msvc: remove conjoined msvc/ifx detection

Signed-off-by: Gregory Becker <becker33@llnl.gov>

.github/workflows/ci.yaml

@@ -9,6 +9,7 @@ on:
     branches:
       - develop
       - releases/**
+  merge_group:
 
 concurrency:
   group: ci-${{github.ref}}-${{github.event.pull_request.number || github.run_number}}
@@ -25,13 +26,17 @@ jobs:
       packages: ${{ steps.filter.outputs.packages }}
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-        if: ${{ github.event_name == 'push' }}
+        if: ${{ github.event_name == 'push' || github.event_name == 'merge_group' }}
         with:
           fetch-depth: 0
             # For pull requests it's not necessary to checkout the code
       - uses: dorny/paths-filter@de90cc6fb38fc0963ad72b210f1f284cd68cea36
         id: filter
         with:
+          # For merge group events, compare against the target branch (main)
+          base: ${{ github.event_name == 'merge_group' && github.event.merge_group.base_ref || '' }}
+          # For merge group events, use the merge group head ref
+          ref: ${{ github.event_name == 'merge_group' && github.event.merge_group.head_sha || github.ref }}
           # See https://github.com/dorny/paths-filter/issues/56 for the syntax used below
           # Don't run if we only modified packages in the
           # built-in repository or documentation
@@ -76,10 +81,11 @@ jobs:
 
   prechecks:
     needs: [ changes ]
-    uses: ./.github/workflows/valid-style.yml
+    uses: ./.github/workflows/prechecks.yml
     secrets: inherit
     with:
       with_coverage: ${{ needs.changes.outputs.core }}
+      with_packages: ${{ needs.changes.outputs.packages }}
 
   import-check:
     needs: [ changes ]
@@ -93,7 +99,7 @@ jobs:
     - name: Success
       run: |
         if [ "${{ needs.prechecks.result }}" == "failure" ] || [ "${{ needs.prechecks.result }}" == "canceled" ]; then
-          echo "Unit tests failed." 
+          echo "Unit tests failed."
           exit 1
         else
           exit 0
@@ -101,6 +107,7 @@ jobs:
 
   coverage:
     needs: [ unit-tests, prechecks ]
+    if: ${{ needs.changes.outputs.core }}
     uses: ./.github/workflows/coverage.yml
     secrets: inherit
 
@@ -113,10 +120,10 @@ jobs:
     - name: Status summary
       run: |
         if [ "${{ needs.unit-tests.result }}" == "failure" ] || [ "${{ needs.unit-tests.result }}" == "canceled" ]; then
-          echo "Unit tests failed." 
+          echo "Unit tests failed."
           exit 1
         elif [ "${{ needs.bootstrap.result }}" == "failure" ] || [ "${{ needs.bootstrap.result }}" == "canceled" ]; then
-          echo "Bootstrap tests failed." 
+          echo "Bootstrap tests failed."
           exit 1
         else
           exit 0

.github/workflows/prechecks.yml

@@ -1,4 +1,4 @@
-name: style
+name: prechecks
 
 on:
   workflow_call:
@@ -6,6 +6,9 @@ on:
       with_coverage:
         required: true
         type: string
+      with_packages:
+        required: true
+        type: string
 
 concurrency:
   group: style-${{github.ref}}-${{github.event.pull_request.number || github.run_number}}
@@ -30,6 +33,7 @@ jobs:
       run: vermin --backport importlib --backport argparse --violations --backport typing -t=3.6- -vvv lib/spack/spack/ lib/spack/llnl/ bin/
     - name: vermin (Repositories)
       run: vermin --backport importlib --backport argparse --violations --backport typing -t=3.6- -vvv var/spack/repos
+
   # Run style checks on the files that have been changed
   style:
     runs-on: ubuntu-latest
@@ -53,12 +57,25 @@ jobs:
     - name: Run style tests
       run: |
           share/spack/qa/run-style-tests
+
   audit:
     uses: ./.github/workflows/audit.yaml
     secrets: inherit
     with:
       with_coverage: ${{ inputs.with_coverage }}
       python_version: '3.13'
+
+  verify-checksums:
+    if: ${{ inputs.with_packages == 'true' }}
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29
+      with:
+        fetch-depth: 2
+    - name: Verify Added Checksums
+      run: |
+        bin/spack ci verify-versions HEAD^1 HEAD
+
   # Check that spack can bootstrap the development environment on Python 3.6 - RHEL8
   bootstrap-dev-rhel8:
     runs-on: ubuntu-latest

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

@@ -1,7 +1,7 @@
 black==25.1.0
 clingo==5.7.1
 flake8==7.1.2
-isort==6.0.0
+isort==6.0.1
 mypy==1.15.0
-types-six==1.17.0.20241205
+types-six==1.17.0.20250304
 vermin==1.6.0

.gitignore

@@ -201,7 +201,6 @@ tramp
 
 # Org-mode
 .org-id-locations
-*_archive
 
 # flymake-mode
 *_flymake.*

etc/spack/defaults/config.yaml

@@ -19,7 +19,7 @@ config:
   install_tree:
     root: $spack/opt/spack
     projections:
-      all: "{architecture}/{compiler.name}-{compiler.version}/{name}-{version}-{hash}"
+      all: "{architecture.platform}-{architecture.target}/{name}-{version}-{hash}"
     # install_tree can include an optional padded length (int or boolean)
     # default is False (do not pad)
     # if padded_length is True, Spack will pad as close to the system max path

etc/spack/defaults/darwin/packages.yaml

@@ -15,12 +15,11 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler:
-    - apple-clang
-    - clang
-    - gcc
     providers:
+      c: [apple-clang, llvm, gcc]
+      cxx: [apple-clang, llvm, gcc]
       elf: [libelf]
+      fortran: [gcc]
       fuse: [macfuse]
       gl: [apple-gl]
       glu: [apple-glu]
@@ -50,3 +49,12 @@ packages:
     # although the version number used here isn't critical
     - spec: apple-libuuid@1353.100.2
       prefix: /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
+  c:
+    prefer:
+    - apple-clang
+  cxx:
+    prefer:
+    - apple-clang
+  fortran:
+    prefer:
+    - gcc

etc/spack/defaults/packages.yaml

@@ -15,19 +15,18 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler: [gcc, clang, oneapi, xl, nag, fj, aocc]
     providers:
       awk: [gawk]
       armci: [armcimpi]
       blas: [openblas, amdblis]
-      c: [gcc]
+      c: [gcc, llvm, intel-oneapi-compilers]
-      cxx: [gcc]
+      cxx: [gcc, llvm, intel-oneapi-compilers]
       D: [ldc]
       daal: [intel-oneapi-daal]
       elf: [elfutils]
       fftw-api: [fftw, amdfftw]
       flame: [libflame, amdlibflame]
-      fortran: [gcc]
+      fortran: [gcc, llvm, intel-oneapi-compilers]
       fortran-rt: [gcc-runtime, intel-oneapi-runtime]
       fuse: [libfuse]
       gl: [glx, osmesa]

etc/spack/defaults/windows/packages.yaml

@@ -15,8 +15,8 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler:
-    - msvc
     providers:
+      c : [msvc]
+      cxx: [msvc]
       mpi: [msmpi]
       gl: [wgl]

lib/spack/docs/build_systems.rst

@@ -63,7 +63,6 @@ on these ideas for each distinct build system that Spack supports:
    build_systems/cudapackage
    build_systems/custompackage
    build_systems/inteloneapipackage
-   build_systems/intelpackage
    build_systems/rocmpackage
    build_systems/sourceforgepackage
 

lib/spack/docs/build_systems/inteloneapipackage.rst

@@ -33,9 +33,6 @@ For more information on a specific package, do::
 
   spack info --all <package-name>
 
-Intel no longer releases new versions of Parallel Studio, which can be
-used in Spack via the :ref:`intelpackage`. All of its components can
-now be found in oneAPI.
 
 Examples
 ========
@@ -50,34 +47,8 @@ Install the oneAPI compilers::
 
   spack install intel-oneapi-compilers
 
-Add the compilers to your ``compilers.yaml`` so spack can use them::
 
-  spack compiler add `spack location -i intel-oneapi-compilers`/compiler/latest/bin
+To build the ``patchelf`` Spack package with ``icx``, do::
-
-Verify that the compilers are available::
-
-  spack compiler list
-
-Note that 2024 and later releases do not include ``icc``. Before 2024,
-the package layout was different::
-  
-  spack compiler add `spack location -i intel-oneapi-compilers`/compiler/latest/linux/bin/intel64
-  spack compiler add `spack location -i intel-oneapi-compilers`/compiler/latest/linux/bin
-
-The ``intel-oneapi-compilers`` package includes 2 families of
-compilers:
-
-* ``intel``: ``icc``, ``icpc``, ``ifort``. Intel's *classic*
-  compilers. 2024 and later releases contain ``ifort``, but not
-  ``icc`` and ``icpc``.
-* ``oneapi``: ``icx``, ``icpx``, ``ifx``. Intel's new generation of
-  compilers based on LLVM.
-
-To build the ``patchelf`` Spack package with ``icc``, do::
-
-  spack install patchelf%intel
-
-To build with with ``icx``, do ::
 
   spack install patchelf%oneapi
 
@@ -92,15 +63,6 @@ Install the oneAPI compilers::
 
   spack install intel-oneapi-compilers
 
-Add the compilers to your ``compilers.yaml`` so Spack can use them::
-
-  spack compiler add `spack location -i intel-oneapi-compilers`/compiler/latest/bin
-  spack compiler add `spack location -i intel-oneapi-compilers`/compiler/latest/bin
-
-Verify that the compilers are available::
-
-  spack compiler list
-
 Clone `spack-configs <https://github.com/spack/spack-configs>`_ repo and activate Intel oneAPI CPU environment::
 
   git clone https://github.com/spack/spack-configs
@@ -149,7 +111,7 @@ Compilers
 ---------
 
 To use the compilers, add some information about the installation to
-``compilers.yaml``. For most users, it is sufficient to do::
+``packages.yaml``. For most users, it is sufficient to do::
 
   spack compiler add /opt/intel/oneapi/compiler/latest/bin
 
@@ -157,7 +119,7 @@ Adapt the paths above if you did not install the tools in the default
 location. After adding the compilers, using them is the same
 as if you had installed the ``intel-oneapi-compilers`` package.
 Another option is to manually add the configuration to
-``compilers.yaml`` as described in :ref:`Compiler configuration
+``packages.yaml`` as described in :ref:`Compiler configuration
 <compiler-config>`.
 
 Before 2024, the directory structure was different::
@@ -200,15 +162,5 @@ You can also use Spack-installed libraries. For example::
 Will update your environment CPATH, LIBRARY_PATH, and other
 environment variables for building an application with oneMKL.
 
-More information
-================
-
-This section describes basic use of oneAPI, especially if it has
-changed compared to Parallel Studio. See :ref:`intelpackage` for more
-information on :ref:`intel-virtual-packages`,
-:ref:`intel-unrelated-packages`,
-:ref:`intel-integrating-external-libraries`, and
-:ref:`using-mkl-tips`.
-
 
 .. _`Intel installers`: https://software.intel.com/content/www/us/en/develop/documentation/installation-guide-for-intel-oneapi-toolkits-linux/top.html

lib/spack/docs/build_systems/rocmpackage.rst

@@ -12,8 +12,7 @@ The ``ROCmPackage`` is not a build system but a helper package. Like ``CudaPacka
 it provides standard variants, dependencies, and conflicts to facilitate building
 packages using GPUs though for AMD in this case.
 
-You can find the source for this package (and suggestions for setting up your
+You can find the source for this package (and suggestions for setting up your ``packages.yaml`` file) at
-``compilers.yaml`` and ``packages.yaml`` files) at
 `<https://github.com/spack/spack/blob/develop/lib/spack/spack/build_systems/rocm.py>`__.
 
 ^^^^^^^^

lib/spack/docs/configuration.rst

@@ -11,9 +11,10 @@ Configuration Files
 Spack has many configuration files.  Here is a quick list of them, in
 case you want to skip directly to specific docs:
 
-* :ref:`compilers.yaml <compiler-config>`
+* :ref:`packages.yaml <compiler-config>`
 * :ref:`concretizer.yaml <concretizer-options>`
 * :ref:`config.yaml <config-yaml>`
+* :ref:`include.yaml <include-yaml>`
 * :ref:`mirrors.yaml <mirrors>`
 * :ref:`modules.yaml <modules>`
 * :ref:`packages.yaml <packages-config>`
@@ -94,7 +95,7 @@ are six configuration scopes. From lowest to highest:
    precedence over all other scopes.
 
 Each configuration directory may contain several configuration files,
-such as ``config.yaml``, ``compilers.yaml``, or ``mirrors.yaml``.  When
+such as ``config.yaml``, ``packages.yaml``, or ``mirrors.yaml``.  When
 configurations conflict, settings from higher-precedence scopes override
 lower-precedence settings.
 

lib/spack/docs/environments.rst

@@ -457,6 +457,13 @@ developed package in the environment are concretized to match the
 version (and other constraints) passed as the spec argument to the
 ``spack develop`` command.
 
+When working deep in the graph it is often desirable to have multiple specs marked
+as ``develop`` so you don't have to restage and/or do full rebuilds each time you
+call ``spack install``.  The ``--recursive`` flag can be used in these scenarios
+to ensure that all the dependents of the initial spec you provide are also marked
+as develop specs.  The ``--recursive`` flag requires a pre-concretized environment
+so the graph can be traversed from the supplied spec all the way to the root specs.
+
 For packages with ``git`` attributes, git branches, tags, and commits can
 also be used as valid concrete versions (see :ref:`version-specifier`).
 This means that for a package ``foo``, ``spack develop foo@git.main`` will clone
@@ -670,24 +677,45 @@ This configuration sets the default compiler for all packages to
 Included configurations
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-Spack environments allow an ``include`` heading in their yaml
+Spack environments allow an ``include`` heading in their yaml schema.
-schema. This heading pulls in external configuration files and applies
+This heading pulls in external configuration files and applies them to
-them to the environment.
+the environment.
 
 .. code-block:: yaml
 
    spack:
      include:
-     - relative/path/to/config.yaml
+     - environment/relative/path/to/config.yaml
-     - https://github.com/path/to/raw/config/compilers.yaml
+     - https://github.com/path/to/raw/config/packages.yaml
      - /absolute/path/to/packages.yaml
+     - path: /path/to/$os/$target/environment
+       optional: true
+     - path: /path/to/os-specific/config-dir
+       when: os == "ventura"
+
+Included configuration files are required *unless* they are explicitly optional
+or the entry's condition evaluates to ``false``. Optional includes are specified
+with the ``optional`` clause and conditional with the ``when`` clause. (See
+:ref:`include-yaml` for more information on optional and conditional entries.)
+
+Files are listed using paths to individual files or directories containing them.
+Path entries may be absolute or relative to the environment or specified as 
+URLs. URLs to individual files need link to the **raw** form of the file's 
+contents (e.g., `GitHub
+<https://docs.github.com/en/repositories/working-with-files/using-files/viewing-and-understanding-files#viewing-or-copying-the-raw-file-content>`_ 
+or `GitLab
+<https://docs.gitlab.com/ee/api/repository_files.html#get-raw-file-from-repository>`_).
+Only the ``file``, ``ftp``, ``http`` and ``https`` protocols (or schemes) are
+supported. Spack-specific, environment and user path variables can be used.
+(See :ref:`config-file-variables` for more information.)
+
+.. warning::
+
+   Recursive includes are not currently processed in a breadth-first manner
+   so the value of a configuration option that is altered by multiple included
+   files may not be what you expect. This will be addressed in a future
+   update.
 
-Environments can include files or URLs. File paths can be relative or
-absolute. URLs include the path to the text for individual files or
-can be the path to a directory containing configuration files.
-Spack supports ``file``, ``http``, ``https`` and ``ftp`` protocols (or
-schemes). Spack-specific, environment and user path variables may be
-used in these paths. See :ref:`config-file-variables` for more information.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^
 Configuration precedence

lib/spack/docs/frequently_asked_questions.rst

@@ -30,7 +30,7 @@ than always choosing the latest versions or default variants.
 
 .. note::
 
-    As a rule of thumb: requirements + constraints > reuse > preferences > defaults.
+    As a rule of thumb: requirements + constraints > strong preferences > reuse > preferences > defaults.
 
 The following set of criteria (from lowest to highest precedence) explain
 common cases where concretization output may seem surprising at first.
@@ -56,7 +56,19 @@ common cases where concretization output may seem surprising at first.
       concretizer:
         reuse: dependencies  # other options are 'true' and 'false'
 
-3. :ref:`Package requirements <package-requirements>` configured in ``packages.yaml``,
+3. :ref:`Strong preferences <package-strong-preferences>` configured in ``packages.yaml``
+   are higher priority than reuse, and can be used to strongly prefer a specific version
+   or variant, without erroring out if it's not possible. Strong preferences are specified
+   as follows:
+
+   .. code-block:: yaml
+
+      packages:
+        foo:
+          prefer:
+          - "@1.1: ~mpi"
+
+4. :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:
 
@@ -66,6 +78,8 @@ common cases where concretization output may seem surprising at first.
         foo:
           require:
           - "@1.2: +mpi"
+          conflicts:
+          - "@1.4"
 
 Requirements and constraints restrict the set of possible solutions, while reuse
 behavior and preferences influence what an optimal solution looks like.

lib/spack/docs/getting_started.rst

@@ -254,12 +254,11 @@ directory.
 Compiler configuration
 ----------------------
 
-Spack has the ability to build packages with multiple compilers and
+Spack has the ability to build packages with multiple compilers and compiler versions.
-compiler versions. Compilers can be made available to Spack by
+Compilers can be made available to Spack by specifying them manually in ``packages.yaml``,
-specifying them manually in ``compilers.yaml`` or ``packages.yaml``,
+or automatically by running ``spack compiler find``.
-or automatically by running ``spack compiler find``, but for
+For convenience, Spack will automatically detect compilers the first time it needs them,
-convenience Spack will automatically detect compilers the first time
+if none is available.
-it needs them.
 
 .. _cmd-spack-compilers:
 
@@ -274,16 +273,11 @@ compilers`` or ``spack compiler list``:
 
    $ spack compilers
    ==> Available compilers
-   -- gcc ---------------------------------------------------------
+   -- gcc ubuntu20.04-x86_64 ---------------------------------------
-       gcc@4.9.0  gcc@4.8.0  gcc@4.7.0  gcc@4.6.2  gcc@4.4.7
+   gcc@9.4.0  gcc@8.4.0  gcc@10.5.0
-       gcc@4.8.2  gcc@4.7.1  gcc@4.6.3  gcc@4.6.1  gcc@4.1.2
+
-   -- intel -------------------------------------------------------
+   -- llvm ubuntu20.04-x86_64 --------------------------------------
-       intel@15.0.0  intel@14.0.0  intel@13.0.0  intel@12.1.0  intel@10.0
+   llvm@12.0.0  llvm@11.0.0  llvm@10.0.0
-       intel@14.0.3  intel@13.1.1  intel@12.1.5  intel@12.0.4  intel@9.1
-       intel@14.0.2  intel@13.1.0  intel@12.1.3  intel@11.1
-       intel@14.0.1  intel@13.0.1  intel@12.1.2  intel@10.1
-   -- clang -------------------------------------------------------
-       clang@3.4  clang@3.3  clang@3.2  clang@3.1
 
 Any of these compilers can be used to build Spack packages.  More on
 how this is done is in :ref:`sec-specs`.
@@ -302,16 +296,22 @@ An alias for ``spack compiler find``.
 ``spack compiler find``
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-Lists the compilers currently available to Spack. If you do not see
+If you do not see a compiler in the list shown by:
-a compiler in this list, but you want to use it with Spack, you can
-simply run ``spack compiler find`` with the path to where the
-compiler is installed.  For example:
 
 .. code-block:: console
 
-   $ spack compiler find /usr/local/tools/ic-13.0.079
+   $ spack compiler list
-   ==> Added 1 new compiler to ~/.spack/linux/compilers.yaml
+
-       intel@13.0.079
+but you want to use it with Spack, you can simply run ``spack compiler find`` with the
+path to where the compiler is installed.  For example:
+
+.. code-block:: console
+
+   $ spack compiler find /opt/intel/oneapi/compiler/2025.1/bin/
+   ==> Added 1 new compiler to /home/user/.spack/packages.yaml
+       intel-oneapi-compilers@2025.1.0
+   ==> Compilers are defined in the following files:
+       /home/user/.spack/packages.yaml
 
 Or you can run ``spack compiler find`` with no arguments to force
 auto-detection.  This is useful if you do not know where compilers are
@@ -322,7 +322,7 @@ installed, but you know that new compilers have been added to your
 
    $ module load gcc/4.9.0
    $ spack compiler find
-   ==> Added 1 new compiler to ~/.spack/linux/compilers.yaml
+   ==> Added 1 new compiler to /home/user/.spack/packages.yaml
        gcc@4.9.0
 
 This loads the environment module for gcc-4.9.0 to add it to
@@ -331,7 +331,7 @@ This loads the environment module for gcc-4.9.0 to add it to
 .. note::
 
    By default, spack does not fill in the ``modules:`` field in the
-   ``compilers.yaml`` file.  If you are using a compiler from a
+   ``packages.yaml`` file.  If you are using a compiler from a
    module, then you should add this field manually.
    See the section on :ref:`compilers-requiring-modules`.
 
@@ -341,91 +341,82 @@ This loads the environment module for gcc-4.9.0 to add it to
 ``spack compiler info``
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-If you want to see specifics on a particular compiler, you can run
+If you want to see additional information on some specific compilers, you can run ``spack compiler info`` on it:
-``spack compiler info`` on it:
 
 .. code-block:: console
 
-   $ spack compiler info intel@15
+   $ spack compiler info gcc
-   intel@15.0.0:
+   gcc@=8.4.0 languages='c,c++,fortran' arch=linux-ubuntu20.04-x86_64:
-     paths:
+     prefix: /usr
-       cc  = /usr/local/bin/icc-15.0.090
+     compilers:
-       cxx = /usr/local/bin/icpc-15.0.090
+       c: /usr/bin/gcc-8
-       f77 = /usr/local/bin/ifort-15.0.090
+       cxx: /usr/bin/g++-8
-       fc  = /usr/local/bin/ifort-15.0.090
+       fortran: /usr/bin/gfortran-8
-     modules = []
-     operating_system = centos6
-   ...
 
-This shows which C, C++, and Fortran compilers were detected by Spack.
+   gcc@=9.4.0 languages='c,c++,fortran' arch=linux-ubuntu20.04-x86_64:
-Notice also that we didn't have to be too specific about the
+     prefix: /usr
-version. We just said ``intel@15``, and information about the only
+     compilers:
-matching Intel compiler was displayed.
+       c: /usr/bin/gcc
+       cxx: /usr/bin/g++
+       fortran: /usr/bin/gfortran
+
+   gcc@=10.5.0 languages='c,c++,fortran' arch=linux-ubuntu20.04-x86_64:
+     prefix: /usr
+     compilers:
+       c: /usr/bin/gcc-10
+       cxx: /usr/bin/g++-10
+       fortran: /usr/bin/gfortran-10
+
+This shows the details of the compilers that were detected by Spack.
+Notice also that we didn't have to be too specific about the version. We just said ``gcc``, and we got information
+about all the matching compilers.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Manual compiler configuration
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-If auto-detection fails, you can manually configure a compiler by
+If auto-detection fails, you can manually configure a compiler by editing your ``~/.spack/packages.yaml`` file.
-editing your ``~/.spack/<platform>/compilers.yaml`` file.  You can do this by running
+You can do this by running ``spack config edit packages``, which will open the file in
-``spack config edit compilers``, which will open the file in
 :ref:`your favorite editor <controlling-the-editor>`.
 
-Each compiler configuration in the file looks like this:
+Each compiler has an "external" entry in the file with some ``extra_attributes``:
 
 .. code-block:: yaml
 
-   compilers:
+   packages:
-   - compiler:
+     gcc:
-       modules: []
+       externals:
-       operating_system: centos6
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
-       paths:
+         prefix: /usr
-         cc: /usr/local/bin/icc-15.0.024-beta
+         extra_attributes:
-         cxx: /usr/local/bin/icpc-15.0.024-beta
+           compilers:
-         f77: /usr/local/bin/ifort-15.0.024-beta
+             c: /usr/bin/gcc-10
-         fc: /usr/local/bin/ifort-15.0.024-beta
+             cxx: /usr/bin/g++-10
-       spec: intel@15.0.0
+             fortran: /usr/bin/gfortran-10
 
-For compilers that do not support Fortran (like ``clang``), put
+The compiler executables are listed under ``extra_attributes:compilers``, and are keyed by language.
-``None`` for ``f77`` and ``fc``:
+Once you save the file, the configured compilers will show up in the list displayed by ``spack compilers``.
 
-.. code-block:: yaml
+You can also add compiler flags to manually configured compilers. These flags should be specified in the
-
+``flags`` section of the compiler specification. The valid flags are ``cflags``, ``cxxflags``, ``fflags``,
-   compilers:
-   - compiler:
-       modules: []
-       operating_system: centos6
-       paths:
-         cc: /usr/bin/clang
-         cxx: /usr/bin/clang++
-         f77: None
-         fc: None
-       spec: clang@3.3svn
-
-Once you save the file, the configured compilers will show up in the
-list displayed by ``spack compilers``.
-
-You can also add compiler flags to manually configured compilers. These
-flags should be specified in the ``flags`` section of the compiler
-specification. The valid flags are ``cflags``, ``cxxflags``, ``fflags``,
 ``cppflags``, ``ldflags``, and ``ldlibs``. For example:
 
 .. code-block:: yaml
 
-   compilers:
+   packages:
-   - compiler:
+     gcc:
-       modules: []
+       externals:
-       operating_system: centos6
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
-       paths:
+         prefix: /usr
-         cc: /usr/bin/gcc
+         extra_attributes:
-         cxx: /usr/bin/g++
+           compilers:
-         f77: /usr/bin/gfortran
+             c: /usr/bin/gcc-10
-         fc: /usr/bin/gfortran
+             cxx: /usr/bin/g++-10
-       flags:
+             fortran: /usr/bin/gfortran-10
-         cflags: -O3 -fPIC
+           flags:
-         cxxflags: -O3 -fPIC
+             cflags: -O3 -fPIC
-         cppflags: -O3 -fPIC
+             cxxflags: -O3 -fPIC
-       spec: gcc@4.7.2
+             cppflags: -O3 -fPIC
 
 These flags will be treated by spack as if they were entered from
 the command line each time this compiler is used. The compiler wrappers
@@ -440,95 +431,44 @@ These variables should be specified in the ``environment`` section of the compil
 specification. The operations available to modify the environment are ``set``, ``unset``,
 ``prepend_path``, ``append_path``, and ``remove_path``. For example:
 
-.. code-block:: yaml
-
-   compilers:
-   - compiler:
-       modules: []
-       operating_system: centos6
-       paths:
-         cc: /opt/intel/oneapi/compiler/latest/linux/bin/icx
-         cxx: /opt/intel/oneapi/compiler/latest/linux/bin/icpx
-         f77: /opt/intel/oneapi/compiler/latest/linux/bin/ifx
-         fc: /opt/intel/oneapi/compiler/latest/linux/bin/ifx
-       spec: oneapi@latest
-       environment:
-         set:
-           MKL_ROOT: "/path/to/mkl/root"
-         unset: # A list of environment variables to unset
-           - CC
-         prepend_path: # Similar for append|remove_path
-           LD_LIBRARY_PATH: /ld/paths/added/by/setvars/sh
-
-.. note::
-
-   Spack is in the process of moving compilers from a separate
-   attribute to be handled like all other packages. As part of this
-   process, the ``compilers.yaml`` section will eventually be replaced
-   by configuration in the ``packages.yaml`` section. This new
-   configuration is now available, although it is not yet the default
-   behavior.
-
-Compilers can also be configured as external packages in the
-``packages.yaml`` config file. Any external package for a compiler
-(e.g. ``gcc`` or ``llvm``) will be treated as a configured compiler
-assuming the paths to the compiler executables are determinable from
-the prefix.
-
-If the paths to the compiler executable are not determinable from the
-prefix, you can add them to the ``extra_attributes`` field. Similarly,
-all other fields from the compilers config can be added to the
-``extra_attributes`` field for an external representing a compiler.
-
-Note that the format for the ``paths`` field in the
-``extra_attributes`` section is different than in the ``compilers``
-config. For compilers configured as external packages, the section is
-named ``compilers`` and the dictionary maps language names (``c``,
-``cxx``, ``fortran``) to paths, rather than using the names ``cc``,
-``fc``, and ``f77``.
-
 .. code-block:: yaml
 
    packages:
-     gcc:
+     intel-oneapi-compilers:
-       external:
+       externals:
-       - spec: gcc@12.2.0 arch=linux-rhel8-skylake
+       - spec: intel-oneapi-compilers@2025.1.0
-         prefix: /usr
+         prefix: /opt/intel/oneapi
-         extra_attributes:
-           environment:
-             set:
-               GCC_ROOT: /usr
-       external:
-       - spec: llvm+clang@15.0.0 arch=linux-rhel8-skylake
-         prefix: /usr
          extra_attributes:
            compilers:
-             c: /usr/bin/clang-with-suffix
+             c: /opt/intel/oneapi/compiler/2025.1/bin/icx
-             cxx: /usr/bin/clang++-with-extra-info
+             cxx: /opt/intel/oneapi/compiler/2025.1/bin/icpx
-             fortran: /usr/bin/gfortran
+             fortran: /opt/intel/oneapi/compiler/2025.1/bin/ifx
-           extra_rpaths:
+           environment:
-           - /usr/lib/llvm/
+             set:
+               MKL_ROOT: "/path/to/mkl/root"
+             unset: # A list of environment variables to unset
+               - CC
+             prepend_path: # Similar for append|remove_path
+               LD_LIBRARY_PATH: /ld/paths/added/by/setvars/sh
 
 ^^^^^^^^^^^^^^^^^^^^^^^
 Build Your Own Compiler
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-If you are particular about which compiler/version you use, you might
+If you are particular about which compiler/version you use, you might wish to have Spack build it for you.
-wish to have Spack build it for you.  For example:
+For example:
 
 .. code-block:: console
 
-   $ spack install gcc@4.9.3
+   $ spack install gcc@14+binutils
 
-Once that has finished, you will need to add it to your
+Once the compiler is installed, you can start using it without additional configuration:
-``compilers.yaml`` file.  You can then set Spack to use it by default
-by adding the following to your ``packages.yaml`` file:
 
-.. code-block:: yaml
+.. code-block:: console
 
-   packages:
+   $ spack install hdf5~mpi %gcc@14
-     all:
+
-       compiler: [gcc@4.9.3]
+The same holds true for compilers that are made available from buildcaches, when reusing them is allowed.
 
 .. _compilers-requiring-modules:
 
@@ -536,30 +476,26 @@ by adding the following to your ``packages.yaml`` file:
 Compilers Requiring Modules
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Many installed compilers will work regardless of the environment they
+Many installed compilers will work regardless of the environment they are called with.
-are called with.  However, some installed compilers require
+However, some installed compilers require environment variables to be set in order to run;
-``$LD_LIBRARY_PATH`` or other environment variables to be set in order
+this is typical for Intel and other proprietary compilers.
-to run; this is typical for Intel and other proprietary compilers.
 
-In such a case, you should tell Spack which module(s) to load in order
+On typical HPC clusters, these environment modifications are usually delegated to some "module" system.
-to run the chosen compiler (If the compiler does not come with a
+In such a case, you should tell Spack which module(s) to load in order to run the chosen compiler:
-module file, you might consider making one by hand).  Spack will load
-this module into the environment ONLY when the compiler is run, and
-NOT in general for a package's ``install()`` method.  See, for
-example, this ``compilers.yaml`` file:
 
 .. code-block:: yaml
 
-   compilers:
+   packages:
-   - compiler:
+     gcc:
-       modules: [other/comp/gcc-5.3-sp3]
+       externals:
-       operating_system: SuSE11
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
-       paths:
+         prefix: /opt/compilers
-         cc: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gcc
+         extra_attributes:
-         cxx: /usr/local/other/SLES11.3/gcc/5.3.0/bin/g++
+           compilers:
-         f77: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gfortran
+             c: /opt/compilers/bin/gcc-10
-         fc: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gfortran
+             cxx: /opt/compilers/bin/g++-10
-       spec: gcc@5.3.0
+             fortran: /opt/compilers/bin/gfortran-10
+         modules: [gcc/10.5.0]
 
 Some compilers require special environment settings to be loaded not just
 to run, but also to execute the code they build, breaking packages that
@@ -580,7 +516,7 @@ Licensed Compilers
 ^^^^^^^^^^^^^^^^^^
 
 Some proprietary compilers require licensing to use.  If you need to
-use a licensed compiler (eg, PGI), the process is similar to a mix of
+use a licensed compiler, the process is similar to a mix of
 build your own, plus modules:
 
 #. Create a Spack package (if it doesn't exist already) to install
@@ -590,24 +526,21 @@ build your own, plus modules:
    using Spack to load the module it just created, and running simple
    builds (eg: ``cc helloWorld.c && ./a.out``)
 
-#. Add the newly-installed compiler to ``compilers.yaml`` as shown
+#. Add the newly-installed compiler to ``packages.yaml`` as shown above.
-   above.
 
 .. _mixed-toolchains:
 
-^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^
-Mixed Toolchains
+Fortran compilers on macOS
-^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Modern compilers typically come with related compilers for C, C++ and
 Fortran bundled together.  When possible, results are best if the same
 compiler is used for all languages.
 
-In some cases, this is not possible.  For example, starting with macOS El
+In some cases, this is not possible.  For example, XCode on macOS provides no Fortran compilers.
-Capitan (10.11), many packages no longer build with GCC, but XCode
+The user is therefore forced to use a mixed toolchain: XCode-provided Clang for C/C++ and e.g.
-provides no Fortran compilers.  The user is therefore forced to use a
+GNU ``gfortran`` for Fortran.
-mixed toolchain: XCode-provided Clang for C/C++ and GNU ``gfortran`` for
-Fortran.
 
 #. You need to make sure that Xcode is installed. Run the following command:
 
@@ -660,45 +593,25 @@ Fortran.
 
    Note: the flag is ``-license``, not ``--license``.
 
-#. Run ``spack compiler find`` to locate Clang.
-
 #. There are different ways to get ``gfortran`` on macOS. For example, you can
    install GCC with Spack (``spack install gcc``), with Homebrew (``brew install
    gcc``), or from a `DMG installer
    <https://github.com/fxcoudert/gfortran-for-macOS/releases>`_.
 
-#. The only thing left to do is to edit ``~/.spack/darwin/compilers.yaml`` to provide
+#. Run ``spack compiler find`` to locate both Apple-Clang and GCC.
-   the path to ``gfortran``:
 
-   .. code-block:: yaml
+Since languages in Spack are modeled as virtual packages, ``apple-clang`` will be used to provide
-
+C and C++, while GCC will be used for Fortran.
-      compilers:
-      - compiler:
-        # ...
-        paths:
-          cc: /usr/bin/clang
-          cxx: /usr/bin/clang++
-          f77: /path/to/bin/gfortran
-          fc: /path/to/bin/gfortran
-        spec: apple-clang@11.0.0
-
-
-   If you used Spack to install GCC, you can get the installation prefix by
-   ``spack location -i gcc`` (this will only work if you have a single version
-   of GCC installed). Whereas for Homebrew, GCC is installed in
-   ``/usr/local/Cellar/gcc/x.y.z``. With the DMG installer, the correct path
-   will be ``/usr/local/gfortran``.
 
 ^^^^^^^^^^^^^^^^^^^^^
 Compiler Verification
 ^^^^^^^^^^^^^^^^^^^^^
 
-You can verify that your compilers are configured properly by installing a
+You can verify that your compilers are configured properly by installing a simple package. For example:
-simple package.  For example:
 
 .. code-block:: console
 
-   $ spack install zlib%gcc@5.3.0
+   $ spack install zlib-ng%gcc@5.3.0
 
 
 .. _vendor-specific-compiler-configuration:
@@ -707,9 +620,7 @@ simple package.  For example:
 Vendor-Specific Compiler Configuration
 --------------------------------------
 
-With Spack, things usually "just work" with GCC.  Not so for other
+This section provides details on how to get vendor-specific compilers working.
-compilers.  This section provides details on how to get specific
-compilers working.
 
 ^^^^^^^^^^^^^^^
 Intel Compilers
@@ -731,8 +642,8 @@ compilers:
       you have installed from the ``PATH`` environment variable.
 
       If you want use a version of ``gcc`` or ``g++`` other than the default
-      version on your system, you need to use either the ``-gcc-name``
+      version on your system, you need to use either the ``--gcc-install-dir``
-      or ``-gxx-name`` compiler option to specify the path to the version of
+      or ``--gcc-toolchain`` compiler option to specify the path to the version of
       ``gcc`` or ``g++`` that you want to use."
 
       -- `Intel Reference Guide <https://software.intel.com/en-us/node/522750>`_
@@ -740,76 +651,12 @@ compilers:
 Intel compilers may therefore be configured in one of two ways with
 Spack: using modules, or using compiler flags.
 
-""""""""""""""""""""""""""
-Configuration with Modules
-""""""""""""""""""""""""""
-
-One can control which GCC is seen by the Intel compiler with modules.
-A module must be loaded both for the Intel Compiler (so it will run)
-and GCC (so the compiler can find the intended GCC).  The following
-configuration in ``compilers.yaml`` illustrates this technique:
-
-.. code-block:: yaml
-
-   compilers:
-   - compiler:
-       modules: [gcc-4.9.3, intel-15.0.24]
-       operating_system: centos7
-       paths:
-         cc: /opt/intel-15.0.24/bin/icc-15.0.24-beta
-         cxx: /opt/intel-15.0.24/bin/icpc-15.0.24-beta
-         f77: /opt/intel-15.0.24/bin/ifort-15.0.24-beta
-         fc: /opt/intel-15.0.24/bin/ifort-15.0.24-beta
-       spec: intel@15.0.24.4.9.3
-
-
-.. note::
-
-   The version number on the Intel compiler is a combination of
-   the "native" Intel version number and the GNU compiler it is
-   targeting.
-
-""""""""""""""""""""""""""
-Command Line Configuration
-""""""""""""""""""""""""""
-
-One can also control which GCC is seen by the Intel compiler by adding
-flags to the ``icc`` command:
-
-#. Identify the location of the compiler you just installed:
-
-   .. code-block:: console
-
-       $ spack location --install-dir gcc
-       ~/spack/opt/spack/linux-centos7-x86_64/gcc-4.9.3-iy4rw...
-
-#. Set up ``compilers.yaml``, for example:
-
-   .. code-block:: yaml
-
-       compilers:
-       - compiler:
-           modules: [intel-15.0.24]
-           operating_system: centos7
-           paths:
-             cc: /opt/intel-15.0.24/bin/icc-15.0.24-beta
-             cxx: /opt/intel-15.0.24/bin/icpc-15.0.24-beta
-             f77: /opt/intel-15.0.24/bin/ifort-15.0.24-beta
-             fc: /opt/intel-15.0.24/bin/ifort-15.0.24-beta
-           flags:
-             cflags: -gcc-name ~/spack/opt/spack/linux-centos7-x86_64/gcc-4.9.3-iy4rw.../bin/gcc
-             cxxflags: -gxx-name ~/spack/opt/spack/linux-centos7-x86_64/gcc-4.9.3-iy4rw.../bin/g++
-             fflags: -gcc-name ~/spack/opt/spack/linux-centos7-x86_64/gcc-4.9.3-iy4rw.../bin/gcc
-           spec: intel@15.0.24.4.9.3
-
-
 ^^^
 NAG
 ^^^
 
-The Numerical Algorithms Group provides a licensed Fortran compiler. Like Clang,
+The Numerical Algorithms Group provides a licensed Fortran compiler.
-this requires you to set up a :ref:`mixed-toolchains`. It is recommended to use
+It is recommended to use GCC for your C/C++ compilers.
-GCC for your C/C++ compilers.
 
 The NAG Fortran compilers are a bit more strict than other compilers, and many
 packages will fail to install with error messages like:
@@ -826,44 +673,40 @@ the command line:
 
    $ spack install openmpi fflags="-mismatch"
 
-Or it can be set permanently in your ``compilers.yaml``:
+Or it can be set permanently in your ``packages.yaml``:
 
 .. code-block:: yaml
 
-   - compiler:
+   packages:
-    modules: []
+     nag:
-    operating_system: centos6
+       externals:
-    paths:
+       - spec: nag@6.1
-      cc: /soft/spack/opt/spack/linux-x86_64/gcc-5.3.0/gcc-6.1.0-q2zosj3igepi3pjnqt74bwazmptr5gpj/bin/gcc
+         prefix: /opt/nag/bin
-      cxx: /soft/spack/opt/spack/linux-x86_64/gcc-5.3.0/gcc-6.1.0-q2zosj3igepi3pjnqt74bwazmptr5gpj/bin/g++
+         extra_attributes:
-      f77: /soft/spack/opt/spack/linux-x86_64/gcc-4.4.7/nag-6.1-jt3h5hwt5myezgqguhfsan52zcskqene/bin/nagfor
+           compilers:
-      fc: /soft/spack/opt/spack/linux-x86_64/gcc-4.4.7/nag-6.1-jt3h5hwt5myezgqguhfsan52zcskqene/bin/nagfor
+             fortran: /opt/nag/bin/nagfor
-    flags:
+         flags:
-      fflags: -mismatch
+           fflags: -mismatch
-    spec: nag@6.1
-
 
 ---------------
 System Packages
 ---------------
 
-Once compilers are configured, one needs to determine which
+Once compilers are configured, one needs to determine which pre-installed system packages,
-pre-installed system packages, if any, to use in builds.  This is
+if any, to use in builds.  These are also configured in the ``~/.spack/packages.yaml`` file.
-configured in the file ``~/.spack/packages.yaml``.  For example, to use
+For example, to use an OpenMPI installed in /opt/local, one would use:
-an OpenMPI installed in /opt/local, one would use:
 
 .. code-block:: yaml
 
-    packages:
+   packages:
-        openmpi:
+     openmpi:
-            externals:
+       buildable: False
-            - spec: openmpi@1.10.1
+       externals:
-              prefix: /opt/local
+       - spec: openmpi@1.10.1
-            buildable: False
+         prefix: /opt/local
 
-In general, Spack is easier to use and more reliable if it builds all of
+In general, *Spack is easier to use and more reliable if it builds all of its own dependencies*.
-its own dependencies.  However, there are several packages for which one
+However, there are several packages for which one commonly needs to use system versions:
-commonly needs to use system versions:
 
 ^^^
 MPI
@@ -876,8 +719,7 @@ you are unlikely to get a working MPI from Spack.  Instead, use an
 appropriate pre-installed MPI.
 
 If you choose a pre-installed MPI, you should consider using the
-pre-installed compiler used to build that MPI; see above on
+pre-installed compiler used to build that MPI.
-``compilers.yaml``.
 
 ^^^^^^^
 OpenSSL
@@ -1441,9 +1283,9 @@ To configure Spack, first run the following command inside the Spack console:
    spack compiler find
 
 This creates a ``.staging`` directory in our Spack prefix, along with a ``windows`` subdirectory
-containing a ``compilers.yaml`` file. On a fresh Windows install with the above packages
+containing a ``packages.yaml`` file. On a fresh Windows install with the above packages
 installed, this command should only detect Microsoft Visual Studio and the Intel Fortran
-compiler will be integrated within the first version of MSVC present in the ``compilers.yaml``
+compiler will be integrated within the first version of MSVC present in the ``packages.yaml``
 output.
 
 Spack provides a default ``config.yaml`` file for Windows that it will use unless overridden.

lib/spack/docs/include_yaml.rst

@@ -0,0 +1,51 @@
+.. Copyright Spack Project Developers. See COPYRIGHT file for details.
+
+   SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+.. _include-yaml:
+
+===============================
+Include Settings (include.yaml)
+===============================
+
+Spack allows you to include configuration files through ``include.yaml``.
+Using the ``include:`` heading results in pulling in external configuration
+information to be used by any Spack command.
+
+Included configuration files are required *unless* they are explicitly optional
+or the entry's condition evaluates to ``false``. Optional includes are specified
+with the ``optional`` clause and conditional with the ``when`` clause. For
+example,
+
+.. code-block:: yaml
+
+   include:
+   - /path/to/a/required/config.yaml
+   - path: /path/to/$os/$target/config
+     optional: true
+   - path: /path/to/os-specific/config-dir
+     when: os == "ventura"
+
+shows all three. The first entry, ``/path/to/a/required/config.yaml``,
+indicates that included ``config.yaml`` file is required (so must exist).
+Use of ``optional: true`` for ``/path/to/$os/$target/config`` means
+the path is only included if it exists. The condition ``os == "ventura"``
+in the ``when`` clause for ``/path/to/os-specific/config-dir`` means the
+path is only included when the operating system (``os``) is ``ventura``.
+
+The same conditions and variables in `Spec List References 
+<https://spack.readthedocs.io/en/latest/environments.html#spec-list-references>`_
+can be used for conditional activation in the ``when`` clauses.
+
+Included files can be specified by path or by their parent directory.
+Paths may be absolute, relative (to the configuration file including the path), 
+or specified as URLs. Only the ``file``, ``ftp``, ``http`` and ``https`` protocols (or
+schemes) are supported. Spack-specific, environment and user path variables
+can be used. (See :ref:`config-file-variables` for more information.)
+
+.. warning::
+
+   Recursive includes are not currently processed in a breadth-first manner
+   so the value of a configuration option that is altered by multiple included
+   files may not be what you expect. This will be addressed in a future
+   update.

lib/spack/docs/index.rst

@@ -71,6 +71,7 @@ or refer to the full manual below.
 
    configuration
    config_yaml
+   include_yaml
    packages_yaml
    build_settings
    environments

lib/spack/docs/packages_yaml.rst

@@ -486,6 +486,8 @@ present. For instance with a configuration like:
 
 you will use ``mvapich2~cuda %gcc`` as an ``mpi`` provider.
 
+.. _package-strong-preferences:
+
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Conflicts and strong preferences
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

lib/spack/docs/pipelines.rst

@@ -330,7 +330,7 @@ that ``--tests`` is passed to ``spack ci rebuild`` as part of the
           - spack --version
           - cd ${SPACK_CONCRETE_ENV_DIR}
           - spack env activate --without-view .
-          - spack config add "config:install_tree:projections:${SPACK_JOB_SPEC_PKG_NAME}:'morepadding/{architecture}/{compiler.name}-{compiler.version}/{name}-{version}-{hash}'"
+          - spack config add "config:install_tree:projections:${SPACK_JOB_SPEC_PKG_NAME}:'morepadding/{architecture.platform}-{architecture.target}/{name}-{version}-{hash}'"
            - mkdir -p ${SPACK_ARTIFACTS_ROOT}/user_data
            - if [[ -r /mnt/key/intermediate_ci_signing_key.gpg ]]; then spack gpg trust /mnt/key/intermediate_ci_signing_key.gpg; fi
            - if [[ -r /mnt/key/spack_public_key.gpg ]]; then spack gpg trust /mnt/key/spack_public_key.gpg; fi

lib/spack/docs/requirements.txt

@@ -1,13 +1,13 @@
-sphinx==8.2.1
+sphinx==8.2.3
 sphinxcontrib-programoutput==0.18
 sphinx_design==0.6.1
 sphinx-rtd-theme==3.0.2
-python-levenshtein==0.26.1
+python-levenshtein==0.27.1
 docutils==0.21.2
 pygments==2.19.1
 urllib3==2.3.0
-pytest==8.3.4
+pytest==8.3.5
-isort==6.0.0
+isort==6.0.1
 black==25.1.0
 flake8==7.1.2
 mypy==1.11.1

lib/spack/env/aocc/clang

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

lib/spack/env/aocc/clang++

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

lib/spack/env/aocc/flang

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

lib/spack/env/arm/armclang

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

lib/spack/env/arm/armclang++

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

lib/spack/env/arm/armflang

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

lib/spack/env/c++

@@ -1 +0,0 @@
-cc

lib/spack/env/c89

@@ -1 +0,0 @@
-cc

lib/spack/env/c99

@@ -1 +0,0 @@
-cc

lib/spack/env/case-insensitive/CC

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

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

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

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

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

lib/spack/env/cce/cc

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

lib/spack/env/cce/craycc

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

lib/spack/env/cce/crayftn

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

lib/spack/env/cce/ftn

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

lib/spack/env/clang/clang

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

lib/spack/env/clang/clang++

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

lib/spack/env/clang/flang

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

lib/spack/env/clang/gfortran

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

lib/spack/env/cpp

@@ -1 +0,0 @@
-cc

lib/spack/env/f77

@@ -1 +0,0 @@
-cc

lib/spack/env/f90

@@ -1 +0,0 @@
-cc

lib/spack/env/f95

@@ -1 +0,0 @@
-cc

lib/spack/env/fc

@@ -1 +0,0 @@
-cc

lib/spack/env/fj/case-insensitive/FCC

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

lib/spack/env/fj/fcc

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

lib/spack/env/fj/frt

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

lib/spack/env/ftn

@@ -1 +0,0 @@
-cc

lib/spack/env/gcc/g++

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

lib/spack/env/gcc/gcc

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

lib/spack/env/gcc/gfortran

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

lib/spack/env/intel/icc

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

lib/spack/env/intel/icpc

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

lib/spack/env/intel/ifort

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

lib/spack/env/ld

@@ -1 +0,0 @@
-cc

lib/spack/env/ld.gold

@@ -1 +0,0 @@
-cc

lib/spack/env/ld.lld

@@ -1 +0,0 @@
-cc

lib/spack/env/nag/nagfor

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

lib/spack/env/nvhpc/nvc

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

lib/spack/env/nvhpc/nvc++

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

lib/spack/env/nvhpc/nvfortran

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

lib/spack/env/oneapi/dpcpp

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

lib/spack/env/oneapi/icpx

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

lib/spack/env/oneapi/icx

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

lib/spack/env/oneapi/ifx

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

lib/spack/env/pgi/pgc++

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

lib/spack/env/pgi/pgcc

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

lib/spack/env/pgi/pgfortran

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

lib/spack/env/rocmcc/amdclang

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

lib/spack/env/rocmcc/amdclang++

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

lib/spack/env/rocmcc/amdflang

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

lib/spack/env/xl/xlc

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

lib/spack/env/xl/xlc++

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

lib/spack/env/xl/xlf

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

lib/spack/env/xl/xlf90

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

lib/spack/env/xl_r/xlc++_r

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

lib/spack/env/xl_r/xlc_r

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

lib/spack/env/xl_r/xlf90_r

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

lib/spack/env/xl_r/xlf_r

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

lib/spack/llnl/util/lang.py

@@ -11,6 +11,7 @@
 import re
 import sys
 import traceback
+import types
 import typing
 import warnings
 from datetime import datetime, timedelta
@@ -72,7 +73,7 @@ def index_by(objects, *funcs):
     if isinstance(f, str):
         f = lambda x: getattr(x, funcs[0])
     elif isinstance(f, tuple):
-        f = lambda x: tuple(getattr(x, p) for p in funcs[0])
+        f = lambda x: tuple(getattr(x, p, None) for p in funcs[0])
 
     result = {}
     for o in objects:
@@ -707,14 +708,24 @@ def __init__(self, wrapped_object):
 
 
 class Singleton:
-    """Simple wrapper for lazily initialized singleton objects."""
+    """Wrapper for lazily initialized singleton objects."""
 
-    def __init__(self, factory):
+    def __init__(self, factory: Callable[[], object]):
         """Create a new singleton to be inited with the factory function.
 
+        Most factories will simply create the object to be initialized and
+        return it.
+
+        In some cases, e.g. when bootstrapping some global state, the singleton
+        may need to be initialized incrementally. If the factory returns a generator
+        instead of a regular object, the singleton will assign each result yielded by
+        the generator to the singleton instance. This allows methods called by
+        the factory in later stages to refer back to the singleton.
+
         Args:
-            factory (function): function taking no arguments that
+            factory (function): function taking no arguments that creates the
-                creates the singleton instance.
+                singleton instance.
+
         """
         self.factory = factory
         self._instance = None
@@ -722,7 +733,16 @@ def __init__(self, factory):
     @property
     def instance(self):
         if self._instance is None:
-            self._instance = self.factory()
+            instance = self.factory()
+
+            if isinstance(instance, types.GeneratorType):
+                # if it's a generator, assign every value
+                for value in instance:
+                    self._instance = value
+            else:
+                # if not, just assign the result like a normal singleton
+                self._instance = instance
+
         return self._instance
 
     def __getattr__(self, name):
@@ -996,11 +1016,8 @@ def _receive_forwarded(self, context: str, exc: Exception, tb: List[str]):
     def grouped_message(self, with_tracebacks: bool = True) -> str:
         """Print out an error message coalescing all the forwarded errors."""
         each_exception_message = [
-            "{0} raised {1}: {2}{3}".format(
+            "\n\t{0} raised {1}: {2}\n{3}".format(
-                context,
+                context, exc.__class__.__name__, exc, f"\n{''.join(tb)}" if with_tracebacks else ""
-                exc.__class__.__name__,
-                exc,
-                "\n{0}".format("".join(tb)) if with_tracebacks else "",
             )
             for context, exc, tb in self.exceptions
         ]

lib/spack/spack/__init__.py

@@ -13,6 +13,18 @@
 __version__ = "1.0.0.dev0"
 spack_version = __version__
 
+#: The current Package API version implemented by this version of Spack. The Package API defines
+#: the Python interface for packages as well as the layout of package repositories. The minor
+#: version is incremented when the package API is extended in a backwards-compatible way. The major
+#: version is incremented upon breaking changes. This version is changed independently from the
+#: Spack version.
+package_api_version = (1, 0)
+
+#: The minimum Package API version that this version of Spack is compatible with. This should
+#: always be a tuple of the form ``(major, 0)``, since compatibility with vX.Y implies
+#: compatibility with vX.0.
+min_package_api_version = (1, 0)
+
 
 def __try_int(v):
     try:
@@ -79,4 +91,6 @@ def get_short_version() -> str:
     "get_version",
     "get_spack_commit",
     "get_short_version",
+    "package_api_version",
+    "min_package_api_version",
 ]

lib/spack/spack/aliases.py

@@ -0,0 +1,20 @@
+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+"""Alias names to convert legacy compilers to builtin packages and vice-versa"""
+
+BUILTIN_TO_LEGACY_COMPILER = {
+    "llvm": "clang",
+    "intel-oneapi-compilers": "oneapi",
+    "llvm-amdgpu": "rocmcc",
+    "intel-oneapi-compiler-classic": "intel",
+    "acfl": "arm",
+}
+
+LEGACY_COMPILER_TO_BUILTIN = {
+    "clang": "llvm",
+    "oneapi": "intel-oneapi-compilers",
+    "rocmcc": "llvm-amdgpu",
+    "intel": "intel-oneapi-compiler-classic",
+    "arm": "acfl",
+}

lib/spack/spack/binary_distribution.py

@@ -110,6 +110,13 @@ def __init__(self, root):
         self._write_transaction_impl = llnl.util.lang.nullcontext
         self._read_transaction_impl = llnl.util.lang.nullcontext
 
+    def _handle_old_db_versions_read(self, check, db, *, reindex: bool):
+        if not self.is_readable():
+            raise spack_db.DatabaseNotReadableError(
+                f"cannot read buildcache v{self.db_version} at {self.root}"
+            )
+        return self._handle_current_version_read(check, db)
+
 
 class FetchCacheError(Exception):
     """Error thrown when fetching the cache failed, usually a composite error list."""
@@ -242,7 +249,7 @@ def _associate_built_specs_with_mirror(self, cache_key, mirror_url):
                 self._index_file_cache.init_entry(cache_key)
                 cache_path = self._index_file_cache.cache_path(cache_key)
                 with self._index_file_cache.read_transaction(cache_key):
-                    db._read_from_file(cache_path)
+                    db._read_from_file(pathlib.Path(cache_path))
             except spack_db.InvalidDatabaseVersionError as e:
                 tty.warn(
                     f"you need a newer Spack version to read the buildcache index for the "

lib/spack/spack/bootstrap/_common.py

@@ -234,14 +234,6 @@ def _root_spec(spec_str: str) -> str:
     # Add a compiler and platform requirement to the root spec.
     platform = str(spack.platforms.host())
 
-    if platform == "darwin":
-        spec_str += " %apple-clang"
-    elif platform == "windows":
-        spec_str += " %msvc"
-    elif platform == "linux":
-        spec_str += " %gcc"
-    elif platform == "freebsd":
-        spec_str += " %clang"
     spec_str += f" platform={platform}"
     target = archspec.cpu.host().family
     spec_str += f" target={target}"

lib/spack/spack/bootstrap/clingo.py

@@ -15,11 +15,13 @@
 
 import archspec.cpu
 
-import spack.compiler
+import spack.compilers.config
-import spack.compilers
+import spack.compilers.libraries
+import spack.config
 import spack.platforms
 import spack.spec
 import spack.traverse
+import spack.version
 
 from .config import spec_for_current_python
 
@@ -38,7 +40,7 @@ def __init__(self, configuration):
 
         self.external_cmake, self.external_bison = self._externals_from_yaml(configuration)
 
-    def _valid_compiler_or_raise(self) -> "spack.compiler.Compiler":
+    def _valid_compiler_or_raise(self):
         if str(self.host_platform) == "linux":
             compiler_name = "gcc"
         elif str(self.host_platform) == "darwin":
@@ -46,17 +48,30 @@ def _valid_compiler_or_raise(self) -> "spack.compiler.Compiler":
         elif str(self.host_platform) == "windows":
             compiler_name = "msvc"
         elif str(self.host_platform) == "freebsd":
-            compiler_name = "clang"
+            compiler_name = "llvm"
         else:
             raise RuntimeError(f"Cannot bootstrap clingo from sources on {self.host_platform}")
-        candidates = spack.compilers.compilers_for_spec(
+
-            compiler_name, arch_spec=self.host_architecture
+        candidates = [
-        )
+            x
+            for x in spack.compilers.config.CompilerFactory.from_packages_yaml(spack.config.CONFIG)
+            if x.name == compiler_name
+        ]
         if not candidates:
             raise RuntimeError(
                 f"Cannot find any version of {compiler_name} to bootstrap clingo from sources"
             )
-        candidates.sort(key=lambda x: x.spec.version, reverse=True)
+        candidates.sort(key=lambda x: x.version, reverse=True)
+        best = candidates[0]
+        # Get compilers for bootstrapping from the 'builtin' repository
+        best.namespace = "builtin"
+        # If the compiler does not support C++ 14, fail with a legible error message
+        try:
+            _ = best.package.standard_flag(language="cxx", standard="14")
+        except RuntimeError as e:
+            raise RuntimeError(
+                "cannot find a compiler supporting C++ 14 [needed to bootstrap clingo]"
+            ) from e
         return candidates[0]
 
     def _externals_from_yaml(
@@ -75,9 +90,6 @@ def _externals_from_yaml(
                 if not s.satisfies(requirements[pkg_name]):
                     continue
 
-                if not s.intersects(f"%{self.host_compiler.spec}"):
-                    continue
-
                 if not s.intersects(f"arch={self.host_architecture}"):
                     continue
 
@@ -110,11 +122,14 @@ def concretize(self) -> "spack.spec.Spec":
         # Tweak it to conform to the host architecture
         for node in s.traverse():
             node.architecture.os = str(self.host_os)
-            node.compiler = self.host_compiler.spec
             node.architecture = self.host_architecture
 
             if node.name == "gcc-runtime":
-                node.versions = self.host_compiler.spec.versions
+                node.versions = self.host_compiler.versions
+
+        # Can't use re2c@3.1 with Python 3.6
+        if self.host_python.satisfies("@3.6"):
+            s["re2c"].versions.versions = [spack.version.from_string("=2.2")]
 
         for edge in spack.traverse.traverse_edges([s], cover="edges"):
             if edge.spec.name == "python":
@@ -126,6 +141,9 @@ def concretize(self) -> "spack.spec.Spec":
             if edge.spec.name == "cmake" and self.external_cmake:
                 edge.spec = self.external_cmake
 
+            if edge.spec.name == self.host_compiler.name:
+                edge.spec = self.host_compiler
+
             if "libc" in edge.virtuals:
                 edge.spec = self.host_libc
 
@@ -141,12 +159,12 @@ def python_external_spec(self) -> "spack.spec.Spec":
         return self._external_spec(result)
 
     def libc_external_spec(self) -> "spack.spec.Spec":
-        result = self.host_compiler.default_libc
+        detector = spack.compilers.libraries.CompilerPropertyDetector(self.host_compiler)
+        result = detector.default_libc()
         return self._external_spec(result)
 
     def _external_spec(self, initial_spec) -> "spack.spec.Spec":
         initial_spec.namespace = "builtin"
-        initial_spec.compiler = self.host_compiler.spec
         initial_spec.architecture = self.host_architecture
         for flag_type in spack.spec.FlagMap.valid_compiler_flags():
             initial_spec.compiler_flags[flag_type] = []

lib/spack/spack/bootstrap/config.py

@@ -10,7 +10,7 @@
 
 from llnl.util import tty
 
-import spack.compilers
+import spack.compilers.config
 import spack.config
 import spack.environment
 import spack.modules
@@ -142,8 +142,8 @@ def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
 
 def _add_compilers_if_missing() -> None:
     arch = spack.spec.ArchSpec.default_arch()
-    if not spack.compilers.compilers_for_arch(arch):
+    if not spack.compilers.config.compilers_for_arch(arch):
-        spack.compilers.find_compilers()
+        spack.compilers.config.find_compilers()
 
 
 @contextlib.contextmanager

lib/spack/spack/build_environment.py

@@ -36,7 +36,6 @@
 import multiprocessing
 import os
 import re
-import stat
 import sys
 import traceback
 import types
@@ -71,7 +70,7 @@
 import spack.build_systems.meson
 import spack.build_systems.python
 import spack.builder
-import spack.compilers
+import spack.compilers.libraries
 import spack.config
 import spack.deptypes as dt
 import spack.error
@@ -85,7 +84,6 @@
 import spack.store
 import spack.subprocess_context
 import spack.util.executable
-import spack.util.libc
 from spack import traverse
 from spack.context import Context
 from spack.error import InstallError, NoHeadersError, NoLibrariesError
@@ -93,6 +91,8 @@
 from spack.util.environment import (
     SYSTEM_DIR_CASE_ENTRY,
     EnvironmentModifications,
+    ModificationList,
+    PrependPath,
     env_flag,
     filter_system_paths,
     get_path,
@@ -113,7 +113,7 @@
 # set_wrapper_variables and used to pass parameters to
 # Spack's compiler wrappers.
 #
-SPACK_ENV_PATH = "SPACK_ENV_PATH"
+SPACK_COMPILER_WRAPPER_PATH = "SPACK_COMPILER_WRAPPER_PATH"
 SPACK_MANAGED_DIRS = "SPACK_MANAGED_DIRS"
 SPACK_INCLUDE_DIRS = "SPACK_INCLUDE_DIRS"
 SPACK_LINK_DIRS = "SPACK_LINK_DIRS"
@@ -390,62 +390,10 @@ def _add_werror_handling(keep_werror, env):
     env.set("SPACK_COMPILER_FLAGS_REPLACE", " ".join(["|".join(item) for item in replace_flags]))
 
 
-def set_compiler_environment_variables(pkg, env):
+def set_wrapper_environment_variables_for_flags(pkg, env):
     assert pkg.spec.concrete
-    compiler = pkg.compiler
     spec = pkg.spec
 
-    # Make sure the executables for this compiler exist
-    compiler.verify_executables()
-
-    # Set compiler variables used by CMake and autotools
-    assert all(key in compiler.link_paths for key in ("cc", "cxx", "f77", "fc"))
-
-    # Populate an object with the list of environment modifications
-    # and return it
-    # TODO : add additional kwargs for better diagnostics, like requestor,
-    # ttyout, ttyerr, etc.
-    link_dir = spack.paths.build_env_path
-
-    # 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)
-    env.set("SPACK_CXX_RPATH_ARG", compiler.cxx_rpath_arg)
-    env.set("SPACK_F77_RPATH_ARG", compiler.f77_rpath_arg)
-    env.set("SPACK_FC_RPATH_ARG", compiler.fc_rpath_arg)
-    env.set("SPACK_LINKER_ARG", compiler.linker_arg)
-
-    # Check whether we want to force RPATH or RUNPATH
-    if spack.config.get("config:shared_linking:type") == "rpath":
-        env.set("SPACK_DTAGS_TO_STRIP", compiler.enable_new_dtags)
-        env.set("SPACK_DTAGS_TO_ADD", compiler.disable_new_dtags)
-    else:
-        env.set("SPACK_DTAGS_TO_STRIP", compiler.disable_new_dtags)
-        env.set("SPACK_DTAGS_TO_ADD", compiler.enable_new_dtags)
-
     if pkg.keep_werror is not None:
         keep_werror = pkg.keep_werror
     else:
@@ -453,10 +401,6 @@ def set_compiler_environment_variables(pkg, env):
 
     _add_werror_handling(keep_werror, env)
 
-    # Set the target parameters that the compiler will add
-    isa_arg = optimization_flags(compiler, spec.target)
-    env.set("SPACK_TARGET_ARGS", isa_arg)
-
     # Trap spack-tracked compiler flags as appropriate.
     # env_flags are easy to accidentally override.
     inject_flags = {}
@@ -489,75 +433,23 @@ def set_compiler_environment_variables(pkg, env):
             # implicit variables
             env.set(flag.upper(), " ".join(f for f in env_flags[flag]))
     pkg.flags_to_build_system_args(build_system_flags)
-
-    env.set("SPACK_COMPILER_SPEC", str(spec.compiler))
-
     env.set("SPACK_SYSTEM_DIRS", SYSTEM_DIR_CASE_ENTRY)
-
-    compiler.setup_custom_environment(pkg, env)
-
     return env
 
 
 def optimization_flags(compiler, target):
-    if spack.compilers.is_mixed_toolchain(compiler):
-        msg = (
-            "microarchitecture specific optimizations are not "
-            "supported yet on mixed compiler toolchains [check"
-            f" {compiler.name}@{compiler.version} for further details]"
-        )
-        tty.debug(msg)
-        return ""
-
     # Try to check if the current compiler comes with a version number or
     # has an unexpected suffix. If so, treat it as a compiler with a
     # custom spec.
-    compiler_version = compiler.version
+    version_number, _ = archspec.cpu.version_components(compiler.version.dotted_numeric_string)
-    version_number, suffix = archspec.cpu.version_components(compiler.version)
-    if not version_number or suffix:
-        try:
-            compiler_version = compiler.real_version
-        except spack.util.executable.ProcessError as e:
-            # log this and just return compiler.version instead
-            tty.debug(str(e))
-
     try:
-        result = target.optimization_flags(compiler.name, compiler_version.dotted_numeric_string)
+        result = target.optimization_flags(compiler.name, version_number)
     except (ValueError, archspec.cpu.UnsupportedMicroarchitecture):
         result = ""
 
     return result
 
 
-class FilterDefaultDynamicLinkerSearchPaths:
-    """Remove rpaths to directories that are default search paths of the dynamic linker."""
-
-    def __init__(self, dynamic_linker: Optional[str]) -> None:
-        # Identify directories by (inode, device) tuple, which handles symlinks too.
-        self.default_path_identifiers: Set[Tuple[int, int]] = set()
-        if not dynamic_linker:
-            return
-        for path in spack.util.libc.default_search_paths_from_dynamic_linker(dynamic_linker):
-            try:
-                s = os.stat(path)
-                if stat.S_ISDIR(s.st_mode):
-                    self.default_path_identifiers.add((s.st_ino, s.st_dev))
-            except OSError:
-                continue
-
-    def is_dynamic_loader_default_path(self, p: str) -> bool:
-        try:
-            s = os.stat(p)
-            return (s.st_ino, s.st_dev) in self.default_path_identifiers
-        except OSError:
-            return False
-
-    def __call__(self, dirs: List[str]) -> List[str]:
-        if not self.default_path_identifiers:
-            return dirs
-        return [p for p in dirs if not self.is_dynamic_loader_default_path(p)]
-
-
 def set_wrapper_variables(pkg, env):
     """Set environment variables used by the Spack compiler wrapper (which have the prefix
     `SPACK_`) and also add the compiler wrappers to PATH.
@@ -566,39 +458,8 @@ def set_wrapper_variables(pkg, env):
     this function computes these options in a manner that is intended to match the DAG traversal
     order in `SetupContext`. TODO: this is not the case yet, we're using post order, SetupContext
     is using topo order."""
-    # Set environment variables if specified for
+    # Set compiler flags injected from the spec
-    # the given compiler
+    set_wrapper_environment_variables_for_flags(pkg, env)
-    compiler = pkg.compiler
-    env.extend(spack.schema.environment.parse(compiler.environment))
-
-    if compiler.extra_rpaths:
-        extra_rpaths = ":".join(compiler.extra_rpaths)
-        env.set("SPACK_COMPILER_EXTRA_RPATHS", extra_rpaths)
-
-    # Add spack build environment path with compiler wrappers first in
-    # the path. We add the compiler wrapper path, which includes default
-    # wrappers (cc, c++, f77, f90), AND a subdirectory containing
-    # compiler-specific symlinks.  The latter ensures that builds that
-    # are sensitive to the *name* of the compiler see the right name when
-    # we're building with the wrappers.
-    #
-    # Conflicts on case-insensitive systems (like "CC" and "cc") are
-    # handled by putting one in the <build_env_path>/case-insensitive
-    # directory.  Add that to the path too.
-    env_paths = []
-    compiler_specific = os.path.join(
-        spack.paths.build_env_path, os.path.dirname(pkg.compiler.link_paths["cc"])
-    )
-    for item in [spack.paths.build_env_path, compiler_specific]:
-        env_paths.append(item)
-        ci = os.path.join(item, "case-insensitive")
-        if os.path.isdir(ci):
-            env_paths.append(ci)
-
-    tty.debug("Adding compiler bin/ paths: " + " ".join(env_paths))
-    for item in env_paths:
-        env.prepend_path("PATH", item)
-    env.set_path(SPACK_ENV_PATH, env_paths)
 
     # Working directory for the spack command itself, for debug logs.
     if spack.config.get("config:debug"):
@@ -664,22 +525,15 @@ def set_wrapper_variables(pkg, env):
         lib_path = os.path.join(pkg.prefix, libdir)
         rpath_dirs.insert(0, lib_path)
 
-    filter_default_dynamic_linker_search_paths = FilterDefaultDynamicLinkerSearchPaths(
-        pkg.compiler.default_dynamic_linker
-    )
-
     # TODO: filter_system_paths is again wrong (and probably unnecessary due to the is_system_path
     # branch above). link_dirs should be filtered with entries from _parse_link_paths.
     link_dirs = list(dedupe(filter_system_paths(link_dirs)))
     include_dirs = list(dedupe(filter_system_paths(include_dirs)))
     rpath_dirs = list(dedupe(filter_system_paths(rpath_dirs)))
-    rpath_dirs = filter_default_dynamic_linker_search_paths(rpath_dirs)
 
-    # TODO: implicit_rpaths is prefiltered by is_system_path, that should be removed in favor of
+    default_dynamic_linker_filter = spack.compilers.libraries.dynamic_linker_filter_for(pkg.spec)
-    # just this filter.
+    if default_dynamic_linker_filter:
-    implicit_rpaths = filter_default_dynamic_linker_search_paths(pkg.compiler.implicit_rpaths())
+        rpath_dirs = default_dynamic_linker_filter(rpath_dirs)
-    if implicit_rpaths:
-        env.set("SPACK_COMPILER_IMPLICIT_RPATHS", ":".join(implicit_rpaths))
 
     # Spack managed directories include the stage, store and upstream stores. We extend this with
     # their real paths to make it more robust (e.g. /tmp vs /private/tmp on macOS).
@@ -731,26 +585,6 @@ def set_package_py_globals(pkg, context: Context = Context.BUILD):
     # Don't use which for this; we want to find it in the current dir.
     module.configure = Executable("./configure")
 
-    # Put spack compiler paths in module scope. (Some packages use it
-    # in setup_run_environment etc, so don't put it context == build)
-    link_dir = spack.paths.build_env_path
-    pkg_compiler = None
-    try:
-        pkg_compiler = pkg.compiler
-    except spack.compilers.NoCompilerForSpecError as e:
-        tty.debug(f"cannot set 'spack_cc': {str(e)}")
-
-    if pkg_compiler is not None:
-        module.spack_cc = os.path.join(link_dir, pkg_compiler.link_paths["cc"])
-        module.spack_cxx = os.path.join(link_dir, pkg_compiler.link_paths["cxx"])
-        module.spack_f77 = os.path.join(link_dir, pkg_compiler.link_paths["f77"])
-        module.spack_fc = os.path.join(link_dir, pkg_compiler.link_paths["fc"])
-    else:
-        module.spack_cc = None
-        module.spack_cxx = None
-        module.spack_f77 = None
-        module.spack_fc = None
-
     # Useful directories within the prefix are encapsulated in
     # a Prefix object.
     module.prefix = pkg.prefix
@@ -881,21 +715,6 @@ def get_rpath_deps(pkg: spack.package_base.PackageBase) -> List[spack.spec.Spec]
     return _get_rpath_deps_from_spec(pkg.spec, pkg.transitive_rpaths)
 
 
-def load_external_modules(pkg):
-    """Traverse a package's spec DAG and load any external modules.
-
-    Traverse a package's dependencies and load any external modules
-    associated with them.
-
-    Args:
-        pkg (spack.package_base.PackageBase): package to load deps for
-    """
-    for dep in list(pkg.spec.traverse()):
-        external_modules = dep.external_modules or []
-        for external_module in external_modules:
-            load_module(external_module)
-
-
 def setup_package(pkg, dirty, context: Context = Context.BUILD):
     """Execute all environment setup routines."""
     if context not in (Context.BUILD, Context.TEST):
@@ -916,7 +735,6 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
         context == Context.TEST and pkg.test_requires_compiler
     )
     if need_compiler:
-        set_compiler_environment_variables(pkg, env_mods)
         set_wrapper_variables(pkg, env_mods)
 
     # Platform specific setup goes before package specific setup. This is for setting
@@ -928,6 +746,26 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
     env_mods.extend(setup_context.get_env_modifications())
     tty.debug("setup_package: collected all modifications from dependencies")
 
+    tty.debug("setup_package: adding compiler wrappers paths")
+    env_by_name = env_mods.group_by_name()
+    for x in env_by_name["SPACK_COMPILER_WRAPPER_PATH"]:
+        assert isinstance(
+            x, PrependPath
+        ), "unexpected setting used for SPACK_COMPILER_WRAPPER_PATH"
+        env_mods.prepend_path("PATH", x.value)
+
+    # Check whether we want to force RPATH or RUNPATH
+    enable_var_name, disable_var_name = "SPACK_ENABLE_NEW_DTAGS", "SPACK_DISABLE_NEW_DTAGS"
+    if enable_var_name in env_by_name and disable_var_name in env_by_name:
+        enable_new_dtags = _extract_dtags_arg(env_by_name, var_name=enable_var_name)
+        disable_new_dtags = _extract_dtags_arg(env_by_name, var_name=disable_var_name)
+        if spack.config.CONFIG.get("config:shared_linking:type") == "rpath":
+            env_mods.set("SPACK_DTAGS_TO_STRIP", enable_new_dtags)
+            env_mods.set("SPACK_DTAGS_TO_ADD", disable_new_dtags)
+        else:
+            env_mods.set("SPACK_DTAGS_TO_STRIP", disable_new_dtags)
+            env_mods.set("SPACK_DTAGS_TO_ADD", enable_new_dtags)
+
     if context == Context.TEST:
         env_mods.prepend_path("PATH", ".")
     elif context == Context.BUILD and not dirty and not env_mods.is_unset("CPATH"):
@@ -941,12 +779,7 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
 
     # Load modules on an already clean environment, just before applying Spack's
     # own environment modifications. This ensures Spack controls CC/CXX/... variables.
-    if need_compiler:
+    load_external_modules(setup_context)
-        tty.debug("setup_package: loading compiler modules")
-        for mod in pkg.compiler.modules:
-            load_module(mod)
-
-    load_external_modules(pkg)
 
     # Make sure nothing's strange about the Spack environment.
     validate(env_mods, tty.warn)
@@ -957,6 +790,14 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
     return env_base
 
 
+def _extract_dtags_arg(env_by_name: Dict[str, ModificationList], *, var_name: str) -> str:
+    try:
+        enable_new_dtags = env_by_name[var_name][0].value  # type: ignore[union-attr]
+    except (KeyError, IndexError, AttributeError):
+        enable_new_dtags = ""
+    return enable_new_dtags
+
+
 class EnvironmentVisitor:
     def __init__(self, *roots: spack.spec.Spec, context: Context):
         # For the roots (well, marked specs) we follow different edges
@@ -1235,6 +1076,21 @@ def _make_runnable(self, dep: spack.spec.Spec, env: EnvironmentModifications):
                 env.prepend_path("PATH", bin_dir)
 
 
+def load_external_modules(context: SetupContext) -> None:
+    """Traverse a package's spec DAG and load any external modules.
+
+    Traverse a package's dependencies and load any external modules
+    associated with them.
+
+    Args:
+        context: A populated SetupContext object
+    """
+    for spec, _ in context.external:
+        external_modules = spec.external_modules or []
+        for external_module in external_modules:
+            load_module(external_module)
+
+
 def _setup_pkg_and_run(
     serialized_pkg: "spack.subprocess_context.PackageInstallContext",
     function: Callable,

lib/spack/spack/build_systems/autotools.py

@@ -11,6 +11,7 @@
 
 import spack.build_environment
 import spack.builder
+import spack.compilers.libraries
 import spack.error
 import spack.package_base
 import spack.phase_callbacks
@@ -398,33 +399,44 @@ def _do_patch_libtool(self) -> None:
             markers[tag] = "LIBTOOL TAG CONFIG: {0}".format(tag.upper())
 
         # Replace empty linker flag prefixes:
-        if self.pkg.compiler.name == "nag":
+        if self.spec.satisfies("%nag"):
             # Nag is mixed with gcc and g++, which are recognized correctly.
             # Therefore, we change only Fortran values:
+            nag_pkg = self.spec["fortran"].package
             for tag in ["fc", "f77"]:
                 marker = markers[tag]
                 x.filter(
                     regex='^wl=""$',
-                    repl='wl="{0}"'.format(self.pkg.compiler.linker_arg),
+                    repl=f'wl="{nag_pkg.linker_arg}"',
-                    start_at="# ### BEGIN {0}".format(marker),
+                    start_at=f"# ### BEGIN {marker}",
-                    stop_at="# ### END {0}".format(marker),
+                    stop_at=f"# ### END {marker}",
                 )
         else:
-            x.filter(regex='^wl=""$', repl='wl="{0}"'.format(self.pkg.compiler.linker_arg))
+            compiler_spec = spack.compilers.libraries.compiler_spec(self.spec)
+            if compiler_spec:
+                x.filter(regex='^wl=""$', repl='wl="{0}"'.format(compiler_spec.package.linker_arg))
 
         # Replace empty PIC flag values:
-        for cc, marker in markers.items():
+        for compiler, marker in markers.items():
+            if compiler == "cc":
+                language = "c"
+            elif compiler == "cxx":
+                language = "cxx"
+            else:
+                language = "fortran"
+
+            if language not in self.spec:
+                continue
+
             x.filter(
                 regex='^pic_flag=""$',
-                repl='pic_flag="{0}"'.format(
+                repl=f'pic_flag="{self.spec[language].package.pic_flag}"',
-                    getattr(self.pkg.compiler, "{0}_pic_flag".format(cc))
+                start_at=f"# ### BEGIN {marker}",
-                ),
+                stop_at=f"# ### END {marker}",
-                start_at="# ### BEGIN {0}".format(marker),
-                stop_at="# ### END {0}".format(marker),
             )
 
         # Other compiler-specific patches:
-        if self.pkg.compiler.name == "fj":
+        if self.spec.satisfies("%fj"):
             x.filter(regex="-nostdlib", repl="", string=True)
             rehead = r"/\S*/"
             for o in [
@@ -437,7 +449,7 @@ def _do_patch_libtool(self) -> None:
                 r"crtendS\.o",
             ]:
                 x.filter(regex=(rehead + o), repl="")
-        elif self.pkg.compiler.name == "nag":
+        elif self.spec.satisfies("%nag"):
             for tag in ["fc", "f77"]:
                 marker = markers[tag]
                 start_at = "# ### BEGIN {0}".format(marker)

lib/spack/spack/build_systems/cached_cmake.py

@@ -70,12 +70,8 @@ class CachedCMakeBuilder(CMakeBuilder):
 
     @property
     def cache_name(self):
-        return "{0}-{1}-{2}@{3}.cmake".format(
+        compiler_str = f"{self.spec['c'].name}-{self.spec['c'].version}"
-            self.pkg.name,
+        return f"{self.pkg.name}-{self.spec.architecture.platform}-{compiler_str}.cmake"
-            self.pkg.spec.architecture,
-            self.pkg.spec.compiler.name,
-            self.pkg.spec.compiler.version,
-        )
 
     @property
     def cache_path(self):
@@ -118,7 +114,9 @@ def initconfig_compiler_entries(self):
         # Fortran compiler is optional
         if "FC" in os.environ:
             spack_fc_entry = cmake_cache_path("CMAKE_Fortran_COMPILER", os.environ["FC"])
-            system_fc_entry = cmake_cache_path("CMAKE_Fortran_COMPILER", self.pkg.compiler.fc)
+            system_fc_entry = cmake_cache_path(
+                "CMAKE_Fortran_COMPILER", self.spec["fortran"].package.fortran
+            )
         else:
             spack_fc_entry = "# No Fortran compiler defined in spec"
             system_fc_entry = "# No Fortran compiler defined in spec"
@@ -134,8 +132,8 @@ def initconfig_compiler_entries(self):
             "  " + cmake_cache_path("CMAKE_CXX_COMPILER", os.environ["CXX"]),
             "  " + spack_fc_entry,
             "else()\n",
-            "  " + cmake_cache_path("CMAKE_C_COMPILER", self.pkg.compiler.cc),
+            "  " + cmake_cache_path("CMAKE_C_COMPILER", self.spec["c"].package.cc),
-            "  " + cmake_cache_path("CMAKE_CXX_COMPILER", self.pkg.compiler.cxx),
+            "  " + cmake_cache_path("CMAKE_CXX_COMPILER", self.spec["cxx"].package.cxx),
             "  " + system_fc_entry,
             "endif()\n",
         ]
@@ -278,17 +276,24 @@ def initconfig_hardware_entries(self):
             entries.append("# ROCm")
             entries.append("#------------------{0}\n".format("-" * 30))
 
-            # Explicitly setting HIP_ROOT_DIR may be a patch that is no longer necessary
+            if spec.satisfies("^blt@0.7:"):
-            entries.append(cmake_cache_path("HIP_ROOT_DIR", "{0}".format(spec["hip"].prefix)))
+                rocm_root = os.path.dirname(spec["llvm-amdgpu"].prefix)
-            llvm_bin = spec["llvm-amdgpu"].prefix.bin
+                entries.append(cmake_cache_path("ROCM_PATH", rocm_root))
-            llvm_prefix = spec["llvm-amdgpu"].prefix
+            else:
-            # Some ROCm systems seem to point to /<path>/rocm-<ver>/ and
+                # Explicitly setting HIP_ROOT_DIR may be a patch that is no longer necessary
-            # others point to /<path>/rocm-<ver>/llvm
+                entries.append(cmake_cache_path("HIP_ROOT_DIR", "{0}".format(spec["hip"].prefix)))
-            if os.path.basename(os.path.normpath(llvm_prefix)) != "llvm":
+                llvm_bin = spec["llvm-amdgpu"].prefix.bin
-                llvm_bin = os.path.join(llvm_prefix, "llvm/bin/")
+                llvm_prefix = spec["llvm-amdgpu"].prefix
-            entries.append(
+                # Some ROCm systems seem to point to /<path>/rocm-<ver>/ and
-                cmake_cache_filepath("CMAKE_HIP_COMPILER", os.path.join(llvm_bin, "clang++"))
+                # others point to /<path>/rocm-<ver>/llvm
-            )
+                if os.path.basename(os.path.normpath(llvm_prefix)) != "llvm":
+                    llvm_bin = os.path.join(llvm_prefix, "llvm/bin/")
+                entries.append(
+                    cmake_cache_filepath(
+                        "CMAKE_HIP_COMPILER", os.path.join(llvm_bin, "amdclang++")
+                    )
+                )
+
             archs = self.spec.variants["amdgpu_target"].value
             if archs[0] != "none":
                 arch_str = ";".join(archs)

lib/spack/spack/build_systems/compiler.py

@@ -6,12 +6,13 @@
 import pathlib
 import re
 import sys
-from typing import Dict, List, Sequence, Tuple, Union
+from typing import Dict, List, Optional, Sequence, Tuple, Union
 
 import llnl.util.tty as tty
-from llnl.util.lang import classproperty
+from llnl.util.lang import classproperty, memoized
 
-import spack.compiler
+import spack
+import spack.compilers.error
 import spack.package_base
 import spack.util.executable
 
@@ -43,6 +44,9 @@ class CompilerPackage(spack.package_base.PackageBase):
     #: Static definition of languages supported by this class
     compiler_languages: Sequence[str] = ["c", "cxx", "fortran"]
 
+    #: Relative path to compiler wrappers
+    compiler_wrapper_link_paths: Dict[str, str] = {}
+
     def __init__(self, spec: "spack.spec.Spec"):
         super().__init__(spec)
         msg = f"Supported languages for {spec} are not a subset of possible supported languages"
@@ -77,14 +81,14 @@ def executables(cls) -> Sequence[str]:
         ]
 
     @classmethod
-    def determine_version(cls, exe: Path):
+    def determine_version(cls, exe: Path) -> str:
         version_argument = cls.compiler_version_argument
         if isinstance(version_argument, str):
             version_argument = (version_argument,)
 
         for va in version_argument:
             try:
-                output = spack.compiler.get_compiler_version_output(exe, va)
+                output = compiler_output(exe, version_argument=va)
                 match = re.search(cls.compiler_version_regex, output)
                 if match:
                     return ".".join(match.groups())
@@ -95,10 +99,11 @@ def determine_version(cls, exe: Path):
                     f"[{__file__}] Cannot detect a valid version for the executable "
                     f"{str(exe)}, for package '{cls.name}': {e}"
                 )
+        return ""
 
     @classmethod
     def compiler_bindir(cls, prefix: Path) -> Path:
-        """Overridable method for the location of the compiler bindir within the preifx"""
+        """Overridable method for the location of the compiler bindir within the prefix"""
         return os.path.join(prefix, "bin")
 
     @classmethod
@@ -142,3 +147,109 @@ def determine_compiler_paths(cls, exes: Sequence[Path]) -> Dict[str, Path]:
     def determine_variants(cls, exes: Sequence[Path], version_str: str) -> Tuple:
         # path determination is separated so it can be reused in subclasses
         return "", {"compilers": cls.determine_compiler_paths(exes=exes)}
+
+    #: Returns the argument needed to set the RPATH, or None if it does not exist
+    rpath_arg: Optional[str] = "-Wl,-rpath,"
+    #: Flag that needs to be used to pass an argument to the linker
+    linker_arg: str = "-Wl,"
+    #: Flag used to produce Position Independent Code
+    pic_flag: str = "-fPIC"
+    #: Flag used to get verbose output
+    verbose_flags: str = "-v"
+    #: Flag to activate OpenMP support
+    openmp_flag: str = "-fopenmp"
+
+    implicit_rpath_libs: List[str] = []
+
+    def standard_flag(self, *, language: str, standard: str) -> str:
+        """Returns the flag used to enforce a given standard for a language"""
+        if language not in self.supported_languages:
+            raise spack.compilers.error.UnsupportedCompilerFlag(
+                f"{self.spec} does not provide the '{language}' language"
+            )
+        try:
+            return self._standard_flag(language=language, standard=standard)
+        except (KeyError, RuntimeError) as e:
+            raise spack.compilers.error.UnsupportedCompilerFlag(
+                f"{self.spec} does not provide the '{language}' standard {standard}"
+            ) from e
+
+    def _standard_flag(self, *, language: str, standard: str) -> str:
+        raise NotImplementedError("Must be implemented by derived classes")
+
+    def archspec_name(self) -> str:
+        """Name that archspec uses to refer to this compiler"""
+        return self.spec.name
+
+    @property
+    def cc(self) -> Optional[str]:
+        assert self.spec.concrete, "cannot retrieve C compiler, spec is not concrete"
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("c", None)
+        return self._cc_path()
+
+    def _cc_path(self) -> Optional[str]:
+        """Returns the path to the C compiler, if the package was installed by Spack"""
+        return None
+
+    @property
+    def cxx(self) -> Optional[str]:
+        assert self.spec.concrete, "cannot retrieve C++ compiler, spec is not concrete"
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("cxx", None)
+        return self._cxx_path()
+
+    def _cxx_path(self) -> Optional[str]:
+        """Returns the path to the C++ compiler, if the package was installed by Spack"""
+        return None
+
+    @property
+    def fortran(self):
+        assert self.spec.concrete, "cannot retrieve Fortran compiler, spec is not concrete"
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("fortran", None)
+        return self._fortran_path()
+
+    def _fortran_path(self) -> Optional[str]:
+        """Returns the path to the Fortran compiler, if the package was installed by Spack"""
+        return None
+
+
+@memoized
+def _compiler_output(
+    compiler_path: Path, *, version_argument: str, ignore_errors: Tuple[int, ...] = ()
+) -> str:
+    """Returns the output from the compiler invoked with the given version argument.
+
+    Args:
+        compiler_path: path of the compiler to be invoked
+        version_argument: the argument used to extract version information
+    """
+    compiler = spack.util.executable.Executable(compiler_path)
+    if not version_argument:
+        return compiler(
+            output=str, error=str, ignore_errors=ignore_errors, timeout=120, fail_on_error=True
+        )
+    return compiler(
+        version_argument,
+        output=str,
+        error=str,
+        ignore_errors=ignore_errors,
+        timeout=120,
+        fail_on_error=True,
+    )
+
+
+def compiler_output(
+    compiler_path: Path, *, version_argument: str, ignore_errors: Tuple[int, ...] = ()
+) -> str:
+    """Wrapper for _get_compiler_version_output()."""
+    # This ensures that we memoize compiler output by *absolute path*,
+    # not just executable name. If we don't do this, and the path changes
+    # (e.g., during testing), we can get incorrect results.
+    if not os.path.isabs(compiler_path):
+        compiler_path = spack.util.executable.which_string(str(compiler_path), required=True)
+
+    return _compiler_output(
+        compiler_path, version_argument=version_argument, ignore_errors=ignore_errors
+    )

lib/spack/spack/build_systems/msbuild.py

@@ -76,7 +76,7 @@ def toolchain_version(self):
         Override this method to select a specific version of the toolchain or change
         selection heuristics.
         Default is whatever version of msvc has been selected by concretization"""
-        return "v" + self.pkg.compiler.platform_toolset_ver
+        return "v" + self.spec["msvc"].package.platform_toolset_ver
 
     @property
     def std_msbuild_args(self):