avoid double closing of fd in sub-processes (#47035)

Both `multiprocessing.connection.Connection.__del__` and `io.IOBase.__del__` called `os.close` on the same file descriptor. As of Python 3.13, this is an explicit warning. Ensure we close once by usef `os.fdopen(..., closefd=False)`

.github/workflows/bootstrap.yml

@@ -159,6 +159,9 @@ jobs:
           brew install cmake bison@2.7 tree
       - name: Checkout
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
+      - uses: actions/setup-python@65d7f2d534ac1bc67fcd62888c5f4f3d2cb2b236 # @v2
+        with:
+          python-version: "3.12"
       - name: Bootstrap clingo
         run: |
           source share/spack/setup-env.sh
@@ -173,7 +176,7 @@ jobs:
     runs-on: ${{ matrix.macos-version }}
     strategy:
       matrix:
-        macos-version: ['macos-11', 'macos-12']
+        macos-version: ['macos-12']
     steps:
       - name: Install dependencies
         run: |

.github/workflows/build-containers.yml

@@ -38,12 +38,11 @@ jobs:
         # Meaning of the various items in the matrix list
         # 0: Container name (e.g. ubuntu-bionic)
         # 1: Platforms to build for
-        # 2: Base image (e.g. ubuntu:18.04)
+        # 2: Base image (e.g. ubuntu:22.04)
         dockerfile: [[amazon-linux, 'linux/amd64,linux/arm64', 'amazonlinux:2'],
                      [centos7, 'linux/amd64,linux/arm64,linux/ppc64le', 'centos:7'],
                      [centos-stream, 'linux/amd64,linux/arm64,linux/ppc64le', 'centos:stream'],
                      [leap15, 'linux/amd64,linux/arm64,linux/ppc64le', 'opensuse/leap:15'],
-                     [ubuntu-bionic, 'linux/amd64,linux/arm64,linux/ppc64le', 'ubuntu:18.04'],
                      [ubuntu-focal, 'linux/amd64,linux/arm64,linux/ppc64le', 'ubuntu:20.04'],
                      [ubuntu-jammy, 'linux/amd64,linux/arm64,linux/ppc64le', 'ubuntu:22.04'],
                      [almalinux8, 'linux/amd64,linux/arm64,linux/ppc64le', 'almalinux:8'],
@@ -58,18 +57,20 @@ jobs:
       - name: Checkout
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # @v2
 
-      - name: Set Container Tag Normal (Nightly)
-        run: |
-          container="${{ matrix.dockerfile[0] }}:latest"
-          echo "container=${container}" >> $GITHUB_ENV
-          echo "versioned=${container}" >> $GITHUB_ENV
-
-        # On a new release create a container with the same tag as the release.
-      - name: Set Container Tag on Release
-        if: github.event_name == 'release'
-        run: |
-          versioned="${{matrix.dockerfile[0]}}:${GITHUB_REF##*/}"
-          echo "versioned=${versioned}" >> $GITHUB_ENV
+      - uses: docker/metadata-action@96383f45573cb7f253c731d3b3ab81c87ef81934
+        id: docker_meta
+        with:
+          images: |
+              ghcr.io/${{ github.repository_owner }}/${{ matrix.dockerfile[0] }}
+              ${{ github.repository_owner }}/${{ matrix.dockerfile[0] }}
+          tags: |
+              type=schedule,pattern=nightly
+              type=schedule,pattern=develop
+              type=semver,pattern={{version}}
+              type=semver,pattern={{major}}.{{minor}}
+              type=semver,pattern={{major}}
+              type=ref,event=branch
+              type=ref,event=pr
 
       - name: Generate the Dockerfile
         env:
@@ -92,13 +93,13 @@ jobs:
           path: dockerfiles
 
       - name: Set up QEMU
-        uses: docker/setup-qemu-action@68827325e0b33c7199eb31dd4e31fbe9023e06e3 # @v1
+        uses: docker/setup-qemu-action@68827325e0b33c7199eb31dd4e31fbe9023e06e3
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # @v1
+        uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226
 
       - name: Log in to GitHub Container Registry
-        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # @v1
+        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
@@ -106,21 +107,18 @@ jobs:
 
       - name: Log in to DockerHub
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # @v1
+        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build & Deploy ${{ matrix.dockerfile[0] }}
-        uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09 # @v2
+        uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09
         with:
           context: dockerfiles/${{ matrix.dockerfile[0] }}
           platforms: ${{ matrix.dockerfile[1] }}
           push: ${{ github.event_name != 'pull_request' }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
-          tags: |
-            spack/${{ env.container }}
-            spack/${{ env.versioned }}
-            ghcr.io/spack/${{ env.container }}
-            ghcr.io/spack/${{ env.versioned }}
+          tags: ${{ steps.docker_meta.outputs.tags }}
+          labels: ${{ steps.docker_meta.outputs.labels }}

CHANGELOG.md

@@ -1,3 +1,345 @@
+# v0.21.3 (2024-10-02)
+
+## Bugfixes
+- Forward compatibility with Spack 0.23 packages with language dependencies (#45205, #45191)
+- Forward compatibility with `urllib` from Python 3.12.6+ (#46453, #46483)
+- Bump `archspec` to 0.2.5-dev for better aarch64 and Windows support (#42854, #44005,
+  #45721, #46445)
+- Support macOS Sequoia (#45018, #45127, #43862)
+- CI and test maintenance (#42909, #42728, #46711, #41943, #43363)
+
+# v0.21.2 (2024-03-01)
+
+## Bugfixes
+
+- Containerize: accommodate nested or pre-existing spack-env paths (#41558)
+- Fix setup-env script, when going back and forth between instances (#40924)
+- Fix using fully-qualified namespaces from root specs (#41957)
+- Fix a bug when a required provider is requested for multiple virtuals (#42088)
+- OCI buildcaches:
+  - only push in parallel when forking (#42143)
+  - use pickleable errors (#42160)
+- Fix using sticky variants in externals (#42253)
+- Fix a rare issue with conditional requirements and multi-valued variants (#42566)
+
+## Package updates
+- rust: add v1.75, rework a few variants (#41161,#41903)
+- py-transformers: add v4.35.2 (#41266)
+- mgard: fix OpenMP on AppleClang (#42933)
+
+# v0.21.1 (2024-01-11)
+
+## New features
+- Add support for reading buildcaches created by Spack v0.22 (#41773)
+
+## Bugfixes
+
+- spack graph: fix coloring with environments (#41240)
+- spack info: sort variants in --variants-by-name (#41389)
+- Spec.format: error on old style format strings (#41934)
+- ASP-based solver: 
+  - fix infinite recursion when computing concretization errors (#41061)
+  - don't error for type mismatch on preferences (#41138)
+  - don't emit spurious debug output (#41218)
+- Improve the error message for deprecated preferences (#41075)
+- Fix MSVC preview version breaking clingo build on Windows (#41185)
+- Fix multi-word aliases (#41126)
+- Add a warning for unconfigured compiler (#41213)
+- environment: fix an issue with deconcretization/reconcretization of specs (#41294)
+- buildcache: don't error if a patch is missing, when installing from binaries (#41986)
+- Multiple improvements to unit-tests (#41215,#41369,#41495,#41359,#41361,#41345,#41342,#41308,#41226)
+
+## Package updates
+- root: add a webgui patch to address security issue (#41404)
+- BerkeleyGW: update source urls (#38218)
+
+# v0.21.0 (2023-11-11)
+
+`v0.21.0` is a major feature release.
+
+## Features in this release
+
+1. **Better error messages with condition chaining**
+
+   In v0.18, we added better error messages that could tell you what problem happened,
+   but they couldn't tell you *why* it happened. `0.21` adds *condition chaining* to the
+   solver, and Spack can now trace back through the conditions that led to an error and
+   build a tree of causes potential causes and where they came from. For example:
+
+   ```console
+   $ spack solve hdf5 ^cmake@3.0.1
+   ==> Error: concretization failed for the following reasons:
+
+      1. Cannot satisfy 'cmake@3.0.1'
+      2. Cannot satisfy 'cmake@3.0.1'
+           required because hdf5 ^cmake@3.0.1 requested from CLI
+      3. Cannot satisfy 'cmake@3.18:' and 'cmake@3.0.1
+           required because hdf5 ^cmake@3.0.1 requested from CLI
+           required because hdf5 depends on cmake@3.18: when @1.13:
+             required because hdf5 ^cmake@3.0.1 requested from CLI
+      4. Cannot satisfy 'cmake@3.12:' and 'cmake@3.0.1
+           required because hdf5 depends on cmake@3.12:
+             required because hdf5 ^cmake@3.0.1 requested from CLI
+           required because hdf5 ^cmake@3.0.1 requested from CLI
+   ```
+
+   More details in #40173.
+
+2. **OCI build caches**
+
+   You can now use an arbitrary [OCI](https://opencontainers.org) registry as a build
+   cache:
+
+   ```console
+   $ spack mirror add my_registry oci://user/image # Dockerhub
+   $ spack mirror add my_registry oci://ghcr.io/haampie/spack-test # GHCR
+   $ spack mirror set --push --oci-username ... --oci-password ... my_registry  # set login creds
+   $ spack buildcache push my_registry [specs...]
+   ```
+
+   And you can optionally add a base image to get *runnable* images:
+
+   ```console
+   $ spack buildcache push --base-image ubuntu:23.04 my_registry python
+   Pushed ... as [image]:python-3.11.2-65txfcpqbmpawclvtasuog4yzmxwaoia.spack
+
+   $ docker run --rm -it [image]:python-3.11.2-65txfcpqbmpawclvtasuog4yzmxwaoia.spack
+   ```
+
+   This creates a container image from the Spack installations on the host system,
+   without the need to run `spack install` from a `Dockerfile` or `sif` file. It also
+   addresses the inconvenience of losing binaries of dependencies when `RUN spack
+   install` fails inside `docker build`.
+
+   Further, the container image layers and build cache tarballs are the same files. This
+   means that `spack install` and `docker pull` use the exact same underlying binaries.
+   If you previously used `spack install` inside of `docker build`, this feature helps
+   you save storage by a factor two.
+
+   More details in #38358.
+
+3. **Multiple versions of build dependencies**
+
+   Increasingly, complex package builds require multiple versions of some build
+   dependencies. For example, Python packages frequently require very specific versions
+   of `setuptools`, `cython`, and sometimes different physics packages require different
+   versions of Python to build. The concretizer enforced that every solve was *unified*,
+   i.e., that there only be one version of every package. The concretizer now supports
+   "duplicate" nodes for *build dependencies*, but enforces unification through
+   transitive link and run dependencies. This will allow it to better resolve complex
+   dependency graphs in ecosystems like Python, and it also gets us very close to
+   modeling compilers as proper dependencies.
+
+   This change required a major overhaul of the concretizer, as well as a number of
+   performance optimizations. See #38447, #39621.
+
+4. **Cherry-picking virtual dependencies**
+
+   You can now select only a subset of virtual dependencies from a spec that may provide
+   more. For example, if you want `mpich` to be your `mpi` provider, you can be explicit
+   by writing:
+
+   ```
+   hdf5 ^[virtuals=mpi] mpich
+   ```
+
+   Or, if you want to use, e.g., `intel-parallel-studio` for `blas` along with an external
+   `lapack` like `openblas`, you could write:
+
+   ```
+   strumpack ^[virtuals=mpi] intel-parallel-studio+mkl ^[virtuals=lapack] openblas
+   ```
+
+   The `virtuals=mpi` is an edge attribute, and dependency edges in Spack graphs now
+   track which virtuals they satisfied. More details in #17229 and #35322.
+
+   Note for packaging: in Spack 0.21 `spec.satisfies("^virtual")` is true if and only if
+   the package specifies `depends_on("virtual")`. This is different from Spack 0.20,
+   where depending on a provider implied depending on the virtual provided. See #41002
+   for an example where `^mkl` was being used to test for several `mkl` providers in a
+   package that did not depend on `mkl`.
+
+5. **License directive**
+
+   Spack packages can now have license metadata, with the new `license()` directive:
+
+   ```python
+       license("Apache-2.0")
+   ```
+
+   Licenses use [SPDX identifiers](https://spdx.org/licenses), and you can use SPDX
+   expressions to combine them:
+
+   ```python
+       license("Apache-2.0 OR MIT")
+   ```
+
+   Like other directives in Spack, it's conditional, so you can handle complex cases like
+   Spack itself:
+
+   ```python
+      license("LGPL-2.1", when="@:0.11")
+      license("Apache-2.0 OR MIT", when="@0.12:")
+   ```
+
+   More details in #39346, #40598.
+
+6. **`spack deconcretize` command**
+
+   We are getting close to having a `spack update` command for environments, but we're
+   not quite there yet. This is the next best thing. `spack deconcretize` gives you
+   control over what you want to update in an already concrete environment. If you have
+   an environment built with, say, `meson`, and you want to update your `meson` version,
+   you can run:
+
+   ```console
+   spack deconcretize meson
+   ```
+
+   and have everything that depends on `meson` rebuilt the next time you run `spack
+   concretize`. In a future Spack version, we'll handle all of this in a single command,
+   but for now you can use this to drop bits of your lockfile and resolve your
+   dependencies again. More in #38803.
+
+7. **UI Improvements**
+
+   The venerable `spack info` command was looking shabby compared to the rest of Spack's
+   UI, so we reworked it to have a bit more flair. `spack info` now makes much better
+   use of terminal space and shows variants, their values, and their descriptions much
+   more clearly. Conditional variants are grouped separately so you can more easily
+   understand how packages are structured. More in #40998.
+
+   `spack checksum` now allows you to filter versions from your editor, or by version
+   range. It also notifies you about potential download URL changes. See #40403.
+
+8. **Environments can include definitions**
+
+   Spack did not previously support using `include:` with The
+   [definitions](https://spack.readthedocs.io/en/latest/environments.html#spec-list-references)
+   section of an environment, but now it does. You can use this to curate lists of specs
+   and more easily reuse them across environments. See #33960.
+
+9. **Aliases**
+
+   You can now add aliases to Spack commands in `config.yaml`, e.g. this might enshrine
+   your favorite args to `spack find` as `spack f`:
+
+   ```yaml
+   config:
+     aliases:
+       f: find -lv
+   ```
+
+   See #17229.
+
+10. **Improved autoloading of modules**
+
+    Spack 0.20 was the first release to enable autoloading of direct dependencies in
+    module files.
+
+    The downside of this was that `module avail` and `module load` tab completion would
+    show users too many modules to choose from, and many users disabled generating
+    modules for dependencies through `exclude_implicits: true`. Further, it was
+    necessary to keep hashes in module names to avoid file name clashes.
+
+    In this release, you can start using `hide_implicits: true` instead, which exposes
+    only explicitly installed packages to the user, while still autoloading
+    dependencies. On top of that, you can safely use `hash_length: 0`, as this config
+    now only applies to the modules exposed to the user -- you don't have to worry about
+    file name clashes for hidden dependencies.
+
+   Note: for `tcl` this feature requires Modules 4.7 or higher
+
+11. **Updated container labeling**
+
+    Nightly Docker images from the `develop` branch will now be tagged as `:develop` and
+    `:nightly`. The `:latest` tag is no longer associated with `:develop`, but with the
+    latest stable release. Releases will be tagged with `:{major}`, `:{major}.{minor}`
+    and `:{major}.{minor}.{patch}`. `ubuntu:18.04` has also been removed from the list of
+    generated Docker images, as it is no longer supported. See #40593.
+
+## Other new commands and directives
+
+* `spack env activate` without arguments now loads a `default` environment that you do
+  not have to create (#40756).
+* `spack find -H` / `--hashes`: a new shortcut for piping `spack find` output to
+  other commands (#38663)
+* Add `spack checksum --verify`, fix `--add` (#38458)
+* New `default_args` context manager factors out common args for directives (#39964)
+* `spack compiler find --[no]-mixed-toolchain` lets you easily mix `clang` and
+  `gfortran` on Linux (#40902)
+
+## Performance improvements
+
+* `spack external find` execution is now much faster (#39843)
+* `spack location -i` now much faster on success (#40898)
+* Drop redundant rpaths post install (#38976)
+* ASP-based solver: avoid cycles in clingo using hidden directive (#40720)
+* Fix multiple quadratic complexity issues in environments (#38771)
+
+## Other new features of note
+
+* archspec: update to v0.2.2, support for Sapphire Rapids, Power10, Neoverse V2 (#40917)
+* Propagate variants across nodes that don't have that variant (#38512)
+* Implement fish completion (#29549)
+* Can now distinguish between source/binary mirror; don't ping mirror.spack.io as much (#34523)
+* Improve status reporting on install (add [n/total] display) (#37903)
+
+## Windows
+
+This release has the best Windows support of any Spack release yet, with numerous
+improvements and much larger swaths of tests passing:
+
+* MSVC and SDK improvements (#37711, #37930, #38500, #39823, #39180)
+* Windows external finding: update default paths; treat .bat as executable on Windows (#39850)
+* Windows decompression: fix removal of intermediate file (#38958)
+* Windows: executable/path handling (#37762)
+* Windows build systems: use ninja and enable tests (#33589)
+* Windows testing (#36970, #36972, #36973, #36840, #36977, #36792, #36834, #34696, #36971)
+* Windows PowerShell support (#39118, #37951)
+* Windows symlinking and libraries (#39933, #38599, #34701, #38578, #34701)
+
+## Notable refactors
+* User-specified flags take precedence over others in Spack compiler wrappers (#37376)
+* Improve setup of build, run, and test environments (#35737, #40916)
+* `make` is no longer a required system dependency of Spack (#40380)
+* Support Python 3.12 (#40404, #40155, #40153)
+* docs: Replace package list with packages.spack.io (#40251)
+* Drop Python 2 constructs in Spack (#38720, #38718, #38703)
+
+## Binary cache and stack updates
+* e4s arm stack: duplicate and target neoverse v1 (#40369)
+* Add macOS ML CI stacks (#36586)
+* E4S Cray CI Stack (#37837)
+* e4s cray: expand spec list (#38947)
+* e4s cray sles ci: expand spec list (#39081)
+
+## Removals, deprecations, and syntax changes
+* ASP: targets, compilers and providers soft-preferences are only global (#31261)
+* Parser: fix ambiguity with whitespace in version ranges (#40344)
+* Module file generation is disabled by default; you'll need to enable it to use it (#37258)
+* Remove deprecated "extra_instructions" option for containers (#40365)
+* Stand-alone test feature deprecation postponed to v0.22 (#40600)
+* buildcache push: make `--allow-root` the default and deprecate the option (#38878)
+
+## Notable Bugfixes
+* Bugfix: propagation of multivalued variants (#39833)
+* Allow `/` in git versions (#39398)
+* Fetch & patch: actually acquire stage lock, and many more issues (#38903)
+* Environment/depfile: better escaping of targets with Git versions (#37560)
+* Prevent "spack external find" to error out on wrong permissions (#38755)
+* lmod: allow core compiler to be specified with a version range (#37789)
+
+## Spack community stats
+
+* 7,469 total packages, 303 new since `v0.20.0`
+    * 150 new Python packages
+    * 34 new R packages
+* 353 people contributed to this release
+    * 336 committers to packages
+    * 65 committers to core
+
+
 # v0.20.3 (2023-10-31)
 
 ## Bugfixes

etc/spack/defaults/config.yaml

@@ -229,3 +229,11 @@ config:
   flags:
     # Whether to keep -Werror flags active in package builds.
     keep_werror: 'none'
+
+  # A mapping of aliases that can be used to define new commands. For instance,
+  # `sp: spec -I` will define a new command `sp` that will execute `spec` with
+  # the `-I` argument. Aliases cannot override existing commands.
+  aliases:
+    concretise: concretize
+    containerise: containerize
+    rm: remove

lib/spack/docs/basic_usage.rst

@@ -1526,6 +1526,30 @@ any MPI implementation will do.  If another package depends on
 error.  Likewise, if you try to plug in some package that doesn't
 provide MPI, Spack will raise an error.
 
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Explicit binding of virtual dependencies
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+There are packages that provide more than just one virtual dependency. When interacting with them, users
+might want to utilize just a subset of what they could provide, and use other providers for virtuals they
+need.
+
+It is possible to be more explicit and tell Spack which dependency should provide which virtual, using a
+special syntax:
+
+.. code-block:: console
+
+   $ spack spec strumpack ^[virtuals=mpi] intel-parallel-studio+mkl ^[virtuals=lapack] openblas
+
+Concretizing the spec above produces the following DAG:
+
+.. figure:: images/strumpack_virtuals.svg
+   :scale: 60 %
+   :align: center
+
+where ``intel-parallel-studio`` *could* provide ``mpi``, ``lapack``, and ``blas`` but is used only for the former. The ``lapack``
+and ``blas`` dependencies are satisfied by ``openblas``.
+
 ^^^^^^^^^^^^^^^^^^^^^^^^
 Specifying Specs by Hash
 ^^^^^^^^^^^^^^^^^^^^^^^^

lib/spack/docs/binary_caches.rst

@@ -155,6 +155,33 @@ List of popular build caches
 
 * `Extreme-scale Scientific Software Stack (E4S) <https://e4s-project.github.io/>`_: `build cache <https://oaciss.uoregon.edu/e4s/inventory.html>`_
 
+----------
+Relocation
+----------
+
+When using buildcaches across different machines, it is likely that the install
+root will be different from the one used to build the binaries.
+
+To address this issue, Spack automatically relocates all paths encoded in binaries
+and scripts to their new location upon install.
+
+Note that there are some cases where this is not possible: if binaries are built in
+a relatively short path, and then installed to a longer path, there may not be enough
+space in the binary to encode the new path. In this case, Spack will fail to install
+the package from the build cache, and a source build is required.
+
+To reduce the likelihood of this happening, it is highly recommended to add padding to
+the install root during the build, as specified in the :ref:`config <config-yaml>`
+section of the configuration:
+
+.. code-block:: yaml
+
+   config:
+     install_tree:
+       root: /opt/spack
+       padded_length: 128
+
+
 
 -----------------------------------------
 OCI / Docker V2 registries as build cache
@@ -216,29 +243,34 @@ other system dependencies. However, they are still compatible with tools like
     are `alternative drivers <https://docs.docker.com/storage/storagedriver/>`_.
 
 ------------------------------------
-Using a buildcache in GitHub Actions
+Spack build cache for GitHub Actions
 ------------------------------------
 
-GitHub Actions is a popular CI/CD platform for building and testing software,
-but each CI job has limited resources, making from source builds too slow for
-many applications. Spack build caches can be used to share binaries between CI
-runs, speeding up CI significantly.
+To significantly speed up Spack in GitHub Actions, binaries can be cached in
+GitHub Packages. This service is an OCI registry that can be linked to a GitHub
+repository.
 
 A typical workflow is to include a ``spack.yaml`` environment in your repository
-that specifies the packages to install:
+that specifies the packages to install, the target architecture, and the build
+cache to use under ``mirrors``:
 
 .. code-block:: yaml
 
     spack:
-      specs: [pkg-x, pkg-y]
-    packages:
-      all:
-        require: target=x86_64_v2
-    mirrors:
-      github_packages: oci://ghcr.io/<user>/<repo>
+      specs:
+      - python@3.11
+      config:
+        install_tree:
+          root: /opt/spack
+          padded_length: 128
+      packages:
+        all:
+          require: target=x86_64_v2
+      mirrors:
+        local-buildcache: oci://ghcr.io/<organization>/<repository>
 
-And a GitHub action that sets up Spack, installs packages from the build cache
-or from sources, and pushes newly built binaries to the build cache:
+A GitHub action can then be used to install the packages and push them to the
+build cache:
 
 .. code-block:: yaml
 
@@ -252,26 +284,35 @@ or from sources, and pushes newly built binaries to the build cache:
     jobs:
       example:
         runs-on: ubuntu-22.04
+        permissions:
+          packages: write
         steps:
         - name: Checkout
           uses: actions/checkout@v3
 
-        - name: Install Spack
-          run: |
-            git clone --depth=1 https://github.com/spack/spack.git
-            echo "$PWD/spack/bin/" >> "$GITHUB_PATH"
+        - name: Checkout Spack
+          uses: actions/checkout@v3
+          with:
+            repository: spack/spack
+            path: spack
+
+        - name: Setup Spack
+          run: echo "$PWD/spack/bin" >> "$GITHUB_PATH"
 
         - name: Concretize
           run: spack -e . concretize
 
         - name: Install
-          run: spack -e . install --no-check-signature --fail-fast
+          run: spack -e . install --no-check-signature
+
+        - name: Run tests
+            run: ./my_view/bin/python3 -c 'print("hello world")'
 
         - name: Push to buildcache
           run: |
-            spack -e . mirror set --oci-username <user> --oci-password "${{ secrets.GITHUB_TOKEN }}" github_packages
-            spack -e . buildcache push --base-image ubuntu:22.04 --unsigned --update-index github_packages
-            if: always()
+            spack -e . mirror set --oci-username ${{ github.actor }} --oci-password "${{ secrets.GITHUB_TOKEN }}" local-buildcache
+            spack -e . buildcache push --base-image ubuntu:22.04 --unsigned --update-index local-buildcache
+          if: ${{ !cancelled() }}
 
 The first time this action runs, it will build the packages from source and
 push them to the build cache. Subsequent runs will pull the binaries from the
@@ -281,15 +322,15 @@ over source builds.
 The build cache entries appear in the GitHub Packages section of your repository,
 and contain instructions for pulling and running them with ``docker`` or ``podman``.
 
-----------
-Relocation
-----------
 
-Initial build and later installation do not necessarily happen at the same
-location. Spack provides a relocation capability and corrects for RPATHs and
-non-relocatable scripts. However, many packages compile paths into binary
-artifacts directly. In such cases, the build instructions of this package would
-need to be adjusted for better re-locatability.
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Using Spack's public build cache for GitHub Actions
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Spack offers a public build cache for GitHub Actions with a set of common packages,
+which lets you get started quickly. See the following resources for more information:
+
+* `spack/github-actions-buildcache <https://github.com/spack/github-actions-buildcache>`_
 
 .. _cmd-spack-buildcache:
 

lib/spack/docs/build_settings.rst

@@ -37,7 +37,11 @@ to enable reuse for a single installation, and you can use:
    spack install --fresh <spec>
 
 to do a fresh install if ``reuse`` is enabled by default.
-``reuse: true`` is the default.
+``reuse: dependencies`` is the default.
+
+.. seealso::
+
+   FAQ: :ref:`Why does Spack pick particular versions and variants? <faq-concretizer-precedence>`
 
 ------------------------------------------
 Selection of the target microarchitectures
@@ -99,551 +103,3 @@ while `py-numpy` still needs an older version:
 
 Up to Spack v0.20 ``duplicates:strategy:none`` was the default (and only) behavior. From Spack v0.21 the
 default behavior is ``duplicates:strategy:minimal``.
-
-.. _build-settings:
-
-================================
-Package Settings (packages.yaml)
-================================
-
-Spack allows you to customize how your software is built through the
-``packages.yaml`` file.  Using it, you can make Spack prefer particular
-implementations of virtual dependencies (e.g., MPI or BLAS/LAPACK),
-or you can make it prefer to build with particular compilers.  You can
-also tell Spack to use *external* software installations already
-present on your system.
-
-At a high level, the ``packages.yaml`` file is structured like this:
-
-.. code-block:: yaml
-
-   packages:
-     package1:
-       # settings for package1
-     package2:
-       # settings for package2
-     # ...
-     all:
-       # settings that apply to all packages.
-
-So you can either set build preferences specifically for *one* package,
-or you can specify that certain settings should apply to *all* packages.
-The types of settings you can customize are described in detail below.
-
-Spack's build defaults are in the default
-``etc/spack/defaults/packages.yaml`` file.  You can override them in
-``~/.spack/packages.yaml`` or ``etc/spack/packages.yaml``. For more
-details on how this works, see :ref:`configuration-scopes`.
-
-.. _sec-external-packages:
-
------------------
-External Packages
------------------
-
-Spack can be configured to use externally-installed
-packages rather than building its own packages. This may be desirable
-if machines ship with system packages, such as a customized MPI
-that should be used instead of Spack building its own MPI.
-
-External packages are configured through the ``packages.yaml`` file.
-Here's an example of an external configuration:
-
-.. code-block:: yaml
-
-   packages:
-     openmpi:
-       externals:
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.4.3
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
-         prefix: /opt/openmpi-1.4.3-debug
-       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.6.5-intel
-
-This example lists three installations of OpenMPI, one built with GCC,
-one built with GCC and debug information, and another built with Intel.
-If Spack is asked to build a package that uses one of these MPIs as a
-dependency, it will use the pre-installed OpenMPI in
-the given directory. Note that the specified path is the top-level
-install prefix, not the ``bin`` subdirectory.
-
-``packages.yaml`` can also be used to specify modules to load instead
-of the installation prefixes.  The following example says that module
-``CMake/3.7.2`` provides cmake version 3.7.2.
-
-.. code-block:: yaml
-
-   cmake:
-     externals:
-     - spec: cmake@3.7.2
-       modules:
-       - CMake/3.7.2
-
-Each ``packages.yaml`` begins with a ``packages:`` attribute, followed
-by a list of package names.  To specify externals, add an ``externals:``
-attribute under the package name, which lists externals.
-Each external should specify a ``spec:`` string that should be as
-well-defined as reasonably possible.  If a
-package lacks a spec component, such as missing a compiler or
-package version, then Spack will guess the missing component based
-on its most-favored packages, and it may guess incorrectly.
-
-Each package version and compiler listed in an external should
-have entries in Spack's packages and compiler configuration, even
-though the package and compiler may not ever be built.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Prevent packages from being built from sources
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Adding an external spec in ``packages.yaml`` allows Spack to use an external location,
-but it does not prevent Spack from building packages from sources. In the above example,
-Spack might choose for many valid reasons to start building and linking with the
-latest version of OpenMPI rather than continue using the pre-installed OpenMPI versions.
-
-To prevent this, the ``packages.yaml`` configuration also allows packages
-to be flagged as non-buildable.  The previous example could be modified to
-be:
-
-.. code-block:: yaml
-
-   packages:
-     openmpi:
-       externals:
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.4.3
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
-         prefix: /opt/openmpi-1.4.3-debug
-       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.6.5-intel
-       buildable: False
-
-The addition of the ``buildable`` flag tells Spack that it should never build
-its own version of OpenMPI from sources, and it will instead always rely on a pre-built
-OpenMPI.
-
-.. note::
-
-   If ``concretizer:reuse`` is on (see :ref:`concretizer-options` for more information on that flag)
-   pre-built specs include specs already available from a local store, an upstream store, a registered
-   buildcache or specs marked as externals in ``packages.yaml``. If ``concretizer:reuse`` is off, only
-   external specs in ``packages.yaml`` are included in the list of pre-built specs.
-
-If an external module is specified as not buildable, then Spack will load the
-external module into the build environment which can be used for linking.
-
-The ``buildable`` does not need to be paired with external packages.
-It could also be used alone to forbid packages that may be
-buggy or otherwise undesirable.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Non-buildable virtual packages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Virtual packages in Spack can also be specified as not buildable, and
-external implementations can be provided. In the example above,
-OpenMPI is configured as not buildable, but Spack will often prefer
-other MPI implementations over the externally available OpenMPI. Spack
-can be configured with every MPI provider not buildable individually,
-but more conveniently:
-
-.. code-block:: yaml
-
-   packages:
-     mpi:
-       buildable: False
-     openmpi:
-       externals:
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.4.3
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
-         prefix: /opt/openmpi-1.4.3-debug
-       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.6.5-intel
-
-Spack can then use any of the listed external implementations of MPI
-to satisfy a dependency, and will choose depending on the compiler and
-architecture.
-
-In cases where the concretizer is configured to reuse specs, and other ``mpi`` providers
-(available via stores or buildcaches) are not wanted, Spack can be configured to require
-specs matching only the available externals:
-
-.. code-block:: yaml
-
-   packages:
-     mpi:
-       buildable: False
-       require:
-       - one_of: [
-           "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64",
-           "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug",
-           "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
-         ]
-     openmpi:
-       externals:
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.4.3
-       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
-         prefix: /opt/openmpi-1.4.3-debug
-       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
-         prefix: /opt/openmpi-1.6.5-intel
-
-This configuration prevents any spec using MPI and originating from stores or buildcaches to be reused,
-unless it matches the requirements under ``packages:mpi:require``. For more information on requirements see
-:ref:`package-requirements`.
-
-.. _cmd-spack-external-find:
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Automatically Find External Packages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-You can run the :ref:`spack external find <spack-external-find>` command
-to search for system-provided packages and add them to ``packages.yaml``.
-After running this command your ``packages.yaml`` may include new entries:
-
-.. code-block:: yaml
-
-   packages:
-     cmake:
-       externals:
-       - spec: cmake@3.17.2
-         prefix: /usr
-
-Generally this is useful for detecting a small set of commonly-used packages;
-for now this is generally limited to finding build-only dependencies.
-Specific limitations include:
-
-* Packages are not discoverable by default: For a package to be
-  discoverable with ``spack external find``, it needs to add special
-  logic. See :ref:`here <make-package-findable>` for more details.
-* The logic does not search through module files, it can only detect
-  packages with executables defined in ``PATH``; you can help Spack locate
-  externals which use module files by loading any associated modules for
-  packages that you want Spack to know about before running
-  ``spack external find``.
-* Spack does not overwrite existing entries in the package configuration:
-  If there is an external defined for a spec at any configuration scope,
-  then Spack will not add a new external entry (``spack config blame packages``
-  can help locate all external entries).
-
-.. _package-requirements:
-
---------------------
-Package Requirements
---------------------
-
-Spack can be configured to always use certain compilers, package
-versions, and variants during concretization through package
-requirements.
-
-Package requirements are useful when you find yourself repeatedly
-specifying the same constraints on the command line, and wish that
-Spack respects these constraints whether you mention them explicitly
-or not. Another use case is specifying constraints that should apply
-to all root specs in an environment, without having to repeat the
-constraint everywhere.
-
-Apart from that, requirements config is more flexible than constraints
-on the command line, because it can specify constraints on packages
-*when they occur* as a dependency. In contrast, on the command line it
-is not possible to specify constraints on dependencies while also keeping
-those dependencies optional.
-
-^^^^^^^^^^^^^^^^^^^
-Requirements syntax
-^^^^^^^^^^^^^^^^^^^
-
-The package requirements configuration is specified in ``packages.yaml``,
-keyed by package name and expressed using the Spec syntax. In the simplest
-case you can specify attributes that you always want the package to have
-by providing a single spec string to ``require``:
-
-.. code-block:: yaml
-
-   packages:
-     libfabric:
-       require: "@1.13.2"
-
-In the above example, ``libfabric`` will always build with version 1.13.2. If you
-need to compose multiple configuration scopes ``require`` accepts a list of
-strings:
-
-.. code-block:: yaml
-
-   packages:
-     libfabric:
-       require:
-       - "@1.13.2"
-       - "%gcc"
-
-In this case ``libfabric`` will always build with version 1.13.2 **and** using GCC
-as a compiler.
-
-For more complex use cases, require accepts also a list of objects. These objects
-must have either a ``any_of`` or a ``one_of`` field, containing a list of spec strings,
-and they can optionally have a ``when`` and a ``message`` attribute:
-
-.. code-block:: yaml
-
-   packages:
-     openmpi:
-       require:
-       - any_of: ["@4.1.5", "%gcc"]
-         message: "in this example only 4.1.5 can build with other compilers"
-
-``any_of`` is a list of specs. One of those specs must be satisfied
-and it is also allowed for the concretized spec to match more than one.
-In the above example, that means you could build ``openmpi@4.1.5%gcc``,
-``openmpi@4.1.5%clang`` or ``openmpi@3.9%gcc``, but
-not ``openmpi@3.9%clang``.
-
-If a custom message is provided, and the requirement is not satisfiable,
-Spack will print the custom error message:
-
-.. code-block:: console
-
-   $ spack spec openmpi@3.9%clang
-   ==> Error: in this example only 4.1.5 can build with other compilers
-
-We could express a similar requirement using the ``when`` attribute:
-
-.. code-block:: yaml
-
-   packages:
-     openmpi:
-       require:
-       - any_of: ["%gcc"]
-         when: "@:4.1.4"
-         message: "in this example only 4.1.5 can build with other compilers"
-
-In the example above, if the version turns out to be 4.1.4 or less, we require the compiler to be GCC.
-For readability, Spack also allows a ``spec`` key accepting a string when there is only a single
-constraint:
-
-.. code-block:: yaml
-
-   packages:
-     openmpi:
-       require:
-       - spec: "%gcc"
-         when: "@:4.1.4"
-         message: "in this example only 4.1.5 can build with other compilers"
-
-This code snippet and the one before it are semantically equivalent.
-
-Finally, instead of ``any_of`` you can use ``one_of`` which also takes a list of specs. The final
-concretized spec must match one and only one of them:
-
-.. code-block:: yaml
-
-   packages:
-     mpich:
-       require:
-       - one_of: ["+cuda", "+rocm"]
-
-In the example above, that means you could build ``mpich+cuda`` or ``mpich+rocm`` but not ``mpich+cuda+rocm``.
-
-.. note::
-
-   For ``any_of`` and ``one_of``, the order of specs indicates a
-   preference: items that appear earlier in the list are preferred
-   (note that these preferences can be ignored in favor of others).
-
-.. note::
-
-   When using a conditional requirement, Spack is allowed to actively avoid the triggering
-   condition (the ``when=...`` spec) if that leads to a concrete spec with better scores in
-   the optimization criteria. To check the current optimization criteria and their
-   priorities you can run ``spack solve zlib``.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Setting default requirements
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-You can also set default requirements for all packages under ``all``
-like this:
-
-.. code-block:: yaml
-
-   packages:
-     all:
-       require: '%clang'
-
-which means every spec will be required to use ``clang`` as a compiler.
-
-Note that in this case ``all`` represents a *default set of requirements* -
-if there are specific package requirements, then the default requirements
-under ``all`` are disregarded. For example, with a configuration like this:
-
-.. code-block:: yaml
-
-   packages:
-     all:
-       require: '%clang'
-     cmake:
-       require: '%gcc'
-
-Spack requires ``cmake`` to use ``gcc`` and all other nodes (including ``cmake``
-dependencies) to use ``clang``.
-
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Setting requirements on virtual specs
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-A requirement on a virtual spec applies whenever that virtual is present in the DAG.
-This can be useful for fixing which virtual provider you want to use:
-
-.. code-block:: yaml
-
-   packages:
-     mpi:
-       require: 'mvapich2 %gcc'
-
-With the configuration above the only allowed ``mpi`` provider is ``mvapich2 %gcc``.
-
-Requirements on the virtual spec and on the specific provider are both applied, if
-present. For instance with a configuration like:
-
-.. code-block:: yaml
-
-   packages:
-     mpi:
-       require: 'mvapich2 %gcc'
-     mvapich2:
-       require: '~cuda'
-
-you will use ``mvapich2~cuda %gcc`` as an ``mpi`` provider.
-
-.. _package-preferences:
-
--------------------
-Package Preferences
--------------------
-
-In some cases package requirements can be too strong, and package
-preferences are the better option. Package preferences do not impose
-constraints on packages for particular versions or variants values,
-they rather only set defaults -- the concretizer is free to change
-them if it must due to other constraints. Also note that package
-preferences are of lower priority than reuse of already installed
-packages.
-
-Here's an example ``packages.yaml`` file that sets preferred packages:
-
-.. code-block:: yaml
-
-   packages:
-     opencv:
-       compiler: [gcc@4.9]
-       variants: +debug
-     gperftools:
-       version: [2.2, 2.4, 2.3]
-     all:
-       compiler: [gcc@4.4.7, 'gcc@4.6:', intel, clang, pgi]
-       target: [sandybridge]
-       providers:
-         mpi: [mvapich2, mpich, openmpi]
-
-At a high level, this example is specifying how packages are preferably
-concretized.  The opencv package should prefer using GCC 4.9 and
-be built with debug options.  The gperftools package should prefer version
-2.2 over 2.4.  Every package on the system should prefer mvapich2 for
-its MPI and GCC 4.4.7 (except for opencv, which overrides this by preferring GCC 4.9).
-These options are used to fill in implicit defaults.  Any of them can be overwritten
-on the command line if explicitly requested.
-
-Package preferences accept the follow keys or components under
-the specific package (or ``all``) section: ``compiler``, ``variants``,
-``version``, ``providers``, and ``target``.  Each component has an
-ordered list of spec ``constraints``, with earlier entries in the
-list being preferred over later entries.
-
-Sometimes a package installation may have constraints that forbid
-the first concretization rule, in which case Spack will use the first
-legal concretization rule.  Going back to the example, if a user
-requests gperftools 2.3 or later, then Spack will install version 2.4
-as the 2.4 version of gperftools is preferred over 2.3.
-
-An explicit concretization rule in the preferred section will always
-take preference over unlisted concretizations.  In the above example,
-xlc isn't listed in the compiler list.  Every listed compiler from
-gcc to pgi will thus be preferred over the xlc compiler.
-
-The syntax for the ``provider`` section differs slightly from other
-concretization rules.  A provider lists a value that packages may
-``depends_on`` (e.g, MPI) and a list of rules for fulfilling that
-dependency.
-
-.. _package_permissions:
-
--------------------
-Package Permissions
--------------------
-
-Spack can be configured to assign permissions to the files installed
-by a package.
-
-In the ``packages.yaml`` file under ``permissions``, the attributes
-``read``, ``write``, and ``group`` control the package
-permissions. These attributes can be set per-package, or for all
-packages under ``all``. If permissions are set under ``all`` and for a
-specific package, the package-specific settings take precedence.
-
-The ``read`` and ``write`` attributes take one of ``user``, ``group``,
-and ``world``.
-
-.. code-block:: yaml
-
-  packages:
-    all:
-      permissions:
-        write: group
-        group: spack
-    my_app:
-      permissions:
-        read: group
-        group: my_team
-
-The permissions settings describe the broadest level of access to
-installations of the specified packages. The execute permissions of
-the file are set to the same level as read permissions for those files
-that are executable. The default setting for ``read`` is ``world``,
-and for ``write`` is ``user``. In the example above, installations of
-``my_app`` will be installed with user and group permissions but no
-world permissions, and owned by the group ``my_team``. All other
-packages will be installed with user and group write privileges, and
-world read privileges. Those packages will be owned by the group
-``spack``.
-
-The ``group`` attribute assigns a Unix-style group to a package. All
-files installed by the package will be owned by the assigned group,
-and the sticky group bit will be set on the install prefix and all
-directories inside the install prefix. This will ensure that even
-manually placed files within the install prefix are owned by the
-assigned group. If no group is assigned, Spack will allow the OS
-default behavior to go as expected.
-
-----------------------------
-Assigning Package Attributes
-----------------------------
-
-You can assign class-level attributes in the configuration:
-
-.. code-block:: yaml
-
-  packages:
-    mpileaks:
-      # Override existing attributes
-      url: http://www.somewhereelse.com/mpileaks-1.0.tar.gz
-      # ... or add new ones
-      x: 1
-
-Attributes set this way will be accessible to any method executed
-in the package.py file (e.g. the ``install()`` method). Values for these
-attributes may be any value parseable by yaml.
-
-These can only be applied to specific packages, not "all" or
-virtual packages.

lib/spack/docs/build_systems/intelpackage.rst

@@ -392,7 +392,7 @@ See section
 :ref:`Configuration Scopes <configuration-scopes>`
 for an explanation about the different files
 and section
-:ref:`Build customization <build-settings>`
+:ref:`Build customization <packages-config>`
 for specifics and examples for ``packages.yaml`` files.
 
 .. If your system administrator did not provide modules for pre-installed Intel

lib/spack/docs/config_yaml.rst

@@ -304,3 +304,17 @@ To work properly, this requires your terminal to reset its title after
 Spack has finished its work, otherwise Spack's status information will
 remain in the terminal's title indefinitely. Most terminals should already
 be set up this way and clear Spack's status information.
+
+-----------
+``aliases``
+-----------
+
+Aliases can be used to define new Spack commands. They can be either shortcuts
+for longer commands or include specific arguments for convenience. For instance,
+if users want to use ``spack install``'s ``-v`` argument all the time, they can
+create a new alias called ``inst`` that will always call ``install -v``:
+
+.. code-block:: yaml
+
+   aliases:
+     inst: install -v

lib/spack/docs/configuration.rst

@@ -17,7 +17,7 @@ case you want to skip directly to specific docs:
 * :ref:`config.yaml <config-yaml>`
 * :ref:`mirrors.yaml <mirrors>`
 * :ref:`modules.yaml <modules>`
-* :ref:`packages.yaml <build-settings>`
+* :ref:`packages.yaml <packages-config>`
 * :ref:`repos.yaml <repositories>`
 
 You can also add any of these as inline configuration in the YAML

lib/spack/docs/frequently_asked_questions.rst

@@ -0,0 +1,77 @@
+.. Copyright 2013-2023 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)
+
+==========================
+Frequently Asked Questions
+==========================
+
+This page contains answers to frequently asked questions about Spack.
+If you have questions that are not answered here, feel free to ask on
+`Slack <https://slack.spack.io>`_ or `GitHub Discussions
+<https://github.com/spack/spack/discussions>`_. If you've learned the
+answer to a question that you think should be here, please consider
+contributing to this page.
+
+.. _faq-concretizer-precedence:
+
+-----------------------------------------------------
+Why does Spack pick particular versions and variants?
+-----------------------------------------------------
+
+This question comes up in a variety of forms:
+
+ 1. Why does Spack seem to ignore my package preferences from ``packages.yaml`` config?
+ 2. Why does Spack toggle a variant instead of using the default from the ``package.py`` file?
+
+The short answer is that Spack always picks an optimal configuration
+based on a complex set of criteria\ [#f1]_. These criteria are more nuanced
+than always choosing the latest versions or default variants.
+
+.. note::
+
+    As a rule of thumb: requirements + constraints > reuse > preferences > defaults.
+
+The following set of criteria (from lowest to highest precedence) explain
+common cases where concretization output may seem surprising at first.
+
+1. :ref:`Package preferences <package-preferences>` configured in ``packages.yaml``
+   override variant defaults from ``package.py`` files, and influence the optimal
+   ordering of versions. Preferences are specified as follows:
+
+   .. code-block:: yaml
+
+      packages:
+        foo:
+          version: [1.0, 1.1]
+          variants: ~mpi
+
+2. :ref:`Reuse concretization <concretizer-options>` configured in ``concretizer.yaml``
+   overrides preferences, since it's typically faster to reuse an existing spec than to
+   build a preferred one from sources. When build caches are enabled, specs may be reused
+   from a remote location too. Reuse concretization is configured as follows:
+
+   .. code-block:: yaml
+
+      concretizer:
+        reuse: dependencies  # other options are 'true' and 'false'
+
+3. :ref:`Package requirements <package-requirements>` configured in ``packages.yaml``,
+   and constraints from the command line as well as ``package.py`` files override all
+   of the above. Requirements are specified as follows:
+
+   .. code-block:: yaml
+
+      packages:
+        foo:
+          require:
+          - "@1.2: +mpi"
+
+Requirements and constraints restrict the set of possible solutions, while reuse
+behavior and preferences influence what an optimal solution looks like.
+
+
+.. rubric:: Footnotes
+
+.. [#f1] The exact list of criteria can be retrieved with the ``spack solve`` command

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lib/spack/docs/index.rst

@@ -55,6 +55,7 @@ or refer to the full manual below.
    getting_started
    basic_usage
    replace_conda_homebrew
+   frequently_asked_questions
 
 .. toctree::
    :maxdepth: 2
@@ -70,7 +71,7 @@ or refer to the full manual below.
 
    configuration
    config_yaml
-   bootstrapping
+   packages_yaml
    build_settings
    environments
    containers
@@ -78,6 +79,7 @@ or refer to the full manual below.
    module_file_support
    repositories
    binary_caches
+   bootstrapping
    command_index
    chain
    extensions

lib/spack/docs/module_file_support.rst

@@ -519,11 +519,11 @@ inspections and customize them per-module-set.
 
   modules:
     prefix_inspections:
-      bin:
+      ./bin:
         - PATH
-      man:
+      ./man:
         - MANPATH
-      '':
+      ./:
         - CMAKE_PREFIX_PATH
 
 Prefix inspections are only applied if the relative path inside the
@@ -579,7 +579,7 @@ the view.
        view_relative_modules:
          use_view: my_view
        prefix_inspections:
-         bin:
+         ./bin:
            - PATH
      view:
        my_view:

lib/spack/docs/packages_yaml.rst

@@ -0,0 +1,560 @@
+.. Copyright 2013-2023 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)
+
+
+.. _packages-config:
+
+================================
+Package Settings (packages.yaml)
+================================
+
+Spack allows you to customize how your software is built through the
+``packages.yaml`` file.  Using it, you can make Spack prefer particular
+implementations of virtual dependencies (e.g., MPI or BLAS/LAPACK),
+or you can make it prefer to build with particular compilers.  You can
+also tell Spack to use *external* software installations already
+present on your system.
+
+At a high level, the ``packages.yaml`` file is structured like this:
+
+.. code-block:: yaml
+
+   packages:
+     package1:
+       # settings for package1
+     package2:
+       # settings for package2
+     # ...
+     all:
+       # settings that apply to all packages.
+
+So you can either set build preferences specifically for *one* package,
+or you can specify that certain settings should apply to *all* packages.
+The types of settings you can customize are described in detail below.
+
+Spack's build defaults are in the default
+``etc/spack/defaults/packages.yaml`` file.  You can override them in
+``~/.spack/packages.yaml`` or ``etc/spack/packages.yaml``. For more
+details on how this works, see :ref:`configuration-scopes`.
+
+.. _sec-external-packages:
+
+-----------------
+External Packages
+-----------------
+
+Spack can be configured to use externally-installed
+packages rather than building its own packages. This may be desirable
+if machines ship with system packages, such as a customized MPI
+that should be used instead of Spack building its own MPI.
+
+External packages are configured through the ``packages.yaml`` file.
+Here's an example of an external configuration:
+
+.. code-block:: yaml
+
+   packages:
+     openmpi:
+       externals:
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.4.3
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
+         prefix: /opt/openmpi-1.4.3-debug
+       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.6.5-intel
+
+This example lists three installations of OpenMPI, one built with GCC,
+one built with GCC and debug information, and another built with Intel.
+If Spack is asked to build a package that uses one of these MPIs as a
+dependency, it will use the pre-installed OpenMPI in
+the given directory. Note that the specified path is the top-level
+install prefix, not the ``bin`` subdirectory.
+
+``packages.yaml`` can also be used to specify modules to load instead
+of the installation prefixes.  The following example says that module
+``CMake/3.7.2`` provides cmake version 3.7.2.
+
+.. code-block:: yaml
+
+   cmake:
+     externals:
+     - spec: cmake@3.7.2
+       modules:
+       - CMake/3.7.2
+
+Each ``packages.yaml`` begins with a ``packages:`` attribute, followed
+by a list of package names.  To specify externals, add an ``externals:``
+attribute under the package name, which lists externals.
+Each external should specify a ``spec:`` string that should be as
+well-defined as reasonably possible.  If a
+package lacks a spec component, such as missing a compiler or
+package version, then Spack will guess the missing component based
+on its most-favored packages, and it may guess incorrectly.
+
+Each package version and compiler listed in an external should
+have entries in Spack's packages and compiler configuration, even
+though the package and compiler may not ever be built.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Prevent packages from being built from sources
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Adding an external spec in ``packages.yaml`` allows Spack to use an external location,
+but it does not prevent Spack from building packages from sources. In the above example,
+Spack might choose for many valid reasons to start building and linking with the
+latest version of OpenMPI rather than continue using the pre-installed OpenMPI versions.
+
+To prevent this, the ``packages.yaml`` configuration also allows packages
+to be flagged as non-buildable.  The previous example could be modified to
+be:
+
+.. code-block:: yaml
+
+   packages:
+     openmpi:
+       externals:
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.4.3
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
+         prefix: /opt/openmpi-1.4.3-debug
+       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.6.5-intel
+       buildable: False
+
+The addition of the ``buildable`` flag tells Spack that it should never build
+its own version of OpenMPI from sources, and it will instead always rely on a pre-built
+OpenMPI.
+
+.. note::
+
+   If ``concretizer:reuse`` is on (see :ref:`concretizer-options` for more information on that flag)
+   pre-built specs include specs already available from a local store, an upstream store, a registered
+   buildcache or specs marked as externals in ``packages.yaml``. If ``concretizer:reuse`` is off, only
+   external specs in ``packages.yaml`` are included in the list of pre-built specs.
+
+If an external module is specified as not buildable, then Spack will load the
+external module into the build environment which can be used for linking.
+
+The ``buildable`` does not need to be paired with external packages.
+It could also be used alone to forbid packages that may be
+buggy or otherwise undesirable.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Non-buildable virtual packages
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Virtual packages in Spack can also be specified as not buildable, and
+external implementations can be provided. In the example above,
+OpenMPI is configured as not buildable, but Spack will often prefer
+other MPI implementations over the externally available OpenMPI. Spack
+can be configured with every MPI provider not buildable individually,
+but more conveniently:
+
+.. code-block:: yaml
+
+   packages:
+     mpi:
+       buildable: False
+     openmpi:
+       externals:
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.4.3
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
+         prefix: /opt/openmpi-1.4.3-debug
+       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.6.5-intel
+
+Spack can then use any of the listed external implementations of MPI
+to satisfy a dependency, and will choose depending on the compiler and
+architecture.
+
+In cases where the concretizer is configured to reuse specs, and other ``mpi`` providers
+(available via stores or buildcaches) are not wanted, Spack can be configured to require
+specs matching only the available externals:
+
+.. code-block:: yaml
+
+   packages:
+     mpi:
+       buildable: False
+       require:
+       - one_of: [
+           "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64",
+           "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug",
+           "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
+         ]
+     openmpi:
+       externals:
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.4.3
+       - spec: "openmpi@1.4.3%gcc@4.4.7 arch=linux-debian7-x86_64+debug"
+         prefix: /opt/openmpi-1.4.3-debug
+       - spec: "openmpi@1.6.5%intel@10.1 arch=linux-debian7-x86_64"
+         prefix: /opt/openmpi-1.6.5-intel
+
+This configuration prevents any spec using MPI and originating from stores or buildcaches to be reused,
+unless it matches the requirements under ``packages:mpi:require``. For more information on requirements see
+:ref:`package-requirements`.
+
+.. _cmd-spack-external-find:
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Automatically Find External Packages
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You can run the :ref:`spack external find <spack-external-find>` command
+to search for system-provided packages and add them to ``packages.yaml``.
+After running this command your ``packages.yaml`` may include new entries:
+
+.. code-block:: yaml
+
+   packages:
+     cmake:
+       externals:
+       - spec: cmake@3.17.2
+         prefix: /usr
+
+Generally this is useful for detecting a small set of commonly-used packages;
+for now this is generally limited to finding build-only dependencies.
+Specific limitations include:
+
+* Packages are not discoverable by default: For a package to be
+  discoverable with ``spack external find``, it needs to add special
+  logic. See :ref:`here <make-package-findable>` for more details.
+* The logic does not search through module files, it can only detect
+  packages with executables defined in ``PATH``; you can help Spack locate
+  externals which use module files by loading any associated modules for
+  packages that you want Spack to know about before running
+  ``spack external find``.
+* Spack does not overwrite existing entries in the package configuration:
+  If there is an external defined for a spec at any configuration scope,
+  then Spack will not add a new external entry (``spack config blame packages``
+  can help locate all external entries).
+
+.. _package-requirements:
+
+--------------------
+Package Requirements
+--------------------
+
+Spack can be configured to always use certain compilers, package
+versions, and variants during concretization through package
+requirements.
+
+Package requirements are useful when you find yourself repeatedly
+specifying the same constraints on the command line, and wish that
+Spack respects these constraints whether you mention them explicitly
+or not. Another use case is specifying constraints that should apply
+to all root specs in an environment, without having to repeat the
+constraint everywhere.
+
+Apart from that, requirements config is more flexible than constraints
+on the command line, because it can specify constraints on packages
+*when they occur* as a dependency. In contrast, on the command line it
+is not possible to specify constraints on dependencies while also keeping
+those dependencies optional.
+
+.. seealso::
+
+   FAQ: :ref:`Why does Spack pick particular versions and variants? <faq-concretizer-precedence>`
+
+
+^^^^^^^^^^^^^^^^^^^
+Requirements syntax
+^^^^^^^^^^^^^^^^^^^
+
+The package requirements configuration is specified in ``packages.yaml``,
+keyed by package name and expressed using the Spec syntax. In the simplest
+case you can specify attributes that you always want the package to have
+by providing a single spec string to ``require``:
+
+.. code-block:: yaml
+
+   packages:
+     libfabric:
+       require: "@1.13.2"
+
+In the above example, ``libfabric`` will always build with version 1.13.2. If you
+need to compose multiple configuration scopes ``require`` accepts a list of
+strings:
+
+.. code-block:: yaml
+
+   packages:
+     libfabric:
+       require:
+       - "@1.13.2"
+       - "%gcc"
+
+In this case ``libfabric`` will always build with version 1.13.2 **and** using GCC
+as a compiler.
+
+For more complex use cases, require accepts also a list of objects. These objects
+must have either a ``any_of`` or a ``one_of`` field, containing a list of spec strings,
+and they can optionally have a ``when`` and a ``message`` attribute:
+
+.. code-block:: yaml
+
+   packages:
+     openmpi:
+       require:
+       - any_of: ["@4.1.5", "%gcc"]
+         message: "in this example only 4.1.5 can build with other compilers"
+
+``any_of`` is a list of specs. One of those specs must be satisfied
+and it is also allowed for the concretized spec to match more than one.
+In the above example, that means you could build ``openmpi@4.1.5%gcc``,
+``openmpi@4.1.5%clang`` or ``openmpi@3.9%gcc``, but
+not ``openmpi@3.9%clang``.
+
+If a custom message is provided, and the requirement is not satisfiable,
+Spack will print the custom error message:
+
+.. code-block:: console
+
+   $ spack spec openmpi@3.9%clang
+   ==> Error: in this example only 4.1.5 can build with other compilers
+
+We could express a similar requirement using the ``when`` attribute:
+
+.. code-block:: yaml
+
+   packages:
+     openmpi:
+       require:
+       - any_of: ["%gcc"]
+         when: "@:4.1.4"
+         message: "in this example only 4.1.5 can build with other compilers"
+
+In the example above, if the version turns out to be 4.1.4 or less, we require the compiler to be GCC.
+For readability, Spack also allows a ``spec`` key accepting a string when there is only a single
+constraint:
+
+.. code-block:: yaml
+
+   packages:
+     openmpi:
+       require:
+       - spec: "%gcc"
+         when: "@:4.1.4"
+         message: "in this example only 4.1.5 can build with other compilers"
+
+This code snippet and the one before it are semantically equivalent.
+
+Finally, instead of ``any_of`` you can use ``one_of`` which also takes a list of specs. The final
+concretized spec must match one and only one of them:
+
+.. code-block:: yaml
+
+   packages:
+     mpich:
+       require:
+       - one_of: ["+cuda", "+rocm"]
+
+In the example above, that means you could build ``mpich+cuda`` or ``mpich+rocm`` but not ``mpich+cuda+rocm``.
+
+.. note::
+
+   For ``any_of`` and ``one_of``, the order of specs indicates a
+   preference: items that appear earlier in the list are preferred
+   (note that these preferences can be ignored in favor of others).
+
+.. note::
+
+   When using a conditional requirement, Spack is allowed to actively avoid the triggering
+   condition (the ``when=...`` spec) if that leads to a concrete spec with better scores in
+   the optimization criteria. To check the current optimization criteria and their
+   priorities you can run ``spack solve zlib``.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Setting default requirements
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You can also set default requirements for all packages under ``all``
+like this:
+
+.. code-block:: yaml
+
+   packages:
+     all:
+       require: '%clang'
+
+which means every spec will be required to use ``clang`` as a compiler.
+
+Note that in this case ``all`` represents a *default set of requirements* -
+if there are specific package requirements, then the default requirements
+under ``all`` are disregarded. For example, with a configuration like this:
+
+.. code-block:: yaml
+
+   packages:
+     all:
+       require: '%clang'
+     cmake:
+       require: '%gcc'
+
+Spack requires ``cmake`` to use ``gcc`` and all other nodes (including ``cmake``
+dependencies) to use ``clang``.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Setting requirements on virtual specs
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A requirement on a virtual spec applies whenever that virtual is present in the DAG.
+This can be useful for fixing which virtual provider you want to use:
+
+.. code-block:: yaml
+
+   packages:
+     mpi:
+       require: 'mvapich2 %gcc'
+
+With the configuration above the only allowed ``mpi`` provider is ``mvapich2 %gcc``.
+
+Requirements on the virtual spec and on the specific provider are both applied, if
+present. For instance with a configuration like:
+
+.. code-block:: yaml
+
+   packages:
+     mpi:
+       require: 'mvapich2 %gcc'
+     mvapich2:
+       require: '~cuda'
+
+you will use ``mvapich2~cuda %gcc`` as an ``mpi`` provider.
+
+.. _package-preferences:
+
+-------------------
+Package Preferences
+-------------------
+
+In some cases package requirements can be too strong, and package
+preferences are the better option. Package preferences do not impose
+constraints on packages for particular versions or variants values,
+they rather only set defaults. The concretizer is free to change
+them if it must, due to other constraints, and also prefers reusing
+installed packages over building new ones that are a better match for
+preferences.
+
+.. seealso::
+
+   FAQ: :ref:`Why does Spack pick particular versions and variants? <faq-concretizer-precedence>`
+
+
+Most package preferences (``compilers``, ``target`` and ``providers``)
+can only be set globally under the ``all`` section of ``packages.yaml``:
+
+.. code-block:: yaml
+
+   packages:
+     all:
+       compiler: [gcc@12.2.0, clang@12:, oneapi@2023:]
+       target: [x86_64_v3]
+       providers:
+         mpi: [mvapich2, mpich, openmpi]
+
+These preferences override Spack's default and effectively reorder priorities
+when looking for the best compiler, target or virtual package provider. Each
+preference takes an ordered list of spec constraints, with earlier entries in
+the list being preferred over later entries.
+
+In the example above all packages prefer to be compiled with ``gcc@12.2.0``,
+to target the ``x86_64_v3`` microarchitecture and to use ``mvapich2`` if they
+depend on ``mpi``.
+
+The ``variants`` and ``version`` preferences can be set under
+package specific sections of the ``packages.yaml`` file:
+
+.. code-block:: yaml
+
+   packages:
+     opencv:
+       variants: +debug
+     gperftools:
+       version: [2.2, 2.4, 2.3]
+
+In this case, the preference for ``opencv`` is to build with debug options, while
+``gperftools`` prefers version 2.2 over 2.4.
+
+Any preference can be overwritten on the command line if explicitly requested.
+
+Preferences cannot overcome explicit constraints, as they only set a preferred
+ordering among homogeneous attribute values. Going back to the example, if
+``gperftools@2.3:`` was requested, then Spack will install version 2.4
+since the most preferred version 2.2 is prohibited by the version constraint.
+
+.. _package_permissions:
+
+-------------------
+Package Permissions
+-------------------
+
+Spack can be configured to assign permissions to the files installed
+by a package.
+
+In the ``packages.yaml`` file under ``permissions``, the attributes
+``read``, ``write``, and ``group`` control the package
+permissions. These attributes can be set per-package, or for all
+packages under ``all``. If permissions are set under ``all`` and for a
+specific package, the package-specific settings take precedence.
+
+The ``read`` and ``write`` attributes take one of ``user``, ``group``,
+and ``world``.
+
+.. code-block:: yaml
+
+  packages:
+    all:
+      permissions:
+        write: group
+        group: spack
+    my_app:
+      permissions:
+        read: group
+        group: my_team
+
+The permissions settings describe the broadest level of access to
+installations of the specified packages. The execute permissions of
+the file are set to the same level as read permissions for those files
+that are executable. The default setting for ``read`` is ``world``,
+and for ``write`` is ``user``. In the example above, installations of
+``my_app`` will be installed with user and group permissions but no
+world permissions, and owned by the group ``my_team``. All other
+packages will be installed with user and group write privileges, and
+world read privileges. Those packages will be owned by the group
+``spack``.
+
+The ``group`` attribute assigns a Unix-style group to a package. All
+files installed by the package will be owned by the assigned group,
+and the sticky group bit will be set on the install prefix and all
+directories inside the install prefix. This will ensure that even
+manually placed files within the install prefix are owned by the
+assigned group. If no group is assigned, Spack will allow the OS
+default behavior to go as expected.
+
+----------------------------
+Assigning Package Attributes
+----------------------------
+
+You can assign class-level attributes in the configuration:
+
+.. code-block:: yaml
+
+  packages:
+    mpileaks:
+      package_attributes:
+        # Override existing attributes
+        url: http://www.somewhereelse.com/mpileaks-1.0.tar.gz
+        # ... or add new ones
+        x: 1
+
+Attributes set this way will be accessible to any method executed
+in the package.py file (e.g. the ``install()`` method). Values for these
+attributes may be any value parseable by yaml.
+
+These can only be applied to specific packages, not "all" or
+virtual packages.

lib/spack/docs/packaging_guide.rst

@@ -2352,7 +2352,7 @@ the following at the command line of a bash shell:
 
 .. code-block:: console
 
-   $ for i in {1..12}; do nohup spack install -j 4 mpich@3.3.2 >> mpich_install.txt 2>&1 &; done
+   $ for i in {1..12}; do nohup spack install -j 4 mpich@3.3.2 >> mpich_install.txt 2>&1 & done
 
 .. note::
 
@@ -2974,6 +2974,33 @@ The ``provides("mpi")`` call tells Spack that the ``mpich`` package
 can be used to satisfy the dependency of any package that
 ``depends_on("mpi")``.
 
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Providing multiple virtuals simultaneously
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Packages can provide more than one virtual dependency. Sometimes, due to implementation details,
+there are subsets of those virtuals that need to be provided together by the same package.
+
+A well-known example is ``openblas``, which provides both the ``lapack`` and ``blas`` API in a single ``libopenblas``
+library. A package that needs ``lapack`` and ``blas`` must either use ``openblas`` to provide both, or not use
+``openblas`` at all. It cannot pick one or the other.
+
+To express this constraint in a package, the two virtual dependencies must be listed in the same ``provides`` directive:
+
+.. code-block:: python
+
+   provides('blas', 'lapack')
+
+This makes it impossible to select ``openblas`` as a provider for one of the two
+virtual dependencies and not for the other. If you try to, Spack will report an error:
+
+.. code-block:: console
+
+   $ spack spec netlib-scalapack  ^[virtuals=lapack] openblas ^[virtuals=blas] atlas
+   ==> Error: concretization failed for the following reasons:
+
+      1. Package 'openblas' needs to provide both 'lapack' and 'blas' together, but provides only 'lapack'
+
 ^^^^^^^^^^^^^^^^^^^^
 Versioned Interfaces
 ^^^^^^^^^^^^^^^^^^^^
@@ -3476,6 +3503,56 @@ is equivalent to:
 Constraints from nested context managers are also combined together, but they are rarely
 needed or recommended.
 
+.. _default_args:
+
+------------------------
+Common default arguments
+------------------------
+
+Similarly, if directives have a common set of default arguments, you can
+group them together in a ``with default_args()`` block:
+
+.. code-block:: python
+
+   class PyExample(PythonPackage):
+
+       with default_args(type=("build", "run")):
+           depends_on("py-foo")
+           depends_on("py-foo@2:", when="@2:")
+           depends_on("py-bar")
+           depends_on("py-bz")
+
+The above is short for:
+
+.. code-block:: python
+
+   class PyExample(PythonPackage):
+
+       depends_on("py-foo", type=("build", "run"))
+       depends_on("py-foo@2:", when="@2:", type=("build", "run"))
+       depends_on("py-bar", type=("build", "run"))
+       depends_on("py-bz", type=("build", "run"))
+
+.. note::
+
+   The ``with when()`` context manager is composable, while ``with default_args()``
+   merely overrides the default. For example:
+
+   .. code-block:: python
+
+      with default_args(when="+feature"):
+          depends_on("foo")
+          depends_on("bar")
+          depends_on("baz", when="+baz")
+
+   is equivalent to:
+
+   .. code-block:: python
+
+      depends_on("foo", when="+feature")
+      depends_on("bar", when="+feature")
+      depends_on("baz", when="+baz")  # Note: not when="+feature+baz"
+
 .. _install-method:
 
 ------------------

lib/spack/external/__init__.py

@@ -18,7 +18,7 @@
 
 * Homepage: https://pypi.python.org/pypi/archspec
 * Usage: Labeling, comparison and detection of microarchitectures
-* Version: 0.2.1 (commit df43a1834460bf94516136951c4729a3100603ec)
+* Version: 0.2.5-dev (commit cbb1fd5eb397a70d466e5160b393b87b0dbcc78f)
 
 astunparse
 ----------------

lib/spack/external/archspec/__init__.py

@@ -1,2 +1,3 @@
 """Init file to avoid namespace packages"""
-__version__ = "0.2.1"
+
+__version__ = "0.2.4"

lib/spack/external/archspec/__main__.py

@@ -3,6 +3,7 @@
 """
 
 import sys
+
 from .cli import main
 
 sys.exit(main())

lib/spack/external/archspec/cli.py

@@ -46,7 +46,11 @@ def _make_parser() -> argparse.ArgumentParser:
 
 def cpu() -> int:
     """Run the `archspec cpu` subcommand."""
-    print(archspec.cpu.host())
+    try:
+        print(archspec.cpu.host())
+    except FileNotFoundError as exc:
+        print(exc)
+        return 1
     return 0
 
 

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

@@ -5,10 +5,14 @@
 """The "cpu" package permits to query and compare different
 CPU microarchitectures.
 """
-from .microarchitecture import Microarchitecture, UnsupportedMicroarchitecture
-from .microarchitecture import TARGETS, generic_microarchitecture
-from .microarchitecture import version_components
-from .detect import host
+from .detect import brand_string, host
+from .microarchitecture import (
+    TARGETS,
+    Microarchitecture,
+    UnsupportedMicroarchitecture,
+    generic_microarchitecture,
+    version_components,
+)
 
 __all__ = [
     "Microarchitecture",
@@ -17,4 +21,5 @@
     "generic_microarchitecture",
     "host",
     "version_components",
+    "brand_string",
 ]

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

@@ -4,15 +4,17 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 """Detection of CPU microarchitectures"""
 import collections
-import functools
 import os
 import platform
 import re
+import struct
 import subprocess
 import warnings
+from typing import Dict, List, Optional, Set, Tuple, Union
 
-from .microarchitecture import generic_microarchitecture, TARGETS
-from .schema import TARGETS_JSON
+from ..vendor.cpuid.cpuid import CPUID
+from .microarchitecture import TARGETS, Microarchitecture, generic_microarchitecture
+from .schema import CPUID_JSON, TARGETS_JSON
 
 #: Mapping from operating systems to chain of commands
 #: to obtain a dictionary of raw info on the current cpu
@@ -22,43 +24,51 @@
 #: functions checking the compatibility of the host with a given target
 COMPATIBILITY_CHECKS = {}
 
+# Constants for commonly used architectures
+X86_64 = "x86_64"
+AARCH64 = "aarch64"
+PPC64LE = "ppc64le"
+PPC64 = "ppc64"
+RISCV64 = "riscv64"
 
-def info_dict(operating_system):
-    """Decorator to mark functions that are meant to return raw info on
-    the current cpu.
+
+def detection(operating_system: str):
+    """Decorator to mark functions that are meant to return partial information on the current cpu.
 
     Args:
-        operating_system (str or tuple): operating system for which the marked
-            function is a viable factory of raw info dictionaries.
+        operating_system: operating system where this function can be used.
     """
 
     def decorator(factory):
         INFO_FACTORY[operating_system].append(factory)
-
-        @functools.wraps(factory)
-        def _impl():
-            info = factory()
-
-            # Check that info contains a few mandatory fields
-            msg = 'field "{0}" is missing from raw info dictionary'
-            assert "vendor_id" in info, msg.format("vendor_id")
-            assert "flags" in info, msg.format("flags")
-            assert "model" in info, msg.format("model")
-            assert "model_name" in info, msg.format("model_name")
-
-            return info
-
-        return _impl
+        return factory
 
     return decorator
 
 
-@info_dict(operating_system="Linux")
-def proc_cpuinfo():
-    """Returns a raw info dictionary by parsing the first entry of
-    ``/proc/cpuinfo``
-    """
-    info = {}
+def partial_uarch(
+    name: str = "",
+    vendor: str = "",
+    features: Optional[Set[str]] = None,
+    generation: int = 0,
+    cpu_part: str = "",
+) -> Microarchitecture:
+    """Construct a partial microarchitecture, from information gathered during system scan."""
+    return Microarchitecture(
+        name=name,
+        parents=[],
+        vendor=vendor,
+        features=features or set(),
+        compilers={},
+        generation=generation,
+        cpu_part=cpu_part,
+    )
+
+
+@detection(operating_system="Linux")
+def proc_cpuinfo() -> Microarchitecture:
+    """Returns a partial Microarchitecture, obtained from scanning ``/proc/cpuinfo``"""
+    data = {}
     with open("/proc/cpuinfo") as file:  # pylint: disable=unspecified-encoding
         for line in file:
             key, separator, value = line.partition(":")
@@ -70,11 +80,122 @@ def proc_cpuinfo():
             #
             # we are on a blank line separating two cpus. Exit early as
             # we want to read just the first entry in /proc/cpuinfo
-            if separator != ":" and info:
+            if separator != ":" and data:
                 break
 
-            info[key.strip()] = value.strip()
-    return info
+            data[key.strip()] = value.strip()
+
+    architecture = _machine()
+    if architecture == X86_64:
+        return partial_uarch(
+            vendor=data.get("vendor_id", "generic"), features=_feature_set(data, key="flags")
+        )
+
+    if architecture == AARCH64:
+        return partial_uarch(
+            vendor=_canonicalize_aarch64_vendor(data),
+            features=_feature_set(data, key="Features"),
+            cpu_part=data.get("CPU part", ""),
+        )
+
+    if architecture in (PPC64LE, PPC64):
+        generation_match = re.search(r"POWER(\d+)", data.get("cpu", ""))
+        try:
+            generation = int(generation_match.group(1))
+        except AttributeError:
+            # There might be no match under emulated environments. For instance
+            # emulating a ppc64le with QEMU and Docker still reports the host
+            # /proc/cpuinfo and not a Power
+            generation = 0
+        return partial_uarch(generation=generation)
+
+    if architecture == RISCV64:
+        if data.get("uarch") == "sifive,u74-mc":
+            data["uarch"] = "u74mc"
+        return partial_uarch(name=data.get("uarch", RISCV64))
+
+    return generic_microarchitecture(architecture)
+
+
+class CpuidInfoCollector:
+    """Collects the information we need on the host CPU from cpuid"""
+
+    # pylint: disable=too-few-public-methods
+    def __init__(self):
+        self.cpuid = CPUID()
+
+        registers = self.cpuid.registers_for(**CPUID_JSON["vendor"]["input"])
+        self.highest_basic_support = registers.eax
+        self.vendor = struct.pack("III", registers.ebx, registers.edx, registers.ecx).decode(
+            "utf-8"
+        )
+
+        registers = self.cpuid.registers_for(**CPUID_JSON["highest_extension_support"]["input"])
+        self.highest_extension_support = registers.eax
+
+        self.features = self._features()
+
+    def _features(self):
+        result = set()
+
+        def check_features(data):
+            registers = self.cpuid.registers_for(**data["input"])
+            for feature_check in data["bits"]:
+                current = getattr(registers, feature_check["register"])
+                if self._is_bit_set(current, feature_check["bit"]):
+                    result.add(feature_check["name"])
+
+        for call_data in CPUID_JSON["flags"]:
+            if call_data["input"]["eax"] > self.highest_basic_support:
+                continue
+            check_features(call_data)
+
+        for call_data in CPUID_JSON["extension-flags"]:
+            if call_data["input"]["eax"] > self.highest_extension_support:
+                continue
+            check_features(call_data)
+
+        return result
+
+    def _is_bit_set(self, register: int, bit: int) -> bool:
+        mask = 1 << bit
+        return register & mask > 0
+
+    def brand_string(self) -> Optional[str]:
+        """Returns the brand string, if available."""
+        if self.highest_extension_support < 0x80000004:
+            return None
+
+        r1 = self.cpuid.registers_for(eax=0x80000002, ecx=0)
+        r2 = self.cpuid.registers_for(eax=0x80000003, ecx=0)
+        r3 = self.cpuid.registers_for(eax=0x80000004, ecx=0)
+        result = struct.pack(
+            "IIIIIIIIIIII",
+            r1.eax,
+            r1.ebx,
+            r1.ecx,
+            r1.edx,
+            r2.eax,
+            r2.ebx,
+            r2.ecx,
+            r2.edx,
+            r3.eax,
+            r3.ebx,
+            r3.ecx,
+            r3.edx,
+        ).decode("utf-8")
+        return result.strip("\x00")
+
+
+@detection(operating_system="Windows")
+def cpuid_info():
+    """Returns a partial Microarchitecture, obtained from running the cpuid instruction"""
+    architecture = _machine()
+    if architecture == X86_64:
+        data = CpuidInfoCollector()
+        return partial_uarch(vendor=data.vendor, features=data.features)
+
+    return generic_microarchitecture(architecture)
 
 
 def _check_output(args, env):
@@ -83,14 +204,25 @@ def _check_output(args, env):
     return str(output.decode("utf-8"))
 
 
+WINDOWS_MAPPING = {
+    "AMD64": X86_64,
+    "ARM64": AARCH64,
+}
+
+
 def _machine():
-    """ "Return the machine architecture we are on"""
+    """Return the machine architecture we are on"""
     operating_system = platform.system()
 
-    # If we are not on Darwin, trust what Python tells us
-    if operating_system != "Darwin":
+    # If we are not on Darwin or Windows, trust what Python tells us
+    if operating_system not in ("Darwin", "Windows"):
         return platform.machine()
 
+    # Normalize windows specific names
+    if operating_system == "Windows":
+        platform_machine = platform.machine()
+        return WINDOWS_MAPPING.get(platform_machine, platform_machine)
+
     # On Darwin it might happen that we are on M1, but using an interpreter
     # built for x86_64. In that case "platform.machine() == 'x86_64'", so we
     # need to fix that.
@@ -103,54 +235,47 @@ def _machine():
     if "Apple" in output:
         # Note that a native Python interpreter on Apple M1 would return
         # "arm64" instead of "aarch64". Here we normalize to the latter.
-        return "aarch64"
+        return AARCH64
 
-    return "x86_64"
+    return X86_64
 
 
-@info_dict(operating_system="Darwin")
-def sysctl_info_dict():
+@detection(operating_system="Darwin")
+def sysctl_info() -> Microarchitecture:
     """Returns a raw info dictionary parsing the output of sysctl."""
     child_environment = _ensure_bin_usrbin_in_path()
 
-    def sysctl(*args):
+    def sysctl(*args: str) -> str:
         return _check_output(["sysctl"] + list(args), env=child_environment).strip()
 
-    if _machine() == "x86_64":
-        flags = (
-            sysctl("-n", "machdep.cpu.features").lower()
-            + " "
-            + sysctl("-n", "machdep.cpu.leaf7_features").lower()
+    if _machine() == X86_64:
+        features = (
+            f'{sysctl("-n", "machdep.cpu.features").lower()} '
+            f'{sysctl("-n", "machdep.cpu.leaf7_features").lower()}'
         )
-        info = {
-            "vendor_id": sysctl("-n", "machdep.cpu.vendor"),
-            "flags": flags,
-            "model": sysctl("-n", "machdep.cpu.model"),
-            "model name": sysctl("-n", "machdep.cpu.brand_string"),
-        }
-    else:
-        model = "unknown"
-        model_str = sysctl("-n", "machdep.cpu.brand_string").lower()
-        if "m2" in model_str:
-            model = "m2"
-        elif "m1" in model_str:
-            model = "m1"
-        elif "apple" in model_str:
-            model = "m1"
+        features = set(features.split())
 
-        info = {
-            "vendor_id": "Apple",
-            "flags": [],
-            "model": model,
-            "CPU implementer": "Apple",
-            "model name": sysctl("-n", "machdep.cpu.brand_string"),
-        }
-    return info
+        # Flags detected on Darwin turned to their linux counterpart
+        for darwin_flag, linux_flag in TARGETS_JSON["conversions"]["darwin_flags"].items():
+            if darwin_flag in features:
+                features.update(linux_flag.split())
+
+        return partial_uarch(vendor=sysctl("-n", "machdep.cpu.vendor"), features=features)
+
+    model = "unknown"
+    model_str = sysctl("-n", "machdep.cpu.brand_string").lower()
+    if "m2" in model_str:
+        model = "m2"
+    elif "m1" in model_str:
+        model = "m1"
+    elif "apple" in model_str:
+        model = "m1"
+
+    return partial_uarch(name=model, vendor="Apple")
 
 
 def _ensure_bin_usrbin_in_path():
-    # Make sure that /sbin and /usr/sbin are in PATH as sysctl is
-    # usually found there
+    # Make sure that /sbin and /usr/sbin are in PATH as sysctl is usually found there
     child_environment = dict(os.environ.items())
     search_paths = child_environment.get("PATH", "").split(os.pathsep)
     for additional_path in ("/sbin", "/usr/sbin"):
@@ -160,22 +285,10 @@ def _ensure_bin_usrbin_in_path():
     return child_environment
 
 
-def adjust_raw_flags(info):
-    """Adjust the flags detected on the system to homogenize
-    slightly different representations.
-    """
-    # Flags detected on Darwin turned to their linux counterpart
-    flags = info.get("flags", [])
-    d2l = TARGETS_JSON["conversions"]["darwin_flags"]
-    for darwin_flag, linux_flag in d2l.items():
-        if darwin_flag in flags:
-            info["flags"] += " " + linux_flag
-
-
-def adjust_raw_vendor(info):
-    """Adjust the vendor field to make it human readable"""
-    if "CPU implementer" not in info:
-        return
+def _canonicalize_aarch64_vendor(data: Dict[str, str]) -> str:
+    """Adjust the vendor field to make it human-readable"""
+    if "CPU implementer" not in data:
+        return "generic"
 
     # Mapping numeric codes to vendor (ARM). This list is a merge from
     # different sources:
@@ -185,43 +298,37 @@ def adjust_raw_vendor(info):
     # https://github.com/gcc-mirror/gcc/blob/master/gcc/config/aarch64/aarch64-cores.def
     # https://patchwork.kernel.org/patch/10524949/
     arm_vendors = TARGETS_JSON["conversions"]["arm_vendors"]
-    arm_code = info["CPU implementer"]
-    if arm_code in arm_vendors:
-        info["CPU implementer"] = arm_vendors[arm_code]
+    arm_code = data["CPU implementer"]
+    return arm_vendors.get(arm_code, arm_code)
 
 
-def raw_info_dictionary():
-    """Returns a dictionary with information on the cpu of the current host.
+def _feature_set(data: Dict[str, str], key: str) -> Set[str]:
+    return set(data.get(key, "").split())
 
-    This function calls all the viable factories one after the other until
-    there's one that is able to produce the requested information.
+
+def detected_info() -> Microarchitecture:
+    """Returns a partial Microarchitecture with information on the CPU of the current host.
+
+    This function calls all the viable factories one after the other until there's one that is
+    able to produce the requested information. Falls-back to a generic microarchitecture, if none
+    of the calls succeed.
     """
     # pylint: disable=broad-except
-    info = {}
     for factory in INFO_FACTORY[platform.system()]:
         try:
-            info = factory()
+            return factory()
         except Exception as exc:
             warnings.warn(str(exc))
 
-        if info:
-            adjust_raw_flags(info)
-            adjust_raw_vendor(info)
-            break
-
-    return info
+    return generic_microarchitecture(_machine())
 
 
-def compatible_microarchitectures(info):
-    """Returns an unordered list of known micro-architectures that are
-    compatible with the info dictionary passed as argument.
-
-    Args:
-        info (dict): dictionary containing information on the host cpu
+def compatible_microarchitectures(info: Microarchitecture) -> List[Microarchitecture]:
+    """Returns an unordered list of known micro-architectures that are compatible with the
+    partial Microarchitecture passed as input.
     """
     architecture_family = _machine()
-    # If a tester is not registered, be conservative and assume no known
-    # target is compatible with the host
+    # If a tester is not registered, assume no known target is compatible with the host
     tester = COMPATIBILITY_CHECKS.get(architecture_family, lambda x, y: False)
     return [x for x in TARGETS.values() if tester(info, x)] or [
         generic_microarchitecture(architecture_family)
@@ -230,8 +337,8 @@ def compatible_microarchitectures(info):
 
 def host():
     """Detects the host micro-architecture and returns it."""
-    # Retrieve a dictionary with raw information on the host's cpu
-    info = raw_info_dictionary()
+    # Retrieve information on the host's cpu
+    info = detected_info()
 
     # Get a list of possible candidates for this micro-architecture
     candidates = compatible_microarchitectures(info)
@@ -244,6 +351,10 @@ def sorting_fn(item):
     generic_candidates = [c for c in candidates if c.vendor == "generic"]
     best_generic = max(generic_candidates, key=sorting_fn)
 
+    # Relevant for AArch64. Filter on "cpu_part" if we have any match
+    if info.cpu_part != "" and any(c for c in candidates if info.cpu_part == c.cpu_part):
+        candidates = [c for c in candidates if info.cpu_part == c.cpu_part]
+
     # Filter the candidates to be descendant of the best generic candidate.
     # This is to avoid that the lack of a niche feature that can be disabled
     # from e.g. BIOS prevents detection of a reasonably performant architecture
@@ -258,16 +369,15 @@ def sorting_fn(item):
     return max(candidates, key=sorting_fn)
 
 
-def compatibility_check(architecture_family):
+def compatibility_check(architecture_family: Union[str, Tuple[str, ...]]):
     """Decorator to register a function as a proper compatibility check.
 
-    A compatibility check function takes the raw info dictionary as a first
-    argument and an arbitrary target as the second argument. It returns True
-    if the target is compatible with the info dictionary, False otherwise.
+    A compatibility check function takes a partial Microarchitecture object as a first argument,
+    and an arbitrary target Microarchitecture as the second argument. It returns True if the
+    target is compatible with first argument, False otherwise.
 
     Args:
-        architecture_family (str or tuple): architecture family for which
-            this test can be used, e.g. x86_64 or ppc64le etc.
+        architecture_family: architecture family for which this test can be used
     """
     # Turn the argument into something iterable
     if isinstance(architecture_family, str):
@@ -280,86 +390,70 @@ def decorator(func):
     return decorator
 
 
-@compatibility_check(architecture_family=("ppc64le", "ppc64"))
+@compatibility_check(architecture_family=(PPC64LE, PPC64))
 def compatibility_check_for_power(info, target):
     """Compatibility check for PPC64 and PPC64LE architectures."""
-    basename = platform.machine()
-    generation_match = re.search(r"POWER(\d+)", info.get("cpu", ""))
-    try:
-        generation = int(generation_match.group(1))
-    except AttributeError:
-        # There might be no match under emulated environments. For instance
-        # emulating a ppc64le with QEMU and Docker still reports the host
-        # /proc/cpuinfo and not a Power
-        generation = 0
-
     # We can use a target if it descends from our machine type and our
     # generation (9 for POWER9, etc) is at least its generation.
-    arch_root = TARGETS[basename]
+    arch_root = TARGETS[_machine()]
     return (
         target == arch_root or arch_root in target.ancestors
-    ) and target.generation <= generation
+    ) and target.generation <= info.generation
 
 
-@compatibility_check(architecture_family="x86_64")
+@compatibility_check(architecture_family=X86_64)
 def compatibility_check_for_x86_64(info, target):
     """Compatibility check for x86_64 architectures."""
-    basename = "x86_64"
-    vendor = info.get("vendor_id", "generic")
-    features = set(info.get("flags", "").split())
-
     # We can use a target if it descends from our machine type, is from our
     # vendor, and we have all of its features
-    arch_root = TARGETS[basename]
+    arch_root = TARGETS[X86_64]
     return (
         (target == arch_root or arch_root in target.ancestors)
-        and target.vendor in (vendor, "generic")
-        and target.features.issubset(features)
+        and target.vendor in (info.vendor, "generic")
+        and target.features.issubset(info.features)
     )
 
 
-@compatibility_check(architecture_family="aarch64")
+@compatibility_check(architecture_family=AARCH64)
 def compatibility_check_for_aarch64(info, target):
     """Compatibility check for AARCH64 architectures."""
-    basename = "aarch64"
-    features = set(info.get("Features", "").split())
-    vendor = info.get("CPU implementer", "generic")
-
-    # At the moment it's not clear how to detect compatibility with
+    # At the moment, it's not clear how to detect compatibility with
     # a specific version of the architecture
-    if target.vendor == "generic" and target.name != "aarch64":
+    if target.vendor == "generic" and target.name != AARCH64:
         return False
 
-    arch_root = TARGETS[basename]
+    arch_root = TARGETS[AARCH64]
     arch_root_and_vendor = arch_root == target.family and target.vendor in (
-        vendor,
+        info.vendor,
         "generic",
     )
 
     # On macOS it seems impossible to get all the CPU features
     # with syctl info, but for ARM we can get the exact model
     if platform.system() == "Darwin":
-        model_key = info.get("model", basename)
-        model = TARGETS[model_key]
+        model = TARGETS[info.name]
         return arch_root_and_vendor and (target == model or target in model.ancestors)
 
-    return arch_root_and_vendor and target.features.issubset(features)
+    return arch_root_and_vendor and target.features.issubset(info.features)
 
 
-@compatibility_check(architecture_family="riscv64")
+@compatibility_check(architecture_family=RISCV64)
 def compatibility_check_for_riscv64(info, target):
     """Compatibility check for riscv64 architectures."""
-    basename = "riscv64"
-    uarch = info.get("uarch")
-
-    # sifive unmatched board
-    if uarch == "sifive,u74-mc":
-        uarch = "u74mc"
-    # catch-all for unknown uarchs
-    else:
-        uarch = "riscv64"
-
-    arch_root = TARGETS[basename]
+    arch_root = TARGETS[RISCV64]
     return (target == arch_root or arch_root in target.ancestors) and (
-        target == uarch or target.vendor == "generic"
+        target.name == info.name or target.vendor == "generic"
     )
+
+
+def brand_string() -> Optional[str]:
+    """Returns the brand string of the host, if detected, or None."""
+    if platform.system() == "Darwin":
+        return _check_output(
+            ["sysctl", "-n", "machdep.cpu.brand_string"], env=_ensure_bin_usrbin_in_path()
+        ).strip()
+
+    if host().family == X86_64:
+        return CpuidInfoCollector().brand_string()
+
+    return None

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

@@ -2,9 +2,7 @@
 # Archspec Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-"""Types and functions to manage information
-on CPU microarchitectures.
-"""
+"""Types and functions to manage information on CPU microarchitectures."""
 import functools
 import platform
 import re
@@ -13,6 +11,7 @@
 import archspec
 import archspec.cpu.alias
 import archspec.cpu.schema
+
 from .alias import FEATURE_ALIASES
 from .schema import LazyDictionary
 
@@ -47,7 +46,7 @@ class Microarchitecture:
             which has "broadwell" as a parent, supports running binaries
             optimized for "broadwell".
         vendor (str): vendor of the micro-architecture
-        features (list of str): supported CPU flags. Note that the semantic
+        features (set of str): supported CPU flags. Note that the semantic
             of the flags in this field might vary among architectures, if
             at all present. For instance x86_64 processors will list all
             the flags supported by a given CPU while Arm processors will
@@ -64,21 +63,24 @@ class Microarchitecture:
                 passed in as argument above.
             * versions: versions that support this micro-architecture.
 
-        generation (int): generation of the micro-architecture, if
-            relevant.
+        generation (int): generation of the micro-architecture, if relevant.
+        cpu_part (str): cpu part of the architecture, if relevant.
     """
 
-    # pylint: disable=too-many-arguments
+    # pylint: disable=too-many-arguments,too-many-instance-attributes
     #: Aliases for micro-architecture's features
     feature_aliases = FEATURE_ALIASES
 
-    def __init__(self, name, parents, vendor, features, compilers, generation=0):
+    def __init__(self, name, parents, vendor, features, compilers, generation=0, cpu_part=""):
         self.name = name
         self.parents = parents
         self.vendor = vendor
         self.features = features
         self.compilers = compilers
+        # Only relevant for PowerPC
         self.generation = generation
+        # Only relevant for AArch64
+        self.cpu_part = cpu_part
         # Cache the ancestor computation
         self._ancestors = None
 
@@ -110,6 +112,7 @@ def __eq__(self, other):
             and self.parents == other.parents  # avoid ancestors here
             and self.compilers == other.compilers
             and self.generation == other.generation
+            and self.cpu_part == other.cpu_part
         )
 
     @coerce_target_names
@@ -142,7 +145,8 @@ def __repr__(self):
         cls_name = self.__class__.__name__
         fmt = (
             cls_name + "({0.name!r}, {0.parents!r}, {0.vendor!r}, "
-            "{0.features!r}, {0.compilers!r}, {0.generation!r})"
+            "{0.features!r}, {0.compilers!r}, generation={0.generation!r}, "
+            "cpu_part={0.cpu_part!r})"
         )
         return fmt.format(self)
 
@@ -180,24 +184,30 @@ def generic(self):
         generics = [x for x in [self] + self.ancestors if x.vendor == "generic"]
         return max(generics, key=lambda x: len(x.ancestors))
 
-    def to_dict(self, return_list_of_items=False):
-        """Returns a dictionary representation of this object.
+    def to_dict(self):
+        """Returns a dictionary representation of this object."""
+        return {
+            "name": str(self.name),
+            "vendor": str(self.vendor),
+            "features": sorted(str(x) for x in self.features),
+            "generation": self.generation,
+            "parents": [str(x) for x in self.parents],
+            "compilers": self.compilers,
+            "cpupart": self.cpu_part,
+        }
 
-        Args:
-            return_list_of_items (bool): if True returns an ordered list of
-                items instead of the dictionary
-        """
-        list_of_items = [
-            ("name", str(self.name)),
-            ("vendor", str(self.vendor)),
-            ("features", sorted(str(x) for x in self.features)),
-            ("generation", self.generation),
-            ("parents", [str(x) for x in self.parents]),
-        ]
-        if return_list_of_items:
-            return list_of_items
-
-        return dict(list_of_items)
+    @staticmethod
+    def from_dict(data) -> "Microarchitecture":
+        """Construct a microarchitecture from a dictionary representation."""
+        return Microarchitecture(
+            name=data["name"],
+            parents=[TARGETS[x] for x in data["parents"]],
+            vendor=data["vendor"],
+            features=set(data["features"]),
+            compilers=data.get("compilers", {}),
+            generation=data.get("generation", 0),
+            cpu_part=data.get("cpupart", ""),
+        )
 
     def optimization_flags(self, compiler, version):
         """Returns a string containing the optimization flags that needs
@@ -271,9 +281,7 @@ def tuplify(ver):
                 flags = flags_fmt.format(**compiler_entry)
                 return flags
 
-        msg = (
-            "cannot produce optimized binary for micro-architecture '{0}' with {1}@{2}"
-        )
+        msg = "cannot produce optimized binary for micro-architecture '{0}' with {1}@{2}"
         if compiler_info:
             versions = [x["versions"] for x in compiler_info]
             msg += f' [supported compiler versions are {", ".join(versions)}]'
@@ -289,9 +297,7 @@ def generic_microarchitecture(name):
     Args:
         name (str): name of the micro-architecture
     """
-    return Microarchitecture(
-        name, parents=[], vendor="generic", features=[], compilers={}
-    )
+    return Microarchitecture(name, parents=[], vendor="generic", features=set(), compilers={})
 
 
 def version_components(version):
@@ -344,9 +350,10 @@ def fill_target_from_dict(name, data, targets):
         features = set(values["features"])
         compilers = values.get("compilers", {})
         generation = values.get("generation", 0)
+        cpu_part = values.get("cpupart", "")
 
         targets[name] = Microarchitecture(
-            name, parents, vendor, features, compilers, generation
+            name, parents, vendor, features, compilers, generation=generation, cpu_part=cpu_part
         )
 
     known_targets = {}

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

@@ -7,7 +7,9 @@
 """
 import collections.abc
 import json
-import os.path
+import os
+import pathlib
+from typing import Tuple
 
 
 class LazyDictionary(collections.abc.MutableMapping):
@@ -46,21 +48,65 @@ def __len__(self):
         return len(self.data)
 
 
-def _load_json_file(json_file):
-    json_dir = os.path.join(os.path.dirname(__file__), "..", "json", "cpu")
-    json_dir = os.path.abspath(json_dir)
+#: Environment variable that might point to a directory with a user defined JSON file
+DIR_FROM_ENVIRONMENT = "ARCHSPEC_CPU_DIR"
 
-    def _factory():
-        filename = os.path.join(json_dir, json_file)
-        with open(filename, "r", encoding="utf-8") as file:
-            return json.load(file)
+#: Environment variable that might point to a directory with extensions to JSON files
+EXTENSION_DIR_FROM_ENVIRONMENT = "ARCHSPEC_EXTENSION_CPU_DIR"
 
-    return _factory
+
+def _json_file(filename: str, allow_custom: bool = False) -> Tuple[pathlib.Path, pathlib.Path]:
+    """Given a filename, returns the absolute path for the main JSON file, and an
+    optional absolute path for an extension JSON file.
+
+    Args:
+        filename: filename for the JSON file
+        allow_custom: if True, allows overriding the location  where the file resides
+    """
+    json_dir = pathlib.Path(__file__).parent / ".." / "json" / "cpu"
+    if allow_custom and DIR_FROM_ENVIRONMENT in os.environ:
+        json_dir = pathlib.Path(os.environ[DIR_FROM_ENVIRONMENT])
+    json_dir = json_dir.absolute()
+    json_file = json_dir / filename
+
+    extension_file = None
+    if allow_custom and EXTENSION_DIR_FROM_ENVIRONMENT in os.environ:
+        extension_dir = pathlib.Path(os.environ[EXTENSION_DIR_FROM_ENVIRONMENT])
+        extension_dir.absolute()
+        extension_file = extension_dir / filename
+
+    return json_file, extension_file
+
+
+def _load(json_file: pathlib.Path, extension_file: pathlib.Path):
+    with open(json_file, "r", encoding="utf-8") as file:
+        data = json.load(file)
+
+    if not extension_file or not extension_file.exists():
+        return data
+
+    with open(extension_file, "r", encoding="utf-8") as file:
+        extension_data = json.load(file)
+
+    top_level_sections = list(data.keys())
+    for key in top_level_sections:
+        if key not in extension_data:
+            continue
+
+        data[key].update(extension_data[key])
+
+    return data
 
 
 #: In memory representation of the data in microarchitectures.json,
 #: loaded on first access
-TARGETS_JSON = LazyDictionary(_load_json_file("microarchitectures.json"))
+TARGETS_JSON = LazyDictionary(_load, *_json_file("microarchitectures.json", allow_custom=True))
 
 #: JSON schema for microarchitectures.json, loaded on first access
-SCHEMA = LazyDictionary(_load_json_file("microarchitectures_schema.json"))
+TARGETS_JSON_SCHEMA = LazyDictionary(_load, *_json_file("microarchitectures_schema.json"))
+
+#: Information on how to call 'cpuid' to get information on the HOST CPU
+CPUID_JSON = LazyDictionary(_load, *_json_file("cpuid.json", allow_custom=True))
+
+#: JSON schema for cpuid.json, loaded on first access
+CPUID_JSON_SCHEMA = LazyDictionary(_load, *_json_file("cpuid_schema.json"))

lib/spack/external/archspec/json/README.md

@@ -9,11 +9,11 @@ language specific APIs.
 
 Currently the repository contains the following JSON files:
 ```console
-.
-├── COPYRIGHT
-└── cpu
-    ├── microarchitectures.json         # Contains information on CPU microarchitectures
-    └── microarchitectures_schema.json  # Schema for the file above
+cpu/
+├── cpuid.json                     # Contains information on CPUID calls to retrieve vendor and features on x86_64
+├── cpuid_schema.json              # Schema for the file above
+├── microarchitectures.json        # Contains information on CPU microarchitectures
+└── microarchitectures_schema.json # Schema for the file above
  ```
 
 

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

@@ -0,0 +1,134 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Schema for microarchitecture definitions and feature aliases",
+  "type": "object",
+  "additionalProperties": false,
+  "properties": {
+    "vendor": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "description": {
+          "type": "string"
+        },
+        "input": {
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "eax": {
+              "type": "integer"
+            },
+            "ecx": {
+              "type": "integer"
+            }
+          }
+        }
+      }
+    },
+    "highest_extension_support": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "description": {
+          "type": "string"
+        },
+        "input": {
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "eax": {
+              "type": "integer"
+            },
+            "ecx": {
+              "type": "integer"
+            }
+          }
+        }
+      }
+    },
+    "flags": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "additionalProperties": false,
+        "properties": {
+          "description": {
+            "type": "string"
+          },
+          "input": {
+            "type": "object",
+            "additionalProperties": false,
+            "properties": {
+              "eax": {
+                "type": "integer"
+              },
+              "ecx": {
+                "type": "integer"
+              }
+            }
+          },
+          "bits": {
+            "type": "array",
+            "items": {
+              "type": "object",
+              "additionalProperties": false,
+              "properties": {
+                "name": {
+                  "type": "string"
+                },
+                "register": {
+                  "type": "string"
+                },
+                "bit": {
+                  "type": "integer"
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "extension-flags": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "additionalProperties": false,
+        "properties": {
+          "description": {
+            "type": "string"
+          },
+          "input": {
+            "type": "object",
+            "additionalProperties": false,
+            "properties": {
+              "eax": {
+                "type": "integer"
+              },
+              "ecx": {
+                "type": "integer"
+              }
+            }
+          },
+          "bits": {
+            "type": "array",
+            "items": {
+              "type": "object",
+              "additionalProperties": false,
+              "properties": {
+                "name": {
+                  "type": "string"
+                },
+                "register": {
+                  "type": "string"
+                },
+                "bit": {
+                  "type": "integer"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

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

@@ -2225,10 +2225,14 @@
         ],
         "nvhpc": [
           {
-            "versions": "21.11:",
+            "versions": "21.11:23.8",
 	    "name": "zen3",
             "flags": "-tp {name}",
-	    "warnings": "zen4 is not fully supported by nvhpc yet, falling back to zen3"
+	    "warnings": "zen4 is not fully supported by nvhpc versions < 23.9, falling back to zen3"
+          },
+          {
+            "versions": "23.9:",
+            "flags": "-tp {name}"
           }
 	]
       }
@@ -2318,6 +2322,26 @@
         ]
       }
     },
+    "power10": {
+      "from": ["power9"],
+      "vendor": "IBM",
+      "generation": 10,
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "11.1:",
+            "flags": "-mcpu={name} -mtune={name}"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "11.0:",
+            "flags": "-mcpu={name} -mtune={name}"
+          }
+        ]
+      }
+    },
     "ppc64le": {
       "from": [],
       "vendor": "generic",
@@ -2405,6 +2429,29 @@
         ]
       }
     },
+    "power10le": {
+      "from": ["power9le"],
+      "vendor": "IBM",
+      "generation": 10,
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "name": "power10",
+            "versions": "11.1:",
+            "flags": "-mcpu={name} -mtune={name}"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "11.0:",
+            "family": "ppc64le",
+            "name": "power10",
+            "flags": "-mcpu={name} -mtune={name}"
+          }
+        ]
+      }
+    },
     "aarch64": {
       "from": [],
       "vendor": "generic",
@@ -2592,6 +2639,37 @@
         ]
       }
     },
+    "armv9.0a": {
+      "from": ["armv8.5a"],
+      "vendor": "generic",
+      "features": [],
+      "compilers": {
+        "gcc": [
+          {
+            "versions": "12:",
+            "flags": "-march=armv9-a -mtune=generic"
+          }
+        ],
+        "clang": [
+          {
+            "versions": "14:",
+            "flags": "-march=armv9-a -mtune=generic"
+          }
+        ],
+        "apple-clang": [
+          {
+            "versions": ":",
+            "flags": "-march=armv9-a -mtune=generic"
+          }
+        ],
+        "arm": [
+          {
+            "versions": ":",
+            "flags": "-march=armv9-a -mtune=generic"
+          }
+        ]
+      }
+    },
     "thunderx2": {
       "from": ["armv8.1a"],
       "vendor": "Cavium",
@@ -2637,7 +2715,8 @@
             "flags": "-mcpu=thunderx2t99"
           }
         ]
-      }
+      },
+      "cpupart": "0x0af"
     },
     "a64fx": {
       "from": ["armv8.2a"],
@@ -2705,7 +2784,8 @@
             "flags": "-march=armv8.2-a+crc+crypto+fp16+sve"
           }
         ]
-      }
+      },
+      "cpupart": "0x001"
     },
     "cortex_a72": {
       "from": ["aarch64"],
@@ -2742,7 +2822,8 @@
                   "flags" : "-mcpu=cortex-a72"
               }
           ]
-      }
+      },
+      "cpupart": "0xd08"
     },
     "neoverse_n1": {
       "from": ["cortex_a72", "armv8.2a"],
@@ -2763,8 +2844,7 @@
           "asimdrdm",
           "lrcpc",
           "dcpop",
-          "asimddp",
-          "ssbs"
+          "asimddp"
       ],
       "compilers" : {
           "gcc": [
@@ -2813,8 +2893,12 @@
           ],
           "arm" : [
               {
-                  "versions": "20:",
+                  "versions": "20:21.9",
                   "flags" : "-march=armv8.2-a+fp16+rcpc+dotprod+crypto"
+              },
+              {
+                  "versions": "22:",
+                  "flags" : "-mcpu=neoverse-n1"
               }
           ],
           "nvhpc" : [
@@ -2824,7 +2908,8 @@
                   "flags": "-tp {name}"
               }
           ]
-      }
+      },
+      "cpupart": "0xd0c"
     },
     "neoverse_v1": {
       "from": ["neoverse_n1", "armv8.4a"],
@@ -2848,8 +2933,6 @@
           "lrcpc",
           "dcpop",
           "sha3",
-          "sm3",
-          "sm4",
           "asimddp",
           "sha512",
           "sve",
@@ -2858,9 +2941,6 @@
           "uscat",
           "ilrcpc",
           "flagm",
-          "ssbs",
-          "paca",
-          "pacg",
           "dcpodp",
           "svei8mm",
           "svebf16",
@@ -2928,7 +3008,7 @@
               },
               {
                   "versions": "11:",
-                  "flags" : "-march=armv8.4-a+sve+ssbs+fp16+bf16+crypto+i8mm+rng"
+                  "flags" : "-march=armv8.4-a+sve+fp16+bf16+crypto+i8mm+rng"
               },
               {
                   "versions": "12:",
@@ -2942,7 +3022,7 @@
               },
 	            {
                   "versions": "22:",
-                  "flags" : "-march=armv8.4-a+sve+ssbs+fp16+bf16+crypto+i8mm+rng"
+                  "flags" : "-mcpu=neoverse-v1"
               }
           ],
           "nvhpc" : [
@@ -2952,7 +3032,224 @@
                   "flags": "-tp {name}"
               }
           ]
-      }
+      },
+      "cpupart": "0xd40"
+    },
+    "neoverse_v2": {
+      "from": ["neoverse_n1", "armv9.0a"],
+      "vendor": "ARM",
+      "features": [
+          "fp",
+	  "asimd",
+	  "evtstrm",
+	  "aes",
+	  "pmull",
+	  "sha1",
+	  "sha2",
+	  "crc32",
+	  "atomics",
+	  "fphp",
+	  "asimdhp",
+	  "cpuid",
+	  "asimdrdm",
+	  "jscvt",
+	  "fcma",
+	  "lrcpc",
+	  "dcpop",
+	  "sha3",
+	  "asimddp",
+	  "sha512",
+	  "sve",
+	  "asimdfhm",
+	  "uscat",
+	  "ilrcpc",
+	  "flagm",
+	  "sb",
+	  "dcpodp",
+	  "sve2",
+	  "flagm2",
+	  "frint",
+	  "svei8mm",
+	  "svebf16",
+	  "i8mm",
+	  "bf16"
+      ],
+      "compilers" : {
+          "gcc": [
+              {
+                  "versions": "4.8:5.99",
+                  "flags": "-march=armv8-a"
+              },
+              {
+                  "versions": "6:6.99",
+                  "flags" : "-march=armv8.1-a"
+              },
+              {
+                  "versions": "7.0:7.99",
+                  "flags" : "-march=armv8.2-a -mtune=cortex-a72"
+              },
+              {
+                  "versions": "8.0:8.99",
+                  "flags" : "-march=armv8.4-a+sve -mtune=cortex-a72"
+              },
+              {
+                  "versions": "9.0:9.99",
+                  "flags" : "-march=armv8.5-a+sve -mtune=cortex-a76"
+              },
+              {
+                  "versions": "10.0:11.3.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16 -mtune=cortex-a77"
+              },
+	      {
+                  "versions": "11.4:11.99",
+                  "flags" : "-mcpu=neoverse-v2"
+              },
+              {
+                  "versions": "12.0:12.2.99",
+                  "flags" : "-march=armv9-a+i8mm+bf16 -mtune=cortex-a710"
+              },
+	      {
+                  "versions": "12.3:",
+                  "flags" : "-mcpu=neoverse-v2"
+              }
+          ],
+          "clang" : [
+              {
+                  "versions": "9.0:10.99",
+                  "flags" : "-march=armv8.5-a+sve"
+              },
+              {
+                  "versions": "11.0:13.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16"
+              },
+              {
+                  "versions": "14.0:15.99",
+                  "flags" : "-march=armv9-a+i8mm+bf16"
+              },
+              {
+                  "versions": "16.0:",
+                  "flags" : "-mcpu=neoverse-v2"
+              }
+          ],
+          "arm" : [
+              {
+                  "versions": "23.04.0:",
+                  "flags" : "-mcpu=neoverse-v2"
+              }
+          ],
+          "nvhpc" : [
+              {
+                  "versions": "23.3:",
+                  "name": "neoverse-v2",
+                  "flags": "-tp {name}"
+              }
+          ]
+      },
+      "cpupart": "0xd4f"
+    },
+    "neoverse_n2": {
+      "from": ["neoverse_n1", "armv9.0a"],
+      "vendor": "ARM",
+      "features": [
+          "fp",
+	  "asimd",
+	  "evtstrm",
+	  "aes",
+	  "pmull",
+	  "sha1",
+	  "sha2",
+	  "crc32",
+	  "atomics",
+	  "fphp",
+	  "asimdhp",
+	  "cpuid",
+	  "asimdrdm",
+	  "jscvt",
+	  "fcma",
+	  "lrcpc",
+	  "dcpop",
+	  "sha3",
+	  "asimddp",
+	  "sha512",
+	  "sve",
+	  "asimdfhm",
+	  "uscat",
+	  "ilrcpc",
+	  "flagm",
+	  "sb",
+	  "dcpodp",
+	  "sve2",
+	  "flagm2",
+	  "frint",
+	  "svei8mm",
+	  "svebf16",
+	  "i8mm",
+	  "bf16"
+      ],
+      "compilers" : {
+          "gcc": [
+              {
+                  "versions": "4.8:5.99",
+                  "flags": "-march=armv8-a"
+              },
+              {
+                  "versions": "6:6.99",
+                  "flags" : "-march=armv8.1-a"
+              },
+              {
+                  "versions": "7.0:7.99",
+                  "flags" : "-march=armv8.2-a -mtune=cortex-a72"
+              },
+              {
+                  "versions": "8.0:8.99",
+                  "flags" : "-march=armv8.4-a+sve -mtune=cortex-a72"
+              },
+              {
+                  "versions": "9.0:9.99",
+                  "flags" : "-march=armv8.5-a+sve -mtune=cortex-a76"
+              },
+              {
+                  "versions": "10.0:10.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16 -mtune=cortex-a77"
+              },
+              {
+                  "versions": "11.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "clang" : [
+              {
+                  "versions": "9.0:10.99",
+                  "flags" : "-march=armv8.5-a+sve"
+              },
+              {
+                  "versions": "11.0:13.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16"
+              },
+              {
+                  "versions": "14.0:15.99",
+                  "flags" : "-march=armv9-a+i8mm+bf16"
+              },
+              {
+                  "versions": "16.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "arm" : [
+              {
+                  "versions": "23.04.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "nvhpc" : [
+              {
+                  "versions": "23.3:",
+                  "name": "neoverse-n1",
+                  "flags": "-tp {name}"
+              }
+          ]
+      },
+      "cpupart": "0xd49"
     },
     "m1": {
       "from": ["armv8.4a"],
@@ -3018,7 +3315,8 @@
             "flags" : "-mcpu=apple-m1"
           }
         ]
-      }
+      },
+      "cpupart": "0x022"
     },
     "m2": {
       "from": ["m1", "armv8.5a"],
@@ -3096,7 +3394,8 @@
             "flags" : "-mcpu=apple-m2"
           }
         ]
-      }
+      },
+      "cpupart": "0x032"
     },
     "arm": {
       "from": [],

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

@@ -52,6 +52,9 @@
                   }
                 }
               }
+            },
+            "cpupart": {
+              "type": "string"
             }
           },
           "required": [
@@ -107,4 +110,4 @@
       "additionalProperties": false
     }
   }
-}
+}

lib/spack/external/archspec/vendor/cpuid/LICENSE

@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Anders Høst
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

lib/spack/external/archspec/vendor/cpuid/README.md

@@ -0,0 +1,76 @@
+cpuid.py
+========
+
+Now, this is silly!
+
+Pure Python library for accessing information about x86 processors
+by querying the [CPUID](http://en.wikipedia.org/wiki/CPUID)
+instruction. Well, not exactly pure Python...
+
+It works by allocating a small piece of virtual memory, copying
+a raw x86 function to that memory, giving the memory execute
+permissions and then calling the memory as a function. The injected
+function executes the CPUID instruction and copies the result back
+to a ctypes.Structure where is can be read by Python.
+
+It should work fine on both 32 and 64 bit versions of Windows and Linux
+running x86 processors. Apple OS X and other BSD systems should also work,
+not tested though...
+
+
+Why?
+----
+For poops and giggles. Plus, having access to a low-level feature
+without having to compile a C wrapper is pretty neat.
+
+
+Examples
+--------
+Getting info with eax=0:
+
+    import cpuid
+
+    q = cpuid.CPUID()
+    eax, ebx, ecx, edx = q(0)
+
+Running the files:
+
+    $ python example.py 
+    Vendor ID : GenuineIntel
+    CPU name  : Intel(R) Xeon(R) CPU           W3550  @ 3.07GHz
+    
+    Vector instructions supported:
+    SSE       : Yes
+    SSE2      : Yes
+    SSE3      : Yes
+    SSSE3     : Yes
+    SSE4.1    : Yes
+    SSE4.2    : Yes
+    SSE4a     : --
+    AVX       : --
+    AVX2      : --
+    
+    $ python cpuid.py
+    CPUID    A        B        C        D
+    00000000 0000000b 756e6547 6c65746e 49656e69
+    00000001 000106a5 00100800 009ce3bd bfebfbff
+    00000002 55035a01 00f0b2e4 00000000 09ca212c
+    00000003 00000000 00000000 00000000 00000000
+    00000004 00000000 00000000 00000000 00000000
+    00000005 00000040 00000040 00000003 00001120
+    00000006 00000003 00000002 00000001 00000000
+    00000007 00000000 00000000 00000000 00000000
+    00000008 00000000 00000000 00000000 00000000
+    00000009 00000000 00000000 00000000 00000000
+    0000000a 07300403 00000044 00000000 00000603
+    0000000b 00000000 00000000 00000095 00000000
+    80000000 80000008 00000000 00000000 00000000
+    80000001 00000000 00000000 00000001 28100800
+    80000002 65746e49 2952286c 6f655820 2952286e
+    80000003 55504320 20202020 20202020 57202020
+    80000004 30353533 20402020 37302e33 007a4847
+    80000005 00000000 00000000 00000000 00000000
+    80000006 00000000 00000000 01006040 00000000
+    80000007 00000000 00000000 00000000 00000100
+    80000008 00003024 00000000 00000000 00000000
+

lib/spack/external/archspec/vendor/cpuid/cpuid.py

@@ -0,0 +1,172 @@
+# -*- coding: utf-8 -*-
+#
+#     Copyright (c) 2024 Anders Høst
+#
+
+from __future__ import print_function
+
+import platform
+import os
+import ctypes
+from ctypes import c_uint32, c_long, c_ulong, c_size_t, c_void_p, POINTER, CFUNCTYPE
+
+# Posix x86_64:
+# Three first call registers : RDI, RSI, RDX
+# Volatile registers         : RAX, RCX, RDX, RSI, RDI, R8-11
+
+# Windows x86_64:
+# Three first call registers : RCX, RDX, R8
+# Volatile registers         : RAX, RCX, RDX, R8-11
+
+# cdecl 32 bit:
+# Three first call registers : Stack (%esp)
+# Volatile registers         : EAX, ECX, EDX
+
+_POSIX_64_OPC = [
+        0x53,                    # push   %rbx
+        0x89, 0xf0,              # mov    %esi,%eax
+        0x89, 0xd1,              # mov    %edx,%ecx
+        0x0f, 0xa2,              # cpuid
+        0x89, 0x07,              # mov    %eax,(%rdi)
+        0x89, 0x5f, 0x04,        # mov    %ebx,0x4(%rdi)
+        0x89, 0x4f, 0x08,        # mov    %ecx,0x8(%rdi)
+        0x89, 0x57, 0x0c,        # mov    %edx,0xc(%rdi)
+        0x5b,                    # pop    %rbx
+        0xc3                     # retq
+]
+
+_WINDOWS_64_OPC = [
+        0x53,                    # push   %rbx
+        0x89, 0xd0,              # mov    %edx,%eax
+        0x49, 0x89, 0xc9,        # mov    %rcx,%r9
+        0x44, 0x89, 0xc1,        # mov    %r8d,%ecx
+        0x0f, 0xa2,              # cpuid
+        0x41, 0x89, 0x01,        # mov    %eax,(%r9)
+        0x41, 0x89, 0x59, 0x04,  # mov    %ebx,0x4(%r9)
+        0x41, 0x89, 0x49, 0x08,  # mov    %ecx,0x8(%r9)
+        0x41, 0x89, 0x51, 0x0c,  # mov    %edx,0xc(%r9)
+        0x5b,                    # pop    %rbx
+        0xc3                     # retq
+]
+
+_CDECL_32_OPC = [
+        0x53,                    # push   %ebx
+        0x57,                    # push   %edi
+        0x8b, 0x7c, 0x24, 0x0c,  # mov    0xc(%esp),%edi
+        0x8b, 0x44, 0x24, 0x10,  # mov    0x10(%esp),%eax
+        0x8b, 0x4c, 0x24, 0x14,  # mov    0x14(%esp),%ecx
+        0x0f, 0xa2,              # cpuid
+        0x89, 0x07,              # mov    %eax,(%edi)
+        0x89, 0x5f, 0x04,        # mov    %ebx,0x4(%edi)
+        0x89, 0x4f, 0x08,        # mov    %ecx,0x8(%edi)
+        0x89, 0x57, 0x0c,        # mov    %edx,0xc(%edi)
+        0x5f,                    # pop    %edi
+        0x5b,                    # pop    %ebx
+        0xc3                     # ret
+]
+
+is_windows = os.name == "nt"
+is_64bit = ctypes.sizeof(ctypes.c_voidp) == 8
+
+
+class CPUID_struct(ctypes.Structure):
+    _register_names = ("eax", "ebx", "ecx", "edx")
+    _fields_ = [(r, c_uint32) for r in _register_names]
+
+    def __getitem__(self, item):
+        if item not in self._register_names:
+            raise KeyError(item)
+        return getattr(self, item)
+
+    def __repr__(self):
+        return "eax=0x{:x}, ebx=0x{:x}, ecx=0x{:x}, edx=0x{:x}".format(self.eax, self.ebx, self.ecx, self.edx)
+
+
+class CPUID(object):
+    def __init__(self):
+        if platform.machine() not in ("AMD64", "x86_64", "x86", "i686"):
+            raise SystemError("Only available for x86")
+
+        if is_windows:
+            if is_64bit:
+                # VirtualAlloc seems to fail under some weird
+                # circumstances when ctypes.windll.kernel32 is
+                # used under 64 bit Python. CDLL fixes this.
+                self.win = ctypes.CDLL("kernel32.dll")
+                opc = _WINDOWS_64_OPC
+            else:
+                # Here ctypes.windll.kernel32 is needed to get the
+                # right DLL. Otherwise it will fail when running
+                # 32 bit Python on 64 bit Windows.
+                self.win = ctypes.windll.kernel32
+                opc = _CDECL_32_OPC
+        else:
+            opc = _POSIX_64_OPC if is_64bit else _CDECL_32_OPC
+
+        size = len(opc)
+        code = (ctypes.c_ubyte * size)(*opc)
+
+        if is_windows:
+            self.win.VirtualAlloc.restype = c_void_p
+            self.win.VirtualAlloc.argtypes = [ctypes.c_void_p, ctypes.c_size_t, ctypes.c_ulong, ctypes.c_ulong]
+            self.addr = self.win.VirtualAlloc(None, size, 0x1000, 0x40)
+            if not self.addr:
+                raise MemoryError("Could not allocate RWX memory")
+            ctypes.memmove(self.addr, code, size)
+        else:
+            from mmap import (
+                mmap,
+                MAP_PRIVATE,
+                MAP_ANONYMOUS,
+                PROT_WRITE,
+                PROT_READ,
+                PROT_EXEC,
+            )
+            self.mm = mmap(
+                -1,
+                size,
+                flags=MAP_PRIVATE | MAP_ANONYMOUS,
+                prot=PROT_WRITE | PROT_READ | PROT_EXEC,
+            )
+            self.mm.write(code)
+            self.addr = ctypes.addressof(ctypes.c_int.from_buffer(self.mm))
+
+        func_type = CFUNCTYPE(None, POINTER(CPUID_struct), c_uint32, c_uint32)
+        self.func_ptr = func_type(self.addr)
+
+    def __call__(self, eax, ecx=0):
+        struct = self.registers_for(eax=eax, ecx=ecx)
+        return struct.eax, struct.ebx, struct.ecx, struct.edx
+
+    def registers_for(self, eax, ecx=0):
+        """Calls cpuid with eax and ecx set as the input arguments, and returns a structure
+        containing eax, ebx, ecx, and edx.
+        """
+        struct = CPUID_struct()
+        self.func_ptr(struct, eax, ecx)
+        return struct
+
+    def __del__(self):
+        if is_windows:
+            self.win.VirtualFree.restype = c_long
+            self.win.VirtualFree.argtypes = [c_void_p, c_size_t, c_ulong]
+            self.win.VirtualFree(self.addr, 0, 0x8000)
+        else:
+            self.mm.close()
+
+
+
+if __name__ == "__main__":
+    def valid_inputs():
+        cpuid = CPUID()
+        for eax in (0x0, 0x80000000):
+            highest, _, _, _ = cpuid(eax)
+            while eax <= highest:
+                regs = cpuid(eax)
+                yield (eax, regs)
+                eax += 1
+
+
+    print(" ".join(x.ljust(8) for x in ("CPUID", "A", "B", "C", "D")).strip())
+    for eax, regs in valid_inputs():
+        print("%08x" % eax, " ".join("%08x" % reg for reg in regs))

lib/spack/external/archspec/vendor/cpuid/example.py

@@ -0,0 +1,62 @@
+# -*- coding: utf-8 -*-
+#
+#     Copyright (c) 2024 Anders Høst
+#
+
+from __future__ import print_function
+
+import struct
+import cpuid
+
+
+def cpu_vendor(cpu):
+    _, b, c, d = cpu(0)
+    return struct.pack("III", b, d, c).decode("utf-8")
+
+
+def cpu_name(cpu):
+    name = "".join((struct.pack("IIII", *cpu(0x80000000 + i)).decode("utf-8")
+                    for i in range(2, 5)))
+
+    return name.split('\x00', 1)[0]
+
+
+def is_set(cpu, leaf, subleaf, reg_idx, bit):
+    """
+    @param {leaf} %eax
+    @param {sublead} %ecx, 0 in most cases
+    @param {reg_idx} idx of [%eax, %ebx, %ecx, %edx], 0-based
+    @param {bit} bit of reg selected by {reg_idx}, 0-based
+    """
+
+    regs = cpu(leaf, subleaf)
+
+    if (1 << bit) & regs[reg_idx]:
+        return "Yes"
+    else:
+        return "--"
+
+
+if __name__ == "__main__":
+    cpu = cpuid.CPUID()
+
+    print("Vendor ID : %s" % cpu_vendor(cpu))
+    print("CPU name  : %s" % cpu_name(cpu))
+    print()
+    print("Vector instructions supported:")
+    print("SSE       : %s" % is_set(cpu, 1, 0, 3, 25))
+    print("SSE2      : %s" % is_set(cpu, 1, 0, 3, 26))
+    print("SSE3      : %s" % is_set(cpu, 1, 0, 2, 0))
+    print("SSSE3     : %s" % is_set(cpu, 1, 0, 2, 9))
+    print("SSE4.1    : %s" % is_set(cpu, 1, 0, 2, 19))
+    print("SSE4.2    : %s" % is_set(cpu, 1, 0, 2, 20))
+    print("SSE4a     : %s" % is_set(cpu, 0x80000001, 0, 2, 6))
+    print("AVX       : %s" % is_set(cpu, 1, 0, 2, 28))
+    print("AVX2      : %s" % is_set(cpu, 7, 0, 1, 5))
+    print("BMI1      : %s" % is_set(cpu, 7, 0, 1, 3))
+    print("BMI2      : %s" % is_set(cpu, 7, 0, 1, 8))
+    # Intel RDT CMT/MBM
+    print("L3 Monitoring : %s" % is_set(cpu, 0xf, 0, 3, 1))
+    print("L3 Occupancy  : %s" % is_set(cpu, 0xf, 1, 3, 0))
+    print("L3 Total BW   : %s" % is_set(cpu, 0xf, 1, 3, 1))
+    print("L3 Local BW   : %s" % is_set(cpu, 0xf, 1, 3, 2))

lib/spack/llnl/util/tty/log.py

@@ -332,7 +332,19 @@ def close(self):
 class MultiProcessFd:
     """Return an object which stores a file descriptor and can be passed as an
     argument to a function run with ``multiprocessing.Process``, such that
-    the file descriptor is available in the subprocess."""
+    the file descriptor is available in the subprocess. It provides access via
+    the `fd` property.
+
+    This object takes control over the associated FD: files opened from this
+    using `fdopen` need to use `closefd=False`.
+    """
+
+    # As for why you have to fdopen(..., closefd=False): when a
+    # multiprocessing.connection.Connection object stores an fd, it assumes
+    # control over it, and will attempt to close it when gc'ed during __del__;
+    # if you fdopen(multiprocessfd.fd, closefd=True) then the resulting file
+    # will also assume control, and you can see warnings when there is an
+    # attempted double close.
 
     def __init__(self, fd):
         self._connection = None
@@ -345,33 +357,20 @@ def __init__(self, fd):
     @property
     def fd(self):
         if self._connection:
-            return self._connection._handle
+            return self._connection.fileno()
         else:
             return self._fd
 
     def close(self):
+        """Rather than `.close()`ing any file opened from the associated
+        `.fd`, the `MultiProcessFd` should be closed with this.
+        """
         if self._connection:
             self._connection.close()
         else:
             os.close(self._fd)
 
 
-def close_connection_and_file(multiprocess_fd, file):
-    # MultiprocessFd is intended to transmit a FD
-    # to a child process, this FD is then opened to a Python File object
-    # (using fdopen). In >= 3.8, MultiprocessFd encapsulates a
-    # multiprocessing.connection.Connection; Connection closes the FD
-    # when it is deleted, and prints a warning about duplicate closure if
-    # it is not explicitly closed. In < 3.8, MultiprocessFd encapsulates a
-    # simple FD; closing the FD here appears to conflict with
-    # closure of the File object (in < 3.8 that is). Therefore this needs
-    # to choose whether to close the File or the Connection.
-    if sys.version_info >= (3, 8):
-        multiprocess_fd.close()
-    else:
-        file.close()
-
-
 @contextmanager
 def replace_environment(env):
     """Replace the current environment (`os.environ`) with `env`.
@@ -916,10 +915,10 @@ def _writer_daemon(
     # 1. Use line buffering (3rd param = 1) since Python 3 has a bug
     # that prevents unbuffered text I/O.
     # 2. Python 3.x before 3.7 does not open with UTF-8 encoding by default
-    in_pipe = os.fdopen(read_multiprocess_fd.fd, "r", 1, encoding="utf-8")
+    in_pipe = os.fdopen(read_multiprocess_fd.fd, "r", 1, encoding="utf-8", closefd=False)
 
     if stdin_multiprocess_fd:
-        stdin = os.fdopen(stdin_multiprocess_fd.fd)
+        stdin = os.fdopen(stdin_multiprocess_fd.fd, closefd=False)
     else:
         stdin = None
 
@@ -1009,9 +1008,9 @@ def _writer_daemon(
         if isinstance(log_file, io.StringIO):
             control_pipe.send(log_file.getvalue())
         log_file_wrapper.close()
-        close_connection_and_file(read_multiprocess_fd, in_pipe)
+        read_multiprocess_fd.close()
         if stdin_multiprocess_fd:
-            close_connection_and_file(stdin_multiprocess_fd, stdin)
+            stdin_multiprocess_fd.close()
 
         # send echo value back to the parent so it can be preserved.
         control_pipe.send(echo)

lib/spack/spack/__init__.py

@@ -4,7 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 #: PEP440 canonical <major>.<minor>.<micro>.<devN> string
-__version__ = "0.21.0.dev0"
+__version__ = "0.21.3"
 spack_version = __version__
 
 

lib/spack/spack/audit.py

@@ -40,6 +40,7 @@ def _search_duplicate_compilers(error_cls):
 import collections.abc
 import glob
 import inspect
+import io
 import itertools
 import pathlib
 import pickle
@@ -54,6 +55,7 @@ def _search_duplicate_compilers(error_cls):
 import spack.repo
 import spack.spec
 import spack.util.crypto
+import spack.util.spack_yaml as syaml
 import spack.variant
 
 #: Map an audit tag to a list of callables implementing checks
@@ -250,6 +252,88 @@ def _search_duplicate_specs_in_externals(error_cls):
     return errors
 
 
+@config_packages
+def _deprecated_preferences(error_cls):
+    """Search package preferences deprecated in v0.21 (and slated for removal in v0.22)"""
+    # TODO (v0.22): remove this audit as the attributes will not be allowed in config
+    errors = []
+    packages_yaml = spack.config.CONFIG.get_config("packages")
+
+    def make_error(attribute_name, config_data, summary):
+        s = io.StringIO()
+        s.write("Occurring in the following file:\n")
+        dict_view = syaml.syaml_dict((k, v) for k, v in config_data.items() if k == attribute_name)
+        syaml.dump_config(dict_view, stream=s, blame=True)
+        return error_cls(summary=summary, details=[s.getvalue()])
+
+    if "all" in packages_yaml and "version" in packages_yaml["all"]:
+        summary = "Using the deprecated 'version' attribute under 'packages:all'"
+        errors.append(make_error("version", packages_yaml["all"], summary))
+
+    for package_name in packages_yaml:
+        if package_name == "all":
+            continue
+
+        package_conf = packages_yaml[package_name]
+        for attribute in ("compiler", "providers", "target"):
+            if attribute not in package_conf:
+                continue
+            summary = (
+                f"Using the deprecated '{attribute}' attribute " f"under 'packages:{package_name}'"
+            )
+            errors.append(make_error(attribute, package_conf, summary))
+
+    return errors
+
+
+@config_packages
+def _avoid_mismatched_variants(error_cls):
+    """Warns if variant preferences have mismatched types or names."""
+    errors = []
+    packages_yaml = spack.config.CONFIG.get_config("packages")
+
+    def make_error(config_data, summary):
+        s = io.StringIO()
+        s.write("Occurring in the following file:\n")
+        syaml.dump_config(config_data, stream=s, blame=True)
+        return error_cls(summary=summary, details=[s.getvalue()])
+
+    for pkg_name in packages_yaml:
+        # 'all:' must be more forgiving, since it is setting defaults for everything
+        if pkg_name == "all" or "variants" not in packages_yaml[pkg_name]:
+            continue
+
+        preferences = packages_yaml[pkg_name]["variants"]
+        if not isinstance(preferences, list):
+            preferences = [preferences]
+
+        for variants in preferences:
+            current_spec = spack.spec.Spec(variants)
+            pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
+            for variant in current_spec.variants.values():
+                # Variant does not exist at all
+                if variant.name not in pkg_cls.variants:
+                    summary = (
+                        f"Setting a preference for the '{pkg_name}' package to the "
+                        f"non-existing variant '{variant.name}'"
+                    )
+                    errors.append(make_error(preferences, summary))
+                    continue
+
+                # Variant cannot accept this value
+                s = spack.spec.Spec(pkg_name)
+                try:
+                    s.update_variant_validate(variant.name, variant.value)
+                except Exception:
+                    summary = (
+                        f"Setting the variant '{variant.name}' of the '{pkg_name}' package "
+                        f"to the invalid value '{str(variant)}'"
+                    )
+                    errors.append(make_error(preferences, summary))
+
+    return errors
+
+
 #: Sanity checks on package directives
 package_directives = AuditClass(
     group="packages",
@@ -776,7 +860,7 @@ def _version_constraints_are_satisfiable_by_some_version_in_repo(pkgs, error_cls
                 )
             except Exception:
                 summary = (
-                    "{0}: dependency on {1} cannot be satisfied " "by known versions of {1.name}"
+                    "{0}: dependency on {1} cannot be satisfied by known versions of {1.name}"
                 ).format(pkg_name, s)
                 details = ["happening in " + filename]
                 if dependency_pkg_cls is not None:
@@ -818,6 +902,53 @@ def _analyze_variants_in_directive(pkg, constraint, directive, error_cls):
     return errors
 
 
+@package_directives
+def _named_specs_in_when_arguments(pkgs, error_cls):
+    """Reports named specs in the 'when=' attribute of a directive.
+
+    Note that 'conflicts' is the only directive allowing that.
+    """
+    errors = []
+    for pkg_name in pkgs:
+        pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
+
+        def _extracts_errors(triggers, summary):
+            _errors = []
+            for trigger in list(triggers):
+                when_spec = spack.spec.Spec(trigger)
+                if when_spec.name is not None and when_spec.name != pkg_name:
+                    details = [f"using '{trigger}', should be '^{trigger}'"]
+                    _errors.append(error_cls(summary=summary, details=details))
+            return _errors
+
+        for dname, triggers in pkg_cls.dependencies.items():
+            summary = f"{pkg_name}: wrong 'when=' condition for the '{dname}' dependency"
+            errors.extend(_extracts_errors(triggers, summary))
+
+        for vname, (variant, triggers) in pkg_cls.variants.items():
+            summary = f"{pkg_name}: wrong 'when=' condition for the '{vname}' variant"
+            errors.extend(_extracts_errors(triggers, summary))
+
+        for provided, triggers in pkg_cls.provided.items():
+            summary = f"{pkg_name}: wrong 'when=' condition for the '{provided}' virtual"
+            errors.extend(_extracts_errors(triggers, summary))
+
+        for _, triggers in pkg_cls.requirements.items():
+            triggers = [when_spec for when_spec, _, _ in triggers]
+            summary = f"{pkg_name}: wrong 'when=' condition in 'requires' directive"
+            errors.extend(_extracts_errors(triggers, summary))
+
+        triggers = list(pkg_cls.patches)
+        summary = f"{pkg_name}: wrong 'when=' condition in 'patch' directives"
+        errors.extend(_extracts_errors(triggers, summary))
+
+        triggers = list(pkg_cls.resources)
+        summary = f"{pkg_name}: wrong 'when=' condition in 'resource' directives"
+        errors.extend(_extracts_errors(triggers, summary))
+
+    return llnl.util.lang.dedupe(errors)
+
+
 #: Sanity checks on package directives
 external_detection = AuditClass(
     group="externals",

lib/spack/spack/binary_distribution.py

@@ -66,8 +66,10 @@
 from spack.stage import Stage
 from spack.util.executable import which
 
-_build_cache_relative_path = "build_cache"
-_build_cache_keys_relative_path = "_pgp"
+BUILD_CACHE_RELATIVE_PATH = "build_cache"
+BUILD_CACHE_KEYS_RELATIVE_PATH = "_pgp"
+CURRENT_BUILD_CACHE_LAYOUT_VERSION = 1
+FORWARD_COMPAT_BUILD_CACHE_LAYOUT_VERSION = 2
 
 
 class BuildCacheDatabase(spack_db.Database):
@@ -481,7 +483,7 @@ def _fetch_and_cache_index(self, mirror_url, cache_entry={}):
         scheme = urllib.parse.urlparse(mirror_url).scheme
 
         if scheme != "oci" and not web_util.url_exists(
-            url_util.join(mirror_url, _build_cache_relative_path, "index.json")
+            url_util.join(mirror_url, BUILD_CACHE_RELATIVE_PATH, "index.json")
         ):
             return False
 
@@ -600,6 +602,10 @@ def __init__(self, msg):
         super().__init__(msg)
 
 
+class InvalidMetadataFile(spack.error.SpackError):
+    pass
+
+
 class UnsignedPackageException(spack.error.SpackError):
     """
     Raised if installation of unsigned package is attempted without
@@ -614,11 +620,11 @@ def compute_hash(data):
 
 
 def build_cache_relative_path():
-    return _build_cache_relative_path
+    return BUILD_CACHE_RELATIVE_PATH
 
 
 def build_cache_keys_relative_path():
-    return _build_cache_keys_relative_path
+    return BUILD_CACHE_KEYS_RELATIVE_PATH
 
 
 def build_cache_prefix(prefix):
@@ -1401,7 +1407,7 @@ def _build_tarball_in_stage_dir(spec: Spec, out_url: str, stage_dir: str, option
             spec_dict = sjson.load(content)
         else:
             raise ValueError("{0} not a valid spec file type".format(spec_file))
-    spec_dict["buildcache_layout_version"] = 1
+    spec_dict["buildcache_layout_version"] = CURRENT_BUILD_CACHE_LAYOUT_VERSION
     spec_dict["binary_cache_checksum"] = {"hash_algorithm": "sha256", "hash": checksum}
 
     with open(specfile_path, "w") as outfile:
@@ -1560,6 +1566,42 @@ def _delete_staged_downloads(download_result):
     download_result["specfile_stage"].destroy()
 
 
+def _get_valid_spec_file(path: str, max_supported_layout: int) -> Tuple[Dict, int]:
+    """Read and validate a spec file, returning the spec dict with its layout version, or raising
+    InvalidMetadataFile if invalid."""
+    try:
+        with open(path, "rb") as f:
+            binary_content = f.read()
+    except OSError:
+        raise InvalidMetadataFile(f"No such file: {path}")
+
+    # In the future we may support transparently decompressing compressed spec files.
+    if binary_content[:2] == b"\x1f\x8b":
+        raise InvalidMetadataFile("Compressed spec files are not supported")
+
+    try:
+        as_string = binary_content.decode("utf-8")
+        if path.endswith(".json.sig"):
+            spec_dict = Spec.extract_json_from_clearsig(as_string)
+        else:
+            spec_dict = json.loads(as_string)
+    except Exception as e:
+        raise InvalidMetadataFile(f"Could not parse {path} due to: {e}") from e
+
+    # Ensure this version is not too new.
+    try:
+        layout_version = int(spec_dict.get("buildcache_layout_version", 0))
+    except ValueError as e:
+        raise InvalidMetadataFile("Could not parse layout version") from e
+
+    if layout_version > max_supported_layout:
+        raise InvalidMetadataFile(
+            f"Layout version {layout_version} is too new for this version of Spack"
+        )
+
+    return spec_dict, layout_version
+
+
 def download_tarball(spec, unsigned=False, mirrors_for_spec=None):
     """
     Download binary tarball for given package into stage area, returning
@@ -1652,6 +1694,18 @@ def download_tarball(spec, unsigned=False, mirrors_for_spec=None):
                     try:
                         local_specfile_stage.fetch()
                         local_specfile_stage.check()
+                        try:
+                            _get_valid_spec_file(
+                                local_specfile_stage.save_filename,
+                                FORWARD_COMPAT_BUILD_CACHE_LAYOUT_VERSION,
+                            )
+                        except InvalidMetadataFile as e:
+                            tty.warn(
+                                f"Ignoring binary package for {spec.name}/{spec.dag_hash()[:7]} "
+                                f"from {mirror} due to invalid metadata file: {e}"
+                            )
+                            local_specfile_stage.destroy()
+                            continue
                     except Exception:
                         continue
                     local_specfile_stage.cache_local()
@@ -1674,14 +1728,26 @@ def download_tarball(spec, unsigned=False, mirrors_for_spec=None):
 
             else:
                 ext = "json.sig" if try_signed else "json"
-                specfile_path = url_util.join(mirror, _build_cache_relative_path, specfile_prefix)
+                specfile_path = url_util.join(mirror, BUILD_CACHE_RELATIVE_PATH, specfile_prefix)
                 specfile_url = f"{specfile_path}.{ext}"
-                spackfile_url = url_util.join(mirror, _build_cache_relative_path, tarball)
+                spackfile_url = url_util.join(mirror, BUILD_CACHE_RELATIVE_PATH, tarball)
                 local_specfile_stage = try_fetch(specfile_url)
                 if local_specfile_stage:
                     local_specfile_path = local_specfile_stage.save_filename
                     signature_verified = False
 
+                    try:
+                        _get_valid_spec_file(
+                            local_specfile_path, FORWARD_COMPAT_BUILD_CACHE_LAYOUT_VERSION
+                        )
+                    except InvalidMetadataFile as e:
+                        tty.warn(
+                            f"Ignoring binary package for {spec.name}/{spec.dag_hash()[:7]} "
+                            f"from {mirror} due to invalid metadata file: {e}"
+                        )
+                        local_specfile_stage.destroy()
+                        continue
+
                     if try_signed and not unsigned:
                         # If we found a signed specfile at the root, try to verify
                         # the signature immediately.  We will not download the
@@ -1961,11 +2027,12 @@ def _extract_inner_tarball(spec, filename, extract_to, unsigned, remote_checksum
 
 
 def _tar_strip_component(tar: tarfile.TarFile, prefix: str):
-    """Strip the top-level directory `prefix` from the member names in a tarfile."""
+    """Yield all members of tarfile that start with given prefix, and strip that prefix (including
+    symlinks)"""
     # Including trailing /, otherwise we end up with absolute paths.
     regex = re.compile(re.escape(prefix) + "/*")
 
-    # Remove the top-level directory from the member (link)names.
+    # Only yield members in the package prefix.
     # Note: when a tarfile is created, relative in-prefix symlinks are
     # expanded to matching member names of tarfile entries. So, we have
     # to ensure that those are updated too.
@@ -1973,12 +2040,14 @@ def _tar_strip_component(tar: tarfile.TarFile, prefix: str):
     # them.
     for m in tar.getmembers():
         result = regex.match(m.name)
-        assert result is not None
+        if not result:
+            continue
         m.name = m.name[result.end() :]
         if m.linkname:
             result = regex.match(m.linkname)
             if result:
                 m.linkname = m.linkname[result.end() :]
+        yield m
 
 
 def extract_tarball(spec, download_result, unsigned=False, force=False, timer=timer.NULL_TIMER):
@@ -2001,24 +2070,16 @@ def extract_tarball(spec, download_result, unsigned=False, force=False, timer=ti
     )
 
     specfile_path = download_result["specfile_stage"].save_filename
-
-    with open(specfile_path, "r") as inputfile:
-        content = inputfile.read()
-        if specfile_path.endswith(".json.sig"):
-            spec_dict = Spec.extract_json_from_clearsig(content)
-        else:
-            spec_dict = sjson.load(content)
-
+    spec_dict, layout_version = _get_valid_spec_file(
+        specfile_path, FORWARD_COMPAT_BUILD_CACHE_LAYOUT_VERSION
+    )
     bchecksum = spec_dict["binary_cache_checksum"]
 
     filename = download_result["tarball_stage"].save_filename
     signature_verified = download_result["signature_verified"]
     tmpdir = None
 
-    if (
-        "buildcache_layout_version" not in spec_dict
-        or int(spec_dict["buildcache_layout_version"]) < 1
-    ):
+    if layout_version == 0:
         # Handle the older buildcache layout where the .spack file
         # contains a spec json, maybe an .asc file (signature),
         # and another tarball containing the actual install tree.
@@ -2029,7 +2090,7 @@ def extract_tarball(spec, download_result, unsigned=False, force=False, timer=ti
             _delete_staged_downloads(download_result)
             shutil.rmtree(tmpdir)
             raise e
-    else:
+    elif 1 <= layout_version <= 2:
         # Newer buildcache layout: the .spack file contains just
         # in the install tree, the signature, if it exists, is
         # wrapped around the spec.json at the root.  If sig verify
@@ -2053,12 +2114,13 @@ def extract_tarball(spec, download_result, unsigned=False, force=False, timer=ti
             raise NoChecksumException(
                 tarfile_path, size, contents, "sha256", expected, local_checksum
             )
-
     try:
         with closing(tarfile.open(tarfile_path, "r")) as tar:
             # Remove install prefix from tarfil to extract directly into spec.prefix
-            _tar_strip_component(tar, prefix=_ensure_common_prefix(tar))
-            tar.extractall(path=spec.prefix)
+            tar.extractall(
+                path=spec.prefix,
+                members=_tar_strip_component(tar, prefix=_ensure_common_prefix(tar)),
+            )
     except Exception:
         shutil.rmtree(spec.prefix, ignore_errors=True)
         _delete_staged_downloads(download_result)
@@ -2093,20 +2155,47 @@ def extract_tarball(spec, download_result, unsigned=False, force=False, timer=ti
 
 
 def _ensure_common_prefix(tar: tarfile.TarFile) -> str:
-    # Get the shortest length directory.
-    common_prefix = min((e.name for e in tar.getmembers() if e.isdir()), key=len, default=None)
+    # Find the lowest `binary_distribution` file (hard-coded forward slash is on purpose).
+    binary_distribution = min(
+        (
+            e.name
+            for e in tar.getmembers()
+            if e.isfile() and e.name.endswith(".spack/binary_distribution")
+        ),
+        key=len,
+        default=None,
+    )
 
-    if common_prefix is None:
-        raise ValueError("Tarball does not contain a common prefix")
+    if binary_distribution is None:
+        raise ValueError("Tarball is not a Spack package, missing binary_distribution file")
 
-    # Validate that each file starts with the prefix
+    pkg_path = pathlib.PurePosixPath(binary_distribution).parent.parent
+
+    # Even the most ancient Spack version has required to list the dir of the package itself, so
+    # guard against broken tarballs where `path.parent.parent` is empty.
+    if pkg_path == pathlib.PurePosixPath():
+        raise ValueError("Invalid tarball, missing package prefix dir")
+
+    pkg_prefix = str(pkg_path)
+
+    # Ensure all tar entries are in the pkg_prefix dir, and if they're not, they should be parent
+    # dirs of it.
+    has_prefix = False
     for member in tar.getmembers():
-        if not member.name.startswith(common_prefix):
-            raise ValueError(
-                f"Tarball contains file {member.name} outside of prefix {common_prefix}"
-            )
+        stripped = member.name.rstrip("/")
+        if not (
+            stripped.startswith(pkg_prefix) or member.isdir() and pkg_prefix.startswith(stripped)
+        ):
+            raise ValueError(f"Tarball contains file {stripped} outside of prefix {pkg_prefix}")
+        if member.isdir() and stripped == pkg_prefix:
+            has_prefix = True
 
-    return common_prefix
+    # This is technically not required, but let's be defensive about the existence of the package
+    # prefix dir.
+    if not has_prefix:
+        raise ValueError(f"Tarball does not contain a common prefix {pkg_prefix}")
+
+    return pkg_prefix
 
 
 def install_root_node(spec, unsigned=False, force=False, sha256=None):
@@ -2184,10 +2273,10 @@ def try_direct_fetch(spec, mirrors=None):
 
     for mirror in binary_mirrors:
         buildcache_fetch_url_json = url_util.join(
-            mirror.fetch_url, _build_cache_relative_path, specfile_name
+            mirror.fetch_url, BUILD_CACHE_RELATIVE_PATH, specfile_name
         )
         buildcache_fetch_url_signed_json = url_util.join(
-            mirror.fetch_url, _build_cache_relative_path, signed_specfile_name
+            mirror.fetch_url, BUILD_CACHE_RELATIVE_PATH, signed_specfile_name
         )
         try:
             _, _, fs = web_util.read_from_url(buildcache_fetch_url_signed_json)
@@ -2291,8 +2380,11 @@ def get_keys(install=False, trust=False, force=False, mirrors=None):
 
     for mirror in mirror_collection.values():
         fetch_url = mirror.fetch_url
+        # TODO: oci:// does not support signing.
+        if fetch_url.startswith("oci://"):
+            continue
         keys_url = url_util.join(
-            fetch_url, _build_cache_relative_path, _build_cache_keys_relative_path
+            fetch_url, BUILD_CACHE_RELATIVE_PATH, BUILD_CACHE_KEYS_RELATIVE_PATH
         )
         keys_index = url_util.join(keys_url, "index.json")
 
@@ -2357,7 +2449,7 @@ def push_keys(*mirrors, **kwargs):
         for mirror in mirrors:
             push_url = getattr(mirror, "push_url", mirror)
             keys_url = url_util.join(
-                push_url, _build_cache_relative_path, _build_cache_keys_relative_path
+                push_url, BUILD_CACHE_RELATIVE_PATH, BUILD_CACHE_KEYS_RELATIVE_PATH
             )
             keys_local = url_util.local_file_path(keys_url)
 
@@ -2495,11 +2587,11 @@ def download_buildcache_entry(file_descriptions, mirror_url=None):
         )
 
     if mirror_url:
-        mirror_root = os.path.join(mirror_url, _build_cache_relative_path)
+        mirror_root = os.path.join(mirror_url, BUILD_CACHE_RELATIVE_PATH)
         return _download_buildcache_entry(mirror_root, file_descriptions)
 
     for mirror in spack.mirror.MirrorCollection(binary=True).values():
-        mirror_root = os.path.join(mirror.fetch_url, _build_cache_relative_path)
+        mirror_root = os.path.join(mirror.fetch_url, BUILD_CACHE_RELATIVE_PATH)
 
         if _download_buildcache_entry(mirror_root, file_descriptions):
             return True
@@ -2590,7 +2682,7 @@ def __init__(self, url, local_hash, urlopen=web_util.urlopen):
 
     def get_remote_hash(self):
         # Failure to fetch index.json.hash is not fatal
-        url_index_hash = url_util.join(self.url, _build_cache_relative_path, "index.json.hash")
+        url_index_hash = url_util.join(self.url, BUILD_CACHE_RELATIVE_PATH, "index.json.hash")
         try:
             response = self.urlopen(urllib.request.Request(url_index_hash, headers=self.headers))
         except urllib.error.URLError:
@@ -2611,7 +2703,7 @@ def conditional_fetch(self) -> FetchIndexResult:
             return FetchIndexResult(etag=None, hash=None, data=None, fresh=True)
 
         # Otherwise, download index.json
-        url_index = url_util.join(self.url, _build_cache_relative_path, "index.json")
+        url_index = url_util.join(self.url, BUILD_CACHE_RELATIVE_PATH, "index.json")
 
         try:
             response = self.urlopen(urllib.request.Request(url_index, headers=self.headers))
@@ -2655,7 +2747,7 @@ def __init__(self, url, etag, urlopen=web_util.urlopen):
 
     def conditional_fetch(self) -> FetchIndexResult:
         # Just do a conditional fetch immediately
-        url = url_util.join(self.url, _build_cache_relative_path, "index.json")
+        url = url_util.join(self.url, BUILD_CACHE_RELATIVE_PATH, "index.json")
         headers = {
             "User-Agent": web_util.SPACK_USER_AGENT,
             "If-None-Match": '"{}"'.format(self.etag),

lib/spack/spack/bootstrap/_common.py

@@ -213,7 +213,8 @@ def _root_spec(spec_str: str) -> str:
     if str(spack.platforms.host()) == "darwin":
         spec_str += " %apple-clang"
     elif str(spack.platforms.host()) == "windows":
-        spec_str += " %msvc"
+        # TODO (johnwparent): Remove version constraint when clingo patch is up
+        spec_str += " %msvc@:19.37"
     else:
         spec_str += " %gcc"
 

lib/spack/spack/bootstrap/config.py

@@ -143,7 +143,9 @@ def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
 def _add_compilers_if_missing() -> None:
     arch = spack.spec.ArchSpec.frontend_arch()
     if not spack.compilers.compilers_for_arch(arch):
-        new_compilers = spack.compilers.find_new_compilers()
+        new_compilers = spack.compilers.find_new_compilers(
+            mixed_toolchain=sys.platform == "darwin"
+        )
         if new_compilers:
             spack.compilers.add_compilers_to_config(new_compilers, init_config=False)
 

lib/spack/spack/bootstrap/core.py

@@ -291,6 +291,10 @@ def try_import(self, module: str, abstract_spec_str: str) -> bool:
         with spack_python_interpreter():
             # Add hint to use frontend operating system on Cray
             concrete_spec = spack.spec.Spec(abstract_spec_str + " ^" + spec_for_current_python())
+            # This is needed to help the old concretizer taking the `setuptools` dependency
+            # only when bootstrapping from sources on Python 3.12
+            if spec_for_current_python() == "python@3.12":
+                concrete_spec.constrain("+force_setuptools")
 
             if module == "clingo":
                 # TODO: remove when the old concretizer is deprecated  # pylint: disable=fixme

lib/spack/spack/build_environment.py

@@ -324,19 +324,29 @@ def set_compiler_environment_variables(pkg, env):
     # ttyout, ttyerr, etc.
     link_dir = spack.paths.build_env_path
 
-    # Set SPACK compiler variables so that our wrapper knows what to call
+    # Set SPACK compiler variables so that our wrapper knows what to
+    # call.  If there is no compiler configured then use a default
+    # wrapper which will emit an error if it is used.
     if compiler.cc:
         env.set("SPACK_CC", compiler.cc)
         env.set("CC", os.path.join(link_dir, compiler.link_paths["cc"]))
+    else:
+        env.set("CC", os.path.join(link_dir, "cc"))
     if compiler.cxx:
         env.set("SPACK_CXX", compiler.cxx)
         env.set("CXX", os.path.join(link_dir, compiler.link_paths["cxx"]))
+    else:
+        env.set("CC", os.path.join(link_dir, "c++"))
     if compiler.f77:
         env.set("SPACK_F77", compiler.f77)
         env.set("F77", os.path.join(link_dir, compiler.link_paths["f77"]))
+    else:
+        env.set("F77", os.path.join(link_dir, "f77"))
     if compiler.fc:
         env.set("SPACK_FC", compiler.fc)
         env.set("FC", os.path.join(link_dir, compiler.link_paths["fc"]))
+    else:
+        env.set("FC", os.path.join(link_dir, "fc"))
 
     # Set SPACK compiler rpath flags so that our wrapper knows what to use
     env.set("SPACK_CC_RPATH_ARG", compiler.cc_rpath_arg)
@@ -743,15 +753,16 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
         set_compiler_environment_variables(pkg, env_mods)
         set_wrapper_variables(pkg, env_mods)
 
-    tty.debug("setup_package: grabbing modifications from dependencies")
-    env_mods.extend(setup_context.get_env_modifications())
-    tty.debug("setup_package: collected all modifications from dependencies")
-
-    # architecture specific setup
+    # Platform specific setup goes before package specific setup. This is for setting
+    # defaults like MACOSX_DEPLOYMENT_TARGET on macOS.
     platform = spack.platforms.by_name(pkg.spec.architecture.platform)
     target = platform.target(pkg.spec.architecture.target)
     platform.setup_platform_environment(pkg, env_mods)
 
+    tty.debug("setup_package: grabbing modifications from dependencies")
+    env_mods.extend(setup_context.get_env_modifications())
+    tty.debug("setup_package: collected all modifications from dependencies")
+
     if context == Context.TEST:
         env_mods.prepend_path("PATH", ".")
     elif context == Context.BUILD and not dirty and not env_mods.is_unset("CPATH"):
@@ -778,7 +789,7 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
         for mod in ["cray-mpich", "cray-libsci"]:
             module("unload", mod)
 
-    if target.module_name:
+    if target and target.module_name:
         load_module(target.module_name)
 
     load_external_modules(pkg)
@@ -1016,10 +1027,17 @@ def get_env_modifications(self) -> EnvironmentModifications:
                 self._make_runnable(dspec, env)
 
             if self.should_setup_run_env & flag:
+                run_env_mods = EnvironmentModifications()
                 for spec in dspec.dependents(deptype=dt.LINK | dt.RUN):
                     if id(spec) in self.nodes_in_subdag:
-                        pkg.setup_dependent_run_environment(env, spec)
-                pkg.setup_run_environment(env)
+                        pkg.setup_dependent_run_environment(run_env_mods, spec)
+                pkg.setup_run_environment(run_env_mods)
+                if self.context == Context.BUILD:
+                    # Don't let the runtime environment of comiler like dependencies leak into the
+                    # build env
+                    run_env_mods.drop("CC", "CXX", "F77", "FC")
+                env.extend(run_env_mods)
+
         return env
 
     def _make_buildtime_detectable(self, dep: spack.spec.Spec, env: EnvironmentModifications):
@@ -1080,7 +1098,7 @@ def _setup_pkg_and_run(
         # that the parent process is not going to read from it till we
         # are done with the child, so we undo Python's precaution.
         if input_multiprocess_fd is not None:
-            sys.stdin = os.fdopen(input_multiprocess_fd.fd)
+            sys.stdin = os.fdopen(input_multiprocess_fd.fd, closefd=False)
 
         pkg = serialized_pkg.restore()
 
@@ -1315,7 +1333,7 @@ def make_stack(tb, stack=None):
             # don't provide context if the code is actually in the base classes.
             obj = frame.f_locals["self"]
             func = getattr(obj, tb.tb_frame.f_code.co_name, "")
-            if func:
+            if func and hasattr(func, "__qualname__"):
                 typename, *_ = func.__qualname__.partition(".")
                 if isinstance(obj, CONTEXT_BASES) and typename not in basenames:
                     break

lib/spack/spack/build_systems/oneapi.py

@@ -9,11 +9,10 @@
 import shutil
 from os.path import basename, dirname, isdir
 
-from llnl.util.filesystem import find_headers, find_libraries, join_path
+from llnl.util.filesystem import find_headers, find_libraries, join_path, mkdirp
 from llnl.util.link_tree import LinkTree
 
 from spack.directives import conflicts, variant
-from spack.package import mkdirp
 from spack.util.environment import EnvironmentModifications
 from spack.util.executable import Executable
 
@@ -212,3 +211,7 @@ def link_flags(self):
     @property
     def ld_flags(self):
         return "{0} {1}".format(self.search_flags, self.link_flags)
+
+
+#: Tuple of Intel math libraries, exported to packages
+INTEL_MATH_LIBRARIES = ("intel-mkl", "intel-oneapi-mkl", "intel-parallel-studio")

lib/spack/spack/cmd/audit.py

@@ -2,6 +2,8 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import warnings
+
 import llnl.util.tty as tty
 import llnl.util.tty.colify
 import llnl.util.tty.color as cl
@@ -52,8 +54,10 @@ def setup_parser(subparser):
 
 
 def configs(parser, args):
-    reports = spack.audit.run_group(args.subcommand)
-    _process_reports(reports)
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        reports = spack.audit.run_group(args.subcommand)
+        _process_reports(reports)
 
 
 def packages(parser, args):

lib/spack/spack/cmd/buildcache.py

@@ -7,13 +7,14 @@
 import glob
 import hashlib
 import json
+import multiprocessing
 import multiprocessing.pool
 import os
 import shutil
 import sys
 import tempfile
 import urllib.request
-from typing import Dict, List, Optional, Tuple
+from typing import Dict, List, Optional, Tuple, Union
 
 import llnl.util.tty as tty
 from llnl.string import plural
@@ -307,8 +308,30 @@ def _progress(i: int, total: int):
     return ""
 
 
-def _make_pool():
-    return multiprocessing.pool.Pool(determine_number_of_jobs(parallel=True))
+class NoPool:
+    def map(self, func, args):
+        return [func(a) for a in args]
+
+    def starmap(self, func, args):
+        return [func(*a) for a in args]
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        pass
+
+
+MaybePool = Union[multiprocessing.pool.Pool, NoPool]
+
+
+def _make_pool() -> MaybePool:
+    """Can't use threading because it's unsafe, and can't use spawned processes because of globals.
+    That leaves only forking"""
+    if multiprocessing.get_start_method() == "fork":
+        return multiprocessing.pool.Pool(determine_number_of_jobs(parallel=True))
+    else:
+        return NoPool()
 
 
 def push_fn(args):
@@ -591,7 +614,7 @@ def _push_oci(
     image_ref: ImageReference,
     installed_specs_with_deps: List[Spec],
     tmpdir: str,
-    pool: multiprocessing.pool.Pool,
+    pool: MaybePool,
 ) -> List[str]:
     """Push specs to an OCI registry
 
@@ -692,11 +715,10 @@ def _config_from_tag(image_ref: ImageReference, tag: str) -> Optional[dict]:
     return config if "spec" in config else None
 
 
-def _update_index_oci(
-    image_ref: ImageReference, tmpdir: str, pool: multiprocessing.pool.Pool
-) -> None:
-    response = spack.oci.opener.urlopen(urllib.request.Request(url=image_ref.tags_url()))
-    spack.oci.opener.ensure_status(response, 200)
+def _update_index_oci(image_ref: ImageReference, tmpdir: str, pool: MaybePool) -> None:
+    request = urllib.request.Request(url=image_ref.tags_url())
+    response = spack.oci.opener.urlopen(request)
+    spack.oci.opener.ensure_status(request, response, 200)
     tags = json.load(response)["tags"]
 
     # Fetch all image config files in parallel

lib/spack/spack/cmd/commands.py

@@ -796,7 +796,9 @@ def names(args: Namespace, out: IO) -> None:
     commands = copy.copy(spack.cmd.all_commands())
 
     if args.aliases:
-        commands.extend(spack.main.aliases.keys())
+        aliases = spack.config.get("config:aliases")
+        if aliases:
+            commands.extend(aliases.keys())
 
     colify(commands, output=out)
 
@@ -812,8 +814,10 @@ def bash(args: Namespace, out: IO) -> None:
     parser = spack.main.make_argument_parser()
     spack.main.add_all_commands(parser)
 
-    aliases = ";".join(f"{key}:{val}" for key, val in spack.main.aliases.items())
-    out.write(f'SPACK_ALIASES="{aliases}"\n\n')
+    aliases_config = spack.config.get("config:aliases")
+    if aliases_config:
+        aliases = ";".join(f"{key}:{val}" for key, val in aliases_config.items())
+        out.write(f'SPACK_ALIASES="{aliases}"\n\n')
 
     writer = BashCompletionWriter(parser.prog, out, args.aliases)
     writer.write(parser)

lib/spack/spack/cmd/common/confirmation.py

@@ -0,0 +1,30 @@
+# Copyright 2013-2023 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 sys
+from typing import List
+
+import llnl.util.tty as tty
+
+import spack.cmd
+
+display_args = {"long": True, "show_flags": False, "variants": False, "indent": 4}
+
+
+def confirm_action(specs: List[spack.spec.Spec], participle: str, noun: str):
+    """Display the list of specs to be acted on and ask for confirmation.
+
+    Args:
+        specs: specs to be removed
+        participle: action expressed as a participle, e.g. "uninstalled"
+        noun: action expressed as a noun, e.g. "uninstallation"
+    """
+    tty.msg(f"The following {len(specs)} packages will be {participle}:\n")
+    spack.cmd.display_specs(specs, **display_args)
+    print("")
+    answer = tty.get_yes_or_no("Do you want to proceed?", default=False)
+    if not answer:
+        tty.msg(f"Aborting {noun}")
+        sys.exit(0)

lib/spack/spack/cmd/compiler.py

@@ -31,6 +31,19 @@ def setup_parser(subparser):
         aliases=["add"],
         help="search the system for compilers to add to Spack configuration",
     )
+    mixed_toolchain_group = find_parser.add_mutually_exclusive_group()
+    mixed_toolchain_group.add_argument(
+        "--mixed-toolchain",
+        action="store_true",
+        default=sys.platform == "darwin",
+        help="Allow mixed toolchains (for example: clang, clang++, gfortran)",
+    )
+    mixed_toolchain_group.add_argument(
+        "--no-mixed-toolchain",
+        action="store_false",
+        dest="mixed_toolchain",
+        help="Do not allow mixed toolchains (for example: clang, clang++, gfortran)",
+    )
     find_parser.add_argument("add_paths", nargs=argparse.REMAINDER)
     find_parser.add_argument(
         "--scope",
@@ -86,7 +99,9 @@ def compiler_find(args):
 
     # Below scope=None because we want new compilers that don't appear
     # in any other configuration.
-    new_compilers = spack.compilers.find_new_compilers(paths, scope=None)
+    new_compilers = spack.compilers.find_new_compilers(
+        paths, scope=None, mixed_toolchain=args.mixed_toolchain
+    )
     if new_compilers:
         spack.compilers.add_compilers_to_config(new_compilers, scope=args.scope, init_config=False)
         n = len(new_compilers)

lib/spack/spack/cmd/config.py

@@ -407,7 +407,9 @@ def config_prefer_upstream(args):
     pkgs = {}
     for spec in pref_specs:
         # Collect all the upstream compilers and versions for this package.
-        pkg = pkgs.get(spec.name, {"version": [], "compiler": []})
+        pkg = pkgs.get(spec.name, {"version": []})
+        all = pkgs.get("all", {"compiler": []})
+        pkgs["all"] = all
         pkgs[spec.name] = pkg
 
         # We have no existing variant if this is our first added version.
@@ -418,8 +420,8 @@ def config_prefer_upstream(args):
             pkg["version"].append(version)
 
         compiler = str(spec.compiler)
-        if compiler not in pkg["compiler"]:
-            pkg["compiler"].append(compiler)
+        if compiler not in all["compiler"]:
+            all["compiler"].append(compiler)
 
         # Get and list all the variants that differ from the default.
         variants = []

lib/spack/spack/cmd/deconcretize.py

@@ -0,0 +1,103 @@
+# Copyright 2013-2023 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 argparse
+import sys
+from typing import List
+
+import llnl.util.tty as tty
+
+import spack.cmd
+import spack.cmd.common.arguments as arguments
+import spack.cmd.common.confirmation as confirmation
+import spack.environment as ev
+import spack.spec
+
+description = "remove specs from the concretized lockfile of an environment"
+section = "environments"
+level = "long"
+
+# Arguments for display_specs when we find ambiguity
+display_args = {"long": True, "show_flags": False, "variants": False, "indent": 4}
+
+
+def setup_parser(subparser):
+    subparser.add_argument(
+        "--root", action="store_true", help="deconcretize only specific environment roots"
+    )
+    arguments.add_common_arguments(subparser, ["yes_to_all", "specs"])
+    subparser.add_argument(
+        "-a",
+        "--all",
+        action="store_true",
+        dest="all",
+        help="deconcretize ALL specs that match each supplied spec",
+    )
+
+
+def get_deconcretize_list(
+    args: argparse.Namespace, specs: List[spack.spec.Spec], env: ev.Environment
+) -> List[spack.spec.Spec]:
+    """
+    Get list of environment roots to deconcretize
+    """
+    env_specs = [s for _, s in env.concretized_specs()]
+    to_deconcretize = []
+    errors = []
+
+    for s in specs:
+        if args.root:
+            # find all roots matching given spec
+            to_deconc = [e for e in env_specs if e.satisfies(s)]
+        else:
+            # find all roots matching or depending on a matching spec
+            to_deconc = [e for e in env_specs if any(d.satisfies(s) for d in e.traverse())]
+
+        if len(to_deconc) < 1:
+            tty.warn(f"No matching specs to deconcretize for {s}")
+
+        elif len(to_deconc) > 1 and not args.all:
+            errors.append((s, to_deconc))
+
+        to_deconcretize.extend(to_deconc)
+
+    if errors:
+        for spec, matching in errors:
+            tty.error(f"{spec} matches multiple concrete specs:")
+            sys.stderr.write("\n")
+            spack.cmd.display_specs(matching, output=sys.stderr, **display_args)
+            sys.stderr.write("\n")
+            sys.stderr.flush()
+        tty.die("Use '--all' to deconcretize all matching specs, or be more specific")
+
+    return to_deconcretize
+
+
+def deconcretize_specs(args, specs):
+    env = spack.cmd.require_active_env(cmd_name="deconcretize")
+
+    if args.specs:
+        deconcretize_list = get_deconcretize_list(args, specs, env)
+    else:
+        deconcretize_list = [s for _, s in env.concretized_specs()]
+
+    if not args.yes_to_all:
+        confirmation.confirm_action(deconcretize_list, "deconcretized", "deconcretization")
+
+    with env.write_transaction():
+        for spec in deconcretize_list:
+            env.deconcretize(spec)
+        env.write()
+
+
+def deconcretize(parser, args):
+    if not args.specs and not args.all:
+        tty.die(
+            "deconcretize requires at least one spec argument.",
+            " Use `spack deconcretize --all` to deconcretize ALL specs.",
+        )
+
+    specs = spack.cmd.parse_specs(args.specs) if args.specs else [any]
+    deconcretize_specs(args, specs)

lib/spack/spack/cmd/dev_build.py

@@ -99,10 +99,7 @@ def dev_build(self, args):
 
     spec = specs[0]
     if not spack.repo.PATH.exists(spec.name):
-        tty.die(
-            "No package for '{0}' was found.".format(spec.name),
-            "  Use `spack create` to create a new package",
-        )
+        raise spack.repo.UnknownPackageError(spec.name)
 
     if not spec.versions.concrete_range_as_version:
         tty.die(

lib/spack/spack/cmd/edit.py

@@ -43,10 +43,7 @@ def edit_package(name, repo_path, namespace):
         if not os.access(path, os.R_OK):
             tty.die("Insufficient permissions on '%s'!" % path)
     else:
-        tty.die(
-            "No package for '{0}' was found.".format(spec.name),
-            "  Use `spack create` to create a new package",
-        )
+        raise spack.repo.UnknownPackageError(spec.name)
 
     editor(path)
 

lib/spack/spack/cmd/env.py

@@ -5,6 +5,7 @@
 
 import argparse
 import os
+import shlex
 import shutil
 import sys
 import tempfile
@@ -144,10 +145,13 @@ def create_temp_env_directory():
     return tempfile.mkdtemp(prefix="spack-")
 
 
-def env_activate(args):
-    if not args.activate_env and not args.dir and not args.temp:
-        tty.die("spack env activate requires an environment name, directory, or --temp")
+def _tty_info(msg):
+    """tty.info like function that prints the equivalent printf statement for eval."""
+    decorated = f'{colorize("@*b{==>}")} {msg}\n'
+    print(f"printf {shlex.quote(decorated)};")
 
+
+def env_activate(args):
     if not args.shell:
         spack.cmd.common.shell_init_instructions(
             "spack env activate", "    eval `spack env activate {sh_arg} [...]`"
@@ -160,12 +164,25 @@ def env_activate(args):
 
     env_name_or_dir = args.activate_env or args.dir
 
+    # When executing `spack env activate` without further arguments, activate
+    # the default environment. It's created when it doesn't exist yet.
+    if not env_name_or_dir and not args.temp:
+        short_name = "default"
+        if not ev.exists(short_name):
+            ev.create(short_name)
+            action = "Created and activated"
+        else:
+            action = "Activated"
+        env_path = ev.root(short_name)
+        _tty_info(f"{action} default environment in {env_path}")
+
     # Temporary environment
-    if args.temp:
+    elif args.temp:
         env = create_temp_env_directory()
         env_path = os.path.abspath(env)
         short_name = os.path.basename(env_path)
         ev.create_in_dir(env).write(regenerate=False)
+        _tty_info(f"Created and activated temporary environment in {env_path}")
 
     # Managed environment
     elif ev.exists(env_name_or_dir) and not args.dir:
@@ -385,7 +402,7 @@ def env_remove(args):
         try:
             env = ev.read(env_name)
             read_envs.append(env)
-        except spack.config.ConfigFormatError:
+        except (spack.config.ConfigFormatError, ev.SpackEnvironmentConfigError):
             bad_envs.append(env_name)
 
     if not args.yes_to_all:
@@ -553,8 +570,8 @@ def env_update_setup_parser(subparser):
 def env_update(args):
     manifest_file = ev.manifest_file(args.update_env)
     backup_file = manifest_file + ".bkp"
-    needs_update = not ev.is_latest_format(manifest_file)
 
+    needs_update = not ev.is_latest_format(manifest_file)
     if not needs_update:
         tty.msg('No update needed for the environment "{0}"'.format(args.update_env))
         return
@@ -672,18 +689,31 @@ def env_depfile(args):
     # Currently only make is supported.
     spack.cmd.require_active_env(cmd_name="env depfile")
 
+    env = ev.active_environment()
+
     # What things do we build when running make? By default, we build the
     # root specs. If specific specs are provided as input, we build those.
     filter_specs = spack.cmd.parse_specs(args.specs) if args.specs else None
     template = spack.tengine.make_environment().get_template(os.path.join("depfile", "Makefile"))
     model = depfile.MakefileModel.from_env(
-        ev.active_environment(),
+        env,
         filter_specs=filter_specs,
         pkg_buildcache=depfile.UseBuildCache.from_string(args.use_buildcache[0]),
         dep_buildcache=depfile.UseBuildCache.from_string(args.use_buildcache[1]),
         make_prefix=args.make_prefix,
         jobserver=args.jobserver,
     )
+
+    # Warn in case we're generating a depfile for an empty environment. We don't automatically
+    # concretize; the user should do that explicitly. Could be changed in the future if requested.
+    if model.empty:
+        if not env.user_specs:
+            tty.warn("no specs in the environment")
+        elif filter_specs is not None:
+            tty.warn("no concrete matching specs found in environment")
+        else:
+            tty.warn("environment is not concretized. Run `spack concretize` first")
+
     makefile = template.render(model.to_dict())
 
     # Finally write to stdout/file.

lib/spack/spack/cmd/gc.py

@@ -6,6 +6,7 @@
 import llnl.util.tty as tty
 
 import spack.cmd.common.arguments
+import spack.cmd.common.confirmation
 import spack.cmd.uninstall
 import spack.environment as ev
 import spack.store
@@ -41,6 +42,6 @@ def gc(parser, args):
         return
 
     if not args.yes_to_all:
-        spack.cmd.uninstall.confirm_removal(specs)
+        spack.cmd.common.confirmation.confirm_action(specs, "uninstalled", "uninstallation")
 
     spack.cmd.uninstall.do_uninstall(specs, force=False)

lib/spack/spack/cmd/graph.py

@@ -61,7 +61,7 @@ def graph(parser, args):
         args.dot = True
         env = ev.active_environment()
         if env:
-            specs = env.all_specs()
+            specs = env.concrete_roots()
         else:
             specs = spack.store.STORE.db.query()
 

lib/spack/spack/cmd/info.py

@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+import sys
 import textwrap
 from itertools import zip_longest
 
@@ -16,6 +17,7 @@
 import spack.install_test
 import spack.repo
 import spack.spec
+import spack.version
 from spack.package_base import preferred_version
 
 description = "get detailed information on a particular package"
@@ -53,6 +55,7 @@ def setup_parser(subparser):
         ("--tags", print_tags.__doc__),
         ("--tests", print_tests.__doc__),
         ("--virtuals", print_virtuals.__doc__),
+        ("--variants-by-name", "list variants in strict name order; don't group by condition"),
     ]
     for opt, help_comment in options:
         subparser.add_argument(opt, action="store_true", help=help_comment)
@@ -77,35 +80,10 @@ def license(s):
 
 
 class VariantFormatter:
-    def __init__(self, variants):
-        self.variants = variants
+    def __init__(self, pkg):
+        self.variants = pkg.variants
         self.headers = ("Name [Default]", "When", "Allowed values", "Description")
 
-        # Formats
-        fmt_name = "{0} [{1}]"
-
-        # Initialize column widths with the length of the
-        # corresponding headers, as they cannot be shorter
-        # than that
-        self.column_widths = [len(x) for x in self.headers]
-
-        # Expand columns based on max line lengths
-        for k, e in variants.items():
-            v, w = e
-            candidate_max_widths = (
-                len(fmt_name.format(k, self.default(v))),  # Name [Default]
-                len(str(w)),
-                len(v.allowed_values),  # Allowed values
-                len(v.description),  # Description
-            )
-
-            self.column_widths = (
-                max(self.column_widths[0], candidate_max_widths[0]),
-                max(self.column_widths[1], candidate_max_widths[1]),
-                max(self.column_widths[2], candidate_max_widths[2]),
-                max(self.column_widths[3], candidate_max_widths[3]),
-            )
-
         # Don't let name or possible values be less than max widths
         _, cols = tty.terminal_size()
         max_name = min(self.column_widths[0], 30)
@@ -137,6 +115,8 @@ def default(self, v):
     def lines(self):
         if not self.variants:
             yield "    None"
+            return
+
         else:
             yield "    " + self.fmt % self.headers
             underline = tuple([w * "=" for w in self.column_widths])
@@ -271,15 +251,165 @@ def print_tests(pkg):
         color.cprint("    None")
 
 
-def print_variants(pkg):
+def _fmt_value(v):
+    if v is None or isinstance(v, bool):
+        return str(v).lower()
+    else:
+        return str(v)
+
+
+def _fmt_name_and_default(variant):
+    """Print colorized name [default] for a variant."""
+    return color.colorize(f"@c{{{variant.name}}} @C{{[{_fmt_value(variant.default)}]}}")
+
+
+def _fmt_when(when, indent):
+    return color.colorize(f"{indent * ' '}@B{{when}} {color.cescape(when)}")
+
+
+def _fmt_variant_description(variant, width, indent):
+    """Format a variant's description, preserving explicit line breaks."""
+    return "\n".join(
+        textwrap.fill(
+            line, width=width, initial_indent=indent * " ", subsequent_indent=indent * " "
+        )
+        for line in variant.description.split("\n")
+    )
+
+
+def _fmt_variant(variant, max_name_default_len, indent, when=None, out=None):
+    out = out or sys.stdout
+
+    _, cols = tty.terminal_size()
+
+    name_and_default = _fmt_name_and_default(variant)
+    name_default_len = color.clen(name_and_default)
+
+    values = variant.values
+    if not isinstance(variant.values, (tuple, list, spack.variant.DisjointSetsOfValues)):
+        values = [variant.values]
+
+    # put 'none' first, sort the rest by value
+    sorted_values = sorted(values, key=lambda v: (v != "none", v))
+
+    pad = 4  # min padding between 'name [default]' and values
+    value_indent = (indent + max_name_default_len + pad) * " "  # left edge of values
+
+    # This preserves any formatting (i.e., newlines) from how the description was
+    # written in package.py, but still wraps long lines for small terminals.
+    # This allows some packages to provide detailed help on their variants (see, e.g., gasnet).
+    formatted_values = "\n".join(
+        textwrap.wrap(
+            f"{', '.join(_fmt_value(v) for v in sorted_values)}",
+            width=cols - 2,
+            initial_indent=value_indent,
+            subsequent_indent=value_indent,
+        )
+    )
+    formatted_values = formatted_values[indent + name_default_len + pad :]
+
+    # name [default]   value1, value2, value3, ...
+    padding = pad * " "
+    color.cprint(f"{indent * ' '}{name_and_default}{padding}@c{{{formatted_values}}}", stream=out)
+
+    # when <spec>
+    description_indent = indent + 4
+    if when is not None and when != spack.spec.Spec():
+        out.write(_fmt_when(when, description_indent - 2))
+        out.write("\n")
+
+    # description, preserving explicit line breaks from the way it's written in the package file
+    out.write(_fmt_variant_description(variant, cols - 2, description_indent))
+    out.write("\n")
+
+
+def _variants_by_name_when(pkg):
+    """Adaptor to get variants keyed by { name: { when: { [Variant...] } }."""
+    # TODO: replace with pkg.variants_by_name(when=True) when unified directive dicts are merged.
+    variants = {}
+    for name, (variant, whens) in sorted(pkg.variants.items()):
+        for when in whens:
+            variants.setdefault(name, {}).setdefault(when, []).append(variant)
+    return variants
+
+
+def _variants_by_when_name(pkg):
+    """Adaptor to get variants keyed by { when: { name: Variant } }"""
+    # TODO: replace with pkg.variants when unified directive dicts are merged.
+    variants = {}
+    for name, (variant, whens) in pkg.variants.items():
+        for when in whens:
+            variants.setdefault(when, {})[name] = variant
+    return variants
+
+
+def _print_variants_header(pkg):
     """output variants"""
 
+    if not pkg.variants:
+        print("    None")
+        return
+
     color.cprint("")
     color.cprint(section_title("Variants:"))
 
-    formatter = VariantFormatter(pkg.variants)
-    for line in formatter.lines:
-        color.cprint(color.cescape(line))
+    variants_by_name = _variants_by_name_when(pkg)
+
+    # Calculate the max length of the "name [default]" part of the variant display
+    # This lets us know where to print variant values.
+    max_name_default_len = max(
+        color.clen(_fmt_name_and_default(variant))
+        for name, when_variants in variants_by_name.items()
+        for variants in when_variants.values()
+        for variant in variants
+    )
+
+    return max_name_default_len, variants_by_name
+
+
+def _unconstrained_ver_first(item):
+    """sort key that puts specs with open version ranges first"""
+    spec, _ = item
+    return (spack.version.any_version not in spec.versions, spec)
+
+
+def print_variants_grouped_by_when(pkg):
+    max_name_default_len, _ = _print_variants_header(pkg)
+
+    indent = 4
+    variants = _variants_by_when_name(pkg)
+    for when, variants_by_name in sorted(variants.items(), key=_unconstrained_ver_first):
+        padded_values = max_name_default_len + 4
+        start_indent = indent
+
+        if when != spack.spec.Spec():
+            sys.stdout.write("\n")
+            sys.stdout.write(_fmt_when(when, indent))
+            sys.stdout.write("\n")
+
+            # indent names slightly inside 'when', but line up values
+            padded_values -= 2
+            start_indent += 2
+
+        for name, variant in sorted(variants_by_name.items()):
+            _fmt_variant(variant, padded_values, start_indent, None, out=sys.stdout)
+
+
+def print_variants_by_name(pkg):
+    max_name_default_len, variants_by_name = _print_variants_header(pkg)
+    max_name_default_len += 4
+
+    indent = 4
+    for name, when_variants in variants_by_name.items():
+        for when, variants in sorted(when_variants.items(), key=_unconstrained_ver_first):
+            for variant in variants:
+                _fmt_variant(variant, max_name_default_len, indent, when, out=sys.stdout)
+                sys.stdout.write("\n")
+
+
+def print_variants(pkg):
+    """output variants"""
+    print_variants_grouped_by_when(pkg)
 
 
 def print_versions(pkg):
@@ -300,18 +430,24 @@ def print_versions(pkg):
         pad = padder(pkg.versions, 4)
 
         preferred = preferred_version(pkg)
-        url = ""
-        if pkg.has_code:
-            url = fs.for_package_version(pkg, preferred)
 
+        def get_url(version):
+            try:
+                return fs.for_package_version(pkg, version)
+            except spack.fetch_strategy.InvalidArgsError:
+                return "No URL"
+
+        url = get_url(preferred) if pkg.has_code else ""
         line = version("    {0}".format(pad(preferred))) + color.cescape(url)
-        color.cprint(line)
+        color.cwrite(line)
+
+        print()
 
         safe = []
         deprecated = []
         for v in reversed(sorted(pkg.versions)):
             if pkg.has_code:
-                url = fs.for_package_version(pkg, v)
+                url = get_url(v)
             if pkg.versions[v].get("deprecated", False):
                 deprecated.append((v, url))
             else:
@@ -384,7 +520,12 @@ def info(parser, args):
     else:
         color.cprint("    None")
 
-    color.cprint(section_title("Homepage: ") + pkg.homepage)
+    if getattr(pkg, "homepage"):
+        color.cprint(section_title("Homepage: ") + pkg.homepage)
+
+    _print_variants = (
+        print_variants_by_name if args.variants_by_name else print_variants_grouped_by_when
+    )
 
     # Now output optional information in expected order
     sections = [
@@ -392,7 +533,7 @@ def info(parser, args):
         (args.all or args.detectable, print_detectable),
         (args.all or args.tags, print_tags),
         (args.all or not args.no_versions, print_versions),
-        (args.all or not args.no_variants, print_variants),
+        (args.all or not args.no_variants, _print_variants),
         (args.all or args.phases, print_phases),
         (args.all or not args.no_dependencies, print_dependencies),
         (args.all or args.virtuals, print_virtuals),

lib/spack/spack/cmd/tutorial.py

@@ -23,7 +23,7 @@
 
 
 # tutorial configuration parameters
-tutorial_branch = "releases/v0.20"
+tutorial_branch = "releases/v0.21"
 tutorial_mirror = "file:///mirror"
 tutorial_key = os.path.join(spack.paths.share_path, "keys", "tutorial.pub")
 

lib/spack/spack/cmd/uninstall.py

@@ -11,10 +11,9 @@
 
 import spack.cmd
 import spack.cmd.common.arguments as arguments
+import spack.cmd.common.confirmation as confirmation
 import spack.environment as ev
-import spack.error
 import spack.package_base
-import spack.repo
 import spack.spec
 import spack.store
 import spack.traverse as traverse
@@ -278,7 +277,7 @@ def uninstall_specs(args, specs):
         return
 
     if not args.yes_to_all:
-        confirm_removal(uninstall_list)
+        confirmation.confirm_action(uninstall_list, "uninstalled", "uninstallation")
 
     # Uninstall everything on the list
     do_uninstall(uninstall_list, args.force)
@@ -292,21 +291,6 @@ def uninstall_specs(args, specs):
         env.regenerate_views()
 
 
-def confirm_removal(specs: List[spack.spec.Spec]):
-    """Display the list of specs to be removed and ask for confirmation.
-
-    Args:
-        specs: specs to be removed
-    """
-    tty.msg("The following {} packages will be uninstalled:\n".format(len(specs)))
-    spack.cmd.display_specs(specs, **display_args)
-    print("")
-    answer = tty.get_yes_or_no("Do you want to proceed?", default=False)
-    if not answer:
-        tty.msg("Aborting uninstallation")
-        sys.exit(0)
-
-
 def uninstall(parser, args):
     if not args.specs and not args.all:
         tty.die(

lib/spack/spack/compilers/__init__.py

@@ -10,7 +10,7 @@
 import itertools
 import multiprocessing.pool
 import os
-from typing import Dict, List
+from typing import Dict, List, Optional, Tuple
 
 import archspec.cpu
 
@@ -21,6 +21,7 @@
 import spack.compiler
 import spack.config
 import spack.error
+import spack.operating_systems
 import spack.paths
 import spack.platforms
 import spack.spec
@@ -111,16 +112,16 @@ def _to_dict(compiler):
 def get_compiler_config(scope=None, init_config=True):
     """Return the compiler configuration for the specified architecture."""
 
-    config = spack.config.get("compilers", scope=scope) or []
+    config = spack.config.CONFIG.get("compilers", scope=scope) or []
     if config or not init_config:
         return config
 
-    merged_config = spack.config.get("compilers")
+    merged_config = spack.config.CONFIG.get("compilers")
     if merged_config:
         return config
 
     _init_compiler_config(scope=scope)
-    config = spack.config.get("compilers", scope=scope)
+    config = spack.config.CONFIG.get("compilers", scope=scope)
     return config
 
 
@@ -153,6 +154,14 @@ def add_compilers_to_config(compilers, scope=None, init_config=True):
     """
     compiler_config = get_compiler_config(scope, init_config)
     for compiler in compilers:
+        if not compiler.cc:
+            tty.debug(f"{compiler.spec} does not have a C compiler")
+        if not compiler.cxx:
+            tty.debug(f"{compiler.spec} does not have a C++ compiler")
+        if not compiler.f77:
+            tty.debug(f"{compiler.spec} does not have a Fortran77 compiler")
+        if not compiler.fc:
+            tty.debug(f"{compiler.spec} does not have a Fortran compiler")
         compiler_config.append(_to_dict(compiler))
     spack.config.set("compilers", compiler_config, scope=scope)
 
@@ -223,13 +232,16 @@ def all_compiler_specs(scope=None, init_config=True):
     ]
 
 
-def find_compilers(path_hints=None):
+def find_compilers(
+    path_hints: Optional[List[str]] = None, *, mixed_toolchain=False
+) -> List["spack.compiler.Compiler"]:
     """Return the list of compilers found in the paths given as arguments.
 
     Args:
-        path_hints (list or None): list of path hints where to look for.
-            A sensible default based on the ``PATH`` environment variable
-            will be used if the value is None
+        path_hints: list of path hints where to look for. A sensible default based on the ``PATH``
+            environment variable will be used if the value is None
+        mixed_toolchain: allow mixing compilers from different toolchains if otherwise missing for
+            a certain language
     """
     if path_hints is None:
         path_hints = get_path("PATH")
@@ -250,7 +262,7 @@ def find_compilers(path_hints=None):
     finally:
         tp.close()
 
-    def valid_version(item):
+    def valid_version(item: Tuple[Optional[DetectVersionArgs], Optional[str]]) -> bool:
         value, error = item
         if error is None:
             return True
@@ -262,25 +274,37 @@ def valid_version(item):
             pass
         return False
 
-    def remove_errors(item):
+    def remove_errors(
+        item: Tuple[Optional[DetectVersionArgs], Optional[str]]
+    ) -> DetectVersionArgs:
         value, _ = item
+        assert value is not None
         return value
 
-    return make_compiler_list(map(remove_errors, filter(valid_version, detected_versions)))
+    return make_compiler_list(
+        [remove_errors(detected) for detected in detected_versions if valid_version(detected)],
+        mixed_toolchain=mixed_toolchain,
+    )
 
 
-def find_new_compilers(path_hints=None, scope=None):
+def find_new_compilers(
+    path_hints: Optional[List[str]] = None,
+    scope: Optional[str] = None,
+    *,
+    mixed_toolchain: bool = False,
+):
     """Same as ``find_compilers`` but return only the compilers that are not
     already in compilers.yaml.
 
     Args:
-        path_hints (list or None): list of path hints where to look for.
-            A sensible default based on the ``PATH`` environment variable
-            will be used if the value is None
-        scope (str): scope to look for a compiler. If None consider the
-            merged configuration.
+        path_hints: list of path hints where to look for. A sensible default based on the ``PATH``
+            environment variable will be used if the value is None
+        scope: scope to look for a compiler. If None consider the merged configuration.
+        mixed_toolchain: allow mixing compilers from different toolchains if otherwise missing for
+            a certain language
     """
-    compilers = find_compilers(path_hints)
+    compilers = find_compilers(path_hints, mixed_toolchain=mixed_toolchain)
+
     return select_new_compilers(compilers, scope)
 
 
@@ -490,9 +514,10 @@ def get_compilers(config, cspec=None, arch_spec=None):
     for items in config:
         items = items["compiler"]
 
-        # NOTE: in principle this should be equality not satisfies, but config can still
-        # be written in old format gcc@10.1.0 instead of gcc@=10.1.0.
-        if cspec and not cspec.satisfies(items["spec"]):
+        # We might use equality here.
+        if cspec and not spack.spec.parse_with_version_concrete(
+            items["spec"], compiler=True
+        ).satisfies(cspec):
             continue
 
         # If an arch spec is given, confirm that this compiler
@@ -638,7 +663,9 @@ def all_compiler_types():
 )
 
 
-def arguments_to_detect_version_fn(operating_system, paths):
+def arguments_to_detect_version_fn(
+    operating_system: spack.operating_systems.OperatingSystem, paths: List[str]
+) -> List[DetectVersionArgs]:
     """Returns a list of DetectVersionArgs tuples to be used in a
     corresponding function to detect compiler versions.
 
@@ -646,8 +673,7 @@ def arguments_to_detect_version_fn(operating_system, paths):
     function by providing a method called with the same name.
 
     Args:
-        operating_system (spack.operating_systems.OperatingSystem): the operating system
-            on which we are looking for compilers
+        operating_system: the operating system on which we are looking for compilers
         paths: paths to search for compilers
 
     Returns:
@@ -656,10 +682,10 @@ def arguments_to_detect_version_fn(operating_system, paths):
         compilers in this OS.
     """
 
-    def _default(search_paths):
-        command_arguments = []
+    def _default(search_paths: List[str]) -> List[DetectVersionArgs]:
+        command_arguments: List[DetectVersionArgs] = []
         files_to_be_tested = fs.files_in(*search_paths)
-        for compiler_name in spack.compilers.supported_compilers_for_host_platform():
+        for compiler_name in supported_compilers_for_host_platform():
             compiler_cls = class_for_compiler_name(compiler_name)
 
             for language in ("cc", "cxx", "f77", "fc"):
@@ -684,7 +710,9 @@ def _default(search_paths):
     return fn(paths)
 
 
-def detect_version(detect_version_args):
+def detect_version(
+    detect_version_args: DetectVersionArgs,
+) -> Tuple[Optional[DetectVersionArgs], Optional[str]]:
     """Computes the version of a compiler and adds it to the information
     passed as input.
 
@@ -693,8 +721,7 @@ def detect_version(detect_version_args):
     needs to be checked by the code dispatching the calls.
 
     Args:
-        detect_version_args (DetectVersionArgs): information on the
-            compiler for which we should detect the version.
+        detect_version_args: information on the compiler for which we should detect the version.
 
     Returns:
         A ``(DetectVersionArgs, error)`` tuple. If ``error`` is ``None`` the
@@ -710,7 +737,7 @@ def _default(fn_args):
         path = fn_args.path
 
         # Get compiler names and the callback to detect their versions
-        callback = getattr(compiler_cls, "{0}_version".format(language))
+        callback = getattr(compiler_cls, f"{language}_version")
 
         try:
             version = callback(path)
@@ -736,13 +763,15 @@ def _default(fn_args):
     return fn(detect_version_args)
 
 
-def make_compiler_list(detected_versions):
+def make_compiler_list(
+    detected_versions: List[DetectVersionArgs], mixed_toolchain: bool = False
+) -> List["spack.compiler.Compiler"]:
     """Process a list of detected versions and turn them into a list of
     compiler specs.
 
     Args:
-        detected_versions (list): list of DetectVersionArgs containing a
-            valid version
+        detected_versions: list of DetectVersionArgs containing a valid version
+        mixed_toolchain: allow mixing compilers from different toolchains if langauge is missing
 
     Returns:
         list: list of Compiler objects
@@ -751,7 +780,7 @@ def make_compiler_list(detected_versions):
     sorted_compilers = sorted(detected_versions, key=group_fn)
 
     # Gather items in a dictionary by the id, name variation and language
-    compilers_d = {}
+    compilers_d: Dict[CompilerID, Dict[NameVariation, dict]] = {}
     for sort_key, group in itertools.groupby(sorted_compilers, key=group_fn):
         compiler_id, name_variation, language = sort_key
         by_compiler_id = compilers_d.setdefault(compiler_id, {})
@@ -760,7 +789,7 @@ def make_compiler_list(detected_versions):
 
     def _default_make_compilers(cmp_id, paths):
         operating_system, compiler_name, version = cmp_id
-        compiler_cls = spack.compilers.class_for_compiler_name(compiler_name)
+        compiler_cls = class_for_compiler_name(compiler_name)
         spec = spack.spec.CompilerSpec(compiler_cls.name, f"={version}")
         paths = [paths.get(x, None) for x in ("cc", "cxx", "f77", "fc")]
         # TODO: johnwparent - revist the following line as per discussion at:
@@ -782,13 +811,14 @@ def _default_make_compilers(cmp_id, paths):
         getattr(variation, "suffix", None),
     )
 
-    compilers = []
+    # Flatten to a list of compiler id, primary variation and compiler dictionary
+    flat_compilers: List[Tuple[CompilerID, NameVariation, dict]] = []
     for compiler_id, by_compiler_id in compilers_d.items():
         ordered = sorted(by_compiler_id, key=sort_fn)
         selected_variation = ordered[0]
         selected = by_compiler_id[selected_variation]
 
-        # fill any missing parts from subsequent entries
+        # Fill any missing parts from subsequent entries (without mixing toolchains)
         for lang in ["cxx", "f77", "fc"]:
             if lang not in selected:
                 next_lang = next(
@@ -797,14 +827,63 @@ def _default_make_compilers(cmp_id, paths):
                 if next_lang:
                     selected[lang] = next_lang
 
-        operating_system, _, _ = compiler_id
-        make_compilers = getattr(operating_system, "make_compilers", _default_make_compilers)
+        flat_compilers.append((compiler_id, selected_variation, selected))
 
-        compilers.extend(make_compilers(compiler_id, selected))
+    # Next, fill out the blanks of missing compilers by creating a mixed toolchain (if requested)
+    if mixed_toolchain:
+        make_mixed_toolchain(flat_compilers)
+
+    # Finally, create the compiler list
+    compilers = []
+    for compiler_id, _, compiler in flat_compilers:
+        make_compilers = getattr(compiler_id.os, "make_compilers", _default_make_compilers)
+        compilers.extend(make_compilers(compiler_id, compiler))
 
     return compilers
 
 
+def make_mixed_toolchain(compilers: List[Tuple[CompilerID, NameVariation, dict]]) -> None:
+    """Add missing compilers across toolchains when they are missing for a particular language.
+    This currently only adds the most sensible gfortran to (apple)-clang if it doesn't have a
+    fortran compiler (no flang)."""
+
+    # First collect the clangs that are missing a fortran compiler
+    clangs_without_flang = [
+        (id, variation, compiler)
+        for id, variation, compiler in compilers
+        if id.compiler_name in ("clang", "apple-clang")
+        and "f77" not in compiler
+        and "fc" not in compiler
+    ]
+    if not clangs_without_flang:
+        return
+
+    # Filter on GCCs with fortran compiler
+    gccs_with_fortran = [
+        (id, variation, compiler)
+        for id, variation, compiler in compilers
+        if id.compiler_name == "gcc" and "f77" in compiler and "fc" in compiler
+    ]
+
+    # Sort these GCCs by "best variation" (no prefix / suffix first)
+    gccs_with_fortran.sort(
+        key=lambda x: (getattr(x[1], "prefix", None), getattr(x[1], "suffix", None))
+    )
+
+    # Attach the optimal GCC fortran compiler to the clangs that don't have one
+    for clang_id, _, clang_compiler in clangs_without_flang:
+        gcc_compiler = next(
+            (gcc[2] for gcc in gccs_with_fortran if gcc[0].os == clang_id.os), None
+        )
+
+        if not gcc_compiler:
+            continue
+
+        # Update the fc / f77 entries
+        clang_compiler["f77"] = gcc_compiler["f77"]
+        clang_compiler["fc"] = gcc_compiler["fc"]
+
+
 def is_mixed_toolchain(compiler):
     """Returns True if the current compiler is a mixed toolchain,
     False otherwise.

lib/spack/spack/compilers/aocc.py

@@ -5,7 +5,6 @@
 
 import os
 import re
-import sys
 
 import llnl.util.lang
 
@@ -114,17 +113,6 @@ def extract_version_from_output(cls, output):
             return ".".join(match.groups())
         return "unknown"
 
-    @classmethod
-    def fc_version(cls, fortran_compiler):
-        if sys.platform == "darwin":
-            return cls.default_version("clang")
-
-        return cls.default_version(fortran_compiler)
-
-    @classmethod
-    def f77_version(cls, f77):
-        return cls.fc_version(f77)
-
     @property
     def stdcxx_libs(self):
         return ("-lstdc++",)

lib/spack/spack/compilers/clang.py

@@ -5,7 +5,6 @@
 
 import os
 import re
-import sys
 
 import llnl.util.lang
 
@@ -39,10 +38,10 @@ class Clang(Compiler):
     cxx_names = ["clang++"]
 
     # Subclasses use possible names of Fortran 77 compiler
-    f77_names = ["flang", "gfortran", "xlf_r"]
+    f77_names = ["flang"]
 
     # Subclasses use possible names of Fortran 90 compiler
-    fc_names = ["flang", "gfortran", "xlf90_r"]
+    fc_names = ["flang"]
 
     version_argument = "--version"
 
@@ -182,16 +181,3 @@ def extract_version_from_output(cls, output):
         if match:
             ver = match.group(match.lastindex)
         return ver
-
-    @classmethod
-    def fc_version(cls, fc):
-        # We could map from gcc/gfortran version to clang version, but on macOS
-        # we normally mix any version of gfortran with any version of clang.
-        if sys.platform == "darwin":
-            return cls.default_version("clang")
-        else:
-            return cls.default_version(fc)
-
-    @classmethod
-    def f77_version(cls, f77):
-        return cls.fc_version(f77)

lib/spack/spack/compilers/msvc.py

@@ -9,6 +9,8 @@
 import sys
 from typing import Dict, List, Set
 
+import archspec.cpu
+
 import spack.compiler
 import spack.operating_systems.windows_os
 import spack.platforms
@@ -185,6 +187,9 @@ def __init__(self, *args, **kwargs):
         # get current platform architecture and format for vcvars argument
         arch = spack.platforms.real_host().default.lower()
         arch = arch.replace("-", "_")
+        if str(archspec.cpu.host().family) == "x86_64":
+            arch = "amd64"
+
         self.vcvars_call = VCVarsInvocation(vcvars_script_path, arch, self.msvc_version)
         env_cmds.append(self.vcvars_call)
         # Below is a check for a valid fortran path

lib/spack/spack/config.py

@@ -69,6 +69,7 @@
 SECTION_SCHEMAS = {
     "compilers": spack.schema.compilers.schema,
     "concretizer": spack.schema.concretizer.schema,
+    "definitions": spack.schema.definitions.schema,
     "mirrors": spack.schema.mirrors.schema,
     "repos": spack.schema.repos.schema,
     "packages": spack.schema.packages.schema,
@@ -994,6 +995,7 @@ def read_config_file(filename, schema=None):
                 key = next(iter(data))
                 schema = _ALL_SCHEMAS[key]
             validate(data, schema)
+
         return data
 
     except StopIteration:

lib/spack/spack/database.py

@@ -1522,14 +1522,18 @@ def _query(
         # TODO: like installed and known that can be queried?  Or are
         # TODO: these really special cases that only belong here?
 
-        # Just look up concrete specs with hashes; no fancy search.
-        if isinstance(query_spec, spack.spec.Spec) and query_spec.concrete:
-            # TODO: handling of hashes restriction is not particularly elegant.
-            hash_key = query_spec.dag_hash()
-            if hash_key in self._data and (not hashes or hash_key in hashes):
-                return [self._data[hash_key].spec]
-            else:
-                return []
+        if query_spec is not any:
+            if not isinstance(query_spec, spack.spec.Spec):
+                query_spec = spack.spec.Spec(query_spec)
+
+            # Just look up concrete specs with hashes; no fancy search.
+            if query_spec.concrete:
+                # TODO: handling of hashes restriction is not particularly elegant.
+                hash_key = query_spec.dag_hash()
+                if hash_key in self._data and (not hashes or hash_key in hashes):
+                    return [self._data[hash_key].spec]
+                else:
+                    return []
 
         # Abstract specs require more work -- currently we test
         # against everything.
@@ -1537,6 +1541,9 @@ def _query(
         start_date = start_date or datetime.datetime.min
         end_date = end_date or datetime.datetime.max
 
+        # save specs whose name doesn't match for last, to avoid a virtual check
+        deferred = []
+
         for key, rec in self._data.items():
             if hashes is not None and rec.spec.dag_hash() not in hashes:
                 continue
@@ -1561,8 +1568,26 @@ def _query(
                 if not (start_date < inst_date < end_date):
                     continue
 
-            if query_spec is any or rec.spec.satisfies(query_spec):
+            if query_spec is any:
                 results.append(rec.spec)
+                continue
+
+            # check anon specs and exact name matches first
+            if not query_spec.name or rec.spec.name == query_spec.name:
+                if rec.spec.satisfies(query_spec):
+                    results.append(rec.spec)
+
+            # save potential virtual matches for later, but not if we already found a match
+            elif not results:
+                deferred.append(rec.spec)
+
+        # Checking for virtuals is expensive, so we save it for last and only if needed.
+        # If we get here, we didn't find anything in the DB that matched by name.
+        # If we did fine something, the query spec can't be virtual b/c we matched an actual
+        # package installation, so skip the virtual check entirely. If we *didn't* find anything,
+        # check all the deferred specs *if* the query is virtual.
+        if not results and query_spec is not any and deferred and query_spec.virtual:
+            results = [spec for spec in deferred if spec.satisfies(query_spec)]
 
         return results
 

lib/spack/spack/detection/path.py

@@ -15,9 +15,12 @@
 from typing import Dict, List, Optional, Set, Tuple
 
 import llnl.util.filesystem
+import llnl.util.lang
 import llnl.util.tty
 
+import spack.util.elf as elf_utils
 import spack.util.environment
+import spack.util.environment as environment
 import spack.util.ld_so_conf
 
 from .common import (
@@ -57,6 +60,11 @@ def common_windows_package_paths(pkg_cls=None) -> List[str]:
     return paths
 
 
+def file_identifier(path):
+    s = os.stat(path)
+    return (s.st_dev, s.st_ino)
+
+
 def executables_in_path(path_hints: List[str]) -> Dict[str, str]:
     """Get the paths of all executables available from the current PATH.
 
@@ -75,12 +83,40 @@ def executables_in_path(path_hints: List[str]) -> Dict[str, str]:
     return path_to_dict(search_paths)
 
 
+def get_elf_compat(path):
+    """For ELF files, get a triplet (EI_CLASS, EI_DATA, e_machine) and see if
+    it is host-compatible."""
+    # On ELF platforms supporting, we try to be a bit smarter when it comes to shared
+    # libraries, by dropping those that are not host compatible.
+    with open(path, "rb") as f:
+        elf = elf_utils.parse_elf(f, only_header=True)
+        return (elf.is_64_bit, elf.is_little_endian, elf.elf_hdr.e_machine)
+
+
+def accept_elf(path, host_compat):
+    """Accept an ELF file if the header matches the given compat triplet,
+    obtained with :py:func:`get_elf_compat`. In case it's not an ELF (e.g.
+    static library, or some arbitrary file, fall back to is_readable_file)."""
+    # Fast path: assume libraries at least have .so in their basename.
+    # Note: don't replace with splitext, because of libsmth.so.1.2.3 file names.
+    if ".so" not in os.path.basename(path):
+        return llnl.util.filesystem.is_readable_file(path)
+    try:
+        return host_compat == get_elf_compat(path)
+    except (OSError, elf_utils.ElfParsingError):
+        return llnl.util.filesystem.is_readable_file(path)
+
+
 def libraries_in_ld_and_system_library_path(
     path_hints: Optional[List[str]] = None,
 ) -> Dict[str, str]:
-    """Get the paths of all libraries available from LD_LIBRARY_PATH,
-    LIBRARY_PATH, DYLD_LIBRARY_PATH, DYLD_FALLBACK_LIBRARY_PATH, and
-    standard system library paths.
+    """Get the paths of all libraries available from ``path_hints`` or the
+    following defaults:
+
+    - Environment variables (Linux: ``LD_LIBRARY_PATH``, Darwin: ``DYLD_LIBRARY_PATH``,
+      and ``DYLD_FALLBACK_LIBRARY_PATH``)
+    - Dynamic linker default paths (glibc: ld.so.conf, musl: ld-musl-<arch>.path)
+    - Default system library paths.
 
     For convenience, this is constructed as a dictionary where the keys are
     the library paths and the values are the names of the libraries
@@ -94,17 +130,45 @@ def libraries_in_ld_and_system_library_path(
             constructed based on the set of LD_LIBRARY_PATH, LIBRARY_PATH,
             DYLD_LIBRARY_PATH, and DYLD_FALLBACK_LIBRARY_PATH environment
             variables as well as the standard system library paths.
+        path_hints (list): list of paths to be searched. If ``None``, the default
+            system paths are used.
     """
-    default_lib_search_paths = (
-        spack.util.environment.get_path("LD_LIBRARY_PATH")
-        + spack.util.environment.get_path("DYLD_LIBRARY_PATH")
-        + spack.util.environment.get_path("DYLD_FALLBACK_LIBRARY_PATH")
-        + spack.util.ld_so_conf.host_dynamic_linker_search_paths()
-    )
-    path_hints = path_hints if path_hints is not None else default_lib_search_paths
+    if path_hints:
+        search_paths = llnl.util.filesystem.search_paths_for_libraries(*path_hints)
+    else:
+        search_paths = []
 
-    search_paths = llnl.util.filesystem.search_paths_for_libraries(*path_hints)
-    return path_to_dict(search_paths)
+        # Environment variables
+        if sys.platform == "darwin":
+            search_paths.extend(environment.get_path("DYLD_LIBRARY_PATH"))
+            search_paths.extend(environment.get_path("DYLD_FALLBACK_LIBRARY_PATH"))
+        elif sys.platform.startswith("linux"):
+            search_paths.extend(environment.get_path("LD_LIBRARY_PATH"))
+
+        # Dynamic linker paths
+        search_paths.extend(spack.util.ld_so_conf.host_dynamic_linker_search_paths())
+
+        # Drop redundant paths
+        search_paths = list(filter(os.path.isdir, search_paths))
+
+    # Make use we don't doubly list /usr/lib and /lib etc
+    search_paths = list(llnl.util.lang.dedupe(search_paths, key=file_identifier))
+
+    try:
+        host_compat = get_elf_compat(sys.executable)
+        accept = lambda path: accept_elf(path, host_compat)
+    except (OSError, elf_utils.ElfParsingError):
+        accept = llnl.util.filesystem.is_readable_file
+
+    path_to_lib = {}
+    # Reverse order of search directories so that a lib in the first
+    # search path entry overrides later entries
+    for search_path in reversed(search_paths):
+        for lib in os.listdir(search_path):
+            lib_path = os.path.join(search_path, lib)
+            if accept(lib_path):
+                path_to_lib[lib_path] = lib
+    return path_to_lib
 
 
 def libraries_in_windows_paths(path_hints: Optional[List[str]] = None) -> Dict[str, str]:

lib/spack/spack/directives.py

@@ -137,6 +137,7 @@ class DirectiveMeta(type):
     _directive_dict_names: Set[str] = set()
     _directives_to_be_executed: List[str] = []
     _when_constraints_from_context: List[str] = []
+    _default_args: List[dict] = []
 
     def __new__(cls, name, bases, attr_dict):
         # Initialize the attribute containing the list of directives
@@ -199,6 +200,16 @@ def pop_from_context():
         """Pop the last constraint from the context"""
         return DirectiveMeta._when_constraints_from_context.pop()
 
+    @staticmethod
+    def push_default_args(default_args):
+        """Push default arguments"""
+        DirectiveMeta._default_args.append(default_args)
+
+    @staticmethod
+    def pop_default_args():
+        """Pop default arguments"""
+        return DirectiveMeta._default_args.pop()
+
     @staticmethod
     def directive(dicts=None):
         """Decorator for Spack directives.
@@ -259,7 +270,13 @@ def _decorator(decorated_function):
             directive_names.append(decorated_function.__name__)
 
             @functools.wraps(decorated_function)
-            def _wrapper(*args, **kwargs):
+            def _wrapper(*args, **_kwargs):
+                # First merge default args with kwargs
+                kwargs = dict()
+                for default_args in DirectiveMeta._default_args:
+                    kwargs.update(default_args)
+                kwargs.update(_kwargs)
+
                 # Inject when arguments from the context
                 if DirectiveMeta._when_constraints_from_context:
                     # Check that directives not yet supporting the when= argument
@@ -446,6 +463,8 @@ def _depends_on(pkg, spec, when=None, type=dt.DEFAULT_TYPES, patches=None):
     dep_spec = spack.spec.Spec(spec)
     if not dep_spec.name:
         raise DependencyError("Invalid dependency specification in package '%s':" % pkg.name, spec)
+    elif dep_spec.name in ("c", "cxx", "fortran"):  # forward compat for language deps
+        return
     if pkg.name == dep_spec.name:
         raise CircularReferenceError("Package '%s' cannot depend on itself." % pkg.name)
 
@@ -573,17 +592,21 @@ def _execute_extends(pkg):
     return _execute_extends
 
 
-@directive("provided")
-def provides(*specs, **kwargs):
-    """Allows packages to provide a virtual dependency.  If a package provides
-    'mpi', other packages can declare that they depend on "mpi", and spack
-    can use the providing package to satisfy the dependency.
+@directive(dicts=("provided", "provided_together"))
+def provides(*specs, when: Optional[str] = None):
+    """Allows packages to provide a virtual dependency.
+
+    If a package provides "mpi", other packages can declare that they depend on "mpi",
+    and spack can use the providing package to satisfy the dependency.
+
+    Args:
+        *specs: virtual specs provided by this package
+        when: condition when this provides clause needs to be considered
     """
 
     def _execute_provides(pkg):
         import spack.parser  # Avoid circular dependency
 
-        when = kwargs.get("when")
         when_spec = make_when_spec(when)
         if not when_spec:
             return
@@ -591,15 +614,18 @@ def _execute_provides(pkg):
         # ``when`` specs for ``provides()`` need a name, as they are used
         # to build the ProviderIndex.
         when_spec.name = pkg.name
+        spec_objs = [spack.spec.Spec(x) for x in specs]
+        spec_names = [x.name for x in spec_objs]
+        if len(spec_names) > 1:
+            pkg.provided_together.setdefault(when_spec, []).append(set(spec_names))
 
-        for string in specs:
-            for provided_spec in spack.parser.parse(string):
-                if pkg.name == provided_spec.name:
-                    raise CircularReferenceError("Package '%s' cannot provide itself." % pkg.name)
+        for provided_spec in spec_objs:
+            if pkg.name == provided_spec.name:
+                raise CircularReferenceError("Package '%s' cannot provide itself." % pkg.name)
 
-                if provided_spec not in pkg.provided:
-                    pkg.provided[provided_spec] = set()
-                pkg.provided[provided_spec].add(when_spec)
+            if provided_spec not in pkg.provided:
+                pkg.provided[provided_spec] = set()
+            pkg.provided[provided_spec].add(when_spec)
 
     return _execute_provides
 

lib/spack/spack/environment/__init__.py

@@ -339,6 +339,7 @@
 from .environment import (
     TOP_LEVEL_KEY,
     Environment,
+    SpackEnvironmentConfigError,
     SpackEnvironmentError,
     SpackEnvironmentViewError,
     activate,
@@ -372,6 +373,7 @@
 __all__ = [
     "TOP_LEVEL_KEY",
     "Environment",
+    "SpackEnvironmentConfigError",
     "SpackEnvironmentError",
     "SpackEnvironmentViewError",
     "activate",

lib/spack/spack/environment/depfile.py

@@ -232,6 +232,10 @@ def to_dict(self):
             "pkg_ids": " ".join(self.all_pkg_identifiers),
         }
 
+    @property
+    def empty(self):
+        return len(self.roots) == 0
+
     @staticmethod
     def from_env(
         env: ev.Environment,
@@ -254,15 +258,10 @@ def from_env(
             jobserver: when enabled, make will invoke Spack with jobserver support. For
                 dry-run this should be disabled.
         """
-        # If no specs are provided as a filter, build all the specs in the environment.
-        if filter_specs:
-            entrypoints = [env.matching_spec(s) for s in filter_specs]
-        else:
-            entrypoints = [s for _, s in env.concretized_specs()]
-
+        roots = env.all_matching_specs(*filter_specs) if filter_specs else env.concrete_roots()
         visitor = DepfileSpecVisitor(pkg_buildcache, dep_buildcache)
         traverse.traverse_breadth_first_with_visitor(
-            entrypoints, traverse.CoverNodesVisitor(visitor, key=lambda s: s.dag_hash())
+            roots, traverse.CoverNodesVisitor(visitor, key=lambda s: s.dag_hash())
         )
 
-        return MakefileModel(env, entrypoints, visitor.adjacency_list, make_prefix, jobserver)
+        return MakefileModel(env, roots, visitor.adjacency_list, make_prefix, jobserver)

lib/spack/spack/environment/environment.py

@@ -342,7 +342,7 @@ def create_in_dir(
 
         manifest.flush()
 
-    except spack.config.ConfigFormatError as e:
+    except (spack.config.ConfigFormatError, SpackEnvironmentConfigError) as e:
         shutil.rmtree(manifest_dir)
         raise e
 
@@ -396,7 +396,13 @@ def all_environments():
 
 def _read_yaml(str_or_file):
     """Read YAML from a file for round-trip parsing."""
-    data = syaml.load_config(str_or_file)
+    try:
+        data = syaml.load_config(str_or_file)
+    except syaml.SpackYAMLError as e:
+        raise SpackEnvironmentConfigError(
+            f"Invalid environment configuration detected: {e.message}"
+        )
+
     filename = getattr(str_or_file, "name", None)
     default_data = spack.config.validate(data, spack.schema.env.schema, filename)
     return data, default_data
@@ -781,10 +787,18 @@ def _re_read(self):
         """Reinitialize the environment object."""
         self.clear(re_read=True)
         self.manifest = EnvironmentManifestFile(self.path)
-        self._read()
+        self._read(re_read=True)
 
-    def _read(self):
-        self._construct_state_from_manifest()
+    def _read(self, re_read=False):
+        # If the manifest has included files, then some of the information
+        # (e.g., definitions) MAY be in those files. So we need to ensure
+        # the config is populated with any associated spec lists in order
+        # to fully construct the manifest state.
+        includes = self.manifest[TOP_LEVEL_KEY].get("include", [])
+        if includes and not re_read:
+            prepare_config_scope(self)
+
+        self._construct_state_from_manifest(re_read)
 
         if os.path.exists(self.lock_path):
             with open(self.lock_path) as f:
@@ -798,21 +812,30 @@ def write_transaction(self):
         """Get a write lock context manager for use in a `with` block."""
         return lk.WriteTransaction(self.txlock, acquire=self._re_read)
 
-    def _construct_state_from_manifest(self):
+    def _process_definition(self, item):
+        """Process a single spec definition item."""
+        entry = copy.deepcopy(item)
+        when = _eval_conditional(entry.pop("when", "True"))
+        assert len(entry) == 1
+        if when:
+            name, spec_list = next(iter(entry.items()))
+            user_specs = SpecList(name, spec_list, self.spec_lists.copy())
+            if name in self.spec_lists:
+                self.spec_lists[name].extend(user_specs)
+            else:
+                self.spec_lists[name] = user_specs
+
+    def _construct_state_from_manifest(self, re_read=False):
         """Read manifest file and set up user specs."""
         self.spec_lists = collections.OrderedDict()
+
+        if not re_read:
+            for item in spack.config.get("definitions", []):
+                self._process_definition(item)
+
         env_configuration = self.manifest[TOP_LEVEL_KEY]
         for item in env_configuration.get("definitions", []):
-            entry = copy.deepcopy(item)
-            when = _eval_conditional(entry.pop("when", "True"))
-            assert len(entry) == 1
-            if when:
-                name, spec_list = next(iter(entry.items()))
-                user_specs = SpecList(name, spec_list, self.spec_lists.copy())
-                if name in self.spec_lists:
-                    self.spec_lists[name].extend(user_specs)
-                else:
-                    self.spec_lists[name] = user_specs
+            self._process_definition(item)
 
         spec_list = env_configuration.get(user_speclist_name, [])
         user_specs = SpecList(
@@ -857,7 +880,9 @@ def clear(self, re_read=False):
                 yaml, and need to be maintained when re-reading an existing
                 environment.
         """
-        self.spec_lists = {user_speclist_name: SpecList()}  # specs from yaml
+        self.spec_lists = collections.OrderedDict()
+        self.spec_lists[user_speclist_name] = SpecList()
+
         self.dev_specs = {}  # dev-build specs from yaml
         self.concretized_user_specs = []  # user specs from last concretize
         self.concretized_order = []  # roots of last concretize, in order
@@ -1006,7 +1031,8 @@ def included_config_scopes(self):
 
             elif include_url.scheme:
                 raise ValueError(
-                    "Unsupported URL scheme for environment include: {}".format(config_path)
+                    f"Unsupported URL scheme ({include_url.scheme}) for "
+                    f"environment include: {config_path}"
                 )
 
             # treat relative paths as relative to the environment
@@ -1068,8 +1094,10 @@ def update_stale_references(self, from_list=None):
             from_list = next(iter(self.spec_lists.keys()))
         index = list(self.spec_lists.keys()).index(from_list)
 
-        # spec_lists is an OrderedDict, all list entries after the modified
-        # list may refer to the modified list. Update stale references
+        # spec_lists is an OrderedDict to ensure lists read from the manifest
+        # are maintainted in order, hence, all list entries after the modified
+        # list may refer to the modified list requiring stale references to be
+        # updated.
         for i, (name, speclist) in enumerate(
             list(self.spec_lists.items())[index + 1 :], index + 1
         ):
@@ -1167,7 +1195,7 @@ def change_existing_spec(
     def remove(self, query_spec, list_name=user_speclist_name, force=False):
         """Remove specs from an environment that match a query_spec"""
         err_msg_header = (
-            f"cannot remove {query_spec} from '{list_name}' definition "
+            f"Cannot remove '{query_spec}' from '{list_name}' definition "
             f"in {self.manifest.manifest_file}"
         )
         query_spec = Spec(query_spec)
@@ -1198,11 +1226,10 @@ def remove(self, query_spec, list_name=user_speclist_name, force=False):
                 list_to_change.remove(spec)
                 self.update_stale_references(list_name)
                 new_specs = set(self.user_specs)
-            except spack.spec_list.SpecListError:
+            except spack.spec_list.SpecListError as e:
                 # define new specs list
                 new_specs = set(self.user_specs)
-                msg = f"Spec '{spec}' is part of a spec matrix and "
-                msg += f"cannot be removed from list '{list_to_change}'."
+                msg = str(e)
                 if force:
                     msg += " It will be removed from the concrete specs."
                     # Mock new specs, so we can remove this spec from concrete spec lists
@@ -1331,7 +1358,7 @@ def concretize(self, force=False, tests=False):
 
         # Remove concrete specs that no longer correlate to a user spec
         for spec in set(self.concretized_user_specs) - set(self.user_specs):
-            self.deconcretize(spec)
+            self.deconcretize(spec, concrete=False)
 
         # Pick the right concretization strategy
         if self.unify == "when_possible":
@@ -1346,15 +1373,36 @@ def concretize(self, force=False, tests=False):
         msg = "concretization strategy not implemented [{0}]"
         raise SpackEnvironmentError(msg.format(self.unify))
 
-    def deconcretize(self, spec):
+    def deconcretize(self, spec: spack.spec.Spec, concrete: bool = True):
+        """
+        Remove specified spec from environment concretization
+
+        Arguments:
+            spec: Spec to deconcretize. This must be a root of the environment
+            concrete: If True, find all instances of spec as concrete in the environemnt.
+                If False, find a single instance of the abstract spec as root of the environment.
+        """
         # spec has to be a root of the environment
-        index = self.concretized_user_specs.index(spec)
-        dag_hash = self.concretized_order.pop(index)
-        del self.concretized_user_specs[index]
+        if concrete:
+            dag_hash = spec.dag_hash()
+
+            pairs = zip(self.concretized_user_specs, self.concretized_order)
+            filtered = [(spec, h) for spec, h in pairs if h != dag_hash]
+            # Cannot use zip and unpack two values; it fails if filtered is empty
+            self.concretized_user_specs = [s for s, _ in filtered]
+            self.concretized_order = [h for _, h in filtered]
+        else:
+            index = self.concretized_user_specs.index(spec)
+            dag_hash = self.concretized_order.pop(index)
+
+            del self.concretized_user_specs[index]
 
         # If this was the only user spec that concretized to this concrete spec, remove it
         if dag_hash not in self.concretized_order:
-            del self.specs_by_hash[dag_hash]
+            # if we deconcretized a dependency that doesn't correspond to a root, it
+            # won't be here.
+            if dag_hash in self.specs_by_hash:
+                del self.specs_by_hash[dag_hash]
 
     def _get_specs_to_concretize(
         self,
@@ -1525,7 +1573,11 @@ def _concretize_separately(self, tests=False):
         batch = []
         for j, (i, concrete, duration) in enumerate(
             spack.util.parallel.imap_unordered(
-                _concretize_task, args, processes=num_procs, debug=tty.is_debug()
+                _concretize_task,
+                args,
+                processes=num_procs,
+                debug=tty.is_debug(),
+                maxtaskperchild=1,
             )
         ):
             batch.append((i, concrete))
@@ -1708,11 +1760,14 @@ def _env_modifications_for_view(
         self, view: ViewDescriptor, reverse: bool = False
     ) -> spack.util.environment.EnvironmentModifications:
         try:
-            mods = uenv.environment_modifications_for_specs(*self.concrete_roots(), view=view)
+            with spack.store.STORE.db.read_transaction():
+                installed_roots = [s for s in self.concrete_roots() if s.installed]
+            mods = uenv.environment_modifications_for_specs(*installed_roots, view=view)
         except Exception as e:
             # Failing to setup spec-specific changes shouldn't be a hard error.
             tty.warn(
-                "couldn't load runtime environment due to {}: {}".format(e.__class__.__name__, e)
+                f"could not {'unload' if reverse else 'load'} runtime environment due "
+                f"to {e.__class__.__name__}: {e}"
             )
             return spack.util.environment.EnvironmentModifications()
         return mods.reversed() if reverse else mods
@@ -2063,7 +2118,7 @@ def matching_spec(self, spec):
 
     def removed_specs(self):
         """Tuples of (user spec, concrete spec) for all specs that will be
-        removed on nexg concretize."""
+        removed on next concretize."""
         needed = set()
         for s, c in self.concretized_specs():
             if s in self.user_specs:
@@ -2722,7 +2777,7 @@ def override_user_spec(self, user_spec: str, idx: int) -> None:
         self.changed = True
 
     def add_definition(self, user_spec: str, list_name: str) -> None:
-        """Appends a user spec to the first active definition mathing the name passed as argument.
+        """Appends a user spec to the first active definition matching the name passed as argument.
 
         Args:
             user_spec: user spec to be appended
@@ -2935,3 +2990,7 @@ class SpackEnvironmentError(spack.error.SpackError):
 
 class SpackEnvironmentViewError(SpackEnvironmentError):
     """Class for errors regarding view generation."""
+
+
+class SpackEnvironmentConfigError(SpackEnvironmentError):
+    """Class for Spack environment-specific configuration errors."""

lib/spack/spack/extensions.py

@@ -5,6 +5,7 @@
 """Service functions and classes to implement the hooks
 for Spack's command extensions.
 """
+import difflib
 import importlib
 import os
 import re
@@ -176,10 +177,19 @@ class CommandNotFoundError(spack.error.SpackError):
     """
 
     def __init__(self, cmd_name):
-        super().__init__(
+        msg = (
             "{0} is not a recognized Spack command or extension command;"
             " check with `spack commands`.".format(cmd_name)
         )
+        long_msg = None
+
+        similar = difflib.get_close_matches(cmd_name, spack.cmd.all_commands())
+
+        if 1 <= len(similar) <= 5:
+            long_msg = "\nDid you mean one of the following commands?\n  "
+            long_msg += "\n  ".join(similar)
+
+        super().__init__(msg, long_msg)
 
 
 class ExtensionNamingError(spack.error.SpackError):

lib/spack/spack/graph.py

@@ -528,10 +528,15 @@ def node_entry(self, node):
 
     def edge_entry(self, edge):
         colormap = {"build": "dodgerblue", "link": "crimson", "run": "goldenrod"}
+        label = ""
+        if edge.virtuals:
+            label = f" xlabel=\"virtuals={','.join(edge.virtuals)}\""
         return (
             edge.parent.dag_hash(),
             edge.spec.dag_hash(),
-            f"[color=\"{':'.join(colormap[x] for x in dt.flag_to_tuple(edge.depflag))}\"]",
+            f"[color=\"{':'.join(colormap[x] for x in dt.flag_to_tuple(edge.depflag))}\""
+            + label
+            + "]",
         )
 
 

lib/spack/spack/installer.py

@@ -380,14 +380,13 @@ def _print_timer(pre: str, pkg_id: str, timer: timer.BaseTimer) -> None:
 
 
 def _install_from_cache(
-    pkg: "spack.package_base.PackageBase", cache_only: bool, explicit: bool, unsigned: bool = False
+    pkg: "spack.package_base.PackageBase", explicit: bool, unsigned: bool = False
 ) -> bool:
     """
-    Extract the package from binary cache
+    Install the package from binary cache
 
     Args:
         pkg: package to install from the binary cache
-        cache_only: only extract from binary cache
         explicit: ``True`` if installing the package was explicitly
             requested by the user, otherwise, ``False``
         unsigned: ``True`` if binary package signatures to be checked,
@@ -399,15 +398,11 @@ def _install_from_cache(
     installed_from_cache = _try_install_from_binary_cache(
         pkg, explicit, unsigned=unsigned, timer=t
     )
-    pkg_id = package_id(pkg)
     if not installed_from_cache:
-        pre = f"No binary for {pkg_id} found"
-        if cache_only:
-            tty.die(f"{pre} when cache-only specified")
-
-        tty.msg(f"{pre}: installing from source")
         return False
     t.stop()
+
+    pkg_id = package_id(pkg)
     tty.debug(f"Successfully extracted {pkg_id} from binary cache")
 
     _write_timer_json(pkg, t, True)
@@ -1335,7 +1330,6 @@ def _prepare_for_install(self, task: BuildTask) -> None:
         """
         install_args = task.request.install_args
         keep_prefix = install_args.get("keep_prefix")
-        restage = install_args.get("restage")
 
         # Make sure the package is ready to be locally installed.
         self._ensure_install_ready(task.pkg)
@@ -1367,10 +1361,6 @@ def _prepare_for_install(self, task: BuildTask) -> None:
                 else:
                     tty.debug(f"{task.pkg_id} is partially installed")
 
-            # Destroy the stage for a locally installed, non-DIYStage, package
-            if restage and task.pkg.stage.managed_by_spack:
-                task.pkg.stage.destroy()
-
         if (
             rec
             and installed_in_db
@@ -1671,11 +1661,16 @@ def _install_task(self, task: BuildTask, install_status: InstallStatus) -> None:
         task.status = STATUS_INSTALLING
 
         # Use the binary cache if requested
-        if use_cache and _install_from_cache(pkg, cache_only, explicit, unsigned):
-            self._update_installed(task)
-            if task.compiler:
-                self._add_compiler_package_to_config(pkg)
-            return
+        if use_cache:
+            if _install_from_cache(pkg, explicit, unsigned):
+                self._update_installed(task)
+                if task.compiler:
+                    self._add_compiler_package_to_config(pkg)
+                return
+            elif cache_only:
+                raise InstallError("No binary found when cache-only was specified", pkg=pkg)
+            else:
+                tty.msg(f"No binary for {pkg_id} found: installing from source")
 
         pkg.run_tests = tests if isinstance(tests, bool) else pkg.name in tests
 
@@ -1691,6 +1686,10 @@ def _install_task(self, task: BuildTask, install_status: InstallStatus) -> None:
         try:
             self._setup_install_dir(pkg)
 
+            # Create stage object now and let it be serialized for the child process. That
+            # way monkeypatch in tests works correctly.
+            pkg.stage
+
             # Create a child process to do the actual installation.
             # Preserve verbosity settings across installs.
             spack.package_base.PackageBase._verbose = spack.build_environment.start_build_process(
@@ -2223,11 +2222,6 @@ def install(self) -> None:
                 if not keep_prefix and not action == InstallAction.OVERWRITE:
                     pkg.remove_prefix()
 
-                # The subprocess *may* have removed the build stage. Mark it
-                # not created so that the next time pkg.stage is invoked, we
-                # check the filesystem for it.
-                pkg.stage.created = False
-
             # Perform basic task cleanup for the installed spec to
             # include downgrading the write to a read lock
             self._cleanup_task(pkg)
@@ -2297,6 +2291,9 @@ def __init__(self, pkg: "spack.package_base.PackageBase", install_args: dict):
         # whether to keep the build stage after installation
         self.keep_stage = install_args.get("keep_stage", False)
 
+        # whether to restage
+        self.restage = install_args.get("restage", False)
+
         # whether to skip the patch phase
         self.skip_patch = install_args.get("skip_patch", False)
 
@@ -2327,9 +2324,13 @@ def __init__(self, pkg: "spack.package_base.PackageBase", install_args: dict):
     def run(self) -> bool:
         """Main entry point from ``build_process`` to kick off install in child."""
 
-        self.pkg.stage.keep = self.keep_stage
+        stage = self.pkg.stage
+        stage.keep = self.keep_stage
 
-        with self.pkg.stage:
+        if self.restage:
+            stage.destroy()
+
+        with stage:
             self.timer.start("stage")
 
             if not self.fake:

lib/spack/spack/main.py

@@ -16,11 +16,13 @@
 import os.path
 import pstats
 import re
+import shlex
 import signal
 import subprocess as sp
 import sys
 import traceback
 import warnings
+from typing import List, Tuple
 
 import archspec.cpu
 
@@ -49,9 +51,6 @@
 #: names of profile statistics
 stat_names = pstats.Stats.sort_arg_dict_default
 
-#: top-level aliases for Spack commands
-aliases = {"concretise": "concretize", "containerise": "containerize", "rm": "remove"}
-
 #: help levels in order of detail (i.e., number of commands shown)
 levels = ["short", "long"]
 
@@ -359,7 +358,10 @@ def add_command(self, cmd_name):
             module = spack.cmd.get_module(cmd_name)
 
             # build a list of aliases
-            alias_list = [k for k, v in aliases.items() if v == cmd_name]
+            alias_list = []
+            aliases = spack.config.get("config:aliases")
+            if aliases:
+                alias_list = [k for k, v in aliases.items() if shlex.split(v)[0] == cmd_name]
 
             subparser = self.subparsers.add_parser(
                 cmd_name,
@@ -670,7 +672,6 @@ def __init__(self, command_name, subprocess=False):
                 Windows, where it is always False.
         """
         self.parser = make_argument_parser()
-        self.command = self.parser.add_command(command_name)
         self.command_name = command_name
         # TODO: figure out how to support this on windows
         self.subprocess = subprocess if sys.platform != "win32" else False
@@ -702,13 +703,14 @@ def __call__(self, *argv, **kwargs):
 
         if self.subprocess:
             p = sp.Popen(
-                [spack.paths.spack_script, self.command_name] + prepend + list(argv),
+                [spack.paths.spack_script] + prepend + [self.command_name] + list(argv),
                 stdout=sp.PIPE,
                 stderr=sp.STDOUT,
             )
             out, self.returncode = p.communicate()
             out = out.decode()
         else:
+            command = self.parser.add_command(self.command_name)
             args, unknown = self.parser.parse_known_args(
                 prepend + [self.command_name] + list(argv)
             )
@@ -716,7 +718,7 @@ def __call__(self, *argv, **kwargs):
             out = io.StringIO()
             try:
                 with log_output(out, echo=True):
-                    self.returncode = _invoke_command(self.command, self.parser, args, unknown)
+                    self.returncode = _invoke_command(command, self.parser, args, unknown)
 
             except SystemExit as e:
                 self.returncode = e.code
@@ -870,6 +872,46 @@ def restore_macos_dyld_vars():
             os.environ[dyld_var] = os.environ[stored_var_name]
 
 
+def resolve_alias(cmd_name: str, cmd: List[str]) -> Tuple[str, List[str]]:
+    """Resolves aliases in the given command.
+
+    Args:
+        cmd_name: command name.
+        cmd: command line arguments.
+
+    Returns:
+        new command name and arguments.
+    """
+    all_commands = spack.cmd.all_commands()
+    aliases = spack.config.get("config:aliases")
+
+    if aliases:
+        for key, value in aliases.items():
+            if " " in key:
+                tty.warn(
+                    f"Alias '{key}' (mapping to '{value}') contains a space"
+                    ", which is not supported."
+                )
+            if key in all_commands:
+                tty.warn(
+                    f"Alias '{key}' (mapping to '{value}') attempts to override"
+                    " built-in command."
+                )
+
+    if cmd_name not in all_commands:
+        alias = None
+
+        if aliases:
+            alias = aliases.get(cmd_name)
+
+        if alias is not None:
+            alias_parts = shlex.split(alias)
+            cmd_name = alias_parts[0]
+            cmd = alias_parts + cmd[1:]
+
+    return cmd_name, cmd
+
+
 def _main(argv=None):
     """Logic for the main entry point for the Spack command.
 
@@ -962,7 +1004,7 @@ def _main(argv=None):
 
     # Try to load the particular command the caller asked for.
     cmd_name = args.command[0]
-    cmd_name = aliases.get(cmd_name, cmd_name)
+    cmd_name, args.command = resolve_alias(cmd_name, args.command)
 
     # set up a bootstrap context, if asked.
     # bootstrap context needs to include parsing the command, b/c things
@@ -974,14 +1016,16 @@ def _main(argv=None):
         bootstrap_context = bootstrap.ensure_bootstrap_configuration()
 
     with bootstrap_context:
-        return finish_parse_and_run(parser, cmd_name, env_format_error)
+        return finish_parse_and_run(parser, cmd_name, args, env_format_error)
 
 
-def finish_parse_and_run(parser, cmd_name, env_format_error):
+def finish_parse_and_run(parser, cmd_name, main_args, env_format_error):
     """Finish parsing after we know the command to run."""
     # add the found command to the parser and re-run then re-parse
     command = parser.add_command(cmd_name)
-    args, unknown = parser.parse_known_args()
+    args, unknown = parser.parse_known_args(main_args.command)
+    # we need to inherit verbose since the install command checks for it
+    args.verbose = main_args.verbose
 
     # Now that we know what command this is and what its args are, determine
     # whether we can continue with a bad environment and raise if not.

lib/spack/spack/mixins.py

@@ -93,7 +93,7 @@ def _filter_compiler_wrappers_impl(pkg_or_builder):
         replacements = []
 
         for idx, (env_var, compiler_path) in enumerate(compiler_vars):
-            if env_var in os.environ:
+            if env_var in os.environ and compiler_path is not None:
                 # filter spack wrapper and links to spack wrapper in case
                 # build system runs realpath
                 wrapper = os.environ[env_var]

lib/spack/spack/modules/common.py

@@ -486,43 +486,35 @@ def excluded(self):
         spec = self.spec
         conf = self.module.configuration(self.name)
 
-        # Compute the list of include rules that match
-        include_rules = conf.get("include", [])
-        include_matches = [x for x in include_rules if spec.satisfies(x)]
-
-        # Compute the list of exclude rules that match
-        exclude_rules = conf.get("exclude", [])
-        exclude_matches = [x for x in exclude_rules if spec.satisfies(x)]
+        # Compute the list of matching include / exclude rules, and whether excluded as implicit
+        include_matches = [x for x in conf.get("include", []) if spec.satisfies(x)]
+        exclude_matches = [x for x in conf.get("exclude", []) if spec.satisfies(x)]
+        excluded_as_implicit = not self.explicit and conf.get("exclude_implicits", False)
 
         def debug_info(line_header, match_list):
             if match_list:
-                msg = "\t{0} : {1}".format(line_header, spec.cshort_spec)
-                tty.debug(msg)
+                tty.debug(f"\t{line_header} : {spec.cshort_spec}")
                 for rule in match_list:
-                    tty.debug("\t\tmatches rule: {0}".format(rule))
+                    tty.debug(f"\t\tmatches rule: {rule}")
 
         debug_info("INCLUDE", include_matches)
         debug_info("EXCLUDE", exclude_matches)
 
-        if not include_matches and exclude_matches:
-            return True
+        if excluded_as_implicit:
+            tty.debug(f"\tEXCLUDED_AS_IMPLICIT : {spec.cshort_spec}")
 
-        return False
+        return not include_matches and (exclude_matches or excluded_as_implicit)
 
     @property
     def hidden(self):
         """Returns True if the module has been hidden, False otherwise."""
 
-        # A few variables for convenience of writing the method
-        spec = self.spec
         conf = self.module.configuration(self.name)
 
-        hidden_as_implicit = not self.explicit and conf.get(
-            "hide_implicits", conf.get("exclude_implicits", False)
-        )
+        hidden_as_implicit = not self.explicit and conf.get("hide_implicits", False)
 
         if hidden_as_implicit:
-            tty.debug(f"\tHIDDEN_AS_IMPLICIT : {spec.cshort_spec}")
+            tty.debug(f"\tHIDDEN_AS_IMPLICIT : {self.spec.cshort_spec}")
 
         return hidden_as_implicit
 

lib/spack/spack/multimethod.py

@@ -26,6 +26,7 @@
 """
 import functools
 import inspect
+from contextlib import contextmanager
 
 from llnl.util.lang import caller_locals
 
@@ -271,6 +272,13 @@ def __exit__(self, exc_type, exc_val, exc_tb):
         spack.directives.DirectiveMeta.pop_from_context()
 
 
+@contextmanager
+def default_args(**kwargs):
+    spack.directives.DirectiveMeta.push_default_args(kwargs)
+    yield
+    spack.directives.DirectiveMeta.pop_default_args()
+
+
 class MultiMethodError(spack.error.SpackError):
     """Superclass for multimethod dispatch errors"""
 

lib/spack/spack/oci/image.py

@@ -9,8 +9,10 @@
 
 import spack.spec
 
-# all the building blocks
-alphanumeric = r"[a-z0-9]+"
+# notice: Docker is more strict (no uppercase allowed). We parse image names *with* uppercase
+# and normalize, so: example.com/Organization/Name -> example.com/organization/name. Tags are
+# case sensitive though.
+alphanumeric_with_uppercase = r"[a-zA-Z0-9]+"
 separator = r"(?:[._]|__|[-]+)"
 localhost = r"localhost"
 domainNameComponent = r"(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])"
@@ -25,7 +27,7 @@
 domainAndPort = rf"{host}{optionalPort}"
 
 # image name
-pathComponent = rf"{alphanumeric}(?:{separator}{alphanumeric})*"
+pathComponent = rf"{alphanumeric_with_uppercase}(?:{separator}{alphanumeric_with_uppercase})*"
 remoteName = rf"{pathComponent}(?:\/{pathComponent})*"
 namePat = rf"(?:{domainAndPort}\/)?{remoteName}"
 
@@ -130,6 +132,11 @@ def from_string(cls, string) -> "ImageReference":
             name = f"{domain}/{name}"
             domain = "index.docker.io"
 
+        # Lowercase the image name. This is enforced by Docker, although the OCI spec isn't clear?
+        # We do this anyways, cause for example in Github Actions the <organization>/<repository>
+        # part can have uppercase, and may be interpolated when specifying the relevant OCI image.
+        name = name.lower()
+
         if not tag:
             tag = "latest"
 

lib/spack/spack/oci/oci.py

@@ -134,7 +134,7 @@ def upload_blob(
             return True
 
         # Otherwise, do another PUT request.
-        spack.oci.opener.ensure_status(response, 202)
+        spack.oci.opener.ensure_status(request, response, 202)
         assert "Location" in response.headers
 
         # Can be absolute or relative, joining handles both
@@ -143,19 +143,16 @@ def upload_blob(
         )
         f.seek(0)
 
-        response = _urlopen(
-            Request(
-                url=upload_url,
-                method="PUT",
-                data=f,
-                headers={
-                    "Content-Type": "application/octet-stream",
-                    "Content-Length": str(file_size),
-                },
-            )
+        request = Request(
+            url=upload_url,
+            method="PUT",
+            data=f,
+            headers={"Content-Type": "application/octet-stream", "Content-Length": str(file_size)},
         )
 
-        spack.oci.opener.ensure_status(response, 201)
+        response = _urlopen(request)
+
+        spack.oci.opener.ensure_status(request, response, 201)
 
     # print elapsed time and # MB/s
     _log_upload_progress(digest, file_size, time.time() - start)
@@ -189,16 +186,16 @@ def upload_manifest(
     if not tag:
         ref = ref.with_digest(digest)
 
-    response = _urlopen(
-        Request(
-            url=ref.manifest_url(),
-            method="PUT",
-            data=data,
-            headers={"Content-Type": oci_manifest["mediaType"]},
-        )
+    request = Request(
+        url=ref.manifest_url(),
+        method="PUT",
+        data=data,
+        headers={"Content-Type": oci_manifest["mediaType"]},
     )
 
-    spack.oci.opener.ensure_status(response, 201)
+    response = _urlopen(request)
+
+    spack.oci.opener.ensure_status(request, response, 201)
     return digest, size
 
 

lib/spack/spack/oci/opener.py

@@ -310,19 +310,15 @@ def http_error_401(self, req: Request, fp, code, msg, headers):
         # Login failed, avoid infinite recursion where we go back and
         # forth between auth server and registry
         if hasattr(req, "login_attempted"):
-            raise urllib.error.HTTPError(
-                req.full_url, code, f"Failed to login to {req.full_url}: {msg}", headers, fp
+            raise spack.util.web.DetailedHTTPError(
+                req, code, f"Failed to login: {msg}", headers, fp
             )
 
         # On 401 Unauthorized, parse the WWW-Authenticate header
         # to determine what authentication is required
         if "WWW-Authenticate" not in headers:
-            raise urllib.error.HTTPError(
-                req.full_url,
-                code,
-                "Cannot login to registry, missing WWW-Authenticate header",
-                headers,
-                fp,
+            raise spack.util.web.DetailedHTTPError(
+                req, code, "Cannot login to registry, missing WWW-Authenticate header", headers, fp
             )
 
         header_value = headers["WWW-Authenticate"]
@@ -330,8 +326,8 @@ def http_error_401(self, req: Request, fp, code, msg, headers):
         try:
             challenge = get_bearer_challenge(parse_www_authenticate(header_value))
         except ValueError as e:
-            raise urllib.error.HTTPError(
-                req.full_url,
+            raise spack.util.web.DetailedHTTPError(
+                req,
                 code,
                 f"Cannot login to registry, malformed WWW-Authenticate header: {header_value}",
                 headers,
@@ -340,8 +336,8 @@ def http_error_401(self, req: Request, fp, code, msg, headers):
 
         # If there is no bearer challenge, we can't handle it
         if not challenge:
-            raise urllib.error.HTTPError(
-                req.full_url,
+            raise spack.util.web.DetailedHTTPError(
+                req,
                 code,
                 f"Cannot login to registry, unsupported authentication scheme: {header_value}",
                 headers,
@@ -356,8 +352,8 @@ def http_error_401(self, req: Request, fp, code, msg, headers):
                 timeout=req.timeout,
             )
         except ValueError as e:
-            raise urllib.error.HTTPError(
-                req.full_url,
+            raise spack.util.web.DetailedHTTPError(
+                req,
                 code,
                 f"Cannot login to registry, failed to obtain bearer token: {e}",
                 headers,
@@ -412,13 +408,13 @@ def create_opener():
     return opener
 
 
-def ensure_status(response: HTTPResponse, status: int):
+def ensure_status(request: urllib.request.Request, response: HTTPResponse, status: int):
     """Raise an error if the response status is not the expected one."""
     if response.status == status:
         return
 
-    raise urllib.error.HTTPError(
-        response.geturl(), response.status, response.reason, response.info(), None
+    raise spack.util.web.DetailedHTTPError(
+        request, response.status, response.reason, response.info(), None
     )
 
 

lib/spack/spack/operating_systems/mac_os.py

@@ -143,6 +143,7 @@ def __init__(self):
             "12": "monterey",
             "13": "ventura",
             "14": "sonoma",
+            "15": "sequoia",
         }
 
         version = macos_version()

lib/spack/spack/package.py

@@ -49,6 +49,7 @@
 from spack.build_systems.nmake import NMakePackage
 from spack.build_systems.octave import OctavePackage
 from spack.build_systems.oneapi import (
+    INTEL_MATH_LIBRARIES,
     IntelOneApiLibraryPackage,
     IntelOneApiPackage,
     IntelOneApiStaticLibraryList,
@@ -85,7 +86,7 @@
     UpstreamPackageError,
 )
 from spack.mixins import filter_compiler_wrappers
-from spack.multimethod import when
+from spack.multimethod import default_args, when
 from spack.package_base import (
     DependencyConflictError,
     build_system_flags,

lib/spack/spack/package_base.py

@@ -24,8 +24,9 @@
 import textwrap
 import time
 import traceback
+import typing
 import warnings
-from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Type, TypeVar
+from typing import Any, Callable, Dict, Iterable, List, Optional, Set, Tuple, Type, TypeVar, Union
 
 import llnl.util.filesystem as fsys
 import llnl.util.tty as tty
@@ -682,13 +683,13 @@ def __init__(self, spec):
     @classmethod
     def possible_dependencies(
         cls,
-        transitive=True,
-        expand_virtuals=True,
+        transitive: bool = True,
+        expand_virtuals: bool = True,
         depflag: dt.DepFlag = dt.ALL,
-        visited=None,
-        missing=None,
-        virtuals=None,
-    ):
+        visited: Optional[dict] = None,
+        missing: Optional[dict] = None,
+        virtuals: Optional[set] = None,
+    ) -> Dict[str, Set[str]]:
         """Return dict of possible dependencies of this package.
 
         Args:
@@ -2449,14 +2450,21 @@ def flatten_dependencies(spec, flat_dir):
         dep_files.merge(flat_dir + "/" + name)
 
 
-def possible_dependencies(*pkg_or_spec, **kwargs):
+def possible_dependencies(
+    *pkg_or_spec: Union[str, spack.spec.Spec, typing.Type[PackageBase]],
+    transitive: bool = True,
+    expand_virtuals: bool = True,
+    depflag: dt.DepFlag = dt.ALL,
+    missing: Optional[dict] = None,
+    virtuals: Optional[set] = None,
+) -> Dict[str, Set[str]]:
     """Get the possible dependencies of a number of packages.
 
     See ``PackageBase.possible_dependencies`` for details.
     """
     packages = []
     for pos in pkg_or_spec:
-        if isinstance(pos, PackageMeta):
+        if isinstance(pos, PackageMeta) and issubclass(pos, PackageBase):
             packages.append(pos)
             continue
 
@@ -2469,9 +2477,16 @@ def possible_dependencies(*pkg_or_spec, **kwargs):
         else:
             packages.append(pos.package_class)
 
-    visited = {}
+    visited: Dict[str, Set[str]] = {}
     for pkg in packages:
-        pkg.possible_dependencies(visited=visited, **kwargs)
+        pkg.possible_dependencies(
+            visited=visited,
+            transitive=transitive,
+            expand_virtuals=expand_virtuals,
+            depflag=depflag,
+            missing=missing,
+            virtuals=virtuals,
+        )
 
     return visited
 

lib/spack/spack/parser.py

@@ -6,7 +6,7 @@
 
 Here is the EBNF grammar for a spec::
 
-    spec          = [name] [node_options] { ^ node } |
+    spec          = [name] [node_options] { ^[edge_properties] node } |
                     [name] [node_options] hash |
                     filename
 
@@ -14,7 +14,8 @@
                      [name] [node_options] hash |
                      filename
 
-    node_options  = [@(version_list|version_pair)] [%compiler] { variant }
+    node_options    = [@(version_list|version_pair)] [%compiler] { variant }
+    edge_properties = [ { bool_variant | key_value } ]
 
     hash          = / id
     filename      = (.|/|[a-zA-Z0-9-_]*/)([a-zA-Z0-9-_./]*)(.json|.yaml)
@@ -64,6 +65,7 @@
 
 from llnl.util.tty import color
 
+import spack.deptypes
 import spack.error
 import spack.spec
 import spack.version
@@ -126,6 +128,8 @@ class TokenType(TokenBase):
     """
 
     # Dependency
+    START_EDGE_PROPERTIES = r"(?:\^\[)"
+    END_EDGE_PROPERTIES = r"(?:\])"
     DEPENDENCY = r"(?:\^)"
     # Version
     VERSION_HASH_PAIR = rf"(?:@(?:{GIT_VERSION_PATTERN})=(?:{VERSION}))"
@@ -280,16 +284,15 @@ def next_spec(
         initial_spec = initial_spec or spack.spec.Spec()
         root_spec = SpecNodeParser(self.ctx).parse(initial_spec)
         while True:
-            if self.ctx.accept(TokenType.DEPENDENCY):
-                dependency = SpecNodeParser(self.ctx).parse()
-
-                if dependency is None:
-                    msg = (
-                        "this dependency sigil needs to be followed by a package name "
-                        "or a node attribute (version, variant, etc.)"
-                    )
-                    raise SpecParsingError(msg, self.ctx.current_token, self.literal_str)
+            if self.ctx.accept(TokenType.START_EDGE_PROPERTIES):
+                edge_properties = EdgeAttributeParser(self.ctx, self.literal_str).parse()
+                edge_properties.setdefault("depflag", 0)
+                edge_properties.setdefault("virtuals", ())
+                dependency = self._parse_node(root_spec)
+                root_spec._add_dependency(dependency, **edge_properties)
 
+            elif self.ctx.accept(TokenType.DEPENDENCY):
+                dependency = self._parse_node(root_spec)
                 root_spec._add_dependency(dependency, depflag=0, virtuals=())
 
             else:
@@ -297,6 +300,18 @@ def next_spec(
 
         return root_spec
 
+    def _parse_node(self, root_spec):
+        dependency = SpecNodeParser(self.ctx).parse()
+        if dependency is None:
+            msg = (
+                "the dependency sigil and any optional edge attributes must be followed by a "
+                "package name or a node attribute (version, variant, etc.)"
+            )
+            raise SpecParsingError(msg, self.ctx.current_token, self.literal_str)
+        if root_spec.concrete:
+            raise spack.spec.RedundantSpecError(root_spec, "^" + str(dependency))
+        return dependency
+
     def all_specs(self) -> List["spack.spec.Spec"]:
         """Return all the specs that remain to be parsed"""
         return list(iter(self.next_spec, None))
@@ -438,6 +453,41 @@ def parse(self, initial_spec: "spack.spec.Spec") -> "spack.spec.Spec":
         return initial_spec
 
 
+class EdgeAttributeParser:
+    __slots__ = "ctx", "literal_str"
+
+    def __init__(self, ctx, literal_str):
+        self.ctx = ctx
+        self.literal_str = literal_str
+
+    def parse(self):
+        attributes = {}
+        while True:
+            if self.ctx.accept(TokenType.KEY_VALUE_PAIR):
+                name, value = self.ctx.current_token.value.split("=", maxsplit=1)
+                name = name.strip("'\" ")
+                value = value.strip("'\" ").split(",")
+                attributes[name] = value
+                if name not in ("deptypes", "virtuals"):
+                    msg = (
+                        "the only edge attributes that are currently accepted "
+                        'are "deptypes" and "virtuals"'
+                    )
+                    raise SpecParsingError(msg, self.ctx.current_token, self.literal_str)
+            # TODO: Add code to accept bool variants here as soon as use variants are implemented
+            elif self.ctx.accept(TokenType.END_EDGE_PROPERTIES):
+                break
+            else:
+                msg = "unexpected token in edge attributes"
+                raise SpecParsingError(msg, self.ctx.next_token, self.literal_str)
+
+        # Turn deptypes=... to depflag representation
+        if "deptypes" in attributes:
+            deptype_string = attributes.pop("deptypes")
+            attributes["depflag"] = spack.deptypes.canonicalize(deptype_string)
+        return attributes
+
+
 def parse(text: str) -> List["spack.spec.Spec"]:
     """Parse text into a list of strings
 

lib/spack/spack/provider_index.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 """Classes and functions to manage providers of virtual dependencies"""
-import itertools
 from typing import Dict, List, Optional, Set
 
 import spack.error
@@ -11,33 +10,6 @@
 import spack.util.spack_json as sjson
 
 
-def _cross_provider_maps(lmap, rmap):
-    """Return a dictionary that combines constraint requests from both input.
-
-    Args:
-        lmap: main provider map
-        rmap: provider map with additional constraints
-    """
-    # TODO: this is pretty darned nasty, and inefficient, but there
-    # TODO: are not that many vdeps in most specs.
-    result = {}
-    for lspec, rspec in itertools.product(lmap, rmap):
-        try:
-            constrained = lspec.constrained(rspec)
-        except spack.error.UnsatisfiableSpecError:
-            continue
-
-        # lp and rp are left and right provider specs.
-        for lp_spec, rp_spec in itertools.product(lmap[lspec], rmap[rspec]):
-            if lp_spec.name == rp_spec.name:
-                try:
-                    const = lp_spec.constrained(rp_spec, deps=False)
-                    result.setdefault(constrained, set()).add(const)
-                except spack.error.UnsatisfiableSpecError:
-                    continue
-    return result
-
-
 class _IndexBase:
     #: This is a dict of dicts used for finding providers of particular
     #: virtual dependencies. The dict of dicts looks like:
@@ -81,29 +53,6 @@ def providers_for(self, virtual_spec):
     def __contains__(self, name):
         return name in self.providers
 
-    def satisfies(self, other):
-        """Determine if the providers of virtual specs are compatible.
-
-        Args:
-            other: another provider index
-
-        Returns:
-            True if the providers are compatible, False otherwise.
-        """
-        common = set(self.providers) & set(other.providers)
-        if not common:
-            return True
-
-        # This ensures that some provider in other COULD satisfy the
-        # vpkg constraints on self.
-        result = {}
-        for name in common:
-            crossed = _cross_provider_maps(self.providers[name], other.providers[name])
-            if crossed:
-                result[name] = crossed
-
-        return all(c in result for c in common)
-
     def __eq__(self, other):
         return self.providers == other.providers
 

lib/spack/spack/repo.py

@@ -6,6 +6,7 @@
 import abc
 import collections.abc
 import contextlib
+import difflib
 import errno
 import functools
 import importlib
@@ -489,7 +490,7 @@ def read(self, stream):
         self.index = spack.tag.TagIndex.from_json(stream, self.repository)
 
     def update(self, pkg_fullname):
-        self.index.update_package(pkg_fullname)
+        self.index.update_package(pkg_fullname.split(".")[-1])
 
     def write(self, stream):
         self.index.to_json(stream)
@@ -1516,7 +1517,18 @@ def __init__(self, name, repo=None):
                 long_msg = "Did you mean to specify a filename with './{0}'?"
                 long_msg = long_msg.format(name)
             else:
-                long_msg = "You may need to run 'spack clean -m'."
+                long_msg = "Use 'spack create' to create a new package."
+
+                if not repo:
+                    repo = spack.repo.PATH
+
+                # We need to compare the base package name
+                pkg_name = name.rsplit(".", 1)[-1]
+                similar = difflib.get_close_matches(pkg_name, repo.all_package_names())
+
+                if 1 <= len(similar) <= 5:
+                    long_msg += "\n\nDid you mean one of the following packages?\n  "
+                    long_msg += "\n  ".join(similar)
 
         super().__init__(msg, long_msg)
         self.name = name

lib/spack/spack/schema/__init__.py

@@ -62,3 +62,25 @@ def _deprecated_properties(validator, deprecated, instance, schema):
 
 
 Validator = llnl.util.lang.Singleton(_make_validator)
+
+spec_list_schema = {
+    "type": "array",
+    "default": [],
+    "items": {
+        "anyOf": [
+            {
+                "type": "object",
+                "additionalProperties": False,
+                "properties": {
+                    "matrix": {
+                        "type": "array",
+                        "items": {"type": "array", "items": {"type": "string"}},
+                    },
+                    "exclude": {"type": "array", "items": {"type": "string"}},
+                },
+            },
+            {"type": "string"},
+            {"type": "null"},
+        ]
+    },
+}

lib/spack/spack/schema/config.py

@@ -92,6 +92,7 @@
             "url_fetch_method": {"type": "string", "enum": ["urllib", "curl"]},
             "additional_external_search_paths": {"type": "array", "items": {"type": "string"}},
             "binary_index_ttl": {"type": "integer", "minimum": 0},
+            "aliases": {"type": "object", "patternProperties": {r"\w[\w-]*": {"type": "string"}}},
         },
         "deprecatedProperties": {
             "properties": ["terminal_title"],

lib/spack/spack/schema/definitions.py

@@ -0,0 +1,34 @@
+# Copyright 2013-2023 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)
+
+"""Schema for definitions
+
+.. literalinclude:: _spack_root/lib/spack/spack/schema/definitions.py
+   :lines: 13-
+"""
+
+import spack.schema
+
+#: Properties for inclusion in other schemas
+properties = {
+    "definitions": {
+        "type": "array",
+        "default": [],
+        "items": {
+            "type": "object",
+            "properties": {"when": {"type": "string"}},
+            "patternProperties": {r"^(?!when$)\w*": spack.schema.spec_list_schema},
+        },
+    }
+}
+
+#: Full schema with metadata
+schema = {
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "Spack definitions configuration file schema",
+    "type": "object",
+    "additionalProperties": False,
+    "properties": properties,
+}

lib/spack/spack/schema/env.py

@@ -12,34 +12,11 @@
 
 import spack.schema.gitlab_ci  # DEPRECATED
 import spack.schema.merged
-import spack.schema.packages
 import spack.schema.projections
 
 #: Top level key in a manifest file
 TOP_LEVEL_KEY = "spack"
 
-spec_list_schema = {
-    "type": "array",
-    "default": [],
-    "items": {
-        "anyOf": [
-            {
-                "type": "object",
-                "additionalProperties": False,
-                "properties": {
-                    "matrix": {
-                        "type": "array",
-                        "items": {"type": "array", "items": {"type": "string"}},
-                    },
-                    "exclude": {"type": "array", "items": {"type": "string"}},
-                },
-            },
-            {"type": "string"},
-            {"type": "null"},
-        ]
-    },
-}
-
 projections_scheme = spack.schema.projections.properties["projections"]
 
 schema = {
@@ -75,16 +52,7 @@
                             }
                         },
                     },
-                    "definitions": {
-                        "type": "array",
-                        "default": [],
-                        "items": {
-                            "type": "object",
-                            "properties": {"when": {"type": "string"}},
-                            "patternProperties": {r"^(?!when$)\w*": spec_list_schema},
-                        },
-                    },
-                    "specs": spec_list_schema,
+                    "specs": spack.schema.spec_list_schema,
                     "view": {
                         "anyOf": [
                             {"type": "boolean"},

lib/spack/spack/schema/merged.py

@@ -17,6 +17,7 @@
 import spack.schema.concretizer
 import spack.schema.config
 import spack.schema.container
+import spack.schema.definitions
 import spack.schema.mirrors
 import spack.schema.modules
 import spack.schema.packages
@@ -32,6 +33,7 @@
     spack.schema.config.properties,
     spack.schema.container.properties,
     spack.schema.ci.properties,
+    spack.schema.definitions.properties,
     spack.schema.mirrors.properties,
     spack.schema.modules.properties,
     spack.schema.packages.properties,

lib/spack/spack/schema/modules.py

@@ -18,9 +18,7 @@
 #: IS ADDED IMMEDIATELY BELOW THE MODULE TYPE ATTRIBUTE
 spec_regex = (
     r"(?!hierarchy|core_specs|verbose|hash_length|defaults|filter_hierarchy_specs|hide|"
-    r"whitelist|blacklist|"  # DEPRECATED: remove in 0.20.
-    r"include|exclude|"  # use these more inclusive/consistent options
-    r"projections|naming_scheme|core_compilers|all)(^\w[\w-]*)"
+    r"include|exclude|projections|naming_scheme|core_compilers|all)(^\w[\w-]*)"
 )
 
 #: Matches a valid name for a module set
@@ -46,14 +44,7 @@
             "default": {},
             "additionalProperties": False,
             "properties": {
-                # DEPRECATED: remove in 0.20.
-                "environment_blacklist": {
-                    "type": "array",
-                    "default": [],
-                    "items": {"type": "string"},
-                },
-                # use exclude_env_vars instead
-                "exclude_env_vars": {"type": "array", "default": [], "items": {"type": "string"}},
+                "exclude_env_vars": {"type": "array", "default": [], "items": {"type": "string"}}
             },
         },
         "template": {"type": "string"},
@@ -80,11 +71,6 @@
             "properties": {
                 "verbose": {"type": "boolean", "default": False},
                 "hash_length": {"type": "integer", "minimum": 0, "default": 7},
-                # DEPRECATED: remove in 0.20.
-                "whitelist": array_of_strings,
-                "blacklist": array_of_strings,
-                "blacklist_implicits": {"type": "boolean", "default": False},
-                # whitelist/blacklist have been replaced with include/exclude
                 "include": array_of_strings,
                 "exclude": array_of_strings,
                 "exclude_implicits": {"type": "boolean", "default": False},
@@ -188,52 +174,3 @@
     "additionalProperties": False,
     "properties": properties,
 }
-
-
-# deprecated keys and their replacements
-old_to_new_key = {"exclude_implicits": "hide_implicits"}
-
-
-def update_keys(data, key_translations):
-    """Change blacklist/whitelist to exclude/include.
-
-    Arguments:
-        data (dict): data from a valid modules configuration.
-        key_translations (dict): A dictionary of keys to translate to
-            their respective values.
-
-    Return:
-        (bool) whether anything was changed in data
-    """
-    changed = False
-
-    if isinstance(data, dict):
-        keys = list(data.keys())
-        for key in keys:
-            value = data[key]
-
-            translation = key_translations.get(key)
-            if translation:
-                data[translation] = data.pop(key)
-                changed = True
-
-            changed |= update_keys(value, key_translations)
-
-    elif isinstance(data, list):
-        for elt in data:
-            changed |= update_keys(elt, key_translations)
-
-    return changed
-
-
-def update(data):
-    """Update the data in place to remove deprecated properties.
-
-    Args:
-        data (dict): dictionary to be updated
-
-    Returns:
-        True if data was changed, False otherwise
-    """
-    # translate blacklist/whitelist to exclude/include
-    return update_keys(data, old_to_new_key)

lib/spack/spack/schema/packages.py

@@ -8,6 +8,68 @@
    :lines: 13-
 """
 
+permissions = {
+    "type": "object",
+    "additionalProperties": False,
+    "properties": {
+        "read": {"type": "string", "enum": ["user", "group", "world"]},
+        "write": {"type": "string", "enum": ["user", "group", "world"]},
+        "group": {"type": "string"},
+    },
+}
+
+variants = {"oneOf": [{"type": "string"}, {"type": "array", "items": {"type": "string"}}]}
+
+requirements = {
+    "oneOf": [
+        # 'require' can be a list of requirement_groups.
+        # each requirement group is a list of one or more
+        # specs. Either at least one or exactly one spec
+        # in the group must be satisfied (depending on
+        # whether you use "any_of" or "one_of",
+        # repectively)
+        {
+            "type": "array",
+            "items": {
+                "oneOf": [
+                    {
+                        "type": "object",
+                        "additionalProperties": False,
+                        "properties": {
+                            "one_of": {"type": "array", "items": {"type": "string"}},
+                            "any_of": {"type": "array", "items": {"type": "string"}},
+                            "spec": {"type": "string"},
+                            "message": {"type": "string"},
+                            "when": {"type": "string"},
+                        },
+                    },
+                    {"type": "string"},
+                ]
+            },
+        },
+        # Shorthand for a single requirement group with
+        # one member
+        {"type": "string"},
+    ]
+}
+
+permissions = {
+    "type": "object",
+    "additionalProperties": False,
+    "properties": {
+        "read": {"type": "string", "enum": ["user", "group", "world"]},
+        "write": {"type": "string", "enum": ["user", "group", "world"]},
+        "group": {"type": "string"},
+    },
+}
+
+package_attributes = {
+    "type": "object",
+    "additionalProperties": False,
+    "patternProperties": {r"\w+": {}},
+}
+
+REQUIREMENT_URL = "https://spack.readthedocs.io/en/latest/packages_yaml.html#package-requirements"
 
 #: Properties for inclusion in other schemas
 properties = {
@@ -15,57 +77,14 @@
         "type": "object",
         "default": {},
         "additionalProperties": False,
-        "patternProperties": {
-            r"\w[\w-]*": {  # package name
+        "properties": {
+            "all": {  # package name
                 "type": "object",
                 "default": {},
                 "additionalProperties": False,
                 "properties": {
-                    "require": {
-                        "oneOf": [
-                            # 'require' can be a list of requirement_groups.
-                            # each requirement group is a list of one or more
-                            # specs. Either at least one or exactly one spec
-                            # in the group must be satisfied (depending on
-                            # whether you use "any_of" or "one_of",
-                            # repectively)
-                            {
-                                "type": "array",
-                                "items": {
-                                    "oneOf": [
-                                        {
-                                            "type": "object",
-                                            "additionalProperties": False,
-                                            "properties": {
-                                                "one_of": {
-                                                    "type": "array",
-                                                    "items": {"type": "string"},
-                                                },
-                                                "any_of": {
-                                                    "type": "array",
-                                                    "items": {"type": "string"},
-                                                },
-                                                "spec": {"type": "string"},
-                                                "message": {"type": "string"},
-                                                "when": {"type": "string"},
-                                            },
-                                        },
-                                        {"type": "string"},
-                                    ]
-                                },
-                            },
-                            # Shorthand for a single requirement group with
-                            # one member
-                            {"type": "string"},
-                        ]
-                    },
-                    "version": {
-                        "type": "array",
-                        "default": [],
-                        # version strings (type should be string, number is still possible
-                        # but deprecated. this is to avoid issues with e.g. 3.10 -> 3.1)
-                        "items": {"anyOf": [{"type": "string"}, {"type": "number"}]},
-                    },
+                    "require": requirements,
+                    "version": {},  # Here only to warn users on ignored properties
                     "target": {
                         "type": "array",
                         "default": [],
@@ -78,22 +97,10 @@
                         "items": {"type": "string"},
                     },  # compiler specs
                     "buildable": {"type": "boolean", "default": True},
-                    "permissions": {
-                        "type": "object",
-                        "additionalProperties": False,
-                        "properties": {
-                            "read": {"type": "string", "enum": ["user", "group", "world"]},
-                            "write": {"type": "string", "enum": ["user", "group", "world"]},
-                            "group": {"type": "string"},
-                        },
-                    },
+                    "permissions": permissions,
                     # If 'get_full_repo' is promoted to a Package-level
                     # attribute, it could be useful to set it here
-                    "package_attributes": {
-                        "type": "object",
-                        "additionalProperties": False,
-                        "patternProperties": {r"\w+": {}},
-                    },
+                    "package_attributes": package_attributes,
                     "providers": {
                         "type": "object",
                         "default": {},
@@ -106,12 +113,40 @@
                             }
                         },
                     },
-                    "variants": {
-                        "oneOf": [
-                            {"type": "string"},
-                            {"type": "array", "items": {"type": "string"}},
-                        ]
+                    "variants": variants,
+                },
+                "deprecatedProperties": {
+                    "properties": ["version"],
+                    "message": "setting version preferences in the 'all' section of packages.yaml "
+                    "is deprecated and will be removed in v0.22\n\n\tThese preferences "
+                    "will be ignored by Spack. You can set them only in package-specific sections "
+                    "of the same file.\n",
+                    "error": False,
+                },
+            }
+        },
+        "patternProperties": {
+            r"(?!^all$)(^\w[\w-]*)": {  # package name
+                "type": "object",
+                "default": {},
+                "additionalProperties": False,
+                "properties": {
+                    "require": requirements,
+                    "version": {
+                        "type": "array",
+                        "default": [],
+                        # version strings
+                        "items": {"anyOf": [{"type": "string"}, {"type": "number"}]},
                     },
+                    "target": {},  # Here only to warn users on ignored properties
+                    "compiler": {},  # Here only to warn users on ignored properties
+                    "buildable": {"type": "boolean", "default": True},
+                    "permissions": permissions,
+                    # If 'get_full_repo' is promoted to a Package-level
+                    # attribute, it could be useful to set it here
+                    "package_attributes": package_attributes,
+                    "providers": {},  # Here only to warn users on ignored properties
+                    "variants": variants,
                     "externals": {
                         "type": "array",
                         "items": {
@@ -127,6 +162,18 @@
                         },
                     },
                 },
+                "deprecatedProperties": {
+                    "properties": ["target", "compiler", "providers"],
+                    "message": "setting 'compiler:', 'target:' or 'provider:' preferences in "
+                    "a package-specific section of packages.yaml is deprecated, and will be "
+                    "removed in v0.22.\n\n\tThese preferences will be ignored by Spack, and "
+                    "can be set only in the 'all' section of the same file. "
+                    "You can run:\n\n\t\t$ spack audit configs\n\n\tto get better diagnostics, "
+                    "including files:lines where the deprecated attributes are used.\n\n"
+                    "\tUse requirements to enforce conditions on specific packages: "
+                    f"{REQUIREMENT_URL}\n",
+                    "error": False,
+                },
             }
         },
     }

lib/spack/spack/solver/asp.py

@@ -8,11 +8,13 @@
 import enum
 import itertools
 import os
+import pathlib
 import pprint
 import re
 import types
+import typing
 import warnings
-from typing import Dict, List, NamedTuple, Optional, Sequence, Tuple, Union
+from typing import Callable, Dict, List, NamedTuple, Optional, Sequence, Set, Tuple, Union
 
 import archspec.cpu
 
@@ -337,6 +339,13 @@ def __getattr__(self, name):
 
 fn = AspFunctionBuilder()
 
+TransformFunction = Callable[[spack.spec.Spec, List[AspFunction]], List[AspFunction]]
+
+
+def remove_node(spec: spack.spec.Spec, facts: List[AspFunction]) -> List[AspFunction]:
+    """Transformation that removes all "node" and "virtual_node" from the input list of facts."""
+    return list(filter(lambda x: x.args[0] not in ("node", "virtual_node"), facts))
+
 
 def _create_counter(specs, tests):
     strategy = spack.config.CONFIG.get("concretizer:duplicates:strategy", "none")
@@ -371,7 +380,7 @@ def check_packages_exist(specs):
     for spec in specs:
         for s in spec.traverse():
             try:
-                check_passed = repo.exists(s.name) or repo.is_virtual(s.name)
+                check_passed = repo.repo_for_pkg(s).exists(s.name) or repo.is_virtual(s.name)
             except Exception as e:
                 msg = "Cannot find package: {0}".format(str(e))
                 check_passed = False
@@ -684,7 +693,7 @@ def extract_args(model, predicate_name):
 class ErrorHandler:
     def __init__(self, model):
         self.model = model
-        self.error_args = extract_args(model, "error")
+        self.full_model = None
 
     def multiple_values_error(self, attribute, pkg):
         return f'Cannot select a single "{attribute}" for package "{pkg}"'
@@ -692,6 +701,48 @@ def multiple_values_error(self, attribute, pkg):
     def no_value_error(self, attribute, pkg):
         return f'Cannot select a single "{attribute}" for package "{pkg}"'
 
+    def _get_cause_tree(
+        self,
+        cause: Tuple[str, str],
+        conditions: Dict[str, str],
+        condition_causes: List[Tuple[Tuple[str, str], Tuple[str, str]]],
+        seen: Set,
+        indent: str = "        ",
+    ) -> List[str]:
+        """
+        Implementation of recursion for self.get_cause_tree. Much of this operates on tuples
+        (condition_id, set_id) in which the latter idea means that the condition represented by
+        the former held in the condition set represented by the latter.
+        """
+        seen.add(cause)
+        parents = [c for e, c in condition_causes if e == cause and c not in seen]
+        local = "required because %s " % conditions[cause[0]]
+
+        return [indent + local] + [
+            c
+            for parent in parents
+            for c in self._get_cause_tree(
+                parent, conditions, condition_causes, seen, indent=indent + "  "
+            )
+        ]
+
+    def get_cause_tree(self, cause: Tuple[str, str]) -> List[str]:
+        """
+        Get the cause tree associated with the given cause.
+
+        Arguments:
+            cause: The root cause of the tree (final condition)
+
+        Returns:
+            A list of strings describing the causes, formatted to display tree structure.
+        """
+        conditions: Dict[str, str] = dict(extract_args(self.full_model, "condition_reason"))
+        condition_causes: List[Tuple[Tuple[str, str], Tuple[str, str]]] = list(
+            ((Effect, EID), (Cause, CID))
+            for Effect, EID, Cause, CID in extract_args(self.full_model, "condition_cause")
+        )
+        return self._get_cause_tree(cause, conditions, condition_causes, set())
+
     def handle_error(self, msg, *args):
         """Handle an error state derived by the solver."""
         if msg == "multiple_values_error":
@@ -700,14 +751,31 @@ def handle_error(self, msg, *args):
         if msg == "no_value_error":
             return self.no_value_error(*args)
 
+        try:
+            idx = args.index("startcauses")
+        except ValueError:
+            msg_args = args
+            causes = []
+        else:
+            msg_args = args[:idx]
+            cause_args = args[idx + 1 :]
+            cause_args_conditions = cause_args[::2]
+            cause_args_ids = cause_args[1::2]
+            causes = list(zip(cause_args_conditions, cause_args_ids))
+
+        msg = msg.format(*msg_args)
+
         # For variant formatting, we sometimes have to construct specs
         # to format values properly. Find/replace all occurances of
         # Spec(...) with the string representation of the spec mentioned
-        msg = msg.format(*args)
         specs_to_construct = re.findall(r"Spec\(([^)]*)\)", msg)
         for spec_str in specs_to_construct:
             msg = msg.replace("Spec(%s)" % spec_str, str(spack.spec.Spec(spec_str)))
 
+        for cause in set(causes):
+            for c in self.get_cause_tree(cause):
+                msg += f"\n{c}"
+
         return msg
 
     def message(self, errors) -> str:
@@ -719,13 +787,40 @@ def message(self, errors) -> str:
         return "\n".join([header] + messages)
 
     def raise_if_errors(self):
-        if not self.error_args:
+        initial_error_args = extract_args(self.model, "error")
+        if not initial_error_args:
             return
 
+        error_causation = clingo.Control()
+
+        parent_dir = pathlib.Path(__file__).parent
+        errors_lp = parent_dir / "error_messages.lp"
+
+        def on_model(model):
+            self.full_model = model.symbols(shown=True, terms=True)
+
+        with error_causation.backend() as backend:
+            for atom in self.model:
+                atom_id = backend.add_atom(atom)
+                backend.add_rule([atom_id], [], choice=False)
+
+            error_causation.load(str(errors_lp))
+            error_causation.ground([("base", []), ("error_messages", [])])
+            _ = error_causation.solve(on_model=on_model)
+
+        # No choices so there will be only one model
+        error_args = extract_args(self.full_model, "error")
         errors = sorted(
-            [(int(priority), msg, args) for priority, msg, *args in self.error_args], reverse=True
+            [(int(priority), msg, args) for priority, msg, *args in error_args], reverse=True
         )
-        msg = self.message(errors)
+        try:
+            msg = self.message(errors)
+        except Exception as e:
+            msg = (
+                f"unexpected error during concretization [{str(e)}]. "
+                f"Please report a bug at https://github.com/spack/spack/issues"
+            )
+            raise spack.error.SpackError(msg)
         raise UnsatisfiableSpecError(msg)
 
 
@@ -919,14 +1014,6 @@ def on_model(model):
             # record the possible dependencies in the solve
             result.possible_dependencies = setup.pkgs
 
-            # print any unknown functions in the model
-            for sym in best_model:
-                if sym.name not in ("attr", "error", "opt_criterion"):
-                    tty.debug(
-                        "UNKNOWN SYMBOL: %s(%s)"
-                        % (sym.name, ", ".join(intermediate_repr(sym.arguments)))
-                    )
-
         elif cores:
             result.control = self.control
             result.cores.extend(cores)
@@ -1031,11 +1118,8 @@ def __init__(self, tests=False):
 
         self.reusable_and_possible = ConcreteSpecsByHash()
 
-        # id for dummy variables
-        self._condition_id_counter = itertools.count()
-        self._trigger_id_counter = itertools.count()
+        self._id_counter = itertools.count()
         self._trigger_cache = collections.defaultdict(dict)
-        self._effect_id_counter = itertools.count()
         self._effect_cache = collections.defaultdict(dict)
 
         # Caches to optimize the setup phase of the solver
@@ -1049,6 +1133,7 @@ def __init__(self, tests=False):
 
         # Set during the call to setup
         self.pkgs = None
+        self.explicitly_required_namespaces = {}
 
     def pkg_version_rules(self, pkg):
         """Output declared versions of a package.
@@ -1061,7 +1146,9 @@ def key_fn(version):
             # Origins are sorted by "provenance" first, see the Provenance enumeration above
             return version.origin, version.idx
 
-        pkg = packagize(pkg)
+        if isinstance(pkg, str):
+            pkg = self.pkg_class(pkg)
+
         declared_versions = self.declared_versions[pkg.name]
         partially_sorted_versions = sorted(set(declared_versions), key=key_fn)
 
@@ -1116,7 +1203,7 @@ def conflict_rules(self, pkg):
         default_msg = "{0}: '{1}' conflicts with '{2}'"
         no_constraint_msg = "{0}: conflicts with '{1}'"
         for trigger, constraints in pkg.conflicts.items():
-            trigger_msg = "conflict trigger %s" % str(trigger)
+            trigger_msg = f"conflict is triggered when {str(trigger)}"
             trigger_spec = spack.spec.Spec(trigger)
             trigger_id = self.condition(
                 trigger_spec, name=trigger_spec.name or pkg.name, msg=trigger_msg
@@ -1128,7 +1215,11 @@ def conflict_rules(self, pkg):
                         conflict_msg = no_constraint_msg.format(pkg.name, trigger)
                     else:
                         conflict_msg = default_msg.format(pkg.name, trigger, constraint)
-                constraint_msg = "conflict constraint %s" % str(constraint)
+
+                spec_for_msg = (
+                    spack.spec.Spec(pkg.name) if constraint == spack.spec.Spec() else constraint
+                )
+                constraint_msg = f"conflict applies to spec {str(spec_for_msg)}"
                 constraint_id = self.condition(constraint, name=pkg.name, msg=constraint_msg)
                 self.gen.fact(
                     fn.pkg_fact(pkg.name, fn.conflict(trigger_id, constraint_id, conflict_msg))
@@ -1167,32 +1258,9 @@ def compiler_facts(self):
         matches = sorted(indexed_possible_compilers, key=lambda x: ppk(x[1].spec))
 
         for weight, (compiler_id, cspec) in enumerate(matches):
-            f = fn.default_compiler_preference(compiler_id, weight)
+            f = fn.compiler_weight(compiler_id, weight)
             self.gen.fact(f)
 
-    def package_compiler_defaults(self, pkg):
-        """Facts about packages' compiler prefs."""
-
-        packages = spack.config.get("packages")
-        pkg_prefs = packages.get(pkg.name)
-        if not pkg_prefs or "compiler" not in pkg_prefs:
-            return
-
-        compiler_list = self.possible_compilers
-        compiler_list = sorted(compiler_list, key=lambda x: (x.name, x.version), reverse=True)
-        ppk = spack.package_prefs.PackagePrefs(pkg.name, "compiler", all=False)
-        matches = sorted(compiler_list, key=lambda x: ppk(x.spec))
-
-        for i, compiler in enumerate(reversed(matches)):
-            self.gen.fact(
-                fn.pkg_fact(
-                    pkg.name,
-                    fn.node_compiler_preference(
-                        compiler.spec.name, compiler.spec.version, -i * 100
-                    ),
-                )
-            )
-
     def package_requirement_rules(self, pkg):
         rules = self.requirement_rules_from_package_py(pkg)
         rules.extend(self.requirement_rules_from_packages_yaml(pkg))
@@ -1272,7 +1340,10 @@ def _rule_from_str(
         )
 
     def pkg_rules(self, pkg, tests):
-        pkg = packagize(pkg)
+        pkg = self.pkg_class(pkg)
+
+        # Namespace of the package
+        self.gen.fact(fn.pkg_fact(pkg.name, fn.namespace(pkg.namespace)))
 
         # versions
         self.pkg_version_rules(pkg)
@@ -1284,9 +1355,6 @@ def pkg_rules(self, pkg, tests):
         # conflicts
         self.conflict_rules(pkg)
 
-        # default compilers for this package
-        self.package_compiler_defaults(pkg)
-
         # virtuals
         self.package_provider_rules(pkg)
 
@@ -1310,7 +1378,7 @@ def trigger_rules(self):
         self.gen.h2("Trigger conditions")
         for name in self._trigger_cache:
             cache = self._trigger_cache[name]
-            for spec_str, (trigger_id, requirements) in cache.items():
+            for (spec_str, _), (trigger_id, requirements) in cache.items():
                 self.gen.fact(fn.pkg_fact(name, fn.trigger_id(trigger_id)))
                 self.gen.fact(fn.pkg_fact(name, fn.trigger_msg(spec_str)))
                 for predicate in requirements:
@@ -1323,7 +1391,7 @@ def effect_rules(self):
         self.gen.h2("Imposed requirements")
         for name in self._effect_cache:
             cache = self._effect_cache[name]
-            for spec_str, (effect_id, requirements) in cache.items():
+            for (spec_str, _), (effect_id, requirements) in cache.items():
                 self.gen.fact(fn.pkg_fact(name, fn.effect_id(effect_id)))
                 self.gen.fact(fn.pkg_fact(name, fn.effect_msg(spec_str)))
                 for predicate in requirements:
@@ -1422,18 +1490,26 @@ def variant_rules(self, pkg):
 
             self.gen.newline()
 
-    def condition(self, required_spec, imposed_spec=None, name=None, msg=None, node=False):
+    def condition(
+        self,
+        required_spec: spack.spec.Spec,
+        imposed_spec: Optional[spack.spec.Spec] = None,
+        name: Optional[str] = None,
+        msg: Optional[str] = None,
+        transform_required: Optional[TransformFunction] = None,
+        transform_imposed: Optional[TransformFunction] = remove_node,
+    ):
         """Generate facts for a dependency or virtual provider condition.
 
         Arguments:
-            required_spec (spack.spec.Spec): the spec that triggers this condition
-            imposed_spec (spack.spec.Spec or None): the spec with constraints that
-                are imposed when this condition is triggered
-            name (str or None): name for `required_spec` (required if
-                required_spec is anonymous, ignored if not)
-            msg (str or None): description of the condition
-            node (bool): if False does not emit "node" or "virtual_node" requirements
-                from the imposed spec
+            required_spec: the constraints that triggers this condition
+            imposed_spec: the constraints that are imposed when this condition is triggered
+            name: name for `required_spec` (required if required_spec is anonymous, ignored if not)
+            msg: description of the condition
+            transform_required: transformation applied to facts from the required spec. Defaults
+                to leave facts as they are.
+            transform_imposed: transformation applied to facts from the imposed spec. Defaults
+                to removing "node" and "virtual_node" facts.
         Returns:
             int: id of the condition created by this function
         """
@@ -1445,16 +1521,20 @@ def condition(self, required_spec, imposed_spec=None, name=None, msg=None, node=
         # In this way, if a condition can't be emitted but the exception is handled in the caller,
         # we won't emit partial facts.
 
-        condition_id = next(self._condition_id_counter)
+        condition_id = next(self._id_counter)
         self.gen.fact(fn.pkg_fact(named_cond.name, fn.condition(condition_id)))
         self.gen.fact(fn.condition_reason(condition_id, msg))
 
         cache = self._trigger_cache[named_cond.name]
 
-        named_cond_key = str(named_cond)
+        named_cond_key = (str(named_cond), transform_required)
         if named_cond_key not in cache:
-            trigger_id = next(self._trigger_id_counter)
+            trigger_id = next(self._id_counter)
             requirements = self.spec_clauses(named_cond, body=True, required_from=name)
+
+            if transform_required:
+                requirements = transform_required(named_cond, requirements)
+
             cache[named_cond_key] = (trigger_id, requirements)
         trigger_id, requirements = cache[named_cond_key]
         self.gen.fact(fn.pkg_fact(named_cond.name, fn.condition_trigger(condition_id, trigger_id)))
@@ -1463,14 +1543,14 @@ def condition(self, required_spec, imposed_spec=None, name=None, msg=None, node=
             return condition_id
 
         cache = self._effect_cache[named_cond.name]
-        imposed_spec_key = str(imposed_spec)
+        imposed_spec_key = (str(imposed_spec), transform_imposed)
         if imposed_spec_key not in cache:
-            effect_id = next(self._effect_id_counter)
+            effect_id = next(self._id_counter)
             requirements = self.spec_clauses(imposed_spec, body=False, required_from=name)
-            if not node:
-                requirements = list(
-                    filter(lambda x: x.args[0] not in ("node", "virtual_node"), requirements)
-                )
+
+            if transform_imposed:
+                requirements = transform_imposed(imposed_spec, requirements)
+
             cache[imposed_spec_key] = (effect_id, requirements)
         effect_id, requirements = cache[imposed_spec_key]
         self.gen.fact(fn.pkg_fact(named_cond.name, fn.condition_effect(condition_id, effect_id)))
@@ -1501,6 +1581,17 @@ def package_provider_rules(self, pkg):
                 )
             self.gen.newline()
 
+        for when, sets_of_virtuals in pkg.provided_together.items():
+            condition_id = self.condition(
+                when, name=pkg.name, msg="Virtuals are provided together"
+            )
+            for set_id, virtuals_together in enumerate(sets_of_virtuals):
+                for name in virtuals_together:
+                    self.gen.fact(
+                        fn.pkg_fact(pkg.name, fn.provided_together(condition_id, set_id, name))
+                    )
+            self.gen.newline()
+
     def package_dependencies_rules(self, pkg):
         """Translate 'depends_on' directives into ASP logic."""
         for _, conditions in sorted(pkg.dependencies.items()):
@@ -1519,21 +1610,32 @@ def package_dependencies_rules(self, pkg):
                 if not depflag:
                     continue
 
-                msg = "%s depends on %s" % (pkg.name, dep.spec.name)
+                msg = f"{pkg.name} depends on {dep.spec}"
                 if cond != spack.spec.Spec():
-                    msg += " when %s" % cond
+                    msg += f" when {cond}"
                 else:
                     pass
 
-                condition_id = self.condition(cond, dep.spec, pkg.name, msg)
-                self.gen.fact(
-                    fn.pkg_fact(pkg.name, fn.dependency_condition(condition_id, dep.spec.name))
-                )
+                def track_dependencies(input_spec, requirements):
+                    return requirements + [fn.attr("track_dependencies", input_spec.name)]
 
-                for t in dt.ALL_FLAGS:
-                    if t & depflag:
-                        # there is a declared dependency of type t
-                        self.gen.fact(fn.dependency_type(condition_id, dt.flag_to_string(t)))
+                def dependency_holds(input_spec, requirements):
+                    return remove_node(input_spec, requirements) + [
+                        fn.attr(
+                            "dependency_holds", pkg.name, input_spec.name, dt.flag_to_string(t)
+                        )
+                        for t in dt.ALL_FLAGS
+                        if t & depflag
+                    ]
+
+                self.condition(
+                    cond,
+                    dep.spec,
+                    name=pkg.name,
+                    msg=msg,
+                    transform_required=track_dependencies,
+                    transform_imposed=dependency_holds,
+                )
 
                 self.gen.newline()
 
@@ -1548,6 +1650,7 @@ def virtual_preferences(self, pkg_name, func):
             for i, provider in enumerate(providers):
                 provider_name = spack.spec.Spec(provider).name
                 func(vspec, provider_name, i)
+            self.gen.newline()
 
     def provider_defaults(self):
         self.gen.h2("Default virtual providers")
@@ -1573,9 +1676,10 @@ def provider_requirements(self):
             rules = self._rules_from_requirements(
                 virtual_str, requirements, kind=RequirementKind.VIRTUAL
             )
-            self.emit_facts_from_requirement_rules(rules)
-            self.trigger_rules()
-            self.effect_rules()
+            if rules:
+                self.emit_facts_from_requirement_rules(rules)
+                self.trigger_rules()
+                self.effect_rules()
 
     def emit_facts_from_requirement_rules(self, rules: List[RequirementRule]):
         """Generate facts to enforce requirements.
@@ -1628,8 +1732,17 @@ def emit_facts_from_requirement_rules(self, rules: List[RequirementRule]):
                     when_spec = spack.spec.Spec(pkg_name)
 
                 try:
+                    # With virtual we want to emit "node" and "virtual_node" in imposed specs
+                    transform: Optional[TransformFunction] = remove_node
+                    if virtual:
+                        transform = None
+
                     member_id = self.condition(
-                        required_spec=when_spec, imposed_spec=spec, name=pkg_name, node=virtual
+                        required_spec=when_spec,
+                        imposed_spec=spec,
+                        name=pkg_name,
+                        transform_imposed=transform,
+                        msg=f"{spec_str} is a requirement for package {pkg_name}",
                     )
                 except Exception as e:
                     # Do not raise if the rule comes from the 'all' subsection, since usability
@@ -1692,8 +1805,13 @@ def external_packages(self):
             # Declare external conditions with a local index into packages.yaml
             for local_idx, spec in enumerate(external_specs):
                 msg = "%s available as external when satisfying %s" % (spec.name, spec)
-                condition_id = self.condition(spec, msg=msg)
-                self.gen.fact(fn.pkg_fact(pkg_name, fn.possible_external(condition_id, local_idx)))
+
+                def external_imposition(input_spec, requirements):
+                    return requirements + [
+                        fn.attr("external_conditions_hold", input_spec.name, local_idx)
+                    ]
+
+                self.condition(spec, spec, msg=msg, transform_imposed=external_imposition)
                 self.possible_versions[spec.name].add(spec.version)
                 self.gen.newline()
 
@@ -1715,7 +1833,13 @@ def preferred_variants(self, pkg_name):
 
             # perform validation of the variant and values
             spec = spack.spec.Spec(pkg_name)
-            spec.update_variant_validate(variant_name, values)
+            try:
+                spec.update_variant_validate(variant_name, values)
+            except (spack.variant.InvalidVariantValueError, KeyError, ValueError) as e:
+                tty.debug(
+                    f"[SETUP]: rejected {str(variant)} as a preference for {pkg_name}: {str(e)}"
+                )
+                continue
 
             for value in values:
                 self.variant_values_from_specs.add((pkg_name, variant.name, value))
@@ -1723,8 +1847,8 @@ def preferred_variants(self, pkg_name):
                     fn.variant_default_value_from_packages_yaml(pkg_name, variant.name, value)
                 )
 
-    def target_preferences(self, pkg_name):
-        key_fn = spack.package_prefs.PackagePrefs(pkg_name, "target")
+    def target_preferences(self):
+        key_fn = spack.package_prefs.PackagePrefs("all", "target")
 
         if not self.target_specs_cache:
             self.target_specs_cache = [
@@ -1734,17 +1858,25 @@ def target_preferences(self, pkg_name):
 
         package_targets = self.target_specs_cache[:]
         package_targets.sort(key=key_fn)
-
-        offset = 0
-        best_default = self.default_targets[0][1]
         for i, preferred in enumerate(package_targets):
-            if str(preferred.architecture.target) == best_default and i != 0:
-                offset = 100
-            self.gen.fact(
-                fn.pkg_fact(
-                    pkg_name, fn.target_weight(str(preferred.architecture.target), i + offset)
-                )
-            )
+            self.gen.fact(fn.target_weight(str(preferred.architecture.target), i))
+
+    def flag_defaults(self):
+        self.gen.h2("Compiler flag defaults")
+
+        # types of flags that can be on specs
+        for flag in spack.spec.FlagMap.valid_compiler_flags():
+            self.gen.fact(fn.flag_type(flag))
+        self.gen.newline()
+
+        # flags from compilers.yaml
+        compilers = all_compilers_in_config()
+        for compiler in compilers:
+            for name, flags in compiler.flags.items():
+                for flag in flags:
+                    self.gen.fact(
+                        fn.compiler_version_flag(compiler.name, compiler.version, name, flag)
+                    )
 
     def spec_clauses(self, *args, **kwargs):
         """Wrap a call to `_spec_clauses()` into a try/except block that
@@ -1797,7 +1929,7 @@ class Head:
             node_flag = fn.attr("node_flag_set")
             node_flag_source = fn.attr("node_flag_source")
             node_flag_propagate = fn.attr("node_flag_propagate")
-            variant_propagate = fn.attr("variant_propagate")
+            variant_propagation_candidate = fn.attr("variant_propagation_candidate")
 
         class Body:
             node = fn.attr("node")
@@ -1811,7 +1943,7 @@ class Body:
             node_flag = fn.attr("node_flag")
             node_flag_source = fn.attr("node_flag_source")
             node_flag_propagate = fn.attr("node_flag_propagate")
-            variant_propagate = fn.attr("variant_propagate")
+            variant_propagation_candidate = fn.attr("variant_propagation_candidate")
 
         f = Body if body else Head
 
@@ -1846,7 +1978,7 @@ class Body:
                 if not spec.concrete:
                     reserved_names = spack.directives.reserved_names
                     if not spec.virtual and vname not in reserved_names:
-                        pkg_cls = spack.repo.PATH.get_pkg_class(spec.name)
+                        pkg_cls = self.pkg_class(spec.name)
                         try:
                             variant_def, _ = pkg_cls.variants[vname]
                         except KeyError:
@@ -1860,7 +1992,9 @@ class Body:
                 clauses.append(f.variant_value(spec.name, vname, value))
 
                 if variant.propagate:
-                    clauses.append(f.variant_propagate(spec.name, vname, value, spec.name))
+                    clauses.append(
+                        f.variant_propagation_candidate(spec.name, vname, value, spec.name)
+                    )
 
                 # Tell the concretizer that this is a possible value for the
                 # variant, to account for things like int/str values where we
@@ -1902,6 +2036,16 @@ class Body:
                 clauses.append(fn.attr("package_hash", spec.name, spec._package_hash))
             clauses.append(fn.attr("hash", spec.name, spec.dag_hash()))
 
+        edges = spec.edges_from_dependents()
+        virtuals = [x for x in itertools.chain.from_iterable([edge.virtuals for edge in edges])]
+        if not body:
+            for virtual in virtuals:
+                clauses.append(fn.attr("provider_set", spec.name, virtual))
+                clauses.append(fn.attr("virtual_node", virtual))
+        else:
+            for virtual in virtuals:
+                clauses.append(fn.attr("virtual_on_incoming_edges", spec.name, virtual))
+
         # add all clauses from dependencies
         if transitive:
             # TODO: Eventually distinguish 2 deps on the same pkg (build and link)
@@ -1953,7 +2097,7 @@ def define_package_versions_and_validate_preferences(
         """Declare any versions in specs not declared in packages."""
         packages_yaml = spack.config.get("packages")
         for pkg_name in possible_pkgs:
-            pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
+            pkg_cls = self.pkg_class(pkg_name)
 
             # All the versions from the corresponding package.py file. Since concepts
             # like being a "develop" version or being preferred exist only at a
@@ -2041,7 +2185,7 @@ def _supported_targets(self, compiler_name, compiler_version, targets):
             try:
                 with warnings.catch_warnings():
                     warnings.simplefilter("ignore")
-                    target.optimization_flags(compiler_name, compiler_version)
+                    target.optimization_flags(compiler_name, str(compiler_version))
                 supported.append(target)
             except archspec.cpu.UnsupportedMicroarchitecture:
                 continue
@@ -2188,6 +2332,8 @@ def target_defaults(self, specs):
 
         self.default_targets = list(sorted(set(self.default_targets)))
 
+        self.target_preferences()
+
     def virtual_providers(self):
         self.gen.h2("Virtual providers")
         msg = (
@@ -2411,14 +2557,8 @@ def setup(
             reuse: list of concrete specs that can be reused
             allow_deprecated: if True adds deprecated versions into the solve
         """
-        self._condition_id_counter = itertools.count()
-
-        # preliminary checks
         check_packages_exist(specs)
 
-        # get list of all possible dependencies
-        self.possible_virtuals = set(x.name for x in specs if x.virtual)
-
         node_counter = _create_counter(specs, tests=self.tests)
         self.possible_virtuals = node_counter.possible_virtuals()
         self.pkgs = node_counter.possible_dependencies()
@@ -2431,6 +2571,10 @@ def setup(
             if missing_deps:
                 raise spack.spec.InvalidDependencyError(spec.name, missing_deps)
 
+        for node in spack.traverse.traverse_nodes(specs):
+            if node.namespace is not None:
+                self.explicitly_required_namespaces[node.name] = node.namespace
+
         # driver is used by all the functions below to add facts and
         # rules to generate an ASP program.
         self.gen = driver
@@ -2509,7 +2653,6 @@ def setup(
             self.pkg_rules(pkg, tests=self.tests)
             self.gen.h2("Package preferences: %s" % pkg)
             self.preferred_variants(pkg)
-            self.target_preferences(pkg)
 
         self.gen.h1("Develop specs")
         # Inject dev_path from environment
@@ -2535,20 +2678,43 @@ def setup(
         self.define_target_constraints()
 
     def literal_specs(self, specs):
-        for idx, spec in enumerate(specs):
+        for spec in specs:
             self.gen.h2("Spec: %s" % str(spec))
-            self.gen.fact(fn.literal(idx))
+            condition_id = next(self._id_counter)
+            trigger_id = next(self._id_counter)
 
-            self.gen.fact(fn.literal(idx, "virtual_root" if spec.virtual else "root", spec.name))
-            for clause in self.spec_clauses(spec):
-                self.gen.fact(fn.literal(idx, *clause.args))
-                if clause.args[0] == "variant_set":
-                    self.gen.fact(
-                        fn.literal(idx, "variant_default_value_from_cli", *clause.args[1:])
+            # Special condition triggered by "literal_solved"
+            self.gen.fact(fn.literal(trigger_id))
+            self.gen.fact(fn.pkg_fact(spec.name, fn.condition_trigger(condition_id, trigger_id)))
+            self.gen.fact(fn.condition_reason(condition_id, f"{spec} requested explicitly"))
+
+            imposed_spec_key = str(spec), None
+            cache = self._effect_cache[spec.name]
+            if imposed_spec_key in cache:
+                effect_id, requirements = cache[imposed_spec_key]
+            else:
+                effect_id = next(self._id_counter)
+                requirements = self.spec_clauses(spec)
+            root_name = spec.name
+            for clause in requirements:
+                clause_name = clause.args[0]
+                if clause_name == "variant_set":
+                    requirements.append(
+                        fn.attr("variant_default_value_from_cli", *clause.args[1:])
                     )
+                elif clause_name in ("node", "virtual_node", "hash"):
+                    # These facts are needed to compute the "condition_set" of the root
+                    pkg_name = clause.args[1]
+                    self.gen.fact(fn.mentioned_in_literal(trigger_id, root_name, pkg_name))
+
+            requirements.append(fn.attr("virtual_root" if spec.virtual else "root", spec.name))
+            cache[imposed_spec_key] = (effect_id, requirements)
+            self.gen.fact(fn.pkg_fact(spec.name, fn.condition_effect(condition_id, effect_id)))
 
             if self.concretize_everything:
-                self.gen.fact(fn.solve_literal(idx))
+                self.gen.fact(fn.solve_literal(trigger_id))
+
+        self.effect_rules()
 
     def validate_and_define_versions_from_requirements(
         self, *, allow_deprecated: bool, require_checksum: bool
@@ -2618,6 +2784,13 @@ def _specs_from_requires(self, pkg_name, section):
             for s in spec_group[key]:
                 yield _spec_with_default_name(s, pkg_name)
 
+    def pkg_class(self, pkg_name: str) -> typing.Type["spack.package_base.PackageBase"]:
+        request = pkg_name
+        if pkg_name in self.explicitly_required_namespaces:
+            namespace = self.explicitly_required_namespaces[pkg_name]
+            request = f"{namespace}.{pkg_name}"
+        return spack.repo.PATH.get_pkg_class(request)
+
 
 class SpecBuilder:
     """Class with actions to rebuild a spec from ASP results."""
@@ -2629,9 +2802,11 @@ class SpecBuilder:
                 r"^.*_propagate$",
                 r"^.*_satisfies$",
                 r"^.*_set$",
+                r"^dependency_holds$",
                 r"^node_compiler$",
                 r"^package_hash$",
                 r"^root$",
+                r"^track_dependencies$",
                 r"^variant_default_value_from_cli$",
                 r"^virtual_node$",
                 r"^virtual_root$",
@@ -2675,6 +2850,9 @@ def _arch(self, node):
             self._specs[node].architecture = arch
         return arch
 
+    def namespace(self, node, namespace):
+        self._specs[node].namespace = namespace
+
     def node_platform(self, node, platform):
         self._arch(node).platform = platform
 
@@ -2889,14 +3067,6 @@ def build_specs(self, function_tuples):
 
             action(*args)
 
-        # namespace assignment is done after the fact, as it is not
-        # currently part of the solve
-        for spec in self._specs.values():
-            if spec.namespace:
-                continue
-            repo = spack.repo.PATH.repo_for_pkg(spec)
-            spec.namespace = repo.namespace
-
         # fix flags after all specs are constructed
         self.reorder_flags()
 
@@ -3124,10 +3294,11 @@ def __init__(self, provided, conflicts):
         msg = (
             "Spack concretizer internal error. Please submit a bug report and include the "
             "command, environment if applicable and the following error message."
-            f"\n    {provided} is unsatisfiable, errors are:"
+            f"\n    {provided} is unsatisfiable"
         )
 
-        msg += "".join([f"\n    {conflict}" for conflict in conflicts])
+        if conflicts:
+            msg += ", errors are:" + "".join([f"\n    {conflict}" for conflict in conflicts])
 
         super(spack.error.UnsatisfiableSpecError, self).__init__(msg)
 

lib/spack/spack/solver/concretize.lp

@@ -10,9 +10,8 @@
 % ID of the nodes in the "root" link-run sub-DAG
 #const min_dupe_id = 0.
 
-#const link_run = 0.
-#const direct_link_run =1.
-#const direct_build = 2.
+#const direct_link_run = 0.
+#const direct_build = 1.
 
 % Allow clingo to create nodes
 { attr("node", node(0..X-1, Package))         } :- max_dupes(Package, X), not virtual(Package).
@@ -30,23 +29,24 @@
 :- attr("variant_value", PackageNode, _, _), not attr("node", PackageNode).
 :- attr("node_flag_compiler_default", PackageNode), not attr("node", PackageNode).
 :- attr("node_flag", PackageNode, _, _), not attr("node", PackageNode).
-:- attr("node_flag_source", PackageNode, _, _), not attr("node", PackageNode).
 :- attr("no_flags", PackageNode, _), not attr("node", PackageNode).
 :- attr("external_spec_selected", PackageNode, _), not attr("node", PackageNode).
 :- attr("depends_on", ParentNode, _, _), not attr("node", ParentNode).
 :- attr("depends_on", _, ChildNode, _), not attr("node", ChildNode).
 :- attr("node_flag_source", ParentNode, _, _), not attr("node", ParentNode).
 :- attr("node_flag_source", _, _, ChildNode), not attr("node", ChildNode).
+:- attr("virtual_node", VirtualNode), not provider(_, VirtualNode), internal_error("virtual node with no provider").
+:- provider(_, VirtualNode), not attr("virtual_node", VirtualNode), internal_error("provider with no virtual node").
+:- provider(PackageNode, _), not attr("node", PackageNode), internal_error("provider with no real node").
 
-:- attr("virtual_node", VirtualNode), not provider(_, VirtualNode).
-:- provider(_, VirtualNode), not attr("virtual_node", VirtualNode).
-:- provider(PackageNode, _), not attr("node", PackageNode).
-
-:- attr("root", node(ID, PackageNode)), ID > min_dupe_id.
+:- attr("root", node(ID, PackageNode)), ID > min_dupe_id, internal_error("root with a non-minimal duplicate ID").
 
 % Nodes in the "root" unification set cannot depend on non-root nodes if the dependency is "link" or "run"
-:- attr("depends_on", node(min_dupe_id, Package), node(ID, _), "link"), ID != min_dupe_id, unification_set("root", node(min_dupe_id, Package)).
-:- attr("depends_on", node(min_dupe_id, Package), node(ID, _), "run"),  ID != min_dupe_id, unification_set("root", node(min_dupe_id, Package)).
+:- attr("depends_on", node(min_dupe_id, Package), node(ID, _), "link"), ID != min_dupe_id, unification_set("root", node(min_dupe_id, Package)), internal_error("link dependency out of the root unification set").
+:- attr("depends_on", node(min_dupe_id, Package), node(ID, _), "run"),  ID != min_dupe_id, unification_set("root", node(min_dupe_id, Package)), internal_error("run dependency out of the root unification set").
+
+% Namespaces are statically assigned by a package fact
+attr("namespace", node(ID, Package), Namespace) :- attr("node", node(ID, Package)), pkg_fact(Package, namespace(Namespace)).
 
 % Rules on "unification sets", i.e. on sets of nodes allowing a single configuration of any given package
 unify(SetID, PackageName) :- unification_set(SetID, node(_, PackageName)).
@@ -86,22 +86,24 @@ unification_set(SetID, VirtualNode)
 %----
 
 % In the "root" unification set only ID = 0 are allowed
-:- unification_set("root", node(ID, _)), ID != 0.
+:- unification_set("root", node(ID, _)), ID != 0, internal_error("root unification set has node with non-zero unification set ID").
 
 % In the "root" unification set we allow only packages from the link-run possible subDAG
-:- unification_set("root", node(_, Package)), not possible_in_link_run(Package), not virtual(Package).
+:- unification_set("root", node(_, Package)), not possible_in_link_run(Package), not virtual(Package), internal_error("package outside possible link/run graph in root unification set").
 
 % Each node must belong to at least one unification set
-:- attr("node", PackageNode), not unification_set(_, PackageNode).
+:- attr("node", PackageNode), not unification_set(_, PackageNode), internal_error("node belongs to no unification set").
 
 % Cannot have a node with an ID, if lower ID of the same package are not used
 :- attr("node", node(ID1, Package)),
    not attr("node", node(ID2, Package)),
-   max_dupes(Package, X), ID1=0..X-1, ID2=0..X-1, ID2 < ID1.
+   max_dupes(Package, X), ID1=0..X-1, ID2=0..X-1, ID2 < ID1,
+   internal_error("node skipped id number").
 
 :- attr("virtual_node", node(ID1, Package)),
    not attr("virtual_node", node(ID2, Package)),
-   max_dupes(Package, X), ID1=0..X-1, ID2=0..X-1, ID2 < ID1.
+   max_dupes(Package, X), ID1=0..X-1, ID2=0..X-1, ID2 < ID1,
+   internal_error("virtual node skipped id number").
 
 %-----------------------------------------------------------------------------
 % Map literal input specs to facts that drive the solve
@@ -113,26 +115,30 @@ unification_set(SetID, VirtualNode)
 multiple_nodes_attribute("node_flag_source").
 multiple_nodes_attribute("depends_on").
 multiple_nodes_attribute("virtual_on_edge").
+multiple_nodes_attribute("provider_set").
 
-% Map constraint on the literal ID to facts on the node
-attr(Name, node(min_dupe_id, A1))             :- literal(LiteralID, Name, A1), solve_literal(LiteralID).
-attr(Name, node(min_dupe_id, A1), A2)         :- literal(LiteralID, Name, A1, A2), solve_literal(LiteralID).
-attr(Name, node(min_dupe_id, A1), A2, A3)     :- literal(LiteralID, Name, A1, A2, A3), solve_literal(LiteralID), not multiple_nodes_attribute(Name).
-attr(Name, node(min_dupe_id, A1), A2, A3, A4) :- literal(LiteralID, Name, A1, A2, A3, A4), solve_literal(LiteralID).
+trigger_condition_holds(TriggerID, node(min_dupe_id, Package)) :-
+  solve_literal(TriggerID),
+  pkg_fact(Package, condition_trigger(_, TriggerID)),
+  literal(TriggerID).
 
-% Special cases where nodes occur in arguments other than A1
-attr("node_flag_source", node(min_dupe_id, A1), A2, node(min_dupe_id, A3)) :- literal(LiteralID, "node_flag_source", A1, A2, A3), solve_literal(LiteralID).
-attr("depends_on",       node(min_dupe_id, A1), node(min_dupe_id, A2), A3) :- literal(LiteralID, "depends_on",       A1, A2, A3), solve_literal(LiteralID).
+trigger_node(TriggerID, Node, Node) :-
+  trigger_condition_holds(TriggerID, Node),
+  literal(TriggerID).
+
+% Since we trigger the existence of literal nodes from a condition, we need to construct
+% the condition_set/2 manually below
+mentioned_in_literal(Root, Mentioned) :- mentioned_in_literal(TriggerID, Root, Mentioned), solve_literal(TriggerID).
+condition_set(node(min_dupe_id, Root), node(min_dupe_id, Mentioned)) :-  mentioned_in_literal(Root, Mentioned).
 
 % Discriminate between "roots" that have been explicitly requested, and roots that are deduced from "virtual roots"
-explicitly_requested_root(node(min_dupe_id, A1)) :- literal(LiteralID, "root", A1), solve_literal(LiteralID).
+explicitly_requested_root(node(min_dupe_id, Package)) :-
+  solve_literal(TriggerID),
+  trigger_and_effect(Package, TriggerID, EffectID),
+  imposed_constraint(EffectID, "root", Package).
 
 #defined concretize_everything/0.
 #defined literal/1.
-#defined literal/3.
-#defined literal/4.
-#defined literal/5.
-#defined literal/6.
 
 % Attributes for node packages which must have a single value
 attr_single_value("version").
@@ -230,7 +236,8 @@ possible_version_weight(node(ID, Package), Weight)
 
 1 { version_weight(node(ID, Package), Weight) : pkg_fact(Package, version_declared(Version, Weight)) } 1
   :- attr("version", node(ID, Package), Version),
-     attr("node", node(ID, Package)).
+     attr("node", node(ID, Package)),
+     internal_error("version weights must exist and be unique").
 
 % node_version_satisfies implies that exactly one of the satisfying versions
 % is the package's version, and vice versa.
@@ -244,7 +251,8 @@ possible_version_weight(node(ID, Package), Weight)
 % bound on the choice rule to avoid false positives with the error below
 1 { attr("version", node(ID, Package), Version) : pkg_fact(Package, version_satisfies(Constraint, Version)) }
   :- attr("node_version_satisfies", node(ID, Package), Constraint),
-     pkg_fact(Package, version_satisfies(Constraint, _)).
+     pkg_fact(Package, version_satisfies(Constraint, _)),
+     internal_error("must choose a single version to satisfy version constraints").
 
 % More specific error message if the version cannot satisfy some constraint
 % Otherwise covered by `no_version_error` and `versions_conflict_error`.
@@ -357,7 +365,7 @@ imposed_nodes(ConditionID, PackageNode, node(X, A1))
 
 % Conditions that hold impose may impose constraints on other specs
 attr(Name, node(X, A1))             :- impose(ID, PackageNode), imposed_constraint(ID, Name, A1),             imposed_nodes(ID, PackageNode, node(X, A1)).
-attr(Name, node(X, A1), A2)         :- impose(ID, PackageNode), imposed_constraint(ID, Name, A1, A2),         imposed_nodes(ID, PackageNode, node(X, A1)).
+attr(Name, node(X, A1), A2)         :- impose(ID, PackageNode), imposed_constraint(ID, Name, A1, A2),         imposed_nodes(ID, PackageNode, node(X, A1)), not multiple_nodes_attribute(Name).
 attr(Name, node(X, A1), A2, A3)     :- impose(ID, PackageNode), imposed_constraint(ID, Name, A1, A2, A3),     imposed_nodes(ID, PackageNode, node(X, A1)), not multiple_nodes_attribute(Name).
 attr(Name, node(X, A1), A2, A3, A4) :- impose(ID, PackageNode), imposed_constraint(ID, Name, A1, A2, A3, A4), imposed_nodes(ID, PackageNode, node(X, A1)).
 
@@ -368,6 +376,16 @@ attr("node_flag_source", node(X, A1), A2, node(Y, A3))
      imposed_constraint(ID, "node_flag_source", A1, A2, A3),
      condition_set(node(Y, A3), node(X, A1)).
 
+% Provider set is relevant only for literals, since it's the only place where `^[virtuals=foo] bar`
+% might appear in the HEAD of a rule
+attr("provider_set", node(min_dupe_id, Provider), node(min_dupe_id, Virtual))
+  :- solve_literal(TriggerID),
+     trigger_and_effect(_, TriggerID, EffectID),
+     impose(EffectID, _),
+     imposed_constraint(EffectID, "provider_set", Provider, Virtual).
+
+provider(ProviderNode, VirtualNode) :- attr("provider_set", ProviderNode, VirtualNode).
+
 % Here we can't use the condition set because it's a recursive definition, that doesn't define the
 % node index, and leads to unsatisfiability. Hence we say that one and only one node index must
 % satisfy the dependency.
@@ -427,24 +445,11 @@ depends_on(PackageNode, DependencyNode) :- attr("depends_on", PackageNode, Depen
 % concrete. We chop off dependencies for externals, and dependencies of
 % concrete specs don't need to be resolved -- they arise from the concrete
 % specs themselves.
-dependency_holds(node(NodeID, Package), Dependency, Type) :-
-  pkg_fact(Package, dependency_condition(ID, Dependency)),
-  dependency_type(ID, Type),
-  build(node(NodeID, Package)),
-  not external(node(NodeID, Package)),
-  condition_holds(ID, node(NodeID, Package)).
-
-% We cut off dependencies of externals (as we don't really know them).
-% Don't impose constraints on dependencies that don't exist.
-do_not_impose(EffectID, node(NodeID, Package)) :-
-  not dependency_holds(node(NodeID, Package), Dependency, _),
-  attr("node", node(NodeID, Package)),
-  pkg_fact(Package, dependency_condition(ID, Dependency)),
-  pkg_fact(Package, condition_effect(ID, EffectID)).
+attr("track_dependencies", Node) :- build(Node), not external(Node).
 
 % If a dependency holds on a package node, there must be one and only one dependency node satisfying it
 1 { attr("depends_on", PackageNode, node(0..Y-1, Dependency), Type) : max_dupes(Dependency, Y) } 1
-  :- dependency_holds(PackageNode, Dependency, Type),
+  :- attr("dependency_holds", PackageNode, Dependency, Type),
      not virtual(Dependency).
 
 % all nodes in the graph must be reachable from some root
@@ -476,10 +481,25 @@ error(1, Msg)
 % Virtual dependencies
 %-----------------------------------------------------------------------------
 
+% If the provider is set from the command line, its weight is 0
+possible_provider_weight(ProviderNode, VirtualNode, 0, "Set on the command line")
+  :- attr("provider_set", ProviderNode, VirtualNode).
+
+% Enforces all virtuals to be provided, if multiple of them are provided together
+error(100, "Package '{0}' needs to provide both '{1}' and '{2}' together, but provides only '{1}'", Package, Virtual1, Virtual2)
+:- condition_holds(ID, node(X, Package)),
+   pkg_fact(Package, provided_together(ID, SetID, Virtual1)),
+   pkg_fact(Package, provided_together(ID, SetID, Virtual2)),
+   Virtual1 != Virtual2,
+   attr("virtual_on_incoming_edges", node(X, Package), Virtual1),
+   not attr("virtual_on_incoming_edges", node(X, Package), Virtual2),
+   attr("virtual_node", node(_, Virtual1)),
+   attr("virtual_node", node(_, Virtual2)).
+
 % if a package depends on a virtual, it's not external and we have a
 % provider for that virtual then it depends on the provider
 node_depends_on_virtual(PackageNode, Virtual, Type)
-  :- dependency_holds(PackageNode, Virtual, Type),
+  :- attr("dependency_holds", PackageNode, Virtual, Type),
      virtual(Virtual),
      not external(PackageNode).
 
@@ -489,11 +509,14 @@ node_depends_on_virtual(PackageNode, Virtual) :- node_depends_on_virtual(Package
   :- node_depends_on_virtual(PackageNode, Virtual, Type).
 
 attr("virtual_on_edge", PackageNode, ProviderNode, Virtual)
-  :- dependency_holds(PackageNode, Virtual, Type),
+  :- attr("dependency_holds", PackageNode, Virtual, Type),
      attr("depends_on", PackageNode, ProviderNode, Type),
      provider(ProviderNode, node(_, Virtual)),
      not external(PackageNode).
 
+attr("virtual_on_incoming_edges", ProviderNode, Virtual)
+  :- attr("virtual_on_edge", _, ProviderNode, Virtual).
+
 % dependencies on virtuals also imply that the virtual is a virtual node
 1 { attr("virtual_node", node(0..X-1, Virtual)) : max_dupes(Virtual, X) }
   :- node_depends_on_virtual(PackageNode, Virtual).
@@ -501,6 +524,10 @@ attr("virtual_on_edge", PackageNode, ProviderNode, Virtual)
 % If there's a virtual node, we must select one and only one provider.
 % The provider must be selected among the possible providers.
 
+error(100, "'{0}' cannot be a provider for the '{1}' virtual", Package, Virtual)
+  :-  attr("provider_set", node(min_dupe_id, Package), node(min_dupe_id, Virtual)),
+      not virtual_condition_holds( node(min_dupe_id, Package), Virtual).
+
 error(100, "Cannot find valid provider for virtual {0}", Virtual)
   :- attr("virtual_node", node(X, Virtual)),
      not provider(_, node(X, Virtual)).
@@ -521,20 +548,6 @@ attr("root", PackageNode) :- attr("virtual_root", VirtualNode), provider(Package
     attr("node", PackageNode), virtual_condition_holds(PackageNode, Virtual) } 1
   :- attr("virtual_node", node(X, Virtual)).
 
-% If a spec is selected as a provider, it is for all the virtual it could provide
-:- provider(PackageNode, node(X, Virtual1)),
-   virtual_condition_holds(PackageNode, Virtual2),
-   Virtual2 != Virtual1,
-   unification_set(SetID, PackageNode),
-   unification_set(SetID, node(X, Virtual2)),
-   not provider(PackageNode, node(X, Virtual2)).
-
-% If a spec is a dependency, and could provide a needed virtual, it must be a provider
-:- node_depends_on_virtual(PackageNode, Virtual),
-   depends_on(PackageNode, PossibleProviderNode),
-   virtual_condition_holds(PossibleProviderNode, Virtual),
-   not attr("virtual_on_edge", PackageNode, PossibleProviderNode, Virtual).
-
 % The provider provides the virtual if some provider condition holds.
 virtual_condition_holds(node(ProviderID, Provider), Virtual) :- virtual_condition_holds(ID, node(ProviderID, Provider), Virtual).
 virtual_condition_holds(ID, node(ProviderID, Provider), Virtual) :-
@@ -561,6 +574,8 @@ do_not_impose(EffectID, node(X, Package))
    not virtual_condition_holds(PackageNode, Virtual),
    internal_error("Virtual when provides not respected").
 
+#defined provided_together/4.
+
 %-----------------------------------------------------------------------------
 % Virtual dependency weights
 %-----------------------------------------------------------------------------
@@ -577,21 +592,15 @@ possible_provider_weight(DependencyNode, VirtualNode, 0, "external")
   :- provider(DependencyNode, VirtualNode),
      external(DependencyNode).
 
-% A provider mentioned in packages.yaml can use a weight
-% according to its priority in the list of providers
-possible_provider_weight(node(DependencyID, Dependency), node(VirtualID, Virtual), Weight, "packages_yaml")
-  :- provider(node(DependencyID, Dependency), node(VirtualID, Virtual)),
-     depends_on(node(ID, Package), node(DependencyID, Dependency)),
-     pkg_fact(Package, provider_preference(Virtual, Dependency, Weight)).
-
 % A provider mentioned in the default configuration can use a weight
 % according to its priority in the list of providers
-possible_provider_weight(node(DependencyID, Dependency), node(VirtualID, Virtual), Weight, "default")
-  :- provider(node(DependencyID, Dependency), node(VirtualID, Virtual)),
-     default_provider_preference(Virtual, Dependency, Weight).
+possible_provider_weight(node(ProviderID, Provider), node(VirtualID, Virtual), Weight, "default")
+  :- provider(node(ProviderID, Provider), node(VirtualID, Virtual)),
+     default_provider_preference(Virtual, Provider, Weight).
 
 % Any provider can use 100 as a weight, which is very high and discourage its use
-possible_provider_weight(node(DependencyID, Dependency), VirtualNode, 100, "fallback") :- provider(node(DependencyID, Dependency), VirtualNode).
+possible_provider_weight(node(ProviderID, Provider), VirtualNode, 100, "fallback")
+  :- provider(node(ProviderID, Provider), VirtualNode).
 
 % do not warn if generated program contains none of these.
 #defined virtual/1.
@@ -609,11 +618,11 @@ possible_provider_weight(node(DependencyID, Dependency), VirtualNode, 100, "fall
     pkg_fact(Package, version_declared(Version, Weight, "external")) }
     :- external(node(ID, Package)).
 
-error(100, "Attempted to use external for '{0}' which does not satisfy any configured external spec", Package)
+error(100, "Attempted to use external for '{0}' which does not satisfy any configured external spec version", Package)
   :- external(node(ID, Package)),
      not external_version(node(ID, Package), _, _).
 
-error(100, "Attempted to use external for '{0}' which does not satisfy any configured external spec", Package)
+error(100, "Attempted to use external for '{0}' which does not satisfy a unique configured external spec version", Package)
   :- external(node(ID, Package)),
      2 { external_version(node(ID, Package), Version, Weight) }.
 
@@ -642,18 +651,15 @@ external(PackageNode) :- attr("external_spec_selected", PackageNode, _).
 
 % determine if an external spec has been selected
 attr("external_spec_selected", node(ID, Package), LocalIndex) :-
-    external_conditions_hold(node(ID, Package), LocalIndex),
+    attr("external_conditions_hold", node(ID, Package), LocalIndex),
     attr("node", node(ID, Package)),
     not attr("hash", node(ID, Package), _).
 
-external_conditions_hold(node(PackageID, Package), LocalIndex) :-
-    pkg_fact(Package, possible_external(ID, LocalIndex)), condition_holds(ID, node(PackageID, Package)).
-
 % it cannot happen that a spec is external, but none of the external specs
 % conditions hold.
 error(100, "Attempted to use external for '{0}' which does not satisfy any configured external spec", Package)
  :- external(node(ID, Package)),
-    not external_conditions_hold(node(ID, Package), _).
+    not attr("external_conditions_hold", node(ID, Package), _).
 
 %-----------------------------------------------------------------------------
 % Config required semantics
@@ -692,6 +698,26 @@ requirement_group_satisfied(node(ID, Package), X) :-
   activate_requirement(node(ID, Package), X),
   requirement_group(Package, X).
 
+% Do not impose requirements, if the conditional requirement is not active
+do_not_impose(EffectID, node(ID, Package)) :-
+  trigger_condition_holds(TriggerID, node(ID, Package)),
+  pkg_fact(Package, condition_trigger(ConditionID, TriggerID)),
+  pkg_fact(Package, condition_effect(ConditionID, EffectID)),
+  requirement_group_member(ConditionID , Package, RequirementID),
+  not activate_requirement(node(ID, Package), RequirementID).
+
+% When we have a required provider, we need to ensure that the provider/2 facts respect
+% the requirement. This is particularly important for packages that could provide multiple
+% virtuals independently
+required_provider(Provider, Virtual)
+  :- requirement_group_member(ConditionID, Virtual, RequirementID),
+     condition_holds(ConditionID, _),
+     virtual(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.
+
 % TODO: the following two choice rules allow the solver to add compiler
 % flags if their only source is from a requirement. This is overly-specific
 % and should use a more-generic approach like in https://github.com/spack/spack/pull/37180
@@ -707,7 +733,7 @@ requirement_group_satisfied(node(ID, Package), X) :-
   activate_requirement(node(NodeID1, Package1), RequirementID),
   pkg_fact(Package1, condition_effect(ConditionID, EffectID)),
   imposed_constraint(EffectID, "node_flag_source", Package1, FlagType, Package2),
-  imposed_packages(NodeID2, Package2).
+  imposed_nodes(EffectID, node(NodeID2, Package2), node(NodeID1, Package1)).
 
 requirement_weight(node(ID, Package), Group, W) :-
   W = #min {
@@ -754,23 +780,36 @@ node_has_variant(node(ID, Package), Variant) :-
   pkg_fact(Package, variant(Variant)),
   attr("node", node(ID, Package)).
 
-attr("variant_propagate", PackageNode, Variant, Value, Source) :-
+% Variant propagation is forwarded to dependencies
+attr("variant_propagation_candidate", PackageNode, Variant, Value, Source) :-
   attr("node", PackageNode),
   depends_on(ParentNode, PackageNode),
-  attr("variant_propagate", ParentNode, Variant, Value, Source),
-  not attr("variant_set", PackageNode, Variant).
+  attr("variant_value", node(_, Source), Variant, Value),
+  attr("variant_propagation_candidate", ParentNode, Variant, _, Source).
 
-attr("variant_value", node(ID, Package), Variant, Value) :-
-  attr("node", node(ID, Package)),
+% If the node is a candidate, and it has the variant and value,
+% then those variant and value should be propagated
+attr("variant_propagate", node(ID, Package), Variant, Value, Source) :-
+  attr("variant_propagation_candidate", node(ID, Package), Variant, Value, Source),
   node_has_variant(node(ID, Package), Variant),
-  attr("variant_propagate", node(ID, Package), Variant, Value, _),
-  pkg_fact(Package, variant_possible_value(Variant, Value)).
+  pkg_fact(Package, variant_possible_value(Variant, Value)),
+  not attr("variant_set", node(ID, Package), Variant).
 
+% Propagate the value, if there is the corresponding attribute
+attr("variant_value", PackageNode, Variant, Value) :- attr("variant_propagate", PackageNode, Variant, Value, _).
+
+% If a variant is propagated, we cannot have extraneous values (this is for multi valued variants)
+variant_is_propagated(PackageNode, Variant) :- attr("variant_propagate", PackageNode, Variant, _, _).
+:- variant_is_propagated(PackageNode, Variant),
+   attr("variant_value", PackageNode, Variant, Value),
+   not attr("variant_propagate", PackageNode, Variant, Value, _).
+
+% Cannot receive different values from different sources on the same variant
 error(100, "{0} and {1} cannot both propagate variant '{2}' to package {3} with values '{4}' and '{5}'", Source1, Source2, Variant, Package, Value1, Value2) :-
   attr("variant_propagate", node(X, Package), Variant, Value1, Source1),
   attr("variant_propagate", node(X, Package), Variant, Value2, Source2),
   node_has_variant(node(X, Package), Variant),
-  Value1 < Value2.
+  Value1 < Value2, Source1 < Source2.
 
 % a variant cannot be set if it is not a variant on the package
 error(100, "Cannot set variant '{0}' for package '{1}' because the variant condition cannot be satisfied for the given spec", Variant, Package)
@@ -866,13 +905,15 @@ variant_default_not_used(node(ID, Package), Variant, Value)
   :- variant_default_value(Package, Variant, Value),
      node_has_variant(node(ID, Package), Variant),
      not attr("variant_value", node(ID, Package), Variant, Value),
+     not attr("variant_propagate", node(ID, Package), Variant, _, _),
      attr("node", node(ID, Package)).
 
 % The variant is set in an external spec
 external_with_variant_set(node(NodeID, Package), Variant, Value)
  :- attr("variant_value", node(NodeID, Package), Variant, Value),
-    condition_requirement(ID, "variant_value", Package, Variant, Value),
-    pkg_fact(Package, possible_external(ID, _)),
+    condition_requirement(TriggerID, "variant_value", Package, Variant, Value),
+    trigger_and_effect(Package, TriggerID, EffectID),
+    imposed_constraint(EffectID, "external_conditions_hold", Package, _),
     external(node(NodeID, Package)),
     attr("node", node(NodeID, Package)).
 
@@ -1048,7 +1089,7 @@ attr("node_target", PackageNode, Target)
 node_target_weight(node(ID, Package), Weight)
  :- attr("node", node(ID, Package)),
     attr("node_target", node(ID, Package), Target),
-    pkg_fact(Package, target_weight(Target, Weight)).
+    target_weight(Target, Weight).
 
 % compatibility rules for targets among nodes
 node_target_match(ParentNode, DependencyNode)
@@ -1170,23 +1211,17 @@ compiler_mismatch_required(PackageNode, DependencyNode)
 #defined allow_compiler/2.
 
 % compilers weighted by preference according to packages.yaml
-compiler_weight(node(ID, Package), Weight)
+node_compiler_weight(node(ID, Package), Weight)
  :- node_compiler(node(ID, Package), CompilerID),
     compiler_name(CompilerID, Compiler),
     compiler_version(CompilerID, V),
-    pkg_fact(Package, node_compiler_preference(Compiler, V, Weight)).
-compiler_weight(node(ID, Package), Weight)
+    compiler_weight(CompilerID, Weight).
+
+node_compiler_weight(node(ID, Package), 100)
  :- node_compiler(node(ID, Package), CompilerID),
     compiler_name(CompilerID, Compiler),
     compiler_version(CompilerID, V),
-    not pkg_fact(Package, node_compiler_preference(Compiler, V, _)),
-    default_compiler_preference(CompilerID, Weight).
-compiler_weight(node(ID, Package), 100)
- :- node_compiler(node(ID, Package), CompilerID),
-    compiler_name(CompilerID, Compiler),
-    compiler_version(CompilerID, V),
-    not pkg_fact(Package, node_compiler_preference(Compiler, V, _)),
-    not default_compiler_preference(CompilerID, _).
+    not compiler_weight(CompilerID, _).
 
 % For the time being, be strict and reuse only if the compiler match one we have on the system
 error(100, "Compiler {1}@{2} requested for {0} cannot be found. Set install_missing_compilers:true if intended.", Package, Compiler, Version)
@@ -1194,7 +1229,7 @@ error(100, "Compiler {1}@{2} requested for {0} cannot be found. Set install_miss
     not node_compiler(node(ID, Package), _).
 
 #defined node_compiler_preference/4.
-#defined default_compiler_preference/3.
+#defined compiler_weight/3.
 
 %-----------------------------------------------------------------------------
 % Compiler flags
@@ -1518,7 +1553,7 @@ opt_criterion(15, "non-preferred compilers").
 #minimize{ 0@15: #true }.
 #minimize{
     Weight@15+Priority,PackageNode
-    : compiler_weight(PackageNode, Weight),
+    : node_compiler_weight(PackageNode, Weight),
       build_priority(PackageNode, Priority)
 }.
 

lib/spack/spack/solver/display.lp

@@ -24,4 +24,29 @@
 #show error/5.
 #show error/6.
 
+% for error causation
+#show condition_reason/2.
+
+% For error messages to use later
+#show pkg_fact/2.
+#show condition_holds/2.
+#show imposed_constraint/3.
+#show imposed_constraint/4.
+#show imposed_constraint/5.
+#show imposed_constraint/6.
+#show condition_requirement/3.
+#show condition_requirement/4.
+#show condition_requirement/5.
+#show condition_requirement/6.
+#show node_has_variant/2.
+#show build/1.
+#show external/1.
+#show external_version/3.
+#show trigger_and_effect/3.
+#show unification_set/2.
+#show provider/2.
+#show condition_nodes/3.
+#show trigger_node/3.
+#show imposed_nodes/3.
+
 % debug

lib/spack/spack/solver/error_messages.lp

@@ -0,0 +1,239 @@
+% Copyright 2013-2023 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)
+
+%=============================================================================
+% This logic program adds detailed error messages to Spack's concretizer
+%=============================================================================
+
+#program error_messages.
+
+% Create a causal tree between trigger conditions by locating the effect conditions
+% that are triggers for another condition. Condition2 is caused by Condition1
+condition_cause(Condition2, ID2, Condition1, ID1) :-
+  condition_holds(Condition2, node(ID2, Package2)),
+  pkg_fact(Package2, condition_trigger(Condition2, Trigger)),
+  condition_requirement(Trigger, Name, Package),
+  condition_nodes(Trigger, TriggerNode, node(ID, Package)),
+  trigger_node(Trigger, TriggerNode, node(ID2, Package2)),
+  attr(Name, node(ID, Package)),
+  condition_holds(Condition1, node(ID1, Package1)),
+  pkg_fact(Package1, condition_effect(Condition1, Effect)),
+  imposed_constraint(Effect, Name, Package),
+  imposed_nodes(Effect, node(ID1, Package1), node(ID, Package)).
+
+condition_cause(Condition2, ID2, Condition1, ID1) :-
+  condition_holds(Condition2, node(ID2, Package2)),
+  pkg_fact(Package2, condition_trigger(Condition2, Trigger)),
+  condition_requirement(Trigger, Name, Package, A1),
+  condition_nodes(Trigger, TriggerNode, node(ID, Package)),
+  trigger_node(Trigger, TriggerNode, node(ID2, Package2)),
+  attr(Name, node(ID, Package), A1),
+  condition_holds(Condition1, node(ID1, Package1)),
+  pkg_fact(Package1, condition_effect(Condition1, Effect)),
+  imposed_constraint(Effect, Name, Package, A1),
+  imposed_nodes(Effect, node(ID1, Package1), node(ID, Package)).
+
+condition_cause(Condition2, ID2, Condition1, ID1) :-
+  condition_holds(Condition2, node(ID2, Package2)),
+  pkg_fact(Package2, condition_trigger(Condition2, Trigger)),
+  condition_requirement(Trigger, Name, Package, A1, A2),
+  condition_nodes(Trigger, TriggerNode, node(ID, Package)),
+  trigger_node(Trigger, TriggerNode, node(ID2, Package2)),
+  attr(Name, node(ID, Package), A1, A2),
+  condition_holds(Condition1, node(ID1, Package1)),
+  pkg_fact(Package1, condition_effect(Condition1, Effect)),
+  imposed_constraint(Effect, Name, Package, A1, A2),
+  imposed_nodes(Effect, node(ID1, Package1), node(ID, Package)).
+
+condition_cause(Condition2, ID2, Condition1, ID1) :-
+  condition_holds(Condition2, node(ID2, Package2)),
+  pkg_fact(Package2, condition_trigger(Condition2, Trigger)),
+  condition_requirement(Trigger, Name, Package, A1, A2, A3),
+  condition_nodes(Trigger, TriggerNode, node(ID, Package)),
+  trigger_node(Trigger, TriggerNode, node(ID2, Package2)),
+  attr(Name, node(ID, Package), A1, A2, A3),
+  condition_holds(Condition1, node(ID1, Package1)),
+  pkg_fact(Package1, condition_effect(Condition1, Effect)),
+  imposed_constraint(Effect, Name, Package, A1, A2, A3),
+  imposed_nodes(Effect, node(ID1, Package1), node(ID, Package)).
+
+% special condition cause for dependency conditions
+% we can't simply impose the existence of the node for dependency conditions
+% because we need to allow for the choice of which dupe ID the node gets
+condition_cause(Condition2, ID2, Condition1, ID1) :-
+  condition_holds(Condition2, node(ID2, Package2)),
+  pkg_fact(Package2, condition_trigger(Condition2, Trigger)),
+  condition_requirement(Trigger, "node", Package),
+  condition_nodes(Trigger, TriggerNode, node(ID, Package)),
+  trigger_node(Trigger, TriggerNode, node(ID2, Package2)),
+  attr("node", node(ID, Package)),
+  condition_holds(Condition1, node(ID1, Package1)),
+  pkg_fact(Package1, condition_effect(Condition1, Effect)),
+  imposed_constraint(Effect, "dependency_holds", Parent, Package, Type),
+  imposed_nodes(Effect, node(ID1, Package1), node(ID, Package)),
+  attr("depends_on", node(X, Parent), node(ID, Package), Type).
+
+% The literal startcauses is used to separate the variables that are part of the error from the
+% ones describing the causal tree of the error. After startcauses, each successive pair must be
+% a condition and a condition_set id for which it holds.
+
+% More specific error message if the version cannot satisfy some constraint
+% Otherwise covered by `no_version_error` and `versions_conflict_error`.
+error(1, "Cannot satisfy '{0}@{1}'", Package, Constraint, startcauses, ConstraintCause, CauseID)
+  :- attr("node_version_satisfies", node(ID, Package), Constraint),
+     pkg_fact(TriggerPkg, condition_effect(ConstraintCause, EffectID)),
+     imposed_constraint(EffectID, "node_version_satisfies", Package, Constraint),
+     condition_holds(ConstraintCause, node(CauseID, TriggerPkg)),
+     attr("version", node(ID, Package), Version),
+     not pkg_fact(Package, version_satisfies(Constraint, Version)).
+
+error(0, "Cannot satisfy '{0}@{1}' and '{0}@{2}", Package, Constraint1, Constraint2, startcauses, Cause1, C1ID, Cause2, C2ID)
+  :- attr("node_version_satisfies", node(ID, Package), Constraint1),
+     pkg_fact(TriggerPkg1, condition_effect(Cause1, EffectID1)),
+     imposed_constraint(EffectID1, "node_version_satisfies", Package, Constraint1),
+     condition_holds(Cause1, node(C1ID, TriggerPkg1)),
+     % two constraints
+     attr("node_version_satisfies", node(ID, Package), Constraint2),
+     pkg_fact(TriggerPkg2, condition_effect(Cause2, EffectID2)),
+     imposed_constraint(EffectID2, "node_version_satisfies", Package, Constraint2),
+     condition_holds(Cause2, node(C2ID, TriggerPkg2)),
+     % version chosen
+     attr("version", node(ID, Package), Version),
+     % version satisfies one but not the other
+     pkg_fact(Package, version_satisfies(Constraint1, Version)),
+     not pkg_fact(Package, version_satisfies(Constraint2, Version)).
+
+% causation tracking error for no or multiple virtual providers
+error(0, "Cannot find a valid provider for virtual {0}", Virtual, startcauses, Cause, CID)
+  :- attr("virtual_node", node(X, Virtual)),
+     not provider(_, node(X, Virtual)),
+     imposed_constraint(EID, "dependency_holds", Parent, Virtual, Type),
+     pkg_fact(TriggerPkg, condition_effect(Cause, EID)),
+     condition_holds(Cause, node(CID, TriggerPkg)).
+
+
+% At most one variant value for single-valued variants
+error(0, "'{0}' required multiple values for single-valued variant '{1}'\n    Requested 'Spec({1}={2})' and 'Spec({1}={3})'", Package, Variant, Value1, Value2, startcauses, Cause1, X, Cause2, X)
+  :- attr("node", node(X, Package)),
+     node_has_variant(node(X, Package), Variant),
+     pkg_fact(Package, variant_single_value(Variant)),
+     build(node(X, Package)),
+     attr("variant_value", node(X, Package), Variant, Value1),
+     imposed_constraint(EID1, "variant_set", Package, Variant, Value1),
+     pkg_fact(TriggerPkg1, condition_effect(Cause1, EID1)),
+     condition_holds(Cause1, node(X, TriggerPkg1)),
+     attr("variant_value", node(X, Package), Variant, Value2),
+     imposed_constraint(EID2, "variant_set", Package, Variant, Value2),
+     pkg_fact(TriggerPkg2, condition_effect(Cause2, EID2)),
+     condition_holds(Cause2, node(X, TriggerPkg2)),
+     Value1 < Value2. % see[1] in concretize.lp
+
+% Externals have to specify external conditions
+error(0, "Attempted to use external for {0} which does not satisfy any configured external spec version", Package, startcauses, ExternalCause, CID)
+  :- external(node(ID, Package)),
+     attr("external_spec_selected", node(ID, Package), Index),
+     imposed_constraint(EID, "external_conditions_hold", Package, Index),
+     pkg_fact(TriggerPkg, condition_effect(ExternalCause, EID)),
+     condition_holds(ExternalCause, node(CID, TriggerPkg)),
+     not external_version(node(ID, Package), _, _).
+
+error(0, "Attempted to build package {0} which is not buildable and does not have a satisfying external\n        attr('{1}', '{2}') is an external constraint for {0} which was not satisfied", Package, Name, A1)
+  :- external(node(ID, Package)),
+     not attr("external_conditions_hold", node(ID, Package), _),
+     imposed_constraint(EID, "external_conditions_hold", Package, _),
+     trigger_and_effect(Package, TID, EID),
+     condition_requirement(TID, Name, A1),
+     not attr(Name, node(_, A1)).
+
+error(0, "Attempted to build package {0} which is not buildable and does not have a satisfying external\n        attr('{1}', '{2}', '{3}') is an external constraint for {0} which was not satisfied", Package, Name, A1, A2)
+  :- external(node(ID, Package)),
+     not attr("external_conditions_hold", node(ID, Package), _),
+     imposed_constraint(EID, "external_conditions_hold", Package, _),
+     trigger_and_effect(Package, TID, EID),
+     condition_requirement(TID, Name, A1, A2),
+     not attr(Name, node(_, A1), A2).
+
+error(0, "Attempted to build package {0} which is not buildable and does not have a satisfying external\n        attr('{1}', '{2}', '{3}', '{4}') is an external constraint for {0} which was not satisfied", Package, Name, A1, A2, A3)
+  :- external(node(ID, Package)),
+     not attr("external_conditions_hold", node(ID, Package), _),
+     imposed_constraint(EID, "external_conditions_hold", Package, _),
+     trigger_and_effect(Package, TID, EID),
+     condition_requirement(TID, Name, A1, A2, A3),
+     not attr(Name, node(_, A1), A2, A3).
+
+error(0, "Attempted to build package {0} which is not buildable and does not have a satisfying external\n        'Spec({0} {1}={2})' is an external constraint for {0} which was not satisfied\n        'Spec({0} {1}={3})' required", Package, Variant, Value, OtherValue, startcauses, OtherValueCause, CID)
+  :- external(node(ID, Package)),
+     not attr("external_conditions_hold", node(ID, Package), _),
+     imposed_constraint(EID, "external_conditions_hold", Package, _),
+     trigger_and_effect(Package, TID, EID),
+     condition_requirement(TID, "variant_value", Package, Variant, Value),
+     not attr("variant_value", node(ID, Package), Variant, Value),
+     attr("variant_value", node(ID, Package), Variant, OtherValue),
+     imposed_constraint(EID2, "variant_set", Package, Variant, OtherValue),
+     pkg_fact(TriggerPkg, condition_effect(OtherValueCause, EID2)),
+     condition_holds(OtherValueCause, node(CID, TriggerPkg)).
+
+error(0, "Attempted to build package {0} which is not buildable and does not have a satisfying external\n        attr('{1}', '{2}', '{3}', '{4}', '{5}') is an external constraint for {0} which was not satisfied", Package, Name, A1, A2, A3, A4)
+  :- external(node(ID, Package)),
+     not attr("external_conditions_hold", node(ID, Package), _),
+     imposed_constraint(EID, "external_conditions_hold", Package, _),
+     trigger_and_effect(Package, TID, EID),
+     condition_requirement(TID, Name, A1, A2, A3, A4),
+     not attr(Name, node(_, A1), A2, A3, A4).
+
+% error message with causes for conflicts
+error(0, Msg, startcauses, TriggerID, ID1, ConstraintID, ID2)
+  :- attr("node", node(ID, Package)),
+     pkg_fact(Package, conflict(TriggerID, ConstraintID, Msg)),
+     % node(ID1, TriggerPackage) is node(ID2, Package) in most, but not all, cases
+     condition_holds(TriggerID, node(ID1, TriggerPackage)),
+     condition_holds(ConstraintID, node(ID2, Package)),
+     unification_set(X, node(ID2, Package)),
+     unification_set(X, node(ID1, TriggerPackage)),
+     not external(node(ID, Package)),  % ignore conflicts for externals
+     not attr("hash", node(ID, Package), _).  % ignore conflicts for installed packages
+
+% variables to show
+#show error/2.
+#show error/3.
+#show error/4.
+#show error/5.
+#show error/6.
+#show error/7.
+#show error/8.
+#show error/9.
+#show error/10.
+#show error/11.
+
+#show condition_cause/4.
+#show condition_reason/2.
+
+% Define all variables used to avoid warnings at runtime when the model doesn't happen to have one
+#defined error/2.
+#defined error/3.
+#defined error/4.
+#defined error/5.
+#defined error/6.
+#defined attr/2.
+#defined attr/3.
+#defined attr/4.
+#defined attr/5.
+#defined pkg_fact/2.
+#defined imposed_constraint/3.
+#defined imposed_constraint/4.
+#defined imposed_constraint/5.
+#defined imposed_constraint/6.
+#defined condition_requirement/3.
+#defined condition_requirement/4.
+#defined condition_requirement/5.
+#defined condition_requirement/6.
+#defined condition_holds/2.
+#defined unification_set/2.
+#defined external/1.
+#defined trigger_and_effect/3.
+#defined build/1.
+#defined node_has_variant/2.
+#defined provider/2.
+#defined external_version/3.

lib/spack/spack/solver/heuristic.lp

@@ -11,19 +11,14 @@
 %-----------------
 % Domain heuristic
 %-----------------
-#heuristic attr("hash", node(0, Package), Hash) : literal(_, "root", Package). [45, init]
-#heuristic attr("root", node(0, Package)) : literal(_, "root", Package). [45, true]
-#heuristic attr("node", node(0, Package)) : literal(_, "root", Package). [45, true]
-#heuristic attr("node", node(0, Package)) : literal(_, "node", Package). [45, true]
 
 % Root node
 #heuristic attr("version", node(0, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("root", node(0, Package)). [35, true]
 #heuristic version_weight(node(0, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("root", node(0, Package)). [35, true]
 #heuristic attr("variant_value", node(0, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("root", node(0, Package)). [35, true]
-#heuristic attr("node_target", node(0, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("root", node(0, Package)). [35, true]
+#heuristic attr("node_target", node(0, Package), Target) : target_weight(Target, 0), attr("root", node(0, Package)). [35, true]
 #heuristic node_target_weight(node(0, Package), 0) : attr("root", node(0, Package)). [35, true]
-#heuristic node_compiler(node(0, Package), CompilerID) : default_compiler_preference(ID, 0), compiler_id(ID), attr("root", node(0, Package)). [35, true]
+#heuristic node_compiler(node(0, Package), CompilerID) : compiler_weight(ID, 0), compiler_id(ID), attr("root", node(0, Package)). [35, true]
 
 % Providers
 #heuristic attr("node", node(0, Package)) : default_provider_preference(Virtual, Package, 0), possible_in_link_run(Package). [30, true]
-

lib/spack/spack/solver/heuristic_separate.lp

@@ -13,7 +13,7 @@
 #heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
 #heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
 #heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
-#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : compiler_weight(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
 
 % node(ID, _), split build dependencies
 #heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
@@ -21,4 +21,4 @@
 #heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
 #heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
 #heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
-#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : compiler_weight(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]

lib/spack/spack/solver/os_compatibility.lp

@@ -10,6 +10,9 @@
 %=============================================================================
 
 % macOS
+os_compatible("sequoia", "sonoma").
+os_compatible("sonoma", "ventura").
+os_compatible("ventura", "monterey").
 os_compatible("monterey", "bigsur").
 os_compatible("bigsur", "catalina").
 

lib/spack/spack/spec.py

@@ -59,7 +59,7 @@
 import re
 import socket
 import warnings
-from typing import Any, Callable, Dict, List, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Union
 
 import llnl.path
 import llnl.string
@@ -213,6 +213,19 @@ def __call__(self, match):
     return clr.colorize(re.sub(_SEPARATORS, insert_color(), str(spec)) + "@.")
 
 
+OLD_STYLE_FMT_RE = re.compile(r"\${[A-Z]+}")
+
+
+def ensure_modern_format_string(fmt: str) -> None:
+    """Ensure that the format string does not contain old ${...} syntax."""
+    result = OLD_STYLE_FMT_RE.search(fmt)
+    if result:
+        raise SpecFormatStringError(
+            f"Format string `{fmt}` contains old syntax `{result.group(0)}`. "
+            "This is no longer supported."
+        )
+
+
 @lang.lazy_lexicographic_ordering
 class ArchSpec:
     """Aggregate the target platform, the operating system and the target microarchitecture."""
@@ -1464,6 +1477,26 @@ def edges_to_dependencies(self, name=None, depflag: dt.DepFlag = dt.ALL):
         """
         return [d for d in self._dependencies.select(child=name, depflag=depflag)]
 
+    @property
+    def edge_attributes(self) -> str:
+        """Helper method to print edge attributes in spec literals"""
+        edges = self.edges_from_dependents()
+        if not edges:
+            return ""
+
+        union = DependencySpec(parent=Spec(), spec=self, depflag=0, virtuals=())
+        for edge in edges:
+            union.update_deptypes(edge.depflag)
+            union.update_virtuals(edge.virtuals)
+        deptypes_str = (
+            f"deptypes={','.join(dt.flag_to_tuple(union.depflag))}" if union.depflag else ""
+        )
+        virtuals_str = f"virtuals={','.join(union.virtuals)}" if union.virtuals else ""
+        if not deptypes_str and not virtuals_str:
+            return ""
+        result = f"{deptypes_str} {virtuals_str}".strip()
+        return f"[{result}]"
+
     def dependencies(self, name=None, deptype: Union[dt.DepTypes, dt.DepFlag] = dt.ALL):
         """Return a list of direct dependencies (nodes in the DAG).
 
@@ -3688,8 +3721,15 @@ def intersects(self, other: Union[str, "Spec"], deps: bool = True) -> bool:
         if other.concrete and self.concrete:
             return self.dag_hash() == other.dag_hash()
 
-        self_hash = self.dag_hash() if self.concrete else self.abstract_hash
-        other_hash = other.dag_hash() if other.concrete else other.abstract_hash
+        elif self.concrete:
+            return self.satisfies(other)
+
+        elif other.concrete:
+            return other.satisfies(self)
+
+        # From here we know both self and other are not concrete
+        self_hash = self.abstract_hash
+        other_hash = other.abstract_hash
 
         if (
             self_hash
@@ -3778,10 +3818,6 @@ def _intersects_dependencies(self, other):
             repository=spack.repo.PATH, specs=other.traverse(), restrict=True
         )
 
-        # This handles cases where there are already providers for both vpkgs
-        if not self_index.satisfies(other_index):
-            return False
-
         # These two loops handle cases where there is an overly restrictive
         # vpkg in one spec for a provider in the other (e.g., mpi@3: is not
         # compatible with mpich2)
@@ -3879,7 +3915,46 @@ def satisfies(self, other: Union[str, "Spec"], deps: bool = True) -> bool:
             return False
 
         # If we arrived here, then rhs is abstract. At the moment we don't care about the edge
-        # structure of an abstract DAG - hence the deps=False parameter.
+        # structure of an abstract DAG, so we check if any edge could satisfy the properties
+        # we ask for.
+        lhs_edges: Dict[str, Set[DependencySpec]] = collections.defaultdict(set)
+        for rhs_edge in other.traverse_edges(root=False, cover="edges"):
+            # If we are checking for ^mpi we need to verify if there is any edge
+            if rhs_edge.spec.virtual:
+                rhs_edge.update_virtuals(virtuals=(rhs_edge.spec.name,))
+
+            if not rhs_edge.virtuals:
+                continue
+
+            if not lhs_edges:
+                # Construct a map of the link/run subDAG + direct "build" edges,
+                # keyed by dependency name
+                for lhs_edge in self.traverse_edges(
+                    root=False, cover="edges", deptype=("link", "run")
+                ):
+                    lhs_edges[lhs_edge.spec.name].add(lhs_edge)
+                    for virtual_name in lhs_edge.virtuals:
+                        lhs_edges[virtual_name].add(lhs_edge)
+
+                build_edges = self.edges_to_dependencies(depflag=dt.BUILD)
+                for lhs_edge in build_edges:
+                    lhs_edges[lhs_edge.spec.name].add(lhs_edge)
+                    for virtual_name in lhs_edge.virtuals:
+                        lhs_edges[virtual_name].add(lhs_edge)
+
+            # We don't have edges to this dependency
+            current_dependency_name = rhs_edge.spec.name
+            if current_dependency_name not in lhs_edges:
+                return False
+
+            for virtual in rhs_edge.virtuals:
+                has_virtual = any(
+                    virtual in edge.virtuals for edge in lhs_edges[current_dependency_name]
+                )
+                if not has_virtual:
+                    return False
+
+        # Edges have been checked above already, hence deps=False
         return all(
             any(lhs.satisfies(rhs, deps=False) for lhs in self.traverse(root=False))
             for rhs in other.traverse(root=False)
@@ -4081,9 +4156,7 @@ def __getitem__(self, name):
         """
         query_parameters = name.split(":")
         if len(query_parameters) > 2:
-            msg = "key has more than one ':' symbol."
-            msg += " At most one is admitted."
-            raise KeyError(msg)
+            raise KeyError("key has more than one ':' symbol. At most one is admitted.")
 
         name, query_parameters = query_parameters[0], query_parameters[1:]
         if query_parameters:
@@ -4108,11 +4181,17 @@ def __getitem__(self, name):
                 itertools.chain(
                     # Regular specs
                     (x for x in order() if x.name == name),
+                    (
+                        x
+                        for x in order()
+                        if (not x.virtual)
+                        and any(name in edge.virtuals for edge in x.edges_from_dependents())
+                    ),
                     (x for x in order() if (not x.virtual) and x.package.provides(name)),
                 )
             )
         except StopIteration:
-            raise KeyError("No spec with name %s in %s" % (name, self))
+            raise KeyError(f"No spec with name {name} in {self}")
 
         if self._concrete:
             return SpecBuildInterface(value, name, query_parameters)
@@ -4294,6 +4373,7 @@ def format(self, format_string=DEFAULT_FORMAT, **kwargs):
                 that accepts a string and returns another one
 
         """
+        ensure_modern_format_string(format_string)
         color = kwargs.get("color", False)
         transform = kwargs.get("transform", {})
 
@@ -4490,17 +4570,27 @@ def format_path(
         return str(path_ctor(*output_path_components))
 
     def __str__(self):
-        sorted_nodes = [self] + sorted(
+        root_str = [self.format()]
+        sorted_dependencies = sorted(
             self.traverse(root=False), key=lambda x: (x.name, x.abstract_hash)
         )
-        return " ^".join(d.format() for d in sorted_nodes).strip()
+        sorted_dependencies = [
+            d.format("{edge_attributes} " + DEFAULT_FORMAT) for d in sorted_dependencies
+        ]
+        spec_str = " ^".join(root_str + sorted_dependencies)
+        return spec_str.strip()
 
     @property
     def colored_str(self):
-        sorted_nodes = [self] + sorted(
+        root_str = [self.cformat()]
+        sorted_dependencies = sorted(
             self.traverse(root=False), key=lambda x: (x.name, x.abstract_hash)
         )
-        return " ^".join(d.cformat() for d in sorted_nodes).strip()
+        sorted_dependencies = [
+            d.cformat("{edge_attributes} " + DISPLAY_FORMAT) for d in sorted_dependencies
+        ]
+        spec_str = " ^".join(root_str + sorted_dependencies)
+        return spec_str.strip()
 
     def install_status(self):
         """Helper for tree to print DB install status."""

lib/spack/spack/spec_list.py

@@ -93,8 +93,8 @@ def remove(self, spec):
             if (isinstance(s, str) and not s.startswith("$")) and Spec(s) == Spec(spec)
         ]
         if not remove:
-            msg = "Cannot remove %s from SpecList %s\n" % (spec, self.name)
-            msg += "Either %s is not in %s or %s is " % (spec, self.name, spec)
+            msg = f"Cannot remove {spec} from SpecList {self.name}.\n"
+            msg += f"Either {spec} is not in {self.name} or {spec} is "
             msg += "expanded from a matrix and cannot be removed directly."
             raise SpecListError(msg)
 
@@ -133,9 +133,8 @@ def _parse_reference(self, name):
 
         # Make sure the reference is valid
         if name not in self._reference:
-            msg = "SpecList %s refers to " % self.name
-            msg += "named list %s " % name
-            msg += "which does not appear in its reference dict"
+            msg = f"SpecList '{self.name}' refers to named list '{name}'"
+            msg += " which does not appear in its reference dict."
             raise UndefinedReferenceError(msg)
 
         return (name, sigil)