activate an environment if one was specified on the command line
     env_format_error = None
     if not args.no_env:
@@ -931,6 +924,12 @@ def _main(argv=None):
             e.print_context()
             env_format_error = e
 
+    # Push scopes from the command line last
+    if args.config_scopes:
+        spack.config._add_command_line_scopes(spack.config.CONFIG, args.config_scopes)
+    spack.config.CONFIG.push_scope(spack.config.InternalConfigScope("command_line"))
+    setup_main_options(args)
+
     # ------------------------------------------------------------------------
     # Things that require configuration should go below here
     # ------------------------------------------------------------------------

lib/spack/spack/mirror.py

@@ -18,7 +18,7 @@
 import sys
 import traceback
 import urllib.parse
-from typing import List, Optional, Union
+from typing import Any, Dict, Optional, Tuple, Union
 
 import llnl.url
 import llnl.util.symlink
@@ -29,6 +29,7 @@
 import spack.config
 import spack.error
 import spack.fetch_strategy
+import spack.mirror
 import spack.oci.image
 import spack.repo
 import spack.spec
@@ -153,8 +154,66 @@ def push_url(self):
         """Get the valid, canonicalized fetch URL"""
         return self.get_url("push")
 
+    def ensure_mirror_usable(self, direction: str = "push"):
+        access_pair = self._get_value("access_pair", direction)
+        access_token_variable = self._get_value("access_token_variable", direction)
+
+        errors = []
+
+        # Verify that the credentials that are variables expand
+        if access_pair and isinstance(access_pair, dict):
+            if "id_variable" in access_pair and access_pair["id_variable"] not in os.environ:
+                errors.append(f"id_variable {access_pair['id_variable']} not set in environment")
+            if "secret_variable" in access_pair:
+                if access_pair["secret_variable"] not in os.environ:
+                    errors.append(
+                        f"environment variable `{access_pair['secret_variable']}` "
+                        "(secret_variable) not set"
+                    )
+
+        if access_token_variable:
+            if access_token_variable not in os.environ:
+                errors.append(
+                    f"environment variable `{access_pair['access_token_variable']}` "
+                    "(access_token_variable) not set"
+                )
+
+        if errors:
+            msg = f"invalid {direction} configuration for mirror {self.name}: "
+            msg += "\n    ".join(errors)
+            raise MirrorError(msg)
+
     def _update_connection_dict(self, current_data: dict, new_data: dict, top_level: bool):
-        keys = ["url", "access_pair", "access_token", "profile", "endpoint_url"]
+        # Only allow one to exist in the config
+        if "access_token" in current_data and "access_token_variable" in new_data:
+            current_data.pop("access_token")
+        elif "access_token_variable" in current_data and "access_token" in new_data:
+            current_data.pop("access_token_variable")
+
+        # If updating to a new access_pair that is the deprecated list, warn
+        warn_deprecated_access_pair = False
+        if "access_pair" in new_data:
+            warn_deprecated_access_pair = isinstance(new_data["access_pair"], list)
+        # If the not updating the current access_pair, and it is the deprecated list, warn
+        elif "access_pair" in current_data:
+            warn_deprecated_access_pair = isinstance(current_data["access_pair"], list)
+
+        if warn_deprecated_access_pair:
+            tty.warn(
+                f"in mirror {self.name}: support for plain text secrets in config files "
+                "(access_pair: [id, secret]) is deprecated and will be removed in a future Spack "
+                "version. Use environment variables instead (access_pair: "
+                "{id: ..., secret_variable: ...})"
+            )
+
+        keys = [
+            "url",
+            "access_pair",
+            "access_token",
+            "access_token_variable",
+            "profile",
+            "endpoint_url",
+        ]
         if top_level:
             keys += ["binary", "source", "signed", "autopush"]
         changed = False
@@ -270,11 +329,53 @@ def get_url(self, direction: str) -> str:
 
         return _url_or_path_to_url(url)
 
-    def get_access_token(self, direction: str) -> Optional[str]:
-        return self._get_value("access_token", direction)
+    def get_credentials(self, direction: str) -> Dict[str, Any]:
+        """Get the mirror credentials from the mirror config
 
-    def get_access_pair(self, direction: str) -> Optional[List]:
-        return self._get_value("access_pair", direction)
+        Args:
+            direction: fetch or push mirror config
+
+        Returns:
+            Dictionary from credential type string to value
+
+            Credential Type Map:
+                access_token -> str
+                access_pair  -> tuple(str,str)
+                profile      -> str
+        """
+        creddict: Dict[str, Any] = {}
+        access_token = self.get_access_token(direction)
+        if access_token:
+            creddict["access_token"] = access_token
+
+        access_pair = self.get_access_pair(direction)
+        if access_pair:
+            creddict.update({"access_pair": access_pair})
+
+        profile = self.get_profile(direction)
+        if profile:
+            creddict["profile"] = profile
+
+        return creddict
+
+    def get_access_token(self, direction: str) -> Optional[str]:
+        tok = self._get_value("access_token_variable", direction)
+        if tok:
+            return os.environ.get(tok)
+        else:
+            return self._get_value("access_token", direction)
+        return None
+
+    def get_access_pair(self, direction: str) -> Optional[Tuple[str, str]]:
+        pair = self._get_value("access_pair", direction)
+        if isinstance(pair, (tuple, list)) and len(pair) == 2:
+            return (pair[0], pair[1]) if all(pair) else None
+        elif isinstance(pair, dict):
+            id_ = os.environ.get(pair["id_variable"]) if "id_variable" in pair else pair["id"]
+            secret = os.environ.get(pair["secret_variable"])
+            return (id_, secret) if id_ and secret else None
+        else:
+            return None
 
     def get_profile(self, direction: str) -> Optional[str]:
         return self._get_value("profile", direction)

lib/spack/spack/mixins.py

@@ -10,7 +10,7 @@
 
 import llnl.util.filesystem
 
-import spack.builder
+import spack.phase_callbacks
 
 
 def filter_compiler_wrappers(*files, **kwargs):
@@ -111,4 +111,4 @@ def _filter_compiler_wrappers_impl(pkg_or_builder):
         if pkg.compiler.name == "nag":
             x.filter("-Wl,--enable-new-dtags", "", **filter_kwargs)
 
-    spack.builder.run_after(after)(_filter_compiler_wrappers_impl)
+    spack.phase_callbacks.run_after(after)(_filter_compiler_wrappers_impl)

lib/spack/spack/modules/common.py

@@ -39,7 +39,7 @@
 
 import llnl.util.filesystem
 import llnl.util.tty as tty
-from llnl.util.lang import dedupe, memoized
+from llnl.util.lang import Singleton, dedupe, memoized
 
 import spack.build_environment
 import spack.config
@@ -246,7 +246,7 @@ def _generate_upstream_module_index():
     return UpstreamModuleIndex(spack.store.STORE.db, module_indices)
 
 
-upstream_module_index = llnl.util.lang.Singleton(_generate_upstream_module_index)
+upstream_module_index = Singleton(_generate_upstream_module_index)
 
 
 ModuleIndexEntry = collections.namedtuple("ModuleIndexEntry", ["path", "use_name"])

lib/spack/spack/oci/opener.py

@@ -377,9 +377,10 @@ def credentials_from_mirrors(
         # Prefer push credentials over fetch. Unlikely that those are different
         # but our config format allows it.
         for direction in ("push", "fetch"):
-            pair = mirror.get_access_pair(direction)
-            if pair is None:
+            pair = mirror.get_credentials(direction).get("access_pair")
+            if not pair:
                 continue
+
             url = mirror.get_url(direction)
             if not url.startswith("oci://"):
                 continue

lib/spack/spack/package.py

@@ -11,7 +11,7 @@
 from os import chdir, environ, getcwd, makedirs, mkdir, remove, removedirs
 from shutil import move, rmtree
 
-from spack.error import InstallError
+from spack.error import InstallError, NoHeadersError, NoLibrariesError
 
 # Emulate some shell commands for convenience
 env = environ
@@ -74,7 +74,7 @@
 from spack.build_systems.sourceware import SourcewarePackage
 from spack.build_systems.waf import WafPackage
 from spack.build_systems.xorg import XorgPackage
-from spack.builder import run_after, run_before
+from spack.builder import BaseBuilder
 from spack.config import determine_number_of_jobs
 from spack.deptypes import ALL_TYPES as all_deptypes
 from spack.directives import *
@@ -100,15 +100,11 @@
     on_package_attributes,
 )
 from spack.package_completions import *
+from spack.phase_callbacks import run_after, run_before
 from spack.spec import InvalidSpecDetected, Spec
 from spack.util.executable import *
 from spack.util.filesystem import file_command, fix_darwin_install_name, mime_type
-from spack.variant import (
-    any_combination_of,
-    auto_or_any_combination_of,
-    conditional,
-    disjoint_sets,
-)
+from spack.variant import any_combination_of, auto_or_any_combination_of, disjoint_sets
 from spack.version import Version, ver
 
 # These are just here for editor support; they will be replaced when the build env

lib/spack/spack/package_base.py

@@ -32,18 +32,18 @@
 from llnl.util.lang import classproperty, memoized
 from llnl.util.link_tree import LinkTree
 
-import spack.builder
 import spack.compilers
 import spack.config
 import spack.dependency
 import spack.deptypes as dt
-import spack.directives
+import spack.directives_meta
 import spack.error
 import spack.fetch_strategy as fs
 import spack.hooks
 import spack.mirror
 import spack.multimethod
 import spack.patch
+import spack.phase_callbacks
 import spack.repo
 import spack.spec
 import spack.store
@@ -51,9 +51,9 @@
 import spack.util.environment
 import spack.util.path
 import spack.util.web
+import spack.variant
 from spack.error import InstallError, NoURLError, PackageError
 from spack.filesystem_view import YamlFilesystemView
-from spack.install_test import PackageTest, TestSuite
 from spack.solver.version_order import concretization_version_order
 from spack.stage import DevelopStage, ResourceStage, Stage, StageComposite, compute_stage_name
 from spack.util.package_hash import package_hash
@@ -299,9 +299,9 @@ def determine_variants(cls, objs, version_str):
 
 
 class PackageMeta(
-    spack.builder.PhaseCallbacksMeta,
+    spack.phase_callbacks.PhaseCallbacksMeta,
     DetectablePackageMeta,
-    spack.directives.DirectiveMeta,
+    spack.directives_meta.DirectiveMeta,
     spack.multimethod.MultiMethodMeta,
 ):
     """
@@ -453,7 +453,7 @@ def _names(when_indexed_dictionary: WhenDict) -> List[str]:
     return sorted(all_names)
 
 
-WhenVariantList = List[Tuple["spack.spec.Spec", "spack.variant.Variant"]]
+WhenVariantList = List[Tuple[spack.spec.Spec, spack.variant.Variant]]
 
 
 def _remove_overridden_vdefs(variant_defs: WhenVariantList) -> None:
@@ -492,41 +492,14 @@ class Hipblas:
             i += 1
 
 
-class RedistributionMixin:
-    """Logic for determining whether a Package is source/binary
-    redistributable.
-    """
-
-    #: Store whether a given Spec source/binary should not be
-    #: redistributed.
-    disable_redistribute: Dict["spack.spec.Spec", "spack.directives.DisableRedistribute"]
-
-    # Source redistribution must be determined before concretization
-    # (because source mirrors work with un-concretized Specs).
-    @classmethod
-    def redistribute_source(cls, spec):
-        """Whether it should be possible to add the source of this
-        package to a Spack mirror.
-        """
-        for when_spec, disable_redistribute in cls.disable_redistribute.items():
-            if disable_redistribute.source and spec.satisfies(when_spec):
-                return False
-
-        return True
-
-    @property
-    def redistribute_binary(self):
-        """Whether it should be possible to create a binary out of an
-        installed instance of this package.
-        """
-        for when_spec, disable_redistribute in self.__class__.disable_redistribute.items():
-            if disable_redistribute.binary and self.spec.satisfies(when_spec):
-                return False
-
-        return True
+#: Store whether a given Spec source/binary should not be redistributed.
+class DisableRedistribute:
+    def __init__(self, source, binary):
+        self.source = source
+        self.binary = binary
 
 
-class PackageBase(WindowsRPath, PackageViewMixin, RedistributionMixin, metaclass=PackageMeta):
+class PackageBase(WindowsRPath, PackageViewMixin, metaclass=PackageMeta):
     """This is the superclass for all spack packages.
 
     ***The Package class***
@@ -612,16 +585,20 @@ class PackageBase(WindowsRPath, PackageViewMixin, RedistributionMixin, metaclass
     # Declare versions dictionary as placeholder for values.
     # This allows analysis tools to correctly interpret the class attributes.
     versions: dict
-    dependencies: Dict["spack.spec.Spec", Dict[str, "spack.dependency.Dependency"]]
-    conflicts: Dict["spack.spec.Spec", List[Tuple["spack.spec.Spec", Optional[str]]]]
+    dependencies: Dict[spack.spec.Spec, Dict[str, spack.dependency.Dependency]]
+    conflicts: Dict[spack.spec.Spec, List[Tuple[spack.spec.Spec, Optional[str]]]]
     requirements: Dict[
-        "spack.spec.Spec", List[Tuple[Tuple["spack.spec.Spec", ...], str, Optional[str]]]
+        spack.spec.Spec, List[Tuple[Tuple[spack.spec.Spec, ...], str, Optional[str]]]
     ]
-    provided: Dict["spack.spec.Spec", Set["spack.spec.Spec"]]
-    provided_together: Dict["spack.spec.Spec", List[Set[str]]]
-    patches: Dict["spack.spec.Spec", List["spack.patch.Patch"]]
-    variants: Dict["spack.spec.Spec", Dict[str, "spack.variant.Variant"]]
-    languages: Dict["spack.spec.Spec", Set[str]]
+    provided: Dict[spack.spec.Spec, Set[spack.spec.Spec]]
+    provided_together: Dict[spack.spec.Spec, List[Set[str]]]
+    patches: Dict[spack.spec.Spec, List[spack.patch.Patch]]
+    variants: Dict[spack.spec.Spec, Dict[str, spack.variant.Variant]]
+    languages: Dict[spack.spec.Spec, Set[str]]
+    splice_specs: Dict[spack.spec.Spec, Tuple[spack.spec.Spec, Union[None, str, List[str]]]]
+
+    #: Store whether a given Spec source/binary should not be redistributed.
+    disable_redistribute: Dict[spack.spec.Spec, DisableRedistribute]
 
     #: By default, packages are not virtual
     #: Virtual packages override this attribute
@@ -736,11 +713,11 @@ class PackageBase(WindowsRPath, PackageViewMixin, RedistributionMixin, metaclass
     test_requires_compiler: bool = False
 
     #: TestSuite instance used to manage stand-alone tests for 1+ specs.
-    test_suite: Optional["TestSuite"] = None
+    test_suite: Optional[Any] = None
 
     def __init__(self, spec):
         # this determines how the package should be built.
-        self.spec: "spack.spec.Spec" = spec
+        self.spec: spack.spec.Spec = spec
 
         # Allow custom staging paths for packages
         self.path = None
@@ -758,7 +735,7 @@ def __init__(self, spec):
         # init internal variables
         self._stage: Optional[StageComposite] = None
         self._fetcher = None
-        self._tester: Optional["PackageTest"] = None
+        self._tester: Optional[Any] = None
 
         # Set up timing variables
         self._fetch_time = 0.0
@@ -808,9 +785,7 @@ def variant_definitions(cls, name: str) -> WhenVariantList:
         return defs
 
     @classmethod
-    def variant_items(
-        cls,
-    ) -> Iterable[Tuple["spack.spec.Spec", Dict[str, "spack.variant.Variant"]]]:
+    def variant_items(cls) -> Iterable[Tuple[spack.spec.Spec, Dict[str, spack.variant.Variant]]]:
         """Iterate over ``cls.variants.items()`` with overridden definitions removed."""
         # Note: This is quadratic in the average number of variant definitions per name.
         # That is likely close to linear in practice, as there are few variants with
@@ -828,7 +803,7 @@ def variant_items(
             if filtered_variants_by_name:
                 yield when, filtered_variants_by_name
 
-    def get_variant(self, name: str) -> "spack.variant.Variant":
+    def get_variant(self, name: str) -> spack.variant.Variant:
         """Get the highest precedence variant definition matching this package's spec.
 
         Arguments:
@@ -1003,6 +978,26 @@ def global_license_file(self):
             self.global_license_dir, self.name, os.path.basename(self.license_files[0])
         )
 
+    # Source redistribution must be determined before concretization (because source mirrors work
+    # with abstract specs).
+    @classmethod
+    def redistribute_source(cls, spec):
+        """Whether it should be possible to add the source of this
+        package to a Spack mirror."""
+        for when_spec, disable_redistribute in cls.disable_redistribute.items():
+            if disable_redistribute.source and spec.satisfies(when_spec):
+                return False
+        return True
+
+    @property
+    def redistribute_binary(self):
+        """Whether it should be possible to create a binary out of an installed instance of this
+        package."""
+        for when_spec, disable_redistribute in self.disable_redistribute.items():
+            if disable_redistribute.binary and self.spec.satisfies(when_spec):
+                return False
+        return True
+
     # NOTE: return type should be Optional[Literal['all', 'specific', 'none']] in
     # Python 3.8+, but we still support 3.6.
     @property
@@ -1015,7 +1010,7 @@ def keep_werror(self) -> Optional[str]:
         * ``"none"``: filter out all ``-Werror*`` flags.
         * ``None``: respect the user's configuration (``"none"`` by default).
         """
-        if self.spec.satisfies("%nvhpc@:23.3") or self.spec.satisfies("%pgi"):
+        if self.spec.satisfies("%nvhpc@:23.3"):
             # Filtering works by replacing -Werror with -Wno-error, but older nvhpc and
             # PGI do not understand -Wno-error, so we disable filtering.
             return "all"
@@ -1352,11 +1347,13 @@ def archive_install_test_log(self):
 
     @property
     def tester(self):
+        import spack.install_test
+
         if not self.spec.versions.concrete:
             raise ValueError("Cannot retrieve tester for package without concrete version.")
 
         if not self._tester:
-            self._tester = PackageTest(self)
+            self._tester = spack.install_test.PackageTest(self)
         return self._tester
 
     @property
@@ -2013,72 +2010,58 @@ def build_system_flags(
         """
         return None, None, flags
 
-    def setup_run_environment(self, env):
+    def setup_run_environment(self, env: spack.util.environment.EnvironmentModifications) -> None:
         """Sets up the run environment for a package.
 
         Args:
-            env (spack.util.environment.EnvironmentModifications): environment
-                modifications to be applied when the package is run. Package authors
+            env: environment modifications to be applied when the package is run. Package authors
                 can call methods on it to alter the run environment.
         """
         pass
 
-    def setup_dependent_run_environment(self, env, dependent_spec):
+    def setup_dependent_run_environment(
+        self, env: spack.util.environment.EnvironmentModifications, dependent_spec: spack.spec.Spec
+    ) -> None:
         """Sets up the run environment of packages that depend on this one.
 
-        This is similar to ``setup_run_environment``, but it is used to
-        modify the run environments of packages that *depend* on this one.
+        This is similar to ``setup_run_environment``, but it is used to modify the run environment
+        of a package that *depends* on this one.
 
-        This gives packages like Python and others that follow the extension
-        model a way to implement common environment or run-time settings
-        for dependencies.
+        This gives packages like Python and others that follow the extension model a way to
+        implement common environment or run-time settings for dependencies.
 
         Args:
-            env (spack.util.environment.EnvironmentModifications): environment
-                modifications to be applied when the dependent package is run.
-                Package authors can call methods on it to alter the build environment.
+            env: environment modifications to be applied when the dependent package is run. 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 run. This allows the extendee (self) to query
-                the dependent's state. Note that *this* package's spec is
+            dependent_spec: The spec of the dependent package about to be run. This allows the
+                extendee (self) to query the dependent's state. Note that *this* package's spec is
                 available as ``self.spec``
         """
         pass
 
-    def setup_dependent_package(self, module, dependent_spec):
-        """Set up Python module-scope variables for dependent packages.
+    def setup_dependent_package(self, module, dependent_spec: spack.spec.Spec) -> None:
+        """Set up module-scope global variables for dependent packages.
 
-        Called before the install() method of dependents.
-
-        Default implementation does nothing, but this can be
-        overridden by an extendable package to set up the module of
-        its extensions. This is useful if there are some common steps
-        to installing all extensions for a certain package.
+        This function is called when setting up the build and run environments of a DAG.
 
         Examples:
 
-        1. Extensions often need to invoke the ``python`` interpreter
-           from the Python installation being extended. This routine
-           can put a ``python()`` Executable object in the module scope
-           for the extension package to simplify extension installs.
+        1. Extensions often need to invoke the ``python`` interpreter from the Python installation
+           being extended. This routine can put a ``python`` Executable as a global in the module
+           scope for the extension package to simplify extension installs.
 
-        2. MPI compilers could set some variables in the dependent's
-           scope that point to ``mpicc``, ``mpicxx``, etc., allowing
-           them to be called by common name regardless of which MPI is used.
-
-        3. BLAS/LAPACK implementations can set some variables
-           indicating the path to their libraries, since these
-           paths differ by BLAS/LAPACK implementation.
+        2. MPI compilers could set some variables in the dependent's scope that point to ``mpicc``,
+           ``mpicxx``, etc., allowing them to be called by common name regardless of which MPI is
+           used.
 
         Args:
-            module (spack.package_base.PackageBase.module): The Python ``module``
-                object of the dependent package. Packages can use this to set
-                module-scope variables for the dependent to use.
+            module: The Python ``module`` object of the dependent package. Packages can use this to
+                set module-scope variables for the dependent to use.
 
-            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``.
+            dependent_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``.
         """
         pass
 
@@ -2105,7 +2088,7 @@ def flag_handler(self, var: FLAG_HANDLER_TYPE) -> None:
     #  arguments. This is implemented for build system classes where
     #  appropriate and will otherwise raise a NotImplementedError.
 
-    def flags_to_build_system_args(self, flags):
+    def flags_to_build_system_args(self, flags: Dict[str, List[str]]) -> None:
         # Takes flags as a dict name: list of values
         if any(v for v in flags.values()):
             msg = "The {0} build system".format(self.__class__.__name__)
@@ -2308,10 +2291,6 @@ def rpath_args(self):
         """
         return " ".join("-Wl,-rpath,%s" % p for p in self.rpath)
 
-    @property
-    def builder(self):
-        return spack.builder.create(self)
-
 
 inject_flags = PackageBase.inject_flags
 env_flags = PackageBase.env_flags

lib/spack/spack/phase_callbacks.py

@@ -0,0 +1,105 @@
+# Copyright 2013-2024 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 llnl.util.lang as lang
+
+#: 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=[])
+
+
+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
+
+            # Here we have an adapter from an old-style package. This means there is no
+            # hierarchy of builders, and every callback that had to be combined between
+            # *Package and *Builder has been combined already by _PackageAdapterMeta
+            if name == "Adapter":
+                continue
+
+            # If we are here we have callbacks. To get a complete list, we accumulate all the
+            # callbacks from base classes, we deduplicate them, 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
+            callbacks_from_base = []
+            for base in bases:
+                current_callbacks = getattr(base, temporary_stage.attribute_name, None)
+                if not current_callbacks:
+                    continue
+                callbacks_from_base.extend(current_callbacks)
+            callbacks_from_base = list(lang.dedupe(callbacks_from_base))
+            # 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
+
+
+# Export these names as standalone to be used in packages
+run_after = PhaseCallbacksMeta.run_after
+run_before = PhaseCallbacksMeta.run_before

lib/spack/spack/relocate.py

@@ -13,6 +13,7 @@
 import macholib.mach_o
 import macholib.MachO
 
+import llnl.util.filesystem as fs
 import llnl.util.lang
 import llnl.util.tty as tty
 from llnl.util.lang import memoized
@@ -275,10 +276,10 @@ def modify_macho_object(cur_path, rpaths, deps, idpath, paths_to_paths):
 
     # Deduplicate and flatten
     args = list(itertools.chain.from_iterable(llnl.util.lang.dedupe(args)))
+    install_name_tool = executable.Executable("install_name_tool")
     if args:
-        args.append(str(cur_path))
-        install_name_tool = executable.Executable("install_name_tool")
-        install_name_tool(*args)
+        with fs.edit_in_place_through_temporary_file(cur_path) as temp_path:
+            install_name_tool(*args, temp_path)
 
 
 def macholib_get_paths(cur_path):
@@ -717,8 +718,8 @@ def fixup_macos_rpath(root, filename):
         # No fixes needed
         return False
 
-    args.append(abspath)
-    executable.Executable("install_name_tool")(*args)
+    with fs.edit_in_place_through_temporary_file(abspath) as temp_path:
+        executable.Executable("install_name_tool")(*args, temp_path)
     return True
 
 

lib/spack/spack/schema/concretizer.py

@@ -78,7 +78,8 @@
                                 "transitive": {"type": "boolean", "default": False},
                             },
                         },
-                    }
+                    },
+                    "automatic": {"type": "boolean"},
                 },
             },
             "duplicates": {
@@ -87,6 +88,8 @@
                     "strategy": {"type": "string", "enum": ["none", "minimal", "full"]}
                 },
             },
+            "timeout": {"type": "integer", "minimum": 0},
+            "error_on_timeout": {"type": "boolean"},
             "os_compatible": {"type": "object", "additionalProperties": {"type": "array"}},
         },
     }

lib/spack/spack/schema/mirrors.py

@@ -15,14 +15,42 @@
     "url": {"type": "string"},
     # todo: replace this with named keys "username" / "password" or "id" / "secret"
     "access_pair": {
-        "type": "array",
-        "items": {"type": ["string", "null"], "minItems": 2, "maxItems": 2},
+        "oneOf": [
+            {
+                "type": "array",
+                "items": {"minItems": 2, "maxItems": 2, "type": ["string", "null"]},
+            },  # deprecated
+            {
+                "type": "object",
+                "required": ["secret_variable"],
+                # Only allow id or id_variable to be set, not both
+                "oneOf": [{"required": ["id"]}, {"required": ["id_variable"]}],
+                "properties": {
+                    "id": {"type": "string"},
+                    "id_variable": {"type": "string"},
+                    "secret_variable": {"type": "string"},
+                },
+            },
+        ]
     },
-    "access_token": {"type": ["string", "null"]},
     "profile": {"type": ["string", "null"]},
     "endpoint_url": {"type": ["string", "null"]},
+    "access_token": {"type": ["string", "null"]},  # deprecated
+    "access_token_variable": {"type": ["string", "null"]},
 }
 
+connection_ext = {
+    "deprecatedProperties": [
+        {
+            "names": ["access_token"],
+            "message": "Use of plain text `access_token` in mirror config is deprecated, use "
+            "environment variables instead (access_token_variable)",
+            "error": False,
+        }
+    ]
+}
+
+
 #: Mirror connection inside pull/push keys
 fetch_and_push = {
     "anyOf": [
@@ -31,6 +59,7 @@
             "type": "object",
             "additionalProperties": False,
             "properties": {**connection},  # type: ignore
+            **connection_ext,  # type: ignore
         },
     ]
 }
@@ -49,6 +78,7 @@
         "autopush": {"type": "boolean"},
         **connection,  # type: ignore
     },
+    **connection_ext,  # type: ignore
 }
 
 #: Properties for inclusion in other schemas
@@ -70,3 +100,28 @@
     "additionalProperties": False,
     "properties": properties,
 }
+
+
+def update(data):
+    import jsonschema
+
+    errors = []
+
+    def check_access_pair(name, section):
+        if not section or not isinstance(section, dict):
+            return
+
+        if "access_token" in section and "access_token_variable" in section:
+            errors.append(
+                f'{name}: mirror credential "access_token" conflicts with "access_token_variable"'
+            )
+
+    # Check all of the sections
+    for name, section in data.items():
+        check_access_pair(name, section)
+        if isinstance(section, dict):
+            check_access_pair(name, section.get("fetch"))
+            check_access_pair(name, section.get("push"))
+
+    if errors:
+        raise jsonschema.ValidationError("\n".join(errors))

lib/spack/spack/solver/asp.py

@@ -27,7 +27,7 @@
 
 import spack
 import spack.binary_distribution
-import spack.bootstrap.core
+import spack.compiler
 import spack.compilers
 import spack.concretize
 import spack.config
@@ -53,6 +53,7 @@
 
 from .core import (
     AspFunction,
+    AspVar,
     NodeArgument,
     ast_sym,
     ast_type,
@@ -525,12 +526,14 @@ def _compute_specs_from_answer_set(self):
                 node = SpecBuilder.make_node(pkg=providers[0])
             candidate = answer.get(node)
 
-            if candidate and candidate.build_spec.satisfies(input_spec):
-                if not candidate.satisfies(input_spec):
-                    tty.warn(
-                        "explicit splice configuration has caused the concretized spec"
-                        f" {candidate} not to satisfy the input spec {input_spec}"
-                    )
+            if candidate and candidate.satisfies(input_spec):
+                self._concrete_specs.append(answer[node])
+                self._concrete_specs_by_input[input_spec] = answer[node]
+            elif candidate and candidate.build_spec.satisfies(input_spec):
+                tty.warn(
+                    "explicit splice configuration has caused the concretized spec"
+                    f" {candidate} not to satisfy the input spec {input_spec}"
+                )
                 self._concrete_specs.append(answer[node])
                 self._concrete_specs_by_input[input_spec] = answer[node]
             else:
@@ -816,7 +819,7 @@ def solve(self, setup, specs, reuse=None, output=None, control=None, allow_depre
             solve, and the internal statistics from clingo.
         """
         # avoid circular import
-        import spack.bootstrap
+        import spack.bootstrap.core
 
         output = output or DEFAULT_OUTPUT_CONFIGURATION
         timer = spack.util.timer.Timer()
@@ -855,6 +858,8 @@ def solve(self, setup, specs, reuse=None, output=None, control=None, allow_depre
             self.control.load(os.path.join(parent_dir, "libc_compatibility.lp"))
         else:
             self.control.load(os.path.join(parent_dir, "os_compatibility.lp"))
+        if setup.enable_splicing:
+            self.control.load(os.path.join(parent_dir, "splices.lp"))
 
         timer.stop("load")
 
@@ -881,7 +886,22 @@ def on_model(model):
             solve_kwargs["on_unsat"] = cores.append
 
         timer.start("solve")
-        solve_result = self.control.solve(**solve_kwargs)
+        time_limit = spack.config.CONFIG.get("concretizer:timeout", -1)
+        error_on_timeout = spack.config.CONFIG.get("concretizer:error_on_timeout", True)
+        # Spack uses 0 to set no time limit, clingo API uses -1
+        if time_limit == 0:
+            time_limit = -1
+        with self.control.solve(**solve_kwargs, async_=True) as handle:
+            finished = handle.wait(time_limit)
+            if not finished:
+                specs_str = ", ".join(llnl.util.lang.elide_list([str(s) for s in specs], 4))
+                header = f"Spack is taking more than {time_limit} seconds to solve for {specs_str}"
+                if error_on_timeout:
+                    raise UnsatisfiableSpecError(f"{header}, stopping concretization")
+                warnings.warn(f"{header}, using the best configuration found so far")
+                handle.cancel()
+
+            solve_result = handle.get()
         timer.stop("solve")
 
         # once done, construct the solve result
@@ -889,6 +909,7 @@ def on_model(model):
         result.satisfiable = solve_result.satisfiable
 
         if result.satisfiable:
+            timer.start("construct_specs")
             # get the best model
             builder = SpecBuilder(specs, hash_lookup=setup.reusable_and_possible)
             min_cost, best_model = min(models)
@@ -913,7 +934,8 @@ def on_model(model):
 
             # record the possible dependencies in the solve
             result.possible_dependencies = setup.pkgs
-
+            timer.stop("construct_specs")
+            timer.stop()
         elif cores:
             result.control = self.control
             result.cores.extend(cores)
@@ -1165,6 +1187,9 @@ def __init__(self, tests: bool = False):
         # list of unique libc specs targeted by compilers (or an educated guess if no compiler)
         self.libcs: List[spack.spec.Spec] = []
 
+        # If true, we have to load the code for synthesizing splices
+        self.enable_splicing: bool = spack.config.CONFIG.get("concretizer:splice:automatic")
+
     def pkg_version_rules(self, pkg):
         """Output declared versions of a package.
 
@@ -1335,6 +1360,10 @@ def pkg_rules(self, pkg, tests):
         # dependencies
         self.package_dependencies_rules(pkg)
 
+        # splices
+        if self.enable_splicing:
+            self.package_splice_rules(pkg)
+
         # virtual preferences
         self.virtual_preferences(
             pkg.name,
@@ -1435,14 +1464,13 @@ def define_variant(
         for value in sorted(values):
             pkg_fact(fn.variant_possible_value(vid, value))
 
-            # when=True means unconditional, so no need for conditional values
-            if getattr(value, "when", True) is True:
+            # we're done here for unconditional values
+            if not isinstance(value, vt.ConditionalValue):
                 continue
 
-            # now we have to handle conditional values
-            quoted_value = spack.parser.quote_if_needed(str(value))
-            vstring = f"{name}={quoted_value}"
-            variant_has_value = spack.spec.Spec(vstring)
+            # make a spec indicating whether the variant has this conditional value
+            variant_has_value = spack.spec.Spec()
+            variant_has_value.variants[name] = spack.variant.AbstractVariant(name, value.value)
 
             if value.when:
                 # the conditional value is always "possible", but it imposes its when condition as
@@ -1453,10 +1481,12 @@ def define_variant(
                     imposed_spec=value.when,
                     required_name=pkg.name,
                     imposed_name=pkg.name,
-                    msg=f"{pkg.name} variant {name} has value '{quoted_value}' when {value.when}",
+                    msg=f"{pkg.name} variant {name} has value '{value.value}' when {value.when}",
                 )
             else:
-                # We know the value is never allowed statically (when was false), but we can't just
+                vstring = f"{name}='{value.value}'"
+
+                # We know the value is never allowed statically (when was None), but we can't just
                 # ignore it b/c it could come in as a possible value and we need a good error msg.
                 # So, it's a conflict -- if the value is somehow used, it'll trigger an error.
                 trigger_id = self.condition(
@@ -1672,6 +1702,94 @@ def dependency_holds(input_spec, requirements):
 
                 self.gen.newline()
 
+    def _gen_match_variant_splice_constraints(
+        self,
+        pkg,
+        cond_spec: "spack.spec.Spec",
+        splice_spec: "spack.spec.Spec",
+        hash_asp_var: "AspVar",
+        splice_node,
+        match_variants: List[str],
+    ):
+        # If there are no variants to match, no constraints are needed
+        variant_constraints = []
+        for i, variant_name in enumerate(match_variants):
+            vari_defs = pkg.variant_definitions(variant_name)
+            # the spliceable config of the package always includes the variant
+            if vari_defs != [] and any(cond_spec.satisfies(s) for (s, _) in vari_defs):
+                variant = vari_defs[0][1]
+                if variant.multi:
+                    continue  # cannot automatically match multi-valued variants
+                value_var = AspVar(f"VariValue{i}")
+                attr_constraint = fn.attr("variant_value", splice_node, variant_name, value_var)
+                hash_attr_constraint = fn.hash_attr(
+                    hash_asp_var, "variant_value", splice_spec.name, variant_name, value_var
+                )
+                variant_constraints.append(attr_constraint)
+                variant_constraints.append(hash_attr_constraint)
+        return variant_constraints
+
+    def package_splice_rules(self, pkg):
+        self.gen.h2("Splice rules")
+        for i, (cond, (spec_to_splice, match_variants)) in enumerate(
+            sorted(pkg.splice_specs.items())
+        ):
+            with named_spec(cond, pkg.name):
+                self.version_constraints.add((cond.name, cond.versions))
+                self.version_constraints.add((spec_to_splice.name, spec_to_splice.versions))
+                hash_var = AspVar("Hash")
+                splice_node = fn.node(AspVar("NID"), cond.name)
+                when_spec_attrs = [
+                    fn.attr(c.args[0], splice_node, *(c.args[2:]))
+                    for c in self.spec_clauses(cond, body=True, required_from=None)
+                    if c.args[0] != "node"
+                ]
+                splice_spec_hash_attrs = [
+                    fn.hash_attr(hash_var, *(c.args))
+                    for c in self.spec_clauses(spec_to_splice, body=True, required_from=None)
+                    if c.args[0] != "node"
+                ]
+                if match_variants is None:
+                    variant_constraints = []
+                elif match_variants == "*":
+                    filt_match_variants = set()
+                    for map in pkg.variants.values():
+                        for k in map:
+                            filt_match_variants.add(k)
+                    filt_match_variants = list(filt_match_variants)
+                    variant_constraints = self._gen_match_variant_splice_constraints(
+                        pkg, cond, spec_to_splice, hash_var, splice_node, filt_match_variants
+                    )
+                else:
+                    if any(
+                        v in cond.variants or v in spec_to_splice.variants for v in match_variants
+                    ):
+                        raise Exception(
+                            "Overlap between match_variants and explicitly set variants"
+                        )
+                    variant_constraints = self._gen_match_variant_splice_constraints(
+                        pkg, cond, spec_to_splice, hash_var, splice_node, match_variants
+                    )
+
+                rule_head = fn.abi_splice_conditions_hold(
+                    i, splice_node, spec_to_splice.name, hash_var
+                )
+                rule_body_components = (
+                    [
+                        # splice_set_fact,
+                        fn.attr("node", splice_node),
+                        fn.installed_hash(spec_to_splice.name, hash_var),
+                    ]
+                    + when_spec_attrs
+                    + splice_spec_hash_attrs
+                    + variant_constraints
+                )
+                rule_body = ",\n  ".join(str(r) for r in rule_body_components)
+                rule = f"{rule_head} :-\n  {rule_body}."
+                self.gen.append(rule)
+
+            self.gen.newline()
+
     def virtual_preferences(self, pkg_name, func):
         """Call func(vspec, provider, i) for each of pkg's provider prefs."""
         config = spack.config.get("packages")
@@ -2030,9 +2148,12 @@ def _spec_clauses(
                     for variant_def in variant_defs:
                         self.variant_values_from_specs.add((spec.name, id(variant_def), value))
 
-                clauses.append(f.variant_value(spec.name, vname, value))
                 if variant.propagate:
                     clauses.append(f.propagate(spec.name, fn.variant_value(vname, value)))
+                    if self.pkg_class(spec.name).has_variant(vname):
+                        clauses.append(f.variant_value(spec.name, vname, value))
+                else:
+                    clauses.append(f.variant_value(spec.name, vname, value))
 
         # compiler and compiler version
         if spec.compiler:
@@ -2531,8 +2652,9 @@ def concrete_specs(self):
         for h, spec in self.reusable_and_possible.explicit_items():
             # this indicates that there is a spec like this installed
             self.gen.fact(fn.installed_hash(spec.name, h))
-            # this describes what constraints it imposes on the solve
-            self.impose(h, spec, body=True)
+            # indirection layer between hash constraints and imposition to allow for splicing
+            for pred in self.spec_clauses(spec, body=True, required_from=None):
+                self.gen.fact(fn.hash_attr(h, *pred.args))
             self.gen.newline()
             # Declare as possible parts of specs that are not in package.py
             # - Add versions to possible versions
@@ -3473,6 +3595,14 @@ def consume_facts(self):
         self._setup.effect_rules()
 
 
+# This should be a dataclass, but dataclasses don't work on Python 3.6
+class Splice:
+    def __init__(self, splice_node: NodeArgument, child_name: str, child_hash: str):
+        self.splice_node = splice_node
+        self.child_name = child_name
+        self.child_hash = child_hash
+
+
 class SpecBuilder:
     """Class with actions to rebuild a spec from ASP results."""
 
@@ -3508,10 +3638,11 @@ def make_node(*, pkg: str) -> NodeArgument:
         """
         return NodeArgument(id="0", pkg=pkg)
 
-    def __init__(
-        self, specs: List[spack.spec.Spec], *, hash_lookup: Optional[ConcreteSpecsByHash] = None
-    ):
+    def __init__(self, specs, hash_lookup=None):
         self._specs: Dict[NodeArgument, spack.spec.Spec] = {}
+
+        # Matches parent nodes to splice node
+        self._splices: Dict[NodeArgument, List[Splice]] = {}
         self._result = None
         self._command_line_specs = specs
         self._flag_sources: Dict[Tuple[NodeArgument, str], Set[str]] = collections.defaultdict(
@@ -3595,16 +3726,8 @@ def external_spec_selected(self, node, idx):
 
     def depends_on(self, parent_node, dependency_node, type):
         dependency_spec = self._specs[dependency_node]
-        edges = self._specs[parent_node].edges_to_dependencies(name=dependency_spec.name)
-        edges = [x for x in edges if id(x.spec) == id(dependency_spec)]
         depflag = dt.flag_from_string(type)
-
-        if not edges:
-            self._specs[parent_node].add_dependency_edge(
-                self._specs[dependency_node], depflag=depflag, virtuals=()
-            )
-        else:
-            edges[0].update_deptypes(depflag=depflag)
+        self._specs[parent_node].add_dependency_edge(dependency_spec, depflag=depflag, virtuals=())
 
     def virtual_on_edge(self, parent_node, provider_node, virtual):
         dependencies = self._specs[parent_node].edges_to_dependencies(name=(provider_node.pkg))
@@ -3721,6 +3844,57 @@ def _order_index(flag_group):
     def deprecated(self, node: NodeArgument, version: str) -> None:
         tty.warn(f'using "{node.pkg}@{version}" which is a deprecated version')
 
+    def splice_at_hash(
+        self,
+        parent_node: NodeArgument,
+        splice_node: NodeArgument,
+        child_name: str,
+        child_hash: str,
+    ):
+        splice = Splice(splice_node, child_name=child_name, child_hash=child_hash)
+        self._splices.setdefault(parent_node, []).append(splice)
+
+    def _resolve_automatic_splices(self):
+        """After all of the specs have been concretized, apply all immediate splices.
+
+        Use reverse topological order to ensure that all dependencies are resolved
+        before their parents, allowing for maximal sharing and minimal copying.
+
+        """
+        fixed_specs = {}
+
+        # create a mapping from dag hash to an integer representing position in reverse topo order.
+        specs = self._specs.values()
+        topo_order = list(traverse.traverse_nodes(specs, order="topo", key=traverse.by_dag_hash))
+        topo_lookup = {spec.dag_hash(): index for index, spec in enumerate(reversed(topo_order))}
+
+        # iterate over specs, children before parents
+        for node, spec in sorted(self._specs.items(), key=lambda x: topo_lookup[x[1].dag_hash()]):
+            immediate = self._splices.get(node, [])
+            if not immediate and not any(
+                edge.spec in fixed_specs for edge in spec.edges_to_dependencies()
+            ):
+                continue
+            new_spec = spec.copy(deps=False)
+            new_spec.build_spec = spec
+            for edge in spec.edges_to_dependencies():
+                depflag = edge.depflag & ~dt.BUILD
+                if any(edge.spec.dag_hash() == splice.child_hash for splice in immediate):
+                    splice = [s for s in immediate if s.child_hash == edge.spec.dag_hash()][0]
+                    new_spec.add_dependency_edge(
+                        self._specs[splice.splice_node], depflag=depflag, virtuals=edge.virtuals
+                    )
+                elif edge.spec in fixed_specs:
+                    new_spec.add_dependency_edge(
+                        fixed_specs[edge.spec], depflag=depflag, virtuals=edge.virtuals
+                    )
+                else:
+                    new_spec.add_dependency_edge(
+                        edge.spec, depflag=depflag, virtuals=edge.virtuals
+                    )
+            self._specs[node] = new_spec
+            fixed_specs[spec] = new_spec
+
     @staticmethod
     def sort_fn(function_tuple) -> Tuple[int, int]:
         """Ensure attributes are evaluated in the correct order.
@@ -3750,7 +3924,6 @@ def build_specs(self, function_tuples):
         # them here so that directives that build objects (like node and
         # node_compiler) are called in the right order.
         self.function_tuples = sorted(set(function_tuples), key=self.sort_fn)
-
         self._specs = {}
         for name, args in self.function_tuples:
             if SpecBuilder.ignored_attributes.match(name):
@@ -3780,10 +3953,14 @@ def build_specs(self, function_tuples):
                     continue
 
                 # if we've already gotten a concrete spec for this pkg,
-                # do not bother calling actions on it
+                # do not bother calling actions on it except for node_flag_source,
+                # since node_flag_source is tracking information not in the spec itself
+                # we also need to keep track of splicing information.
                 spec = self._specs.get(args[0])
                 if spec and spec.concrete:
-                    continue
+                    do_not_ignore_attrs = ["node_flag_source", "splice_at_hash"]
+                    if name not in do_not_ignore_attrs:
+                        continue
 
             action(*args)
 
@@ -3793,7 +3970,7 @@ def build_specs(self, function_tuples):
         # inject patches -- note that we' can't use set() to unique the
         # roots here, because the specs aren't complete, and the hash
         # function will loop forever.
-        roots = [spec.root for spec in self._specs.values() if not spec.root.installed]
+        roots = [spec.root for spec in self._specs.values()]
         roots = dict((id(r), r) for r in roots)
         for root in roots.values():
             spack.spec.Spec.inject_patches_variant(root)
@@ -3809,6 +3986,8 @@ def build_specs(self, function_tuples):
         for root in roots.values():
             root._finalize_concretization()
 
+        self._resolve_automatic_splices()
+
         for s in self._specs.values():
             spack.spec.Spec.ensure_no_deprecated(s)
 
@@ -3823,7 +4002,6 @@ def build_specs(self, function_tuples):
                     )
 
         specs = self.execute_explicit_splices()
-
         return specs
 
     def execute_explicit_splices(self):
@@ -4160,7 +4338,6 @@ def reusable_specs(self, specs: List[spack.spec.Spec]) -> List[spack.spec.Spec]:
         result = []
         for reuse_source in self.reuse_sources:
             result.extend(reuse_source.selected_specs())
-
         # If we only want to reuse dependencies, remove the root specs
         if self.reuse_strategy == ReuseStrategy.DEPENDENCIES:
             result = [spec for spec in result if not any(root in spec for root in specs)]
@@ -4191,7 +4368,7 @@ def _check_input_and_extract_concrete_specs(specs):
                 spack.spec.Spec.ensure_valid_variants(s)
         return reusable
 
-    def solve(
+    def solve_with_stats(
         self,
         specs,
         out=None,
@@ -4202,6 +4379,8 @@ def solve(
         allow_deprecated=False,
     ):
         """
+        Concretize a set of specs and track the timing and statistics for the solve
+
         Arguments:
           specs (list): List of ``Spec`` objects to solve for.
           out: Optionally write the generate ASP program to a file-like object.
@@ -4213,15 +4392,22 @@ def solve(
           setup_only (bool): if True, stop after setup and don't solve (default False).
           allow_deprecated (bool): allow deprecated version in the solve
         """
-        # Check upfront that the variants are admissible
         specs = [s.lookup_hash() for s in specs]
         reusable_specs = self._check_input_and_extract_concrete_specs(specs)
         reusable_specs.extend(self.selector.reusable_specs(specs))
         setup = SpackSolverSetup(tests=tests)
         output = OutputConfiguration(timers=timers, stats=stats, out=out, setup_only=setup_only)
-        result, _, _ = self.driver.solve(
+        return self.driver.solve(
             setup, specs, reuse=reusable_specs, output=output, allow_deprecated=allow_deprecated
         )
+
+    def solve(self, specs, **kwargs):
+        """
+        Convenience function for concretizing a set of specs and ignoring timing
+        and statistics. Uses the same kwargs as solve_with_stats.
+        """
+        # Check upfront that the variants are admissible
+        result, _, _ = self.solve_with_stats(specs, **kwargs)
         return result
 
     def solve_in_rounds(
@@ -4321,11 +4507,10 @@ def __init__(self, provided, conflicts):
 
         super().__init__(msg)
 
-        self.provided = provided
-
         # Add attribute expected of the superclass interface
         self.required = None
         self.constraint_type = None
+        self.provided = provided
 
 
 class InvalidSpliceError(spack.error.SpackError):

lib/spack/spack/solver/concretize.lp

@@ -57,6 +57,12 @@
    internal_error("provider with no virtual node").
 :- provider(PackageNode, _), not attr("node", PackageNode),
    internal_error("provider with no real node").
+:- node_has_variant(PackageNode, _, _), not attr("node", PackageNode),
+   internal_error("node has variant for a non-node").
+:- attr("variant_set", PackageNode, _, _), not attr("node", PackageNode),
+   internal_error("variant_set for a non-node").
+:- variant_is_propagated(PackageNode, _), not attr("node", PackageNode),
+   internal_error("variant_is_propagated for a non-node").
 
 :- attr("root", node(ID, PackageNode)), ID > min_dupe_id,
    internal_error("root with a non-minimal duplicate ID").
@@ -575,7 +581,8 @@ attr("virtual_on_edge", PackageNode, ProviderNode, Virtual)
 % or used somewhere
 :- attr("virtual_node", node(_, Virtual)),
    not attr("virtual_on_incoming_edges", _, Virtual),
-   not attr("virtual_root", node(_, Virtual)).
+   not attr("virtual_root", node(_, Virtual)),
+   internal_error("virtual node does not match incoming edge").
 
 attr("virtual_on_incoming_edges", ProviderNode, Virtual)
   :- attr("virtual_on_edge", _, ProviderNode, Virtual).
@@ -629,7 +636,8 @@ do_not_impose(EffectID, node(X, Package))
    virtual_condition_holds(_, PossibleProvider, Virtual),
    PossibleProvider != ProviderNode,
    explicitly_requested_root(PossibleProvider),
-   not explicitly_requested_root(ProviderNode).
+   not explicitly_requested_root(ProviderNode),
+   internal_error("If a root can provide a virtual, it must be the provider").
 
 % A package cannot be the actual provider for a virtual if it does not
 % fulfill the conditions to provide that virtual
@@ -772,7 +780,8 @@ required_provider(Provider, Virtual)
      pkg_fact(Virtual, condition_effect(ConditionID, EffectID)),
      imposed_constraint(EffectID, "node", Provider).
 
-:- provider(node(Y, Package), node(X, Virtual)), required_provider(Provider, Virtual), Package != Provider.
+:- provider(node(Y, Package), node(X, Virtual)), required_provider(Provider, Virtual), Package != Provider,
+   internal_error("If a provider is required the concretizer must use it").
 
 % TODO: the following choice rule allows the solver to add compiler
 % flags if their only source is from a requirement. This is overly-specific
@@ -852,7 +861,8 @@ variant_defined(PackageNode, Name) :- variant_definition(PackageNode, Name, _).
 % for two or more variant definitions, this prefers the last one defined.
 :- node_has_variant(node(NodeID, Package), Name, SelectedVariantID),
    variant_definition(node(NodeID, Package), Name, VariantID),
-   VariantID > SelectedVariantID.
+   VariantID > SelectedVariantID,
+   internal_error("If the solver picks a variant descriptor it must use that variant descriptor").
 
 % B: Associating applicable package rules with nodes
 
@@ -969,6 +979,7 @@ error(100, "{0} variant '{1}' cannot have values '{2}' and '{3}' as they come fr
 
 :- attr("variant_set", node(ID, Package), Variant, Value),
    not attr("variant_value", node(ID, Package), Variant, Value).
+   internal_error("If a variant is set to a value it must have that value").
 
 % The rules below allow us to prefer default values for variants
 % whenever possible. If a variant is set in a spec, or if it is
@@ -979,7 +990,7 @@ variant_not_default(node(ID, Package), Variant, Value)
     % variants set explicitly on the CLI don't count as non-default
     not attr("variant_set", node(ID, Package), Variant, Value),
     % variant values forced by propagation don't count as non-default
-    not propagate(node(ID, Package), variant_value(Variant, Value)),
+    not propagate(node(ID, Package), variant_value(Variant, Value, _)),
     % variants set on externals that we could use don't count as non-default
     % this makes spack prefer to use an external over rebuilding with the
     % default configuration
@@ -991,7 +1002,7 @@ variant_default_not_used(node(ID, Package), Variant, Value)
   :- variant_default_value(node(ID, Package), Variant, Value),
      node_has_variant(node(ID, Package), Variant, _),
      not attr("variant_value", node(ID, Package), Variant, Value),
-     not propagate(node(ID, Package), variant_value(Variant, _)),
+     not propagate(node(ID, Package), variant_value(Variant, _, _)),
      attr("node", node(ID, Package)).
 
 % The variant is set in an external spec
@@ -1036,10 +1047,14 @@ variant_single_value(PackageNode, Variant)
 % Propagation semantics
 %-----------------------------------------------------------------------------
 
+non_default_propagation(variant_value(Name, Value)) :- attr("propagate", RootNode, variant_value(Name, Value)).
+
 % Propagation roots have a corresponding attr("propagate", ...)
-propagate(RootNode, PropagatedAttribute) :- attr("propagate", RootNode, PropagatedAttribute).
+propagate(RootNode, PropagatedAttribute) :- attr("propagate", RootNode, PropagatedAttribute), not non_default_propagation(PropagatedAttribute).
 propagate(RootNode, PropagatedAttribute, EdgeTypes) :- attr("propagate", RootNode, PropagatedAttribute, EdgeTypes).
 
+% Special case variants, to inject the source node in the propagated attribute
+propagate(RootNode, variant_value(Name, Value, RootNode)) :- attr("propagate", RootNode, variant_value(Name, Value)).
 
 % Propagate an attribute along edges to child nodes
 propagate(ChildNode, PropagatedAttribute) :-
@@ -1061,21 +1076,53 @@ propagate(ChildNode, PropagatedAttribute, edge_types(DepType1, DepType2)) :-
 
 % If a variant is propagated, and can be accepted, set its value
 attr("variant_selected", PackageNode, Variant, Value, VariantType, VariantID) :-
-  propagate(PackageNode, variant_value(Variant, Value)),
+  propagate(PackageNode, variant_value(Variant, Value, _)),
   node_has_variant(PackageNode, Variant, VariantID),
   variant_type(VariantID, VariantType),
-  variant_possible_value(PackageNode, Variant, Value),
-  not attr("variant_set", PackageNode, Variant).
+  variant_possible_value(PackageNode, Variant, Value).
 
 % If a variant is propagated, we cannot have extraneous values
 variant_is_propagated(PackageNode, Variant) :-
   attr("variant_value", PackageNode, Variant, Value),
-  propagate(PackageNode, variant_value(Variant, Value)),
+  propagate(PackageNode, variant_value(Variant, Value, _)),
   not attr("variant_set", PackageNode, Variant).
 
 :- variant_is_propagated(PackageNode, Variant),
    attr("variant_selected", PackageNode, Variant, Value, _, _),
-   not propagate(PackageNode, variant_value(Variant, Value)).
+   not propagate(PackageNode, variant_value(Variant, Value, _)).
+
+error(100, "{0} and {1} cannot both propagate variant '{2}' to the shared dependency: {3}",
+  Package1, Package2, Variant, Dependency) :-
+  % The variant is a singlevalued variant
+  variant_single_value(node(X, Package1), Variant),
+  % Dependency is trying to propagate Variant with different values and is not the source package
+  propagate(node(Z, Dependency), variant_value(Variant, Value1, node(X, Package1))),
+  propagate(node(Z, Dependency), variant_value(Variant, Value2, node(Y, Package2))),
+  % Package1 and Package2 and their values are different
+  Package1 > Package2,  Value1 != Value2,
+  not propagate(node(Z, Dependency), variant_value(Variant, _, node(Z, Dependency))).
+
+% Cannot propagate the same variant from two different packages if one is a dependency of the other
+error(100, "{0} and {1} cannot both propagate variant '{2}'", Package1, Package2, Variant) :-
+  % The variant is a single-valued variant
+  variant_single_value(node(X, Package1), Variant),
+  % Package1 and Package2 and their values are different
+  Package1 != Package2,  Value1 != Value2,
+  % Package2 is set to propagate the value from Package1
+  propagate(node(Y, Package2), variant_value(Variant, Value2, node(X, Package2))),
+  propagate(node(Y, Package2), variant_value(Variant, Value1, node(X, Package1))),
+  variant_is_propagated(node(Y, Package2), Variant).
+
+% Cannot propagate a variant if a different value was set for it in a dependency
+error(100, "Cannot propagate the variant '{0}' from the package: {1} because package: {2} is set to exclude it", Variant, Source, Package) :-
+  % Package has a Variant and Source is propagating Variant
+  attr("variant_set", node(X, Package), Variant, Value1),
+  % The packages and values are different
+  Source != Package,  Value1 != Value2,
+  % The variant is a single-valued variant
+  variant_single_value(node(X, Package1), Variant),
+  % A different value is being propagated from somewhere else
+  propagate(node(X, Package), variant_value(Variant, Value2, node(Y, Source))).
 
 %----
 % Flags
@@ -1402,25 +1449,71 @@ attr("node_flag", PackageNode, NodeFlag) :- attr("node_flag_set", PackageNode, N
 
 
 %-----------------------------------------------------------------------------
-% Installed packages
+% Installed Packages
 %-----------------------------------------------------------------------------
-% the solver is free to choose at most one installed hash for each package
-{ attr("hash", node(ID, Package), Hash) : installed_hash(Package, Hash) } 1
- :- attr("node", node(ID, Package)), internal_error("Package must resolve to at most one hash").
 
+#defined installed_hash/2.
+#defined abi_splice_conditions_hold/4.
+
+% These are the previously concretized attributes of the installed package as
+% a hash. It has the general form:
+% hash_attr(Hash, Attribute, PackageName, Args*)
+#defined hash_attr/3.
+#defined hash_attr/4.
+#defined hash_attr/5.
+#defined hash_attr/6.
+#defined hash_attr/7.
+
+{ attr("hash", node(ID, PackageName), Hash): installed_hash(PackageName, Hash) } 1 :-
+  attr("node", node(ID, PackageName)),
+  internal_error("Package must resolve to at most 1 hash").
 % you can't choose an installed hash for a dev spec
 :- attr("hash", PackageNode, Hash), attr("variant_value", PackageNode, "dev_path", _).
-
 % You can't install a hash, if it is not installed
 :- attr("hash", node(ID, Package), Hash), not installed_hash(Package, Hash).
-% This should be redundant given the constraint above
-:- attr("node", PackageNode), 2 { attr("hash", PackageNode, Hash) }.
 
-% if a hash is selected, we impose all the constraints that implies
-impose(Hash, PackageNode) :- attr("hash", PackageNode, Hash).
+% hash_attrs are versions, but can_splice_attr are usually node_version_satisfies
+hash_attr(Hash, "node_version_satisfies", PackageName, Constraint) :-
+  hash_attr(Hash, "version", PackageName, Version),
+  pkg_fact(PackageName, version_satisfies(Constraint, Version)).
+
+% This recovers the exact semantics for hash reuse hash and depends_on are where
+% splices are decided, and virtual_on_edge can result in name-changes, which is
+% why they are all treated separately.
+imposed_constraint(Hash, Attr, PackageName) :-
+  hash_attr(Hash, Attr, PackageName).
+imposed_constraint(Hash, Attr, PackageName, A1) :-
+  hash_attr(Hash, Attr, PackageName, A1), Attr != "hash".
+imposed_constraint(Hash, Attr, PackageName, Arg1, Arg2) :-
+  hash_attr(Hash, Attr, PackageName, Arg1, Arg2),
+  Attr != "depends_on",
+  Attr != "virtual_on_edge".
+imposed_constraint(Hash, Attr, PackageName, A1, A2, A3) :-
+  hash_attr(Hash, Attr, PackageName, A1, A2, A3).
+imposed_constraint(Hash, "hash", PackageName, Hash) :- installed_hash(PackageName, Hash).
+% Without splicing, we simply recover the exact semantics
+imposed_constraint(ParentHash, "hash", ChildName, ChildHash) :-
+  hash_attr(ParentHash, "hash", ChildName, ChildHash),
+  ChildHash != ParentHash,
+  not abi_splice_conditions_hold(_, _, ChildName, ChildHash).
+
+imposed_constraint(Hash, "depends_on", PackageName, DepName, Type) :-
+  hash_attr(Hash, "depends_on", PackageName, DepName, Type),
+  hash_attr(Hash, "hash", DepName, DepHash),
+  not attr("splice_at_hash", _, _, DepName, DepHash).
+
+imposed_constraint(Hash, "virtual_on_edge", PackageName, DepName, VirtName) :-
+  hash_attr(Hash, "virtual_on_edge", PackageName, DepName, VirtName),
+  not attr("splice_at_hash", _, _, DepName,_).
+
+% Rules pertaining to attr("splice_at_hash") and abi_splice_conditions_hold will
+% be conditionally loaded from splices.lp
+
+impose(Hash, PackageNode) :- attr("hash", PackageNode, Hash), attr("node", PackageNode).
+
+% If there is not a hash for a package, we build it.
+build(PackageNode) :- attr("node", PackageNode), not concrete(PackageNode).
 
-% if we haven't selected a hash for a package, we'll be building it
-build(PackageNode) :- not attr("hash", PackageNode, _), attr("node", PackageNode).
 
 % Minimizing builds is tricky. We want a minimizing criterion
 
@@ -1433,6 +1526,7 @@ build(PackageNode) :- not attr("hash", PackageNode, _), attr("node", PackageNode
 % criteria for built specs -- so that they take precedence over the otherwise
 % topmost-priority criterion to reuse what is installed.
 %
+
 % The priority ranges are:
 %   1000+       Optimizations for concretization errors
 %   300 - 1000  Highest priority optimizations for valid solutions
@@ -1458,12 +1552,10 @@ build_priority(PackageNode, 0)   :- not build(PackageNode), attr("node", Package
    pkg_fact(Package, version_declared(Version, Weight, "installed")),
    not optimize_for_reuse().
 
-#defined installed_hash/2.
 
 % This statement, which is a hidden feature of clingo, let us avoid cycles in the DAG
 #edge (A, B) : depends_on(A, B).
 
-
 %-----------------------------------------------------------------
 % Optimization to avoid errors
 %-----------------------------------------------------------------

lib/spack/spack/solver/core.py

@@ -44,6 +44,17 @@ def _id(thing: Any) -> Union[str, AspObject]:
         return f'"{str(thing)}"'
 
 
+class AspVar(AspObject):
+    """Represents a variable in an ASP rule, allows for conditionally generating
+    rules"""
+
+    def __init__(self, name: str):
+        self.name = name
+
+    def __str__(self) -> str:
+        return str(self.name)
+
+
 @lang.key_ordering
 class AspFunction(AspObject):
     """A term in the ASP logic program"""
@@ -88,6 +99,8 @@ def _argify(self, arg: Any) -> Any:
             return clingo().Number(arg)
         elif isinstance(arg, AspFunction):
             return clingo().Function(arg.name, [self._argify(x) for x in arg.args], positive=True)
+        elif isinstance(arg, AspVar):
+            return clingo().Variable(arg.name)
         return clingo().String(str(arg))
 
     def symbol(self):

lib/spack/spack/solver/display.lp

@@ -15,7 +15,6 @@
 #show attr/4.
 #show attr/5.
 #show attr/6.
-
 % names of optimization criteria
 #show opt_criterion/2.
 

lib/spack/spack/solver/splices.lp

@@ -0,0 +1,56 @@
+% Copyright 2013-2024 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)
+
+%=============================================================================
+% These rules are conditionally loaded to handle the synthesis of spliced
+% packages.
+% =============================================================================
+% Consider the concrete spec:
+% foo@2.72%gcc@11.4 arch=linux-ubuntu22.04-icelake build_system=autotools ^bar ...
+% It will emit the following facts for reuse (below is a subset)
+% installed_hash("foo", "xxxyyy")
+% hash_attr("xxxyyy", "hash", "foo", "xxxyyy")
+% hash_attr("xxxyyy", "version", "foo", "2.72")
+% hash_attr("xxxyyy", "node_os", "ubuntu22.04")
+% hash_attr("xxxyyy", "hash", "bar", "zzzqqq")
+% hash_attr("xxxyyy", "depends_on", "foo", "bar", "link")
+% Rules that derive abi_splice_conditions_hold will be generated from 
+% use of the `can_splice` directive. The will have the following form:
+% can_splice("foo@1.0.0+a", when="@1.0.1+a", match_variants=["b"]) --->
+% abi_splice_conditions_hold(0, node(SID, "foo"), "foo", BashHash) :-
+%   installed_hash("foo", BaseHash),
+%   attr("node", node(SID, SpliceName)),
+%   attr("node_version_satisfies", node(SID, "foo"), "1.0.1"),
+%   hash_attr("hash", "node_version_satisfies", "foo", "1.0.1"),
+%   attr("variant_value", node(SID, "foo"), "a", "True"),
+%   hash_attr("hash", "variant_value", "foo", "a", "True"),
+%   attr("variant_value", node(SID, "foo"), "b", VariVar0),
+%   hash_attr("hash", "variant_value", "foo", "b", VariVar0),
+
+% If the splice is valid (i.e. abi_splice_conditions_hold is derived) in the
+% dependency of a concrete spec the solver free to choose whether to continue
+% with the exact hash semantics by simply imposing the child hash, or introducing
+% a spliced node as the dependency instead 
+{ imposed_constraint(ParentHash, "hash", ChildName, ChildHash) } :-
+  hash_attr(ParentHash, "hash", ChildName, ChildHash),
+  abi_splice_conditions_hold(_, node(SID, SpliceName), ChildName, ChildHash).
+
+attr("splice_at_hash", ParentNode, node(SID, SpliceName), ChildName, ChildHash) :-
+  attr("hash", ParentNode, ParentHash),
+  hash_attr(ParentHash, "hash", ChildName, ChildHash),
+  abi_splice_conditions_hold(_, node(SID, SpliceName), ChildName, ChildHash),
+  ParentHash != ChildHash,
+  not imposed_constraint(ParentHash, "hash", ChildName, ChildHash).
+  
+% Names and virtual providers may change when a dependency is spliced in
+imposed_constraint(Hash, "dependency_holds", ParentName, SpliceName, Type) :-
+  hash_attr(Hash, "depends_on", ParentName, DepName, Type),
+  hash_attr(Hash, "hash", DepName, DepHash),
+  attr("splice_at_hash", node(ID, ParentName), node(SID, SpliceName), DepName, DepHash).
+ 
+imposed_constraint(Hash, "virtual_on_edge", ParentName, SpliceName, VirtName) :-
+  hash_attr(Hash, "virtual_on_edge", ParentName, DepName, VirtName),
+  attr("splice_at_hash", node(ID, ParentName), node(SID, SpliceName), DepName, DepHash).
+

lib/spack/spack/spec.py

@@ -59,7 +59,7 @@
 import re
 import socket
 import warnings
-from typing import Any, Callable, Dict, List, Match, Optional, Set, Tuple, Union
+from typing import Any, Callable, Dict, Iterable, List, Match, Optional, Set, Tuple, Union
 
 import archspec.cpu
 
@@ -95,6 +95,8 @@
 import spack.version as vn
 import spack.version.git_ref_lookup
 
+from .enums import InstallRecordStatus
+
 __all__ = [
     "CompilerSpec",
     "Spec",
@@ -877,8 +879,9 @@ def constrain(self, other):
                 # Next, if any flags in other propagate, we force them to propagate in our case
                 shared = list(sorted(set(other[flag_type]) - extra_other))
                 for x, y in _shared_subset_pair_iterate(shared, sorted(self[flag_type])):
-                    if x.propagate:
-                        y.propagate = True
+                    if y.propagate is True and x.propagate is False:
+                        changed = True
+                        y.propagate = False
 
         # TODO: what happens if flag groups with a partial (but not complete)
         # intersection specify different behaviors for flag propagation?
@@ -933,6 +936,7 @@ def _cmp_iter(self):
             def flags():
                 for flag in v:
                     yield flag
+                    yield flag.propagate
 
             yield flags
 
@@ -2069,7 +2073,7 @@ def _lookup_hash(self):
         # First env, then store, then binary cache
         matches = (
             (active_env.all_matching_specs(self) if active_env else [])
-            or spack.store.STORE.db.query(self, installed=any)
+            or spack.store.STORE.db.query(self, installed=InstallRecordStatus.ANY)
             or spack.binary_distribution.BinaryCacheQuery(True)(self)
         )
 
@@ -2826,7 +2830,7 @@ def ensure_no_deprecated(root):
             msg += "    For each package listed, choose another spec\n"
             raise SpecDeprecatedError(msg)
 
-    def concretize(self, tests: Union[bool, List[str]] = False) -> None:
+    def concretize(self, tests: Union[bool, Iterable[str]] = False) -> None:
         """Concretize the current spec.
 
         Args:
@@ -2905,7 +2909,7 @@ def _mark_concrete(self, value=True):
             if (not value) and s.concrete and s.installed:
                 continue
             elif not value:
-                s.clear_cached_hashes()
+                s.clear_caches()
             s._mark_root_concrete(value)
 
     def _finalize_concretization(self):
@@ -2954,7 +2958,7 @@ def _finalize_concretization(self):
         for spec in self.traverse():
             spec._cached_hash(ht.dag_hash)
 
-    def concretized(self, tests=False):
+    def concretized(self, tests: Union[bool, Iterable[str]] = False) -> "spack.spec.Spec":
         """This is a non-destructive version of concretize().
 
         First clones, then returns a concrete version of this package
@@ -3018,7 +3022,12 @@ def ensure_valid_variants(spec):
         pkg_variants = pkg_cls.variant_names()
         # reserved names are variants that may be set on any package
         # but are not necessarily recorded by the package's class
-        not_existing = set(spec.variants) - (set(pkg_variants) | set(vt.reserved_names))
+        propagate_variants = [name for name, variant in spec.variants.items() if variant.propagate]
+
+        not_existing = set(spec.variants) - (
+            set(pkg_variants) | set(vt.reserved_names) | set(propagate_variants)
+        )
+
         if not_existing:
             raise vt.UnknownVariantError(
                 f"No such variant {not_existing} for spec: '{spec}'", list(not_existing)
@@ -3045,6 +3054,10 @@ def constrain(self, other, deps=True):
                 raise spack.error.UnsatisfiableSpecError(self, other, "constrain a concrete spec")
 
         other = self._autospec(other)
+        if other.concrete and other.satisfies(self):
+            self._dup(other)
+            return True
+
         if other.abstract_hash:
             if not self.abstract_hash or other.abstract_hash.startswith(self.abstract_hash):
                 self.abstract_hash = other.abstract_hash
@@ -4245,7 +4258,7 @@ def _splice_detach_and_add_dependents(self, replacement, context):
         for ancestor in ancestors_in_context:
             # Only set it if it hasn't been spliced before
             ancestor._build_spec = ancestor._build_spec or ancestor.copy()
-            ancestor.clear_cached_hashes(ignore=(ht.package_hash.attr,))
+            ancestor.clear_caches(ignore=(ht.package_hash.attr,))
             for edge in ancestor.edges_to_dependencies(depflag=dt.BUILD):
                 if edge.depflag & ~dt.BUILD:
                     edge.depflag &= ~dt.BUILD
@@ -4439,7 +4452,7 @@ def mask_build_deps(in_spec):
 
         return spec
 
-    def clear_cached_hashes(self, ignore=()):
+    def clear_caches(self, ignore=()):
         """
         Clears all cached hashes in a Spec, while preserving other properties.
         """
@@ -4447,7 +4460,9 @@ def clear_cached_hashes(self, ignore=()):
             if h.attr not in ignore:
                 if hasattr(self, h.attr):
                     setattr(self, h.attr, None)
-        self._dunder_hash = None
+        for attr in ("_dunder_hash", "_prefix"):
+            if attr not in ignore:
+                setattr(self, attr, None)
 
     def __hash__(self):
         # If the spec is concrete, we leverage the process hash and just use
@@ -4523,8 +4538,69 @@ def substitute(self, vspec):
         # Set the item
         super().__setitem__(vspec.name, vspec)
 
-    def satisfies(self, other):
-        return all(k in self and self[k].satisfies(other[k]) for k in other)
+    def partition_variants(self):
+        non_prop, prop = lang.stable_partition(self.values(), lambda x: not x.propagate)
+        # Just return the names
+        non_prop = [x.name for x in non_prop]
+        prop = [x.name for x in prop]
+        return non_prop, prop
+
+    def satisfies(self, other: "VariantMap") -> bool:
+        if self.spec.concrete:
+            return self._satisfies_when_self_concrete(other)
+        return self._satisfies_when_self_abstract(other)
+
+    def _satisfies_when_self_concrete(self, other: "VariantMap") -> bool:
+        non_propagating, propagating = other.partition_variants()
+        result = all(
+            name in self and self[name].satisfies(other[name]) for name in non_propagating
+        )
+        if not propagating:
+            return result
+
+        for node in self.spec.traverse():
+            if not all(
+                node.variants[name].satisfies(other[name])
+                for name in propagating
+                if name in node.variants
+            ):
+                return False
+        return result
+
+    def _satisfies_when_self_abstract(self, other: "VariantMap") -> bool:
+        other_non_propagating, other_propagating = other.partition_variants()
+        self_non_propagating, self_propagating = self.partition_variants()
+
+        # First check variants without propagation set
+        result = all(
+            name in self_non_propagating
+            and (self[name].propagate or self[name].satisfies(other[name]))
+            for name in other_non_propagating
+        )
+        if result is False or (not other_propagating and not self_propagating):
+            return result
+
+        # Check that self doesn't contradict variants propagated by other
+        if other_propagating:
+            for node in self.spec.traverse():
+                if not all(
+                    node.variants[name].satisfies(other[name])
+                    for name in other_propagating
+                    if name in node.variants
+                ):
+                    return False
+
+        # Check that other doesn't contradict variants propagated by self
+        if self_propagating:
+            for node in other.spec.traverse():
+                if not all(
+                    node.variants[name].satisfies(self[name])
+                    for name in self_propagating
+                    if name in node.variants
+                ):
+                    return False
+
+        return result
 
     def intersects(self, other):
         return all(self[k].intersects(other[k]) for k in other if k in self)

lib/spack/spack/stage.py

@@ -16,6 +16,7 @@
 
 import llnl.string
 import llnl.util.lang
+import llnl.util.symlink
 import llnl.util.tty as tty
 from llnl.util.filesystem import (
     can_access,

lib/spack/spack/subprocess_context.py

@@ -17,7 +17,6 @@
 import multiprocessing
 import pickle
 import pydoc
-import sys
 from types import ModuleType
 
 import spack.config
@@ -27,9 +26,6 @@
 import spack.repo
 import spack.store
 
-_SERIALIZE = sys.platform == "win32" or (sys.version_info >= (3, 8) and sys.platform == "darwin")
-
-
 patches = None
 
 
@@ -56,7 +52,7 @@ def _restore_and_run(self, fn, test_state):
         fn()
 
     def create(self):
-        test_state = TestState()
+        test_state = GlobalStateMarshaler()
         return multiprocessing.Process(target=self._restore_and_run, args=(self.fn, test_state))
 
 
@@ -65,49 +61,56 @@ class PackageInstallContext:
     needs to be transmitted to a child process.
     """
 
-    def __init__(self, pkg):
-        if _SERIALIZE:
+    def __init__(self, pkg, *, ctx=None):
+        ctx = ctx or multiprocessing.get_context()
+        self.serialize = ctx.get_start_method() != "fork"
+        if self.serialize:
             self.serialized_pkg = serialize(pkg)
+            self.global_state = GlobalStateMarshaler()
             self.serialized_env = serialize(spack.environment.active_environment())
         else:
             self.pkg = pkg
+            self.global_state = None
             self.env = spack.environment.active_environment()
         self.spack_working_dir = spack.paths.spack_working_dir
-        self.test_state = TestState()
 
     def restore(self):
-        self.test_state.restore()
         spack.paths.spack_working_dir = self.spack_working_dir
-        env = pickle.load(self.serialized_env) if _SERIALIZE else self.env
+        env = pickle.load(self.serialized_env) if self.serialize else self.env
+        # Activating the environment modifies the global configuration, so globals have to
+        # be restored afterward, in case other modifications were applied on top (e.g. from
+        # command line)
         if env:
             spack.environment.activate(env)
+
+        if self.serialize:
+            self.global_state.restore()
+
         # Order of operation is important, since the package might be retrieved
         # from a repo defined within the environment configuration
-        pkg = pickle.load(self.serialized_pkg) if _SERIALIZE else self.pkg
+        pkg = pickle.load(self.serialized_pkg) if self.serialize else self.pkg
         return pkg
 
 
-class TestState:
-    """Spack tests may modify state that is normally read from disk in memory;
-    this object is responsible for properly serializing that state to be
-    applied to a subprocess. This isn't needed outside of a testing environment
-    but this logic is designed to behave the same inside or outside of tests.
+class GlobalStateMarshaler:
+    """Class to serialize and restore global state for child processes.
+
+    Spack may modify state that is normally read from disk or command line in memory;
+    this object is responsible for properly serializing that state to be applied to a subprocess.
     """
 
     def __init__(self):
-        if _SERIALIZE:
-            self.config = spack.config.CONFIG
-            self.platform = spack.platforms.host
-            self.test_patches = store_patches()
-            self.store = spack.store.STORE
+        self.config = spack.config.CONFIG.ensure_unwrapped()
+        self.platform = spack.platforms.host
+        self.test_patches = store_patches()
+        self.store = spack.store.STORE
 
     def restore(self):
-        if _SERIALIZE:
-            spack.config.CONFIG = self.config
-            spack.repo.PATH = spack.repo.create(self.config)
-            spack.platforms.host = self.platform
-            spack.store.STORE = self.store
-            self.test_patches.restore()
+        spack.config.CONFIG = self.config
+        spack.repo.PATH = spack.repo.create(self.config)
+        spack.platforms.host = self.platform
+        spack.store.STORE = self.store
+        self.test_patches.restore()
 
 
 class TestPatches:

lib/spack/spack/test/abi_splicing.py

@@ -0,0 +1,247 @@
+# Copyright 2013-2024 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)
+""" Test ABI-based splicing of dependencies """
+
+from typing import List
+
+import pytest
+
+import spack.config
+import spack.deptypes as dt
+import spack.solver.asp
+from spack.installer import PackageInstaller
+from spack.spec import Spec
+
+
+class CacheManager:
+    def __init__(self, specs: List[str]) -> None:
+        self.req_specs = specs
+        self.concr_specs: List[Spec]
+        self.concr_specs = []
+
+    def __enter__(self):
+        self.concr_specs = [Spec(s).concretized() for s in self.req_specs]
+        for s in self.concr_specs:
+            PackageInstaller([s.package], fake=True, explicit=True).install()
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        for s in self.concr_specs:
+            s.package.do_uninstall()
+
+
+# MacOS and Windows only work if you pass this function pointer rather than a
+# closure
+def _mock_has_runtime_dependencies(_x):
+    return True
+
+
+def _make_specs_non_buildable(specs: List[str]):
+    output_config = {}
+    for spec in specs:
+        output_config[spec] = {"buildable": False}
+    return output_config
+
+
+@pytest.fixture
+def splicing_setup(mutable_database, mock_packages, monkeypatch):
+    spack.config.set("concretizer:reuse", True)
+    monkeypatch.setattr(
+        spack.solver.asp, "_has_runtime_dependencies", _mock_has_runtime_dependencies
+    )
+
+
+def _enable_splicing():
+    spack.config.set("concretizer:splice", {"automatic": True})
+
+
+def _has_build_dependency(spec: Spec, name: str):
+    return any(s.name == name for s in spec.dependencies(None, dt.BUILD))
+
+
+def test_simple_reuse(splicing_setup):
+    with CacheManager(["splice-z@1.0.0+compat"]):
+        spack.config.set("packages", _make_specs_non_buildable(["splice-z"]))
+        assert Spec("splice-z").concretized().satisfies(Spec("splice-z"))
+
+
+def test_simple_dep_reuse(splicing_setup):
+    with CacheManager(["splice-z@1.0.0+compat"]):
+        spack.config.set("packages", _make_specs_non_buildable(["splice-z"]))
+        assert Spec("splice-h@1").concretized().satisfies(Spec("splice-h@1"))
+
+
+def test_splice_installed_hash(splicing_setup):
+    cache = [
+        "splice-t@1 ^splice-h@1.0.0+compat ^splice-z@1.0.0",
+        "splice-h@1.0.2+compat ^splice-z@1.0.0",
+    ]
+    with CacheManager(cache):
+        packages_config = _make_specs_non_buildable(["splice-t", "splice-h"])
+        spack.config.set("packages", packages_config)
+        goal_spec = Spec("splice-t@1 ^splice-h@1.0.2+compat ^splice-z@1.0.0")
+        with pytest.raises(Exception):
+            goal_spec.concretized()
+        _enable_splicing()
+        assert goal_spec.concretized().satisfies(goal_spec)
+
+
+def test_splice_build_splice_node(splicing_setup):
+    with CacheManager(["splice-t@1 ^splice-h@1.0.0+compat ^splice-z@1.0.0+compat"]):
+        spack.config.set("packages", _make_specs_non_buildable(["splice-t"]))
+        goal_spec = Spec("splice-t@1 ^splice-h@1.0.2+compat ^splice-z@1.0.0+compat")
+        with pytest.raises(Exception):
+            goal_spec.concretized()
+        _enable_splicing()
+        assert goal_spec.concretized().satisfies(goal_spec)
+
+
+def test_double_splice(splicing_setup):
+    cache = [
+        "splice-t@1 ^splice-h@1.0.0+compat ^splice-z@1.0.0+compat",
+        "splice-h@1.0.2+compat ^splice-z@1.0.1+compat",
+        "splice-z@1.0.2+compat",
+    ]
+    with CacheManager(cache):
+        freeze_builds_config = _make_specs_non_buildable(["splice-t", "splice-h", "splice-z"])
+        spack.config.set("packages", freeze_builds_config)
+        goal_spec = Spec("splice-t@1 ^splice-h@1.0.2+compat ^splice-z@1.0.2+compat")
+        with pytest.raises(Exception):
+            goal_spec.concretized()
+        _enable_splicing()
+        assert goal_spec.concretized().satisfies(goal_spec)
+
+
+# The next two tests are mirrors of one another
+def test_virtual_multi_splices_in(splicing_setup):
+    cache = [
+        "depends-on-virtual-with-abi ^virtual-abi-1",
+        "depends-on-virtual-with-abi ^virtual-abi-2",
+    ]
+    goal_specs = [
+        "depends-on-virtual-with-abi ^virtual-abi-multi abi=one",
+        "depends-on-virtual-with-abi ^virtual-abi-multi abi=two",
+    ]
+    with CacheManager(cache):
+        spack.config.set("packages", _make_specs_non_buildable(["depends-on-virtual-with-abi"]))
+        for gs in goal_specs:
+            with pytest.raises(Exception):
+                Spec(gs).concretized()
+        _enable_splicing()
+        for gs in goal_specs:
+            assert Spec(gs).concretized().satisfies(gs)
+
+
+def test_virtual_multi_can_be_spliced(splicing_setup):
+    cache = [
+        "depends-on-virtual-with-abi ^virtual-abi-multi abi=one",
+        "depends-on-virtual-with-abi ^virtual-abi-multi abi=two",
+    ]
+    goal_specs = [
+        "depends-on-virtual-with-abi ^virtual-abi-1",
+        "depends-on-virtual-with-abi ^virtual-abi-2",
+    ]
+    with CacheManager(cache):
+        spack.config.set("packages", _make_specs_non_buildable(["depends-on-virtual-with-abi"]))
+        with pytest.raises(Exception):
+            for gs in goal_specs:
+                Spec(gs).concretized()
+        _enable_splicing()
+        for gs in goal_specs:
+            assert Spec(gs).concretized().satisfies(gs)
+
+
+def test_manyvariant_star_matching_variant_splice(splicing_setup):
+    cache = [
+        # can_splice("manyvariants@1.0.0", when="@1.0.1", match_variants="*")
+        "depends-on-manyvariants ^manyvariants@1.0.0+a+b c=v1 d=v2",
+        "depends-on-manyvariants ^manyvariants@1.0.0~a~b c=v3 d=v3",
+    ]
+    goal_specs = [
+        Spec("depends-on-manyvariants ^manyvariants@1.0.1+a+b c=v1 d=v2"),
+        Spec("depends-on-manyvariants ^manyvariants@1.0.1~a~b c=v3 d=v3"),
+    ]
+    with CacheManager(cache):
+        freeze_build_config = {"depends-on-manyvariants": {"buildable": False}}
+        spack.config.set("packages", freeze_build_config)
+        for goal in goal_specs:
+            with pytest.raises(Exception):
+                goal.concretized()
+        _enable_splicing()
+        for goal in goal_specs:
+            assert goal.concretized().satisfies(goal)
+
+
+def test_manyvariant_limited_matching(splicing_setup):
+    cache = [
+        # can_splice("manyvariants@2.0.0+a~b", when="@2.0.1~a+b", match_variants=["c", "d"])
+        "depends-on-manyvariants@2.0 ^manyvariants@2.0.0+a~b c=v3 d=v2",
+        # can_splice("manyvariants@2.0.0 c=v1 d=v1", when="@2.0.1+a+b")
+        "depends-on-manyvariants@2.0 ^manyvariants@2.0.0~a~b c=v1 d=v1",
+    ]
+    goal_specs = [
+        Spec("depends-on-manyvariants@2.0 ^manyvariants@2.0.1~a+b c=v3 d=v2"),
+        Spec("depends-on-manyvariants@2.0 ^manyvariants@2.0.1+a+b c=v3 d=v3"),
+    ]
+    with CacheManager(cache):
+        freeze_build_config = {"depends-on-manyvariants": {"buildable": False}}
+        spack.config.set("packages", freeze_build_config)
+        for s in goal_specs:
+            with pytest.raises(Exception):
+                s.concretized()
+        _enable_splicing()
+        for s in goal_specs:
+            assert s.concretized().satisfies(s)
+
+
+def test_external_splice_same_name(splicing_setup):
+    cache = [
+        "splice-h@1.0.0 ^splice-z@1.0.0+compat",
+        "splice-t@1.0 ^splice-h@1.0.1 ^splice-z@1.0.1+compat",
+    ]
+    packages_yaml = {
+        "splice-z": {"externals": [{"spec": "splice-z@1.0.2+compat", "prefix": "/usr"}]}
+    }
+    goal_specs = [
+        Spec("splice-h@1.0.0 ^splice-z@1.0.2"),
+        Spec("splice-t@1.0 ^splice-h@1.0.1 ^splice-z@1.0.2"),
+    ]
+    with CacheManager(cache):
+        spack.config.set("packages", packages_yaml)
+        _enable_splicing()
+        for s in goal_specs:
+            assert s.concretized().satisfies(s)
+
+
+def test_spliced_build_deps_only_in_build_spec(splicing_setup):
+    cache = ["splice-t@1.0 ^splice-h@1.0.1 ^splice-z@1.0.0"]
+    goal_spec = Spec("splice-t@1.0 ^splice-h@1.0.2 ^splice-z@1.0.0")
+
+    with CacheManager(cache):
+        _enable_splicing()
+        concr_goal = goal_spec.concretized()
+        build_spec = concr_goal._build_spec
+        # Spec has been spliced
+        assert build_spec is not None
+        # Build spec has spliced build dependencies
+        assert _has_build_dependency(build_spec, "splice-h")
+        assert _has_build_dependency(build_spec, "splice-z")
+        # Spliced build dependencies are removed
+        assert len(concr_goal.dependencies(None, dt.BUILD)) == 0
+
+
+def test_spliced_transitive_dependency(splicing_setup):
+    cache = ["splice-depends-on-t@1.0 ^splice-h@1.0.1"]
+    goal_spec = Spec("splice-depends-on-t^splice-h@1.0.2")
+
+    with CacheManager(cache):
+        spack.config.set("packages", _make_specs_non_buildable(["splice-depends-on-t"]))
+        _enable_splicing()
+        concr_goal = goal_spec.concretized()
+        # Spec has been spliced
+        assert concr_goal._build_spec is not None
+        assert concr_goal["splice-t"]._build_spec is not None
+        assert concr_goal.satisfies(goal_spec)
+        # Spliced build dependencies are removed
+        assert len(concr_goal.dependencies(None, dt.BUILD)) == 0

lib/spack/spack/test/build_environment.py

@@ -15,6 +15,8 @@
 from llnl.util.filesystem import HeaderList, LibraryList
 
 import spack.build_environment
+import spack.compiler
+import spack.compilers
 import spack.config
 import spack.deptypes as dt
 import spack.package_base

lib/spack/spack/test/build_systems.py

@@ -15,6 +15,7 @@
 
 import spack.build_systems.autotools
 import spack.build_systems.cmake
+import spack.builder
 import spack.environment
 import spack.error
 import spack.paths
@@ -149,7 +150,7 @@ def test_libtool_archive_files_are_deleted_by_default(self, mutable_database):
 
         # Assert the libtool archive is not there and we have
         # a log of removed files
-        assert not os.path.exists(s.package.builder.libtool_archive_file)
+        assert not os.path.exists(spack.builder.create(s.package).libtool_archive_file)
         search_directory = os.path.join(s.prefix, ".spack")
         libtool_deletion_log = fs.find(search_directory, "removed_la_files.txt", recursive=True)
         assert libtool_deletion_log
@@ -160,11 +161,13 @@ def test_libtool_archive_files_might_be_installed_on_demand(
         # Install a package that creates a mock libtool archive,
         # patch its package to preserve the installation
         s = Spec("libtool-deletion").concretized()
-        monkeypatch.setattr(type(s.package.builder), "install_libtool_archives", True)
+        monkeypatch.setattr(
+            type(spack.builder.create(s.package)), "install_libtool_archives", True
+        )
         PackageInstaller([s.package], explicit=True).install()
 
         # Assert libtool archives are installed
-        assert os.path.exists(s.package.builder.libtool_archive_file)
+        assert os.path.exists(spack.builder.create(s.package).libtool_archive_file)
 
     def test_autotools_gnuconfig_replacement(self, mutable_database):
         """
@@ -261,7 +264,7 @@ def test_cmake_std_args(self, default_mock_concretization):
         # Call the function on a CMakePackage instance
         s = default_mock_concretization("cmake-client")
         expected = spack.build_systems.cmake.CMakeBuilder.std_args(s.package)
-        assert s.package.builder.std_cmake_args == expected
+        assert spack.builder.create(s.package).std_cmake_args == expected
 
         # Call it on another kind of package
         s = default_mock_concretization("mpich")
@@ -381,7 +384,9 @@ def test_autotools_args_from_conditional_variant(default_mock_concretization):
     is not met. When this is the case, the variant is not set in the spec."""
     s = default_mock_concretization("autotools-conditional-variants-test")
     assert "example" not in s.variants
-    assert len(s.package.builder._activate_or_not("example", "enable", "disable")) == 0
+    assert (
+        len(spack.builder.create(s.package)._activate_or_not("example", "enable", "disable")) == 0
+    )
 
 
 def test_autoreconf_search_path_args_multiple(default_mock_concretization, tmpdir):