msvc: remove conjoined msvc/ifx detection

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

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]
-      cxx: [gcc]
+      c: [gcc, llvm, intel-oneapi-compilers]
+      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
-
-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 ::
+To build the ``patchelf`` Spack package 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
-``compilers.yaml`` and ``packages.yaml`` files) at
+You can find the source for this package (and suggestions for setting up your ``packages.yaml`` file) at
 `<https://github.com/spack/spack/blob/develop/lib/spack/spack/build_systems/rocm.py>`__.
 
 ^^^^^^^^

lib/spack/docs/configuration.rst

@@ -11,7 +11,7 @@ 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>`
@@ -95,7 +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

@@ -686,7 +686,7 @@ the environment.
    spack:
      include:
      - 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

lib/spack/docs/getting_started.rst

@@ -254,12 +254,11 @@ directory.
 Compiler configuration
 ----------------------
 
-Spack has the ability to build packages with multiple compilers and
-compiler versions. Compilers can be made available to Spack by
-specifying them manually in ``compilers.yaml`` or ``packages.yaml``,
-or automatically by running ``spack compiler find``, but for
-convenience Spack will automatically detect compilers the first time
-it needs them.
+Spack has the ability to build packages with multiple compilers and compiler versions.
+Compilers can be made available to Spack by specifying them manually in ``packages.yaml``,
+or automatically by running ``spack compiler find``.
+For convenience, Spack will automatically detect compilers the first time it needs them,
+if none is available.
 
 .. _cmd-spack-compilers:
 
@@ -274,16 +273,11 @@ compilers`` or ``spack compiler list``:
 
    $ spack compilers
    ==> Available compilers
-   -- gcc ---------------------------------------------------------
-       gcc@4.9.0  gcc@4.8.0  gcc@4.7.0  gcc@4.6.2  gcc@4.4.7
-       gcc@4.8.2  gcc@4.7.1  gcc@4.6.3  gcc@4.6.1  gcc@4.1.2
-   -- intel -------------------------------------------------------
-       intel@15.0.0  intel@14.0.0  intel@13.0.0  intel@12.1.0  intel@10.0
-       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
+   -- gcc ubuntu20.04-x86_64 ---------------------------------------
+   gcc@9.4.0  gcc@8.4.0  gcc@10.5.0
+
+   -- llvm ubuntu20.04-x86_64 --------------------------------------
+   llvm@12.0.0  llvm@11.0.0  llvm@10.0.0
 
 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
-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:
+If you do not see a compiler in the list shown by:
 
 .. code-block:: console
 
-   $ spack compiler find /usr/local/tools/ic-13.0.079
-   ==> Added 1 new compiler to ~/.spack/linux/compilers.yaml
-       intel@13.0.079
+   $ spack compiler 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 /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
-``spack compiler info`` on it:
+If you want to see additional information on some specific compilers, you can run ``spack compiler info`` on it:
 
 .. code-block:: console
 
-   $ spack compiler info intel@15
-   intel@15.0.0:
-     paths:
-       cc  = /usr/local/bin/icc-15.0.090
-       cxx = /usr/local/bin/icpc-15.0.090
-       f77 = /usr/local/bin/ifort-15.0.090
-       fc  = /usr/local/bin/ifort-15.0.090
-     modules = []
-     operating_system = centos6
-   ...
+   $ spack compiler info gcc
+   gcc@=8.4.0 languages='c,c++,fortran' arch=linux-ubuntu20.04-x86_64:
+     prefix: /usr
+     compilers:
+       c: /usr/bin/gcc-8
+       cxx: /usr/bin/g++-8
+       fortran: /usr/bin/gfortran-8
 
-This shows which C, C++, and Fortran compilers were detected by Spack.
-Notice also that we didn't have to be too specific about the
-version. We just said ``intel@15``, and information about the only
-matching Intel compiler was displayed.
+   gcc@=9.4.0 languages='c,c++,fortran' arch=linux-ubuntu20.04-x86_64:
+     prefix: /usr
+     compilers:
+       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
-editing your ``~/.spack/<platform>/compilers.yaml`` file.  You can do this by running
-``spack config edit compilers``, which will open the file in
+If auto-detection fails, you can manually configure a compiler by editing your ``~/.spack/packages.yaml`` file.
+You can do this by running ``spack config edit packages``, 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:
-   - compiler:
-       modules: []
-       operating_system: centos6
-       paths:
-         cc: /usr/local/bin/icc-15.0.024-beta
-         cxx: /usr/local/bin/icpc-15.0.024-beta
-         f77: /usr/local/bin/ifort-15.0.024-beta
-         fc: /usr/local/bin/ifort-15.0.024-beta
-       spec: intel@15.0.0
+   packages:
+     gcc:
+       externals:
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
+         prefix: /usr
+         extra_attributes:
+           compilers:
+             c: /usr/bin/gcc-10
+             cxx: /usr/bin/g++-10
+             fortran: /usr/bin/gfortran-10
 
-For compilers that do not support Fortran (like ``clang``), put
-``None`` for ``f77`` and ``fc``:
+The compiler executables are listed under ``extra_attributes:compilers``, and are keyed by language.
+Once you save the file, the configured compilers will show up in the list displayed by ``spack compilers``.
 
-.. code-block:: yaml
-
-   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``,
+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:
-   - compiler:
-       modules: []
-       operating_system: centos6
-       paths:
-         cc: /usr/bin/gcc
-         cxx: /usr/bin/g++
-         f77: /usr/bin/gfortran
-         fc: /usr/bin/gfortran
-       flags:
-         cflags: -O3 -fPIC
-         cxxflags: -O3 -fPIC
-         cppflags: -O3 -fPIC
-       spec: gcc@4.7.2
+   packages:
+     gcc:
+       externals:
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
+         prefix: /usr
+         extra_attributes:
+           compilers:
+             c: /usr/bin/gcc-10
+             cxx: /usr/bin/g++-10
+             fortran: /usr/bin/gfortran-10
+           flags:
+             cflags: -O3 -fPIC
+             cxxflags: -O3 -fPIC
+             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:
-       external:
-       - spec: gcc@12.2.0 arch=linux-rhel8-skylake
-         prefix: /usr
-         extra_attributes:
-           environment:
-             set:
-               GCC_ROOT: /usr
-       external:
-       - spec: llvm+clang@15.0.0 arch=linux-rhel8-skylake
-         prefix: /usr
+     intel-oneapi-compilers:
+       externals:
+       - spec: intel-oneapi-compilers@2025.1.0
+         prefix: /opt/intel/oneapi
          extra_attributes:
            compilers:
-             c: /usr/bin/clang-with-suffix
-             cxx: /usr/bin/clang++-with-extra-info
-             fortran: /usr/bin/gfortran
-           extra_rpaths:
-           - /usr/lib/llvm/
+             c: /opt/intel/oneapi/compiler/2025.1/bin/icx
+             cxx: /opt/intel/oneapi/compiler/2025.1/bin/icpx
+             fortran: /opt/intel/oneapi/compiler/2025.1/bin/ifx
+           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
 
 ^^^^^^^^^^^^^^^^^^^^^^^
 Build Your Own Compiler
 ^^^^^^^^^^^^^^^^^^^^^^^
 
-If you are particular about which compiler/version you use, you might
-wish to have Spack build it for you.  For example:
+If you are particular about which compiler/version you use, you might wish to have Spack build it for you.
+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
-``compilers.yaml`` file.  You can then set Spack to use it by default
-by adding the following to your ``packages.yaml`` file:
+Once the compiler is installed, you can start using it without additional configuration:
 
-.. code-block:: yaml
+.. code-block:: console
 
-   packages:
-     all:
-       compiler: [gcc@4.9.3]
+   $ spack install hdf5~mpi %gcc@14
+
+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
-are called with.  However, some installed compilers require
-``$LD_LIBRARY_PATH`` or other environment variables to be set in order
-to run; this is typical for Intel and other proprietary compilers.
+Many installed compilers will work regardless of the environment they are called with.
+However, some installed compilers require environment variables to be set in order 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
-to run the chosen compiler (If the compiler does not come with a
-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:
+On typical HPC clusters, these environment modifications are usually delegated to some "module" system.
+In such a case, you should tell Spack which module(s) to load in order to run the chosen compiler:
 
 .. code-block:: yaml
 
-   compilers:
-   - compiler:
-       modules: [other/comp/gcc-5.3-sp3]
-       operating_system: SuSE11
-       paths:
-         cc: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gcc
-         cxx: /usr/local/other/SLES11.3/gcc/5.3.0/bin/g++
-         f77: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gfortran
-         fc: /usr/local/other/SLES11.3/gcc/5.3.0/bin/gfortran
-       spec: gcc@5.3.0
+   packages:
+     gcc:
+       externals:
+       - spec: gcc@10.5.0 languages='c,c++,fortran'
+         prefix: /opt/compilers
+         extra_attributes:
+           compilers:
+             c: /opt/compilers/bin/gcc-10
+             cxx: /opt/compilers/bin/g++-10
+             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
-   above.
+#. Add the newly-installed compiler to ``packages.yaml`` as shown 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
-Capitan (10.11), many packages no longer build with GCC, but XCode
-provides no Fortran compilers.  The user is therefore forced to use a
-mixed toolchain: XCode-provided Clang for C/C++ and GNU ``gfortran`` for
-Fortran.
+In some cases, this is not possible.  For example, XCode on macOS provides no Fortran compilers.
+The user is therefore forced to use a mixed toolchain: XCode-provided Clang for C/C++ and e.g.
+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
-   the path to ``gfortran``:
+#. Run ``spack compiler find`` to locate both Apple-Clang and GCC.
 
-   .. code-block:: yaml
-
-      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``.
+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.
 
 ^^^^^^^^^^^^^^^^^^^^^
 Compiler Verification
 ^^^^^^^^^^^^^^^^^^^^^
 
-You can verify that your compilers are configured properly by installing a
-simple package.  For example:
+You can verify that your compilers are configured properly by installing a 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
-compilers.  This section provides details on how to get specific
-compilers working.
+This section provides details on how to get vendor-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``
-      or ``-gxx-name`` compiler option to specify the path to the version of
+      version on your system, you need to use either the ``--gcc-install-dir``
+      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,
-this requires you to set up a :ref:`mixed-toolchains`. It is recommended to use
-GCC for your C/C++ compilers.
+The Numerical Algorithms Group provides a licensed Fortran compiler.
+It is recommended to use 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:
-    modules: []
-    operating_system: centos6
-    paths:
-      cc: /soft/spack/opt/spack/linux-x86_64/gcc-5.3.0/gcc-6.1.0-q2zosj3igepi3pjnqt74bwazmptr5gpj/bin/gcc
-      cxx: /soft/spack/opt/spack/linux-x86_64/gcc-5.3.0/gcc-6.1.0-q2zosj3igepi3pjnqt74bwazmptr5gpj/bin/g++
-      f77: /soft/spack/opt/spack/linux-x86_64/gcc-4.4.7/nag-6.1-jt3h5hwt5myezgqguhfsan52zcskqene/bin/nagfor
-      fc: /soft/spack/opt/spack/linux-x86_64/gcc-4.4.7/nag-6.1-jt3h5hwt5myezgqguhfsan52zcskqene/bin/nagfor
-    flags:
-      fflags: -mismatch
-    spec: nag@6.1
-
+   packages:
+     nag:
+       externals:
+       - spec: nag@6.1
+         prefix: /opt/nag/bin
+         extra_attributes:
+           compilers:
+             fortran: /opt/nag/bin/nagfor
+         flags:
+           fflags: -mismatch
 
 ---------------
 System Packages
 ---------------
 
-Once compilers are configured, one needs to determine which
-pre-installed system packages, if any, to use in builds.  This is
-configured in the file ``~/.spack/packages.yaml``.  For example, to use
-an OpenMPI installed in /opt/local, one would use:
+Once compilers are configured, one needs to determine which pre-installed system packages,
+if any, to use in builds.  These are also configured in the ``~/.spack/packages.yaml`` file.
+For example, to use an OpenMPI installed in /opt/local, one would use:
 
 .. code-block:: yaml
 
-    packages:
-        openmpi:
-            externals:
-            - spec: openmpi@1.10.1
-              prefix: /opt/local
-            buildable: False
+   packages:
+     openmpi:
+       buildable: False
+       externals:
+       - spec: openmpi@1.10.1
+         prefix: /opt/local
 
-In general, Spack is easier to use and more reliable if it builds all of
-its own dependencies.  However, there are several packages for which one
-commonly needs to use system versions:
+In general, *Spack is easier to use and more reliable if it builds all of its own dependencies*.
+However, there are several packages for which one 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
-``compilers.yaml``.
+pre-installed compiler used to build that MPI.
 
 ^^^^^^^
 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/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/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

@@ -73,7 +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:
@@ -1016,11 +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(
-                context,
-                exc.__class__.__name__,
-                exc,
-                "\n{0}".format("".join(tb)) if with_tracebacks else "",
+            "\n\t{0} raised {1}: {2}\n{3}".format(
+                context, exc.__class__.__name__, exc, f"\n{''.join(tb)}" if with_tracebacks else ""
             )
             for context, exc, tb in self.exceptions
         ]

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
+import spack.compilers.config
+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):
-        spack.compilers.find_compilers()
+    if not spack.compilers.config.compilers_for_arch(arch):
+        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, 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))
-
+    version_number, _ = archspec.cpu.version_components(compiler.version.dotted_numeric_string)
     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
-    # the given compiler
-    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)
+    # Set compiler flags injected from the spec
+    set_wrapper_environment_variables_for_flags(pkg, env)
 
     # 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
-    # just this filter.
-    implicit_rpaths = filter_default_dynamic_linker_search_paths(pkg.compiler.implicit_rpaths())
-    if implicit_rpaths:
-        env.set("SPACK_COMPILER_IMPLICIT_RPATHS", ":".join(implicit_rpaths))
+    default_dynamic_linker_filter = spack.compilers.libraries.dynamic_linker_filter_for(pkg.spec)
+    if default_dynamic_linker_filter:
+        rpath_dirs = default_dynamic_linker_filter(rpath_dirs)
 
     # 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
@@ -901,7 +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
@@ -913,6 +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"):
@@ -926,11 +779,6 @@ 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:
-        tty.debug("setup_package: loading compiler modules")
-        for mod in pkg.compiler.modules:
-            load_module(mod)
-
     load_external_modules(setup_context)
 
     # Make sure nothing's strange about the Spack environment.
@@ -942,6 +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

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=""$',
-                    repl='wl="{0}"'.format(self.pkg.compiler.linker_arg),
-                    start_at="# ### BEGIN {0}".format(marker),
-                    stop_at="# ### END {0}".format(marker),
+                    repl=f'wl="{nag_pkg.linker_arg}"',
+                    start_at=f"# ### BEGIN {marker}",
+                    stop_at=f"# ### END {marker}",
                 )
         else:
-            x.filter(regex='^wl=""$', 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(
-                    getattr(self.pkg.compiler, "{0}_pic_flag".format(cc))
-                ),
-                start_at="# ### BEGIN {0}".format(marker),
-                stop_at="# ### END {0}".format(marker),
+                repl=f'pic_flag="{self.spec[language].package.pic_flag}"',
+                start_at=f"# ### BEGIN {marker}",
+                stop_at=f"# ### END {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(
-            self.pkg.name,
-            self.pkg.spec.architecture,
-            self.pkg.spec.compiler.name,
-            self.pkg.spec.compiler.version,
-        )
+        compiler_str = f"{self.spec['c'].name}-{self.spec['c'].version}"
+        return f"{self.pkg.name}-{self.spec.architecture.platform}-{compiler_str}.cmake"
 
     @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_CXX_COMPILER", self.pkg.compiler.cxx),
+            "  " + cmake_cache_path("CMAKE_C_COMPILER", self.spec["c"].package.cc),
+            "  " + cmake_cache_path("CMAKE_CXX_COMPILER", self.spec["cxx"].package.cxx),
             "  " + system_fc_entry,
             "endif()\n",
         ]

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):

lib/spack/spack/build_systems/oneapi.py

@@ -311,4 +311,4 @@ def ld_flags(self):
 
 
 #: Tuple of Intel math libraries, exported to packages
-INTEL_MATH_LIBRARIES = ("intel-mkl", "intel-oneapi-mkl", "intel-parallel-studio")
+INTEL_MATH_LIBRARIES = ("intel-oneapi-mkl",)

lib/spack/spack/build_systems/python.py

@@ -278,10 +278,6 @@ def update_external_dependencies(self, extendee_spec=None):
                         if not python.architecture.target:
                             python.architecture.target = archspec.cpu.host().family.name
 
-                    # Ensure compiler information is present
-                    if not python.compiler:
-                        python.compiler = self.spec.compiler
-
                     python.external_path = self.spec.external_path
                     python._mark_concrete()
             self.spec.add_dependency_edge(python, depflag=dt.BUILD | dt.LINK | dt.RUN, virtuals=())

lib/spack/spack/ci/__init__.py

@@ -24,7 +24,6 @@
 
 import spack
 import spack.binary_distribution as bindist
-import spack.concretize
 import spack.config as cfg
 import spack.environment as ev
 import spack.error
@@ -421,10 +420,9 @@ def generate_pipeline(env: ev.Environment, args) -> None:
         args: (spack.main.SpackArgumentParser): Parsed arguments from the command
             line.
     """
-    with spack.concretize.disable_compiler_existence_check():
-        with env.write_transaction():
-            env.concretize()
-            env.write()
+    with env.write_transaction():
+        env.concretize()
+        env.write()
 
     options = collect_pipeline_options(env, args)
 

lib/spack/spack/ci/common.py

@@ -209,10 +209,8 @@ def build_name(self, spec: Optional[spack.spec.Spec] = None) -> Optional[str]:
 
         Returns: (str) given spec's CDash build name."""
         if spec:
-            build_name = (
-                f"{spec.name}@{spec.version}%{spec.compiler} "
-                f"hash={spec.dag_hash()} arch={spec.architecture} ({self.build_group})"
-            )
+            spec_str = spec.format("{name}{@version}{%compiler} hash={hash} arch={architecture}")
+            build_name = f"{spec_str} ({self.build_group})"
             tty.debug(f"Generated CDash build name ({build_name}) from the {spec.name}")
             return build_name
 

lib/spack/spack/cmd/__init__.py

@@ -375,8 +375,13 @@ def iter_groups(specs, indent, all_headers):
     index = index_by(specs, ("architecture", "compiler"))
     ispace = indent * " "
 
+    def _key(item):
+        if item is None:
+            return ""
+        return str(item)
+
     # Traverse the index and print out each package
-    for i, (architecture, compiler) in enumerate(sorted(index)):
+    for i, (architecture, compiler) in enumerate(sorted(index, key=_key)):
         if i > 0:
             print()
 
@@ -448,7 +453,6 @@ def get_arg(name, default=None):
     hashes = get_arg("long", False)
     namespaces = get_arg("namespaces", False)
     flags = get_arg("show_flags", False)
-    full_compiler = get_arg("show_full_compiler", False)
     variants = get_arg("variants", False)
     groups = get_arg("groups", True)
     all_headers = get_arg("all_headers", False)
@@ -470,10 +474,8 @@ def get_arg(name, default=None):
     if format_string is None:
         nfmt = "{fullname}" if namespaces else "{name}"
         ffmt = ""
-        if full_compiler or flags:
-            ffmt += "{compiler_flags} {%compiler.name}"
-            if full_compiler:
-                ffmt += "{@compiler.version}"
+        if flags:
+            ffmt += " {compiler_flags}"
         vfmt = "{variants}" if variants else ""
         format_string = nfmt + "{@version}" + vfmt + ffmt
 

lib/spack/spack/cmd/ci.py

@@ -4,7 +4,6 @@
 
 import json
 import os
-import re
 import shutil
 import sys
 from typing import Dict
@@ -26,12 +25,10 @@
 import spack.hash_types as ht
 import spack.mirrors.mirror
 import spack.package_base
-import spack.paths
 import spack.repo
 import spack.spec
 import spack.stage
 import spack.util.executable
-import spack.util.git
 import spack.util.gpg as gpg_util
 import spack.util.timer as timer
 import spack.util.url as url_util
@@ -45,7 +42,6 @@
 SPACK_COMMAND = "spack"
 INSTALL_FAIL_CODE = 1
 FAILED_CREATE_BUILDCACHE_CODE = 100
-BUILTIN = re.compile(r"var\/spack\/repos\/builtin\/packages\/([^\/]+)\/package\.py")
 
 
 def deindent(desc):
@@ -783,18 +779,15 @@ def ci_verify_versions(args):
     then parses the git diff between the two to determine which packages
     have been modified verifies the new checksums inside of them.
     """
-    with fs.working_dir(spack.paths.prefix):
-        # We use HEAD^1 explicitly on the merge commit created by
-        # GitHub Actions. However HEAD~1 is a safer default for the helper function.
-        files = spack.util.git.get_modified_files(from_ref=args.from_ref, to_ref=args.to_ref)
-
-    # Get a list of package names from the modified files.
-    pkgs = [(m.group(1), p) for p in files for m in [BUILTIN.search(p)] if m]
+    # Get a list of all packages that have been changed or added
+    # between from_ref and to_ref
+    pkgs = spack.repo.get_all_package_diffs("AC", args.from_ref, args.to_ref)
 
     failed_version = False
-    for pkg_name, path in pkgs:
+    for pkg_name in pkgs:
         spec = spack.spec.Spec(pkg_name)
         pkg = spack.repo.PATH.get_pkg_class(spec.name)(spec)
+        path = spack.repo.PATH.package_path(pkg_name)
 
         # Skip checking manual download packages and trust the maintainers
         if pkg.manual_download:
@@ -818,7 +811,7 @@ def ci_verify_versions(args):
             # TODO: enforce every version have a commit or a sha256 defined if not
             # an infinite version (there are a lot of package's where this doesn't work yet.)
 
-        with fs.working_dir(spack.paths.prefix):
+        with fs.working_dir(os.path.dirname(path)):
             added_checksums = spack_ci.get_added_versions(
                 checksums_version_dict, path, from_ref=args.from_ref, to_ref=args.to_ref
             )

lib/spack/spack/cmd/compiler.py

@@ -4,13 +4,14 @@
 
 import argparse
 import sys
+import warnings
 
 import llnl.util.tty as tty
 from llnl.util.lang import index_by
 from llnl.util.tty.colify import colify
 from llnl.util.tty.color import colorize
 
-import spack.compilers
+import spack.compilers.config
 import spack.config
 import spack.spec
 from spack.cmd.common import arguments
@@ -33,20 +34,20 @@ def setup_parser(subparser):
     mixed_toolchain_group.add_argument(
         "--mixed-toolchain",
         action="store_true",
-        default=sys.platform == "darwin",
-        help="Allow mixed toolchains (for example: clang, clang++, gfortran)",
+        default=False,
+        help="(DEPRECATED) Allow mixed toolchains (for example: clang, clang++, gfortran)",
     )
     mixed_toolchain_group.add_argument(
         "--no-mixed-toolchain",
         action="store_false",
         dest="mixed_toolchain",
-        help="Do not allow mixed toolchains (for example: clang, clang++, gfortran)",
+        help="(DEPRECATED) Do not allow mixed toolchains (for example: clang, clang++, gfortran)",
     )
     find_parser.add_argument("add_paths", nargs=argparse.REMAINDER)
     find_parser.add_argument(
         "--scope",
         action=arguments.ConfigScope,
-        default=lambda: spack.config.default_modify_scope("compilers"),
+        default=lambda: spack.config.default_modify_scope("packages"),
         help="configuration scope to modify",
     )
     arguments.add_common_arguments(find_parser, ["jobs"])
@@ -79,77 +80,97 @@ def compiler_find(args):
     """Search either $PATH or a list of paths OR MODULES for compilers and
     add them to Spack's configuration.
     """
+    if args.mixed_toolchain:
+        warnings.warn(
+            "The '--mixed-toolchain' option has been deprecated in Spack v0.23, and currently "
+            "has no effect. The option will be removed in Spack v1.1"
+        )
+
     paths = args.add_paths or None
-    new_compilers = spack.compilers.find_compilers(
-        path_hints=paths,
-        scope=args.scope,
-        mixed_toolchain=args.mixed_toolchain,
-        max_workers=args.jobs,
+    new_compilers = spack.compilers.config.find_compilers(
+        path_hints=paths, scope=args.scope, max_workers=args.jobs
     )
     if new_compilers:
         n = len(new_compilers)
         s = "s" if n > 1 else ""
-        filename = spack.config.CONFIG.get_config_filename(args.scope, "compilers")
+        filename = spack.config.CONFIG.get_config_filename(args.scope, "packages")
         tty.msg(f"Added {n:d} new compiler{s} to {filename}")
-        compiler_strs = sorted(f"{c.spec.name}@{c.spec.version}" for c in new_compilers)
+        compiler_strs = sorted(f"{spec.name}@{spec.versions}" for spec in new_compilers)
         colify(reversed(compiler_strs), indent=4)
     else:
         tty.msg("Found no new compilers")
     tty.msg("Compilers are defined in the following files:")
-    colify(spack.compilers.compiler_config_files(), indent=4)
+    colify(spack.compilers.config.compiler_config_files(), indent=4)
 
 
 def compiler_remove(args):
-    compiler_spec = spack.spec.CompilerSpec(args.compiler_spec)
-    candidate_compilers = spack.compilers.compilers_for_spec(compiler_spec, scope=args.scope)
+    remover = spack.compilers.config.CompilerRemover(spack.config.CONFIG)
+    candidates = remover.mark_compilers(match=args.compiler_spec, scope=args.scope)
+    if not candidates:
+        tty.die(f"No compiler matches '{args.compiler_spec}'")
 
-    if not candidate_compilers:
-        tty.die("No compilers match spec %s" % compiler_spec)
+    compiler_strs = reversed(sorted(f"{spec.name}@{spec.versions}" for spec in candidates))
 
-    if not args.all and len(candidate_compilers) > 1:
-        tty.error(f"Multiple compilers match spec {compiler_spec}. Choose one:")
-        colify(reversed(sorted([c.spec.display_str for c in candidate_compilers])), indent=4)
-        tty.msg("Or, use `spack compiler remove -a` to remove all of them.")
+    if not args.all and len(candidates) > 1:
+        tty.error(f"multiple compilers match the spec '{args.compiler_spec}':")
+        print()
+        colify(compiler_strs, indent=4)
+        print()
+        print(
+            "Either use a stricter spec to select only one, or use `spack compiler remove -a`"
+            " to remove all of them."
+        )
         sys.exit(1)
 
-    for current_compiler in candidate_compilers:
-        spack.compilers.remove_compiler_from_config(current_compiler.spec, scope=args.scope)
-        tty.msg(f"{current_compiler.spec.display_str} has been removed")
+    remover.flush()
+    tty.msg("The following compilers have been removed:")
+    print()
+    colify(compiler_strs, indent=4)
+    print()
 
 
 def compiler_info(args):
     """Print info about all compilers matching a spec."""
-    cspec = spack.spec.CompilerSpec(args.compiler_spec)
-    compilers = spack.compilers.compilers_for_spec(cspec, scope=args.scope)
+    query = spack.spec.Spec(args.compiler_spec)
+    all_compilers = spack.compilers.config.all_compilers(scope=args.scope, init_config=False)
+
+    compilers = [x for x in all_compilers if x.satisfies(query)]
 
     if not compilers:
-        tty.die("No compilers match spec %s" % cspec)
+        tty.die(f"No compilers match spec {query.cformat()}")
     else:
         for c in compilers:
-            print(c.spec.display_str + ":")
-            print("\tpaths:")
-            for cpath in ["cc", "cxx", "f77", "fc"]:
-                print("\t\t%s = %s" % (cpath, getattr(c, cpath, None)))
-            if c.flags:
-                print("\tflags:")
-                for flag, flag_value in c.flags.items():
-                    print("\t\t%s = %s" % (flag, flag_value))
-            if len(c.environment) != 0:
-                if len(c.environment.get("set", {})) != 0:
+            print(f"{c.cformat()}:")
+            print(f"  prefix: {c.external_path}")
+            extra_attributes = getattr(c, "extra_attributes", {})
+            if "compilers" in extra_attributes:
+                print("  compilers:")
+                for language, exe in extra_attributes.get("compilers", {}).items():
+                    print(f"    {language}: {exe}")
+            if "flags" in extra_attributes:
+                print("  flags:")
+                for flag, flag_value in extra_attributes["flags"].items():
+                    print(f"    {flag} = {flag_value}")
+            if "environment" in extra_attributes:
+                environment = extra_attributes["environment"]
+                if len(environment.get("set", {})) != 0:
                     print("\tenvironment:")
                     print("\t    set:")
-                    for key, value in c.environment["set"].items():
-                        print("\t        %s = %s" % (key, value))
-            if c.extra_rpaths:
-                print("\tExtra rpaths:")
-                for extra_rpath in c.extra_rpaths:
-                    print("\t\t%s" % extra_rpath)
-            print("\tmodules  = %s" % c.modules)
-            print("\toperating system  = %s" % c.operating_system)
+                    for key, value in environment["set"].items():
+                        print(f"\t        {key} = {value}")
+            if "extra_rpaths" in extra_attributes:
+                print("  extra rpaths:")
+                for extra_rpath in extra_attributes["extra_rpaths"]:
+                    print(f"    {extra_rpath}")
+            if getattr(c, "external_modules", []):
+                print("  modules: ")
+                for module in c.external_modules:
+                    print(f"    {module}")
+            print()
 
 
 def compiler_list(args):
-    compilers = spack.compilers.all_compilers(scope=args.scope, init_config=False)
+    compilers = spack.compilers.config.all_compilers(scope=args.scope, init_config=False)
 
     # If there are no compilers in any scope, and we're outputting to a tty, give a
     # hint to the user.
@@ -162,7 +183,7 @@ def compiler_list(args):
         tty.msg(msg)
         return
 
-    index = index_by(compilers, lambda c: (c.spec.name, c.operating_system, c.target))
+    index = index_by(compilers, spack.compilers.config.name_os_target)
 
     tty.msg("Available compilers")
 
@@ -181,10 +202,10 @@ def compiler_list(args):
         name, os, target = key
         os_str = os
         if target:
-            os_str += "-%s" % target
-        cname = "%s{%s} %s" % (spack.spec.COMPILER_COLOR, name, os_str)
+            os_str += f"-{target}"
+        cname = f"{spack.spec.COMPILER_COLOR}{{{name}}} {os_str}"
         tty.hline(colorize(cname), char="-")
-        colify(reversed(sorted(c.spec.display_str for c in compilers)))
+        colify(reversed(sorted(c.format("{name}@{version}") for c in compilers)))
 
 
 def compiler(parser, args):

lib/spack/spack/cmd/config.py

@@ -521,8 +521,6 @@ def config_prefer_upstream(args):
     for spec in pref_specs:
         # Collect all the upstream compilers and versions for this package.
         pkg = pkgs.get(spec.name, {"version": []})
-        all = pkgs.get("all", {"compiler": []})
-        pkgs["all"] = all
         pkgs[spec.name] = pkg
 
         # We have no existing variant if this is our first added version.
@@ -532,10 +530,6 @@ def config_prefer_upstream(args):
         if version not in pkg["version"]:
             pkg["version"].append(version)
 
-        compiler = str(spec.compiler)
-        if compiler not in all["compiler"]:
-            all["compiler"].append(compiler)
-
         # Get and list all the variants that differ from the default.
         variants = []
         for var_name, variant in spec.variants.items():

lib/spack/spack/cmd/create.py

@@ -572,7 +572,7 @@ def edit(self, spec, prefix):
 class IntelPackageTemplate(PackageTemplate):
     """Provides appropriate overrides for licensed Intel software"""
 
-    base_class_name = "IntelPackage"
+    base_class_name = "IntelOneApiPackage"
 
     body_def = """\
     # FIXME: Override `setup_environment` if necessary."""

lib/spack/spack/cmd/find.py

@@ -98,7 +98,7 @@ def setup_parser(subparser):
         "--show-full-compiler",
         action="store_true",
         dest="show_full_compiler",
-        help="show full compiler specs",
+        help="(DEPRECATED) show full compiler specs. Currently it's a no-op",
     )
     implicit_explicit = subparser.add_mutually_exclusive_group()
     implicit_explicit.add_argument(
@@ -278,7 +278,6 @@ def root_decorator(spec, string):
             # these enforce details in the root specs to show what the user asked for
             namespaces=True,
             show_flags=True,
-            show_full_compiler=True,
             decorator=root_decorator,
             variants=True,
         )
@@ -301,7 +300,6 @@ def root_decorator(spec, string):
             decorator=lambda s, f: color.colorize("@*{%s}" % f),
             namespace=True,
             show_flags=True,
-            show_full_compiler=True,
             variants=True,
         )
         print()