Update version number

Signed-off-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

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

@@ -1,7 +1,7 @@
-black==24.10.0
+black==25.1.0
 clingo==5.7.1
-flake8==7.1.1
-isort==5.13.2
-mypy==1.11.2
+flake8==7.1.2
+isort==6.0.0
+mypy==1.15.0
 types-six==1.17.0.20241205
 vermin==1.6.0

etc/spack/defaults/concretizer.yaml

@@ -43,6 +43,28 @@ concretizer:
     # (e.g. py-setuptools, cmake etc.)
     # "full" (experimental): allows separation of the entire build-tool stack (e.g. the entire "cmake" subDAG)
     strategy: minimal
+    # Maximum number of duplicates in a DAG, when using a strategy that allows duplicates. "default" is the
+    # number used if there isn't a more specific alternative
+    max_dupes:
+      default: 1
+      # Virtuals
+      c: 2
+      cxx: 2
+      fortran: 1
+      # Regular packages
+      cmake: 2
+      gmake: 2
+      python: 2
+      python-venv: 2
+      py-cython: 2
+      py-flit-core: 2
+      py-pip: 2
+      py-setuptools: 2
+      py-wheel: 2
+      xcb-proto: 2
+      # Compilers
+      gcc: 2
+      llvm: 2
   # Option to specify compatibility between operating systems for reuse of compilers and packages
   # Specified as a key: [list] where the key is the os that is being targeted, and the list contains the OS's
   # it can reuse. Note this is a directional compatibility so mutual compatibility between two OS's

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/concretizer.yaml

@@ -0,0 +1,2 @@
+concretizer:
+  static_analysis: true

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 +49,9 @@ packages:
     # although the version number used here isn't critical
     - spec: apple-libuuid@1353.100.2
       prefix: /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
+  c:
+    require: apple-clang
+  cxx:
+    require: apple-clang
+  fortran:
+    require: 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, xl, aocc]
+      cxx: [gcc, llvm, intel-oneapi-compilers, xl, aocc]
       D: [ldc]
       daal: [intel-oneapi-daal]
       elf: [elfutils]
       fftw-api: [fftw, amdfftw]
       flame: [libflame, amdlibflame]
-      fortran: [gcc]
+      fortran: [gcc, llvm]
       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/basic_usage.rst

@@ -1761,19 +1761,24 @@ Verifying installations
 The ``spack verify`` command can be used to verify the validity of
 Spack-installed packages any time after installation.
 
+
+^^^^^^^^^^^^^^^^^^^^^^^^^
+``spack verify manifest``
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
 At installation time, Spack creates a manifest of every file in the
 installation prefix. For links, Spack tracks the mode, ownership, and
 destination. For directories, Spack tracks the mode, and
 ownership. For files, Spack tracks the mode, ownership, modification
-time, hash, and size. The Spack verify command will check, for every
-file in each package, whether any of those attributes have changed. It
-will also check for newly added files or deleted files from the
-installation prefix. Spack can either check all installed packages
+time, hash, and size. The ``spack verify manifest`` command will check,
+for every file in each package, whether any of those attributes have
+changed. It will also check for newly added files or deleted files from
+the installation prefix. Spack can either check all installed packages
 using the `-a,--all` or accept specs listed on the command line to
 verify.
 
-The ``spack verify`` command can also verify for individual files that
-they haven't been altered since installation time. If the given file
+The ``spack verify manifest`` command can also verify for individual files
+that they haven't been altered since installation time. If the given file
 is not in a Spack installation prefix, Spack will report that it is
 not owned by any package. To check individual files instead of specs,
 use the ``-f,--files`` option.
@@ -1788,6 +1793,22 @@ check only local packages (as opposed to those used transparently from
 ``upstream`` spack instances) and the ``-j,--json`` option to output
 machine-readable json data for any errors.
 
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+``spack verify libraries``
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ``spack verify libraries`` command can be used to verify that packages
+do not have accidental system dependencies. This command scans the install
+prefixes of packages for executables and shared libraries, and resolves
+their needed libraries in their RPATHs. When needed libraries cannot be
+located, an error is reported. This typically indicates that a package
+was linked against a system library, instead of a library provided by
+a Spack package.
+
+This verification can also be enabled as a post-install hook by setting
+``config:shared_linking:missing_library_policy`` to ``error`` or ``warn``
+in :ref:`config.yaml <config-yaml>`.
+
 -----------------------
 Filesystem requirements
 -----------------------

lib/spack/docs/conf.py

@@ -223,6 +223,10 @@ def setup(sphinx):
     ("py:class", "spack.compiler.CompilerCache"),
     # TypeVar that is not handled correctly
     ("py:class", "llnl.util.lang.T"),
+    ("py:class", "llnl.util.lang.KT"),
+    ("py:class", "llnl.util.lang.VT"),
+    ("py:obj", "llnl.util.lang.KT"),
+    ("py:obj", "llnl.util.lang.VT"),
 ]
 
 # The reST default role (used for this markup: `text`) to use for all documents.

lib/spack/docs/config_yaml.rst

@@ -125,6 +125,8 @@ are stored in ``$spack/var/spack/cache``.  These are stored indefinitely
 by default. Can be purged with :ref:`spack clean --downloads
 <cmd-spack-clean>`.
 
+.. _Misc Cache:
+
 --------------------
 ``misc_cache``
 --------------------
@@ -334,3 +336,52 @@ create a new alias called ``inst`` that will always call ``install -v``:
 
    aliases:
      inst: install -v
+
+-------------------------------
+``concretization_cache:enable``
+-------------------------------
+
+When set to ``true``, Spack will utilize a cache of solver outputs from
+successful concretization runs. When enabled, Spack will check the concretization
+cache prior to running the solver. If a previous request to solve a given
+problem is present in the cache, Spack will load the concrete specs and other
+solver data from the cache rather than running the solver. Specs not previously
+concretized will be added to the cache on a successful solve. The cache additionally
+holds solver statistics, so commands like ``spack solve`` will still return information
+about the run that produced a given solver result.
+
+This cache is a subcache of the :ref:`Misc Cache` and as such will be cleaned when the Misc
+Cache is cleaned.
+
+When ``false`` or ommitted, all concretization requests will be performed from scatch
+
+----------------------------
+``concretization_cache:url``
+----------------------------
+
+Path to the location where Spack will root the concretization cache. Currently this only supports
+paths on the local filesystem.
+
+Default location is under the :ref:`Misc Cache` at: ``$misc_cache/concretization``
+
+------------------------------------
+``concretization_cache:entry_limit``
+------------------------------------
+
+Sets a limit on the number of concretization results that Spack will cache. The limit is evaluated
+after each concretization run; if Spack has stored more results than the limit allows, the
+oldest concretization results are pruned until 10% of the limit has been removed.
+
+Setting this value to 0 disables the automatic pruning. It is expected users will be
+responsible for maintaining this cache.
+
+-----------------------------------
+``concretization_cache:size_limit``
+-----------------------------------
+
+Sets a limit on the size of the concretization cache in bytes. The limit is evaluated
+after each concretization run; if Spack has stored more results than the limit allows, the
+oldest concretization results are pruned until 10% of the limit has been removed.
+
+Setting this value to 0 disables the automatic pruning. It is expected users will be
+responsible for maintaining this cache.

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
@@ -820,6 +820,69 @@ presence of a ``SPACK_CDASH_AUTH_TOKEN`` environment variable during the
 build group on CDash called "Release Testing" (that group will be created if
 it didn't already exist).
 
+.. _ci_artifacts:
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+CI Artifacts Directory Layout
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When running the CI build using the command ``spack ci rebuild`` a number of directories are created for
+storing data generated during the CI job. The default root directory for artifacts is ``job_scratch_root``.
+This can be overridden by passing the argument ``--artifacts-root`` to the ``spack ci generate`` command
+or by setting the ``SPACK_ARTIFACTS_ROOT`` environment variable in the build job scripts.
+
+The top level directories under the artifact root are ``concrete_environment``, ``logs``, ``reproduction``,
+``tests``, and ``user_data``. Spack does not restrict what is written to any of these directories nor does
+it require user specified files be written to any specific directory.
+
+------------------------
+``concrete_environment``
+------------------------
+
+The directory ``concrete_environment`` is used to communicate the ci generate processed ``spack.yaml`` and
+the concrete ``spack.lock`` for the CI environment.
+
+--------
+``logs``
+--------
+
+The directory ``logs`` contains the spack build log, ``spack-build-out.txt``, and the spack build environment
+modification file, ``spack-build-mod-env.txt``. Additionally all files specified by the packages ``Builder``
+property ``archive_files`` are also copied here (ie. ``CMakeCache.txt`` in ``CMakeBuilder``).
+
+----------------
+``reproduction``
+----------------
+
+The directory ``reproduction`` is used to store the files needed by the ``spack reproduce-build`` command.
+This includes ``repro.json``, copies of all of the files in ``concrete_environment``, the concrete spec
+JSON file for the current spec being built, and all of the files written in the artifacts root directory.
+
+The ``repro.json`` file is not versioned and is only designed to work with the version of spack CI was run with.
+An example of what a ``repro.json`` may look like is here.
+
+.. code:: json
+
+  {
+    "job_name": "adios2@2.9.2 /feaevuj %gcc@11.4.0 arch=linux-ubuntu20.04-x86_64_v3 E4S ROCm External",
+    "job_spec_json": "adios2.json",
+    "ci_project_dir": "/builds/spack/spack"
+  }
+
+---------
+``tests``
+---------
+
+The directory ``tests`` is used to store output from running ``spack test <job spec>``. This may or may not have
+data in it depending on the package that was built and the availability of tests.
+
+-------------
+``user_data``
+-------------
+
+The directory ``user_data`` is used to store everything else that shouldn't be copied to the ``reproduction`` direcotory.
+Users may use this to store additional logs or metrics or other types of files generated by the build job.
+
 -------------------------------------
 Using a custom spack in your pipeline
 -------------------------------------

lib/spack/docs/requirements.txt

@@ -1,4 +1,4 @@
-sphinx==8.1.3
+sphinx==8.2.1
 sphinxcontrib-programoutput==0.18
 sphinx_design==0.6.1
 sphinx-rtd-theme==3.0.2
@@ -7,7 +7,7 @@ docutils==0.21.2
 pygments==2.19.1
 urllib3==2.3.0
 pytest==8.3.4
-isort==5.13.2
-black==24.10.0
-flake8==7.1.1
+isort==6.0.0
+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/filesystem.py

@@ -7,6 +7,7 @@
 import fnmatch
 import glob
 import hashlib
+import io
 import itertools
 import numbers
 import os
@@ -20,6 +21,7 @@
 from contextlib import contextmanager
 from itertools import accumulate
 from typing import (
+    IO,
     Callable,
     Deque,
     Dict,
@@ -2454,26 +2456,69 @@ class WindowsSimulatedRPath:
     and vis versa.
     """
 
-    def __init__(self, package, link_install_prefix=True):
+    def __init__(
+        self,
+        package,
+        base_modification_prefix: Optional[Union[str, pathlib.Path]] = None,
+        link_install_prefix: bool = True,
+    ):
         """
         Args:
             package (spack.package_base.PackageBase): Package requiring links
+            base_modification_prefix (str|pathlib.Path): Path representation indicating
+                the root directory in which to establish the simulated rpath, ie where the
+                symlinks that comprise the "rpath" behavior will be installed.
+
+                Note: This is a mutually exclusive option with `link_install_prefix` using
+                both is an error.
+
+                Default: None
             link_install_prefix (bool): Link against package's own install or stage root.
                 Packages that run their own executables during build and require rpaths to
-                the build directory during build time require this option. Default: install
+                the build directory during build time require this option.
+
+                Default: install
                 root
+
+                Note: This is a mutually exclusive option with `base_modification_prefix`, using
+                both is an error.
         """
         self.pkg = package
-        self._addl_rpaths = set()
+        self._addl_rpaths: set[str] = set()
+        if link_install_prefix and base_modification_prefix:
+            raise RuntimeError(
+                "Invalid combination of arguments given to WindowsSimulated RPath.\n"
+                "Select either `link_install_prefix` to create an install prefix rpath"
+                " or specify a `base_modification_prefix` for any other link type. "
+                "Specifying both arguments is invalid."
+            )
+        if not (link_install_prefix or base_modification_prefix):
+            raise RuntimeError(
+                "Insufficient arguments given to WindowsSimulatedRpath.\n"
+                "WindowsSimulatedRPath requires one of link_install_prefix"
+                " or base_modification_prefix to be specified."
+                " Neither was provided."
+            )
+
         self.link_install_prefix = link_install_prefix
-        self._additional_library_dependents = set()
+        if base_modification_prefix:
+            self.base_modification_prefix = pathlib.Path(base_modification_prefix)
+        else:
+            self.base_modification_prefix = pathlib.Path(self.pkg.prefix)
+        self._additional_library_dependents: set[pathlib.Path] = set()
+        if not self.link_install_prefix:
+            tty.debug(f"Generating rpath for non install context: {base_modification_prefix}")
 
     @property
     def library_dependents(self):
         """
         Set of directories where package binaries/libraries are located.
         """
-        return set([pathlib.Path(self.pkg.prefix.bin)]) | self._additional_library_dependents
+        base_pths = set()
+        if self.link_install_prefix:
+            base_pths.add(pathlib.Path(self.pkg.prefix.bin))
+        base_pths |= self._additional_library_dependents
+        return base_pths
 
     def add_library_dependent(self, *dest):
         """
@@ -2489,6 +2534,12 @@ def add_library_dependent(self, *dest):
                 new_pth = pathlib.Path(pth).parent
             else:
                 new_pth = pathlib.Path(pth)
+            path_is_in_prefix = new_pth.is_relative_to(self.base_modification_prefix)
+            if not path_is_in_prefix:
+                raise RuntimeError(
+                    f"Attempting to generate rpath symlink out of rpath context:\
+{str(self.base_modification_prefix)}"
+                )
             self._additional_library_dependents.add(new_pth)
 
     @property
@@ -2577,6 +2628,33 @@ def establish_link(self):
                 self._link(library, lib_dir)
 
 
+def make_package_test_rpath(pkg, test_dir: Union[str, pathlib.Path]):
+    """Establishes a temp Windows simulated rpath for the pkg in the testing directory
+    so an executable can test the libraries/executables with proper access
+    to dependent dlls
+
+    Note: this is a no-op on all other platforms besides Windows
+
+    Args:
+        pkg (spack.package_base.PackageBase): the package for which the rpath should be computed
+        test_dir: the testing directory in which we should construct an rpath
+    """
+    # link_install_prefix as false ensures we're not linking into the install prefix
+    mini_rpath = WindowsSimulatedRPath(pkg, link_install_prefix=False)
+    # add the testing directory as a location to install rpath symlinks
+    mini_rpath.add_library_dependent(test_dir)
+
+    # check for whether build_directory is available, if not
+    # assume the stage root is the build dir
+    build_dir_attr = getattr(pkg, "build_directory", None)
+    build_directory = build_dir_attr if build_dir_attr else pkg.stage.path
+    # add the build dir & build dir bin
+    mini_rpath.add_rpath(os.path.join(build_directory, "bin"))
+    mini_rpath.add_rpath(os.path.join(build_directory))
+    # construct rpath
+    mini_rpath.establish_link()
+
+
 @system_path_filter
 @memoized
 def can_access_dir(path):
@@ -2805,6 +2883,20 @@ def keep_modification_time(*filenames):
             os.utime(f, (os.path.getatime(f), mtime))
 
 
+@contextmanager
+def temporary_file_position(stream):
+    orig_pos = stream.tell()
+    yield
+    stream.seek(orig_pos)
+
+
+@contextmanager
+def current_file_position(stream: IO[str], loc: int, relative_to=io.SEEK_CUR):
+    with temporary_file_position(stream):
+        stream.seek(loc, relative_to)
+        yield
+
+
 @contextmanager
 def temporary_dir(
     suffix: Optional[str] = None, prefix: Optional[str] = None, dir: Optional[str] = None

lib/spack/llnl/util/lang.py

@@ -14,7 +14,7 @@
 import typing
 import warnings
 from datetime import datetime, timedelta
-from typing import Callable, Dict, Iterable, List, Tuple, TypeVar
+from typing import Callable, Dict, Iterable, List, Mapping, Optional, Tuple, TypeVar
 
 # Ignore emacs backups when listing modules
 ignore_modules = r"^\.#|~$"
@@ -72,7 +72,7 @@ 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:
@@ -996,11 +996,8 @@ 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
         ]
@@ -1080,3 +1077,88 @@ def __set__(self, instance, value):
 
     def factory(self, instance, owner):
         raise NotImplementedError("must be implemented by derived classes")
+
+
+KT = TypeVar("KT")
+VT = TypeVar("VT")
+
+
+class PriorityOrderedMapping(Mapping[KT, VT]):
+    """Mapping that iterates over key according to an integer priority. If the priority is
+    the same for two keys, insertion order is what matters.
+
+    The priority is set when the key/value pair is added. If not set, the highest current priority
+    is used.
+    """
+
+    _data: Dict[KT, VT]
+    _priorities: List[Tuple[int, KT]]
+
+    def __init__(self) -> None:
+        self._data = {}
+        # Tuple of (priority, key)
+        self._priorities = []
+
+    def __getitem__(self, key: KT) -> VT:
+        return self._data[key]
+
+    def __len__(self) -> int:
+        return len(self._data)
+
+    def __iter__(self):
+        yield from (key for _, key in self._priorities)
+
+    def __reversed__(self):
+        yield from (key for _, key in reversed(self._priorities))
+
+    def reversed_keys(self):
+        """Iterates over keys from the highest priority, to the lowest."""
+        return reversed(self)
+
+    def reversed_values(self):
+        """Iterates over values from the highest priority, to the lowest."""
+        yield from (self._data[key] for _, key in reversed(self._priorities))
+
+    def _highest_priority(self) -> int:
+        if not self._priorities:
+            return 0
+        result, _ = self._priorities[-1]
+        return result
+
+    def add(self, key: KT, *, value: VT, priority: Optional[int] = None) -> None:
+        """Adds a key/value pair to the mapping, with a specific priority.
+
+        If the priority is None, then it is assumed to be the highest priority value currently
+        in the container.
+
+        Raises:
+              ValueError: when the same priority is already in the mapping
+        """
+        if priority is None:
+            priority = self._highest_priority()
+
+        if key in self._data:
+            self.remove(key)
+
+        self._priorities.append((priority, key))
+        # We rely on sort being stable
+        self._priorities.sort(key=lambda x: x[0])
+        self._data[key] = value
+        assert len(self._data) == len(self._priorities)
+
+    def remove(self, key: KT) -> VT:
+        """Removes a key from the mapping.
+
+        Returns:
+            The value associated with the key being removed
+
+        Raises:
+            KeyError: if the key is not in the mapping
+        """
+        if key not in self._data:
+            raise KeyError(f"cannot find {key}")
+
+        popped_item = self._data.pop(key)
+        self._priorities = [(p, k) for p, k in self._priorities if k != key]
+        assert len(self._data) == len(self._priorities)
+        return popped_item

lib/spack/llnl/util/link_tree.py

@@ -41,6 +41,16 @@ def __init__(self, dst, src_a=None, src_b=None):
         self.src_a = src_a
         self.src_b = src_b
 
+    def __repr__(self) -> str:
+        return f"MergeConflict(dst={self.dst!r}, src_a={self.src_a!r}, src_b={self.src_b!r})"
+
+
+def _samefile(a: str, b: str):
+    try:
+        return os.path.samefile(a, b)
+    except OSError:
+        return False
+
 
 class SourceMergeVisitor(BaseDirectoryVisitor):
     """
@@ -50,9 +60,14 @@ class SourceMergeVisitor(BaseDirectoryVisitor):
     - A list of merge conflicts in dst/
     """
 
-    def __init__(self, ignore: Optional[Callable[[str], bool]] = None):
+    def __init__(
+        self, ignore: Optional[Callable[[str], bool]] = None, normalize_paths: bool = False
+    ):
         self.ignore = ignore if ignore is not None else lambda f: False
 
+        # On case-insensitive filesystems, normalize paths to detect duplications
+        self.normalize_paths = normalize_paths
+
         # When mapping <src root> to <dst root>/<projection>, we need to prepend the <projection>
         # bit to the relative path in the destination dir.
         self.projection: str = ""
@@ -71,10 +86,88 @@ def __init__(self, ignore: Optional[Callable[[str], bool]] = None):
         # and can run mkdir in order.
         self.directories: Dict[str, Tuple[str, str]] = {}
 
+        # If the visitor is configured to normalize paths, keep a map of
+        # normalized path to: original path, root directory + relative path
+        self._directories_normalized: Dict[str, Tuple[str, str, str]] = {}
+
         # Files to link. Maps dst_rel to (src_root, src_rel). This is an ordered dict, where files
         # are guaranteed to be grouped by src_root in the order they were visited.
         self.files: Dict[str, Tuple[str, str]] = {}
 
+        # If the visitor is configured to normalize paths, keep a map of
+        # normalized path to: original path, root directory + relative path
+        self._files_normalized: Dict[str, Tuple[str, str, str]] = {}
+
+    def _in_directories(self, proj_rel_path: str) -> bool:
+        """
+        Check if a path is already in the directory list
+        """
+        if self.normalize_paths:
+            return proj_rel_path.lower() in self._directories_normalized
+        else:
+            return proj_rel_path in self.directories
+
+    def _directory(self, proj_rel_path: str) -> Tuple[str, str, str]:
+        """
+        Get the directory that is mapped to a path
+        """
+        if self.normalize_paths:
+            return self._directories_normalized[proj_rel_path.lower()]
+        else:
+            return (proj_rel_path, *self.directories[proj_rel_path])
+
+    def _del_directory(self, proj_rel_path: str):
+        """
+        Remove a directory from the list of directories
+        """
+        del self.directories[proj_rel_path]
+        if self.normalize_paths:
+            del self._directories_normalized[proj_rel_path.lower()]
+
+    def _add_directory(self, proj_rel_path: str, root: str, rel_path: str):
+        """
+        Add a directory to the list of directories.
+        Also stores the normalized version for later lookups
+        """
+        self.directories[proj_rel_path] = (root, rel_path)
+        if self.normalize_paths:
+            self._directories_normalized[proj_rel_path.lower()] = (proj_rel_path, root, rel_path)
+
+    def _in_files(self, proj_rel_path: str) -> bool:
+        """
+        Check if a path is already in the files list
+        """
+        if self.normalize_paths:
+            return proj_rel_path.lower() in self._files_normalized
+        else:
+            return proj_rel_path in self.files
+
+    def _file(self, proj_rel_path: str) -> Tuple[str, str, str]:
+        """
+        Get the file that is mapped to a path
+        """
+        if self.normalize_paths:
+            return self._files_normalized[proj_rel_path.lower()]
+        else:
+            return (proj_rel_path, *self.files[proj_rel_path])
+
+    def _del_file(self, proj_rel_path: str):
+        """
+        Remove a file from the list of files
+        """
+        del self.files[proj_rel_path]
+        if self.normalize_paths:
+            del self._files_normalized[proj_rel_path.lower()]
+
+    def _add_file(self, proj_rel_path: str, root: str, rel_path: str):
+        """
+        Add a file to the list of files
+        Also stores the normalized version for later lookups
+        """
+        self.files[proj_rel_path] = (root, rel_path)
+        if self.normalize_paths:
+            self._files_normalized[proj_rel_path.lower()] = (proj_rel_path, root, rel_path)
+
     def before_visit_dir(self, root: str, rel_path: str, depth: int) -> bool:
         """
         Register a directory if dst / rel_path is not blocked by a file or ignored.
@@ -84,23 +177,28 @@ def before_visit_dir(self, root: str, rel_path: str, depth: int) -> bool:
         if self.ignore(rel_path):
             # Don't recurse when dir is ignored.
             return False
-        elif proj_rel_path in self.files:
-            # Can't create a dir where a file is.
-            src_a_root, src_a_relpath = self.files[proj_rel_path]
-            self.fatal_conflicts.append(
-                MergeConflict(
-                    dst=proj_rel_path,
-                    src_a=os.path.join(src_a_root, src_a_relpath),
-                    src_b=os.path.join(root, rel_path),
+        elif self._in_files(proj_rel_path):
+            # A file-dir conflict is fatal except if they're the same file (symlinked dir).
+            src_a = os.path.join(*self._file(proj_rel_path))
+            src_b = os.path.join(root, rel_path)
+
+            if not _samefile(src_a, src_b):
+                self.fatal_conflicts.append(
+                    MergeConflict(dst=proj_rel_path, src_a=src_a, src_b=src_b)
                 )
-            )
-            return False
-        elif proj_rel_path in self.directories:
+                return False
+
+            # Remove the link in favor of the dir.
+            existing_proj_rel_path, _, _ = self._file(proj_rel_path)
+            self._del_file(existing_proj_rel_path)
+            self._add_directory(proj_rel_path, root, rel_path)
+            return True
+        elif self._in_directories(proj_rel_path):
             # No new directory, carry on.
             return True
         else:
             # Register new directory.
-            self.directories[proj_rel_path] = (root, rel_path)
+            self._add_directory(proj_rel_path, root, rel_path)
             return True
 
     def before_visit_symlinked_dir(self, root: str, rel_path: str, depth: int) -> bool:
@@ -132,7 +230,7 @@ def before_visit_symlinked_dir(self, root: str, rel_path: str, depth: int) -> bo
         if handle_as_dir:
             return self.before_visit_dir(root, rel_path, depth)
 
-        self.visit_file(root, rel_path, depth)
+        self.visit_file(root, rel_path, depth, symlink=True)
         return False
 
     def visit_file(self, root: str, rel_path: str, depth: int, *, symlink: bool = False) -> None:
@@ -140,30 +238,23 @@ def visit_file(self, root: str, rel_path: str, depth: int, *, symlink: bool = Fa
 
         if self.ignore(rel_path):
             pass
-        elif proj_rel_path in self.directories:
-            # Can't create a file where a dir is; fatal error
-            self.fatal_conflicts.append(
-                MergeConflict(
-                    dst=proj_rel_path,
-                    src_a=os.path.join(*self.directories[proj_rel_path]),
-                    src_b=os.path.join(root, rel_path),
+        elif self._in_directories(proj_rel_path):
+            # Can't create a file where a dir is, unless they are the same file (symlinked dir),
+            # in which case we simply drop the symlink in favor of the actual dir.
+            src_a = os.path.join(*self._directory(proj_rel_path))
+            src_b = os.path.join(root, rel_path)
+            if not symlink or not _samefile(src_a, src_b):
+                self.fatal_conflicts.append(
+                    MergeConflict(dst=proj_rel_path, src_a=src_a, src_b=src_b)
                 )
-            )
-        elif proj_rel_path in self.files:
+        elif self._in_files(proj_rel_path):
             # When two files project to the same path, they conflict iff they are distinct.
             # If they are the same (i.e. one links to the other), register regular files rather
             # than symlinks. The reason is that in copy-type views, we need a copy of the actual
             # file, not the symlink.
-
-            src_a = os.path.join(*self.files[proj_rel_path])
+            src_a = os.path.join(*self._file(proj_rel_path))
             src_b = os.path.join(root, rel_path)
-
-            try:
-                samefile = os.path.samefile(src_a, src_b)
-            except OSError:
-                samefile = False
-
-            if not samefile:
+            if not _samefile(src_a, src_b):
                 # Distinct files produce a conflict.
                 self.file_conflicts.append(
                     MergeConflict(dst=proj_rel_path, src_a=src_a, src_b=src_b)
@@ -173,12 +264,12 @@ def visit_file(self, root: str, rel_path: str, depth: int, *, symlink: bool = Fa
             if not symlink:
                 # Remove the link in favor of the actual file. The del is necessary to maintain the
                 # order of the files dict, which is grouped by root.
-                del self.files[proj_rel_path]
-                self.files[proj_rel_path] = (root, rel_path)
-
+                existing_proj_rel_path, _, _ = self._file(proj_rel_path)
+                self._del_file(existing_proj_rel_path)
+                self._add_file(proj_rel_path, root, rel_path)
         else:
             # Otherwise register this file to be linked.
-            self.files[proj_rel_path] = (root, rel_path)
+            self._add_file(proj_rel_path, root, rel_path)
 
     def visit_symlinked_file(self, root: str, rel_path: str, depth: int) -> None:
         # Treat symlinked files as ordinary files (without "dereferencing")
@@ -197,11 +288,11 @@ def set_projection(self, projection: str) -> None:
         path = ""
         for part in self.projection.split(os.sep):
             path = os.path.join(path, part)
-            if path not in self.files:
-                self.directories[path] = ("<projection>", path)
+            if not self._in_files(path):
+                self._add_directory(path, "<projection>", path)
             else:
                 # Can't create a dir where a file is.
-                src_a_root, src_a_relpath = self.files[path]
+                _, src_a_root, src_a_relpath = self._file(path)
                 self.fatal_conflicts.append(
                     MergeConflict(
                         dst=path,
@@ -227,8 +318,8 @@ def __init__(self, source_merge_visitor: SourceMergeVisitor):
     def before_visit_dir(self, root: str, rel_path: str, depth: int) -> bool:
         # If destination dir is a file in a src dir, add a conflict,
         # and don't traverse deeper
-        if rel_path in self.src.files:
-            src_a_root, src_a_relpath = self.src.files[rel_path]
+        if self.src._in_files(rel_path):
+            _, src_a_root, src_a_relpath = self.src._file(rel_path)
             self.src.fatal_conflicts.append(
                 MergeConflict(
                     rel_path, os.path.join(src_a_root, src_a_relpath), os.path.join(root, rel_path)
@@ -238,8 +329,9 @@ def before_visit_dir(self, root: str, rel_path: str, depth: int) -> bool:
 
         # If destination dir was also a src dir, remove the mkdir
         # action, and traverse deeper.
-        if rel_path in self.src.directories:
-            del self.src.directories[rel_path]
+        if self.src._in_directories(rel_path):
+            existing_proj_rel_path, _, _ = self.src._directory(rel_path)
+            self.src._del_directory(existing_proj_rel_path)
             return True
 
         # If the destination dir does not appear in the src dir,
@@ -252,38 +344,24 @@ def before_visit_symlinked_dir(self, root: str, rel_path: str, depth: int) -> bo
         be seen as files; we should not accidentally merge
         source dir with a symlinked dest dir.
         """
-        # Always conflict
-        if rel_path in self.src.directories:
-            src_a_root, src_a_relpath = self.src.directories[rel_path]
-            self.src.fatal_conflicts.append(
-                MergeConflict(
-                    rel_path, os.path.join(src_a_root, src_a_relpath), os.path.join(root, rel_path)
-                )
-            )
 
-        if rel_path in self.src.files:
-            src_a_root, src_a_relpath = self.src.files[rel_path]
-            self.src.fatal_conflicts.append(
-                MergeConflict(
-                    rel_path, os.path.join(src_a_root, src_a_relpath), os.path.join(root, rel_path)
-                )
-            )
+        self.visit_file(root, rel_path, depth)
 
         # Never descend into symlinked target dirs.
         return False
 
     def visit_file(self, root: str, rel_path: str, depth: int) -> None:
         # Can't merge a file if target already exists
-        if rel_path in self.src.directories:
-            src_a_root, src_a_relpath = self.src.directories[rel_path]
+        if self.src._in_directories(rel_path):
+            _, src_a_root, src_a_relpath = self.src._directory(rel_path)
             self.src.fatal_conflicts.append(
                 MergeConflict(
                     rel_path, os.path.join(src_a_root, src_a_relpath), os.path.join(root, rel_path)
                 )
             )
 
-        elif rel_path in self.src.files:
-            src_a_root, src_a_relpath = self.src.files[rel_path]
+        elif self.src._in_files(rel_path):
+            _, src_a_root, src_a_relpath = self.src._file(rel_path)
             self.src.fatal_conflicts.append(
                 MergeConflict(
                     rel_path, os.path.join(src_a_root, src_a_relpath), os.path.join(root, rel_path)

lib/spack/llnl/util/lock.py

@@ -269,7 +269,7 @@ def __init__(
 
     @staticmethod
     def _poll_interval_generator(
-        _wait_times: Optional[Tuple[float, float, float]] = None
+        _wait_times: Optional[Tuple[float, float, float]] = None,
     ) -> Generator[float, None, None]:
         """This implements a backoff scheme for polling a contended resource
         by suggesting a succession of wait times between polls.

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

@@ -2,8 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-"""Utility classes for logging the output of blocks of code.
-"""
+"""Utility classes for logging the output of blocks of code."""
 import atexit
 import ctypes
 import errno

lib/spack/spack/__init__.py

@@ -10,7 +10,7 @@
 import spack.util.git
 
 #: PEP440 canonical <major>.<minor>.<micro>.<devN> string
-__version__ = "1.0.0.dev0"
+__version__ = "1.0.0-alpha.4"
 spack_version = __version__
 
 

lib/spack/spack/audit.py

@@ -1010,7 +1010,7 @@ def _issues_in_depends_on_directive(pkgs, error_cls):
             for dep_name, dep in deps_by_name.items():
 
                 def check_virtual_with_variants(spec, msg):
-                    if not spec.virtual or not spec.variants:
+                    if not spack.repo.PATH.is_virtual(spec.name) or not spec.variants:
                         return
                     error = error_cls(
                         f"{pkg_name}: {msg}",

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 "
@@ -629,7 +636,14 @@ def tarball_directory_name(spec):
     Return name of the tarball directory according to the convention
     <os>-<architecture>/<compiler>/<package>-<version>/
     """
-    return spec.format_path("{architecture}/{compiler.name}-{compiler.version}/{name}-{version}")
+    if spec.original_spec_format() < 5:
+        compiler = spec.annotations.compiler_node_attribute
+        assert compiler is not None, "a compiler spec is expected"
+        return spec.format_path(
+            f"{spec.architecture}/{compiler.name}-{compiler.version}/{spec.name}-{spec.version}"
+        )
+
+    return spec.format_path(f"{spec.architecture.platform}/{spec.name}-{spec.version}")
 
 
 def tarball_name(spec, ext):
@@ -637,9 +651,17 @@ def tarball_name(spec, ext):
     Return the name of the tarfile according to the convention
     <os>-<architecture>-<package>-<dag_hash><ext>
     """
-    spec_formatted = spec.format_path(
-        "{architecture}-{compiler.name}-{compiler.version}-{name}-{version}-{hash}"
-    )
+    if spec.original_spec_format() < 5:
+        compiler = spec.annotations.compiler_node_attribute
+        assert compiler is not None, "a compiler spec is expected"
+        spec_formatted = (
+            f"{spec.architecture}-{compiler.name}-{compiler.version}-{spec.name}"
+            f"-{spec.version}-{spec.dag_hash()}"
+        )
+    else:
+        spec_formatted = (
+            f"{spec.architecture.platform}-{spec.name}-{spec.version}-{spec.dag_hash()}"
+        )
     return f"{spec_formatted}{ext}"
 
 
@@ -923,7 +945,7 @@ class FileTypes:
     UNKNOWN = 2
 
 
-NOT_ISO8859_1_TEXT = re.compile(b"[\x00\x7F-\x9F]")
+NOT_ISO8859_1_TEXT = re.compile(b"[\x00\x7f-\x9f]")
 
 
 def file_type(f: IO[bytes]) -> int:
@@ -2529,10 +2551,10 @@ def install_root_node(
         allow_missing: when true, allows installing a node with missing dependencies
     """
     # Early termination
-    if spec.external or spec.virtual:
-        warnings.warn("Skipping external or virtual package {0}".format(spec.format()))
+    if spec.external or not spec.concrete:
+        warnings.warn("Skipping external or abstract spec {0}".format(spec.format()))
         return
-    elif spec.concrete and spec.installed and not force:
+    elif spec.installed and not force:
         warnings.warn("Package for spec {0} already installed.".format(spec.format()))
         return
 

lib/spack/spack/bootstrap/_common.py

@@ -234,12 +234,8 @@ 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":
+    if platform == "windows":
         spec_str += " %msvc"
-    elif platform == "linux":
-        spec_str += " %gcc"
     elif platform == "freebsd":
         spec_str += " %clang"
     spec_str += f" platform={platform}"

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/bootstrap/core.py

@@ -292,7 +292,12 @@ def try_import(self, module: str, abstract_spec_str: str) -> bool:
 
         # Install the spec that should make the module importable
         with spack.config.override(self.mirror_scope):
-            PackageInstaller([concrete_spec.package], fail_fast=True).install()
+            PackageInstaller(
+                [concrete_spec.package],
+                fail_fast=True,
+                package_use_cache=False,
+                dependencies_use_cache=False,
+            ).install()
 
         if _try_import_from_store(module, query_spec=concrete_spec, query_info=info):
             self.last_search = info
@@ -362,6 +367,7 @@ def ensure_module_importable_or_raise(module: str, abstract_spec: Optional[str]
     for current_config in bootstrapping_sources():
         if not source_is_enabled(current_config):
             continue
+
         with exception_handler.forward(current_config["name"], Exception):
             if create_bootstrapper(current_config).try_import(module, abstract_spec):
                 return

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,
@@ -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
@@ -916,7 +750,6 @@ 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 +761,24 @@ 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_ENV_PATH"]:
+        assert isinstance(x, PrependPath), "unexpected setting used for SPACK_ENV_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"):
@@ -941,11 +792,6 @@ 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(pkg)
 
     # Make sure nothing's strange about the Spack environment.
@@ -957,6 +803,14 @@ 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

@@ -12,6 +12,7 @@
 import spack.phase_callbacks
 import spack.spec
 import spack.util.prefix
+from spack.directives import depends_on
 
 from .cmake import CMakeBuilder, CMakePackage
 
@@ -69,12 +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):
@@ -117,7 +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"
@@ -133,8 +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",
         ]
@@ -371,6 +370,10 @@ class CachedCMakePackage(CMakePackage):
 
     CMakeBuilder = CachedCMakeBuilder
 
+    # These dependencies are assumed in the builder
+    depends_on("c", type="build")
+    depends_on("cxx", type="build")
+
     def flag_handler(self, name, flags):
         if name in ("cflags", "cxxflags", "cppflags", "fflags"):
             return None, None, None  # handled in the cmake cache

lib/spack/spack/build_systems/cargo.py

@@ -70,10 +70,16 @@ def build_directory(self):
         """Return the directory containing the main Cargo.toml."""
         return self.pkg.stage.source_path
 
+    @property
+    def std_build_args(self):
+        """Standard arguments for ``cargo build`` provided as a property for
+        convenience of package writers."""
+        return ["-j", str(self.pkg.module.make_jobs)]
+
     @property
     def build_args(self):
         """Arguments for ``cargo build``."""
-        return ["-j", str(self.pkg.module.make_jobs)]
+        return []
 
     @property
     def check_args(self):
@@ -88,7 +94,9 @@ def build(
     ) -> None:
         """Runs ``cargo install`` in the source directory"""
         with fs.working_dir(self.build_directory):
-            pkg.module.cargo("install", "--root", "out", "--path", ".", *self.build_args)
+            pkg.module.cargo(
+                "install", "--root", "out", "--path", ".", *self.std_build_args, *self.build_args
+            )
 
     def install(
         self, pkg: CargoPackage, spec: spack.spec.Spec, prefix: spack.util.prefix.Prefix

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
+    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"
+
+    required_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/meson.py

@@ -48,6 +48,9 @@ class MesonPackage(spack.package_base.PackageBase):
         variant("strip", default=False, description="Strip targets on install")
         depends_on("meson", type="build")
         depends_on("ninja", type="build")
+        # Meson uses pkg-config for dependency detection, and this dependency is
+        # often overlooked by packages that use meson as a build system.
+        depends_on("pkgconfig", type="build")
         # Python detection in meson requires distutils to be importable, but distutils no longer
         # exists in Python 3.12. In Spack, we can't use setuptools as distutils replacement,
         # because the distutils-precedence.pth startup file that setuptools ships with is not run

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

@@ -142,7 +142,7 @@ def setup_run_environment(self, env):
            $ source {prefix}/{component}/{version}/env/vars.sh
         """
         # Only if environment modifications are desired (default is +envmods)
-        if "~envmods" not in self.spec:
+        if "+envmods" in self.spec:
             env.extend(
                 EnvironmentModifications.from_sourcing_file(
                     self.component_prefix.env.join("vars.sh"), *self.env_script_args

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=())