simplify mro stuff

inspect.isclass -> isinstance(..., type)
inspect.getmro -> cls.__mro__

.github/workflows/build-containers.yml

@@ -113,7 +113,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build & Deploy ${{ matrix.dockerfile[0] }}
-        uses: docker/build-push-action@16ebe778df0e7752d2cfcbd924afdbbd89c1a755
+        uses: docker/build-push-action@5cd11c3a4ced054e52742c5fd54dca954e0edd85
         with:
           context: dockerfiles/${{ matrix.dockerfile[0] }}
           platforms: ${{ matrix.dockerfile[1] }}

.github/workflows/unit_tests.yaml

@@ -16,38 +16,27 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12']
-        concretizer: ['clingo']
         on_develop:
         - ${{ github.ref == 'refs/heads/develop' }}
         include:
-        - python-version: '3.11'
-          os: ubuntu-latest
-          concretizer: original
-          on_develop: ${{ github.ref == 'refs/heads/develop' }}
         - python-version: '3.6'
           os: ubuntu-20.04
-          concretizer: clingo
           on_develop: ${{ github.ref == 'refs/heads/develop' }}
         exclude:
         - python-version: '3.7'
           os: ubuntu-latest
-          concretizer: 'clingo'
           on_develop: false
         - python-version: '3.8'
           os: ubuntu-latest
-          concretizer: 'clingo'
           on_develop: false
         - python-version: '3.9'
           os: ubuntu-latest
-          concretizer: 'clingo'
           on_develop: false
         - python-version: '3.10'
           os: ubuntu-latest
-          concretizer: 'clingo'
           on_develop: false
         - python-version: '3.11'
           os: ubuntu-latest
-          concretizer: 'clingo'
           on_develop: false
 
     steps:
@@ -85,7 +74,6 @@ jobs:
     - name: Run unit tests
       env:
           SPACK_PYTHON: python
-          SPACK_TEST_SOLVER: ${{ matrix.concretizer }}
           SPACK_TEST_PARALLEL: 2
           COVERAGE: true
           UNIT_TEST_COVERAGE: ${{ matrix.python-version == '3.11' }}
@@ -182,7 +170,6 @@ jobs:
     - name: Run unit tests (full suite with coverage)
       env:
           COVERAGE: true
-          SPACK_TEST_SOLVER: clingo
       run: |
           share/spack/qa/run-unit-tests
     - uses: codecov/codecov-action@e28ff129e5465c2c0dcc6f003fc735cb6ae0c673
@@ -213,7 +200,6 @@ jobs:
         brew install dash fish gcc gnupg2 kcov
     - name: Run unit tests
       env:
-        SPACK_TEST_SOLVER: clingo
         SPACK_TEST_PARALLEL: 4
       run: |
         git --version

etc/spack/defaults/config.yaml

@@ -170,23 +170,6 @@ config:
   # If set to true, Spack will use ccache to cache C compiles.
   ccache: false
 
-
-  # The concretization algorithm to use in Spack. Options are:
-  #
-  #   'clingo': Uses a logic solver under the hood to solve DAGs with full
-  #       backtracking and optimization for user preferences. Spack will
-  #       try to bootstrap the logic solver, if not already available.
-  #
-  #   'original': Spack's original greedy, fixed-point concretizer. This
-  #       algorithm can make decisions too early and will not backtrack
-  #       sufficiently for many specs. This will soon be deprecated in
-  #       favor of clingo.
-  #
-  # See `concretizer.yaml` for more settings you can fine-tune when
-  # using clingo.
-  concretizer: clingo
-
-
   # How long to wait to lock the Spack installation database. This lock is used
   # when Spack needs to manage its own package metadata and all operations are
   # expected to complete within the default time limit. The timeout should

etc/spack/defaults/packages.yaml

@@ -20,12 +20,14 @@ packages:
       awk: [gawk]
       armci: [armcimpi]
       blas: [openblas, amdblis]
+      c: [gcc]
       cxx: [gcc]
       D: [ldc]
       daal: [intel-oneapi-daal]
       elf: [elfutils]
       fftw-api: [fftw, amdfftw]
       flame: [libflame, amdlibflame]
+      fortran: [gcc]
       fortran-rt: [gcc-runtime, intel-oneapi-runtime]
       fuse: [libfuse]
       gl: [glx, osmesa]

etc/spack/defaults/windows/config.yaml

@@ -1,6 +1,5 @@
 config:
   locks: false
-  concretizer: clingo
   build_stage::
     - '$spack/.staging'
   stage_name: '{name}-{version}-{hash:7}'

lib/spack/docs/conf.py

@@ -206,6 +206,7 @@ def setup(sphinx):
     ("py:class", "six.moves.urllib.parse.ParseResult"),
     ("py:class", "TextIO"),
     ("py:class", "hashlib._Hash"),
+    ("py:class", "concurrent.futures._base.Executor"),
     # Spack classes that are private and we don't want to expose
     ("py:class", "spack.provider_index._IndexBase"),
     ("py:class", "spack.repo._PrependFileLoader"),

lib/spack/docs/packaging_guide.rst

@@ -1263,6 +1263,11 @@ Git fetching supports the following parameters to ``version``:
   option ``--depth 1`` will be used if the version of git and the specified
   transport protocol support it, and ``--single-branch`` will be used if the
   version of git supports it.
+* ``git_sparse_paths``: Use ``sparse-checkout`` to only clone these relative paths.
+  This feature requires ``git`` to be version ``2.25.0`` or later but is useful for
+  large repositories that have separate portions that can be built independently.
+  If paths provided are directories then all the subdirectories and associated files
+  will also be cloned. 
 
 Only one of ``tag``, ``branch``, or ``commit`` can be used at a time.
 
@@ -1361,6 +1366,41 @@ Submodules
   For more information about git submodules see the manpage of git: ``man
   git-submodule``.
 
+Sparse-Checkout
+  You can supply ``git_sparse_paths`` at the package or version level to utilize git's 
+  sparse-checkout feature. This will only clone the paths that are specified in the 
+  ``git_sparse_paths`` attribute for the package along with the files in the top level directory.
+  This feature allows you to only clone what you need from a large repository.
+  Note that this is a newer feature in git and requries git ``2.25.0`` or greater.
+  If ``git_sparse_paths`` is supplied and the git version is too old
+  then a warning will be issued and that package will use the standard cloning operations instead.
+  ``git_sparse_paths`` should be supplied as a list of paths, a callable function for versions,
+  or a more complex package attribute using the ``@property`` decorator. The return value should be
+  a list for a callable implementation of ``git_sparse_paths``.
+
+  .. code-block:: python
+
+    def sparse_path_function(package)
+        """a callable function that can be used in side a version"""
+        # paths can be directories or functions, all subdirectories and files are included
+        paths = ["doe", "rae", "me/file.cpp"]
+        if package.spec.version >  Version("1.2.0"):
+            paths.extend(["fae"])
+        return paths
+
+    class MyPackage(package):
+        # can also be a package attribute that will be used if not specified in versions
+        git_sparse_paths = ["doe", "rae"]
+
+        # use the package attribute
+        version("1.0.0")
+        version("1.1.0")
+        # use the function
+        version("1.1.5", git_sparse_paths=sparse_path_func)
+        version("1.2.0", git_sparse_paths=sparse_path_func)
+        version("1.2.5", git_sparse_paths=sparse_path_func)
+        version("1.1.5", git_sparse_paths=sparse_path_func)
+
 .. _github-fetch:
 
 ^^^^^^

lib/spack/external/__init__.py

@@ -18,7 +18,7 @@
 
 * Homepage: https://pypi.python.org/pypi/archspec
 * Usage: Labeling, comparison and detection of microarchitectures
-* Version: 0.2.4 (commit 48b92512b9ce203ded0ebd1ac41b42593e931f7c)
+* Version: 0.2.5-dev (commit 7e6740012b897ae4a950f0bba7e9726b767e921f)
 
 astunparse
 ----------------

lib/spack/external/_vendoring/distro/distro.py

@@ -1265,27 +1265,29 @@ def _distro_release_info(self) -> Dict[str, str]:
             match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
         else:
             try:
-                basenames = [
-                    basename
-                    for basename in os.listdir(self.etc_dir)
-                    if basename not in _DISTRO_RELEASE_IGNORE_BASENAMES
-                    and os.path.isfile(os.path.join(self.etc_dir, basename))
-                ]
+                with os.scandir(self.etc_dir) as it:
+                    etc_files = [
+                        p.path for p in it
+                        if p.is_file() and p.name not in _DISTRO_RELEASE_IGNORE_BASENAMES
+                    ]
                 # We sort for repeatability in cases where there are multiple
                 # distro specific files; e.g. CentOS, Oracle, Enterprise all
                 # containing `redhat-release` on top of their own.
-                basenames.sort()
+                etc_files.sort()
             except OSError:
                 # This may occur when /etc is not readable but we can't be
                 # sure about the *-release files. Check common entries of
                 # /etc for information. If they turn out to not be there the
                 # error is handled in `_parse_distro_release_file()`.
-                basenames = _DISTRO_RELEASE_BASENAMES
-            for basename in basenames:
-                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+                etc_files = [
+                    os.path.join(self.etc_dir, basename)
+                    for basename in _DISTRO_RELEASE_BASENAMES
+                ]
+
+            for filepath in etc_files:
+                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(os.path.basename(filepath))
                 if match is None:
                     continue
-                filepath = os.path.join(self.etc_dir, basename)
                 distro_info = self._parse_distro_release_file(filepath)
                 # The name is always present if the pattern matches.
                 if "name" not in distro_info:

lib/spack/external/_vendoring/jsonschema/_format.py

@@ -231,96 +231,6 @@ def is_host_name(instance):
     return True
 
 
-try:
-    # The built-in `idna` codec only implements RFC 3890, so we go elsewhere.
-    import idna
-except ImportError:
-    pass
-else:
-    @_checks_drafts(draft7="idn-hostname", raises=idna.IDNAError)
-    def is_idn_host_name(instance):
-        if not isinstance(instance, str_types):
-            return True
-        idna.encode(instance)
-        return True
-
-
-try:
-    import rfc3987
-except ImportError:
-    try:
-        from rfc3986_validator import validate_rfc3986
-    except ImportError:
-        pass
-    else:
-        @_checks_drafts(name="uri")
-        def is_uri(instance):
-            if not isinstance(instance, str_types):
-                return True
-            return validate_rfc3986(instance, rule="URI")
-
-        @_checks_drafts(
-            draft6="uri-reference",
-            draft7="uri-reference",
-            raises=ValueError,
-        )
-        def is_uri_reference(instance):
-            if not isinstance(instance, str_types):
-                return True
-            return validate_rfc3986(instance, rule="URI_reference")
-
-else:
-    @_checks_drafts(draft7="iri", raises=ValueError)
-    def is_iri(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return rfc3987.parse(instance, rule="IRI")
-
-    @_checks_drafts(draft7="iri-reference", raises=ValueError)
-    def is_iri_reference(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return rfc3987.parse(instance, rule="IRI_reference")
-
-    @_checks_drafts(name="uri", raises=ValueError)
-    def is_uri(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return rfc3987.parse(instance, rule="URI")
-
-    @_checks_drafts(
-        draft6="uri-reference",
-        draft7="uri-reference",
-        raises=ValueError,
-    )
-    def is_uri_reference(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return rfc3987.parse(instance, rule="URI_reference")
-
-
-try:
-    from strict_rfc3339 import validate_rfc3339
-except ImportError:
-    try:
-        from rfc3339_validator import validate_rfc3339
-    except ImportError:
-        validate_rfc3339 = None
-
-if validate_rfc3339:
-    @_checks_drafts(name="date-time")
-    def is_datetime(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return validate_rfc3339(instance)
-
-    @_checks_drafts(draft7="time")
-    def is_time(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return is_datetime("1970-01-01T" + instance)
-
-
 @_checks_drafts(name="regex", raises=re.error)
 def is_regex(instance):
     if not isinstance(instance, str_types):
@@ -340,86 +250,3 @@ def is_draft3_time(instance):
     if not isinstance(instance, str_types):
         return True
     return datetime.datetime.strptime(instance, "%H:%M:%S")
-
-
-try:
-    import webcolors
-except ImportError:
-    pass
-else:
-    def is_css_color_code(instance):
-        return webcolors.normalize_hex(instance)
-
-    @_checks_drafts(draft3="color", raises=(ValueError, TypeError))
-    def is_css21_color(instance):
-        if (
-            not isinstance(instance, str_types) or
-            instance.lower() in webcolors.css21_names_to_hex
-        ):
-            return True
-        return is_css_color_code(instance)
-
-    def is_css3_color(instance):
-        if instance.lower() in webcolors.css3_names_to_hex:
-            return True
-        return is_css_color_code(instance)
-
-
-try:
-    import jsonpointer
-except ImportError:
-    pass
-else:
-    @_checks_drafts(
-        draft6="json-pointer",
-        draft7="json-pointer",
-        raises=jsonpointer.JsonPointerException,
-    )
-    def is_json_pointer(instance):
-        if not isinstance(instance, str_types):
-            return True
-        return jsonpointer.JsonPointer(instance)
-
-    # TODO: I don't want to maintain this, so it
-    #       needs to go either into jsonpointer (pending
-    #       https://github.com/stefankoegl/python-json-pointer/issues/34) or
-    #       into a new external library.
-    @_checks_drafts(
-        draft7="relative-json-pointer",
-        raises=jsonpointer.JsonPointerException,
-    )
-    def is_relative_json_pointer(instance):
-        # Definition taken from:
-        # https://tools.ietf.org/html/draft-handrews-relative-json-pointer-01#section-3
-        if not isinstance(instance, str_types):
-            return True
-        non_negative_integer, rest = [], ""
-        for i, character in enumerate(instance):
-            if character.isdigit():
-                non_negative_integer.append(character)
-                continue
-
-            if not non_negative_integer:
-                return False
-
-            rest = instance[i:]
-            break
-        return (rest == "#") or jsonpointer.JsonPointer(rest)
-
-
-try:
-    import uritemplate.exceptions
-except ImportError:
-    pass
-else:
-    @_checks_drafts(
-        draft6="uri-template",
-        draft7="uri-template",
-        raises=uritemplate.exceptions.InvalidTemplate,
-    )
-    def is_uri_template(
-        instance,
-        template_validator=uritemplate.Validator().force_balanced_braces(),
-    ):
-        template = uritemplate.URITemplate(instance)
-        return template_validator.validate(template)

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

@@ -47,7 +47,11 @@ def decorator(factory):
 
 
 def partial_uarch(
-    name: str = "", vendor: str = "", features: Optional[Set[str]] = None, generation: int = 0
+    name: str = "",
+    vendor: str = "",
+    features: Optional[Set[str]] = None,
+    generation: int = 0,
+    cpu_part: str = "",
 ) -> Microarchitecture:
     """Construct a partial microarchitecture, from information gathered during system scan."""
     return Microarchitecture(
@@ -57,6 +61,7 @@ def partial_uarch(
         features=features or set(),
         compilers={},
         generation=generation,
+        cpu_part=cpu_part,
     )
 
 
@@ -90,6 +95,7 @@ def proc_cpuinfo() -> Microarchitecture:
         return partial_uarch(
             vendor=_canonicalize_aarch64_vendor(data),
             features=_feature_set(data, key="Features"),
+            cpu_part=data.get("CPU part", ""),
         )
 
     if architecture in (PPC64LE, PPC64):
@@ -345,6 +351,10 @@ def sorting_fn(item):
     generic_candidates = [c for c in candidates if c.vendor == "generic"]
     best_generic = max(generic_candidates, key=sorting_fn)
 
+    # Relevant for AArch64. Filter on "cpu_part" if we have any match
+    if info.cpu_part != "" and any(c for c in candidates if info.cpu_part == c.cpu_part):
+        candidates = [c for c in candidates if info.cpu_part == c.cpu_part]
+
     # Filter the candidates to be descendant of the best generic candidate.
     # This is to avoid that the lack of a niche feature that can be disabled
     # from e.g. BIOS prevents detection of a reasonably performant architecture

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

@@ -2,9 +2,7 @@
 # Archspec Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-"""Types and functions to manage information
-on CPU microarchitectures.
-"""
+"""Types and functions to manage information on CPU microarchitectures."""
 import functools
 import platform
 import re
@@ -65,21 +63,24 @@ class Microarchitecture:
                 passed in as argument above.
             * versions: versions that support this micro-architecture.
 
-        generation (int): generation of the micro-architecture, if
-            relevant.
+        generation (int): generation of the micro-architecture, if relevant.
+        cpu_part (str): cpu part of the architecture, if relevant.
     """
 
-    # pylint: disable=too-many-arguments
+    # pylint: disable=too-many-arguments,too-many-instance-attributes
     #: Aliases for micro-architecture's features
     feature_aliases = FEATURE_ALIASES
 
-    def __init__(self, name, parents, vendor, features, compilers, generation=0):
+    def __init__(self, name, parents, vendor, features, compilers, generation=0, cpu_part=""):
         self.name = name
         self.parents = parents
         self.vendor = vendor
         self.features = features
         self.compilers = compilers
+        # Only relevant for PowerPC
         self.generation = generation
+        # Only relevant for AArch64
+        self.cpu_part = cpu_part
         # Cache the ancestor computation
         self._ancestors = None
 
@@ -111,6 +112,7 @@ def __eq__(self, other):
             and self.parents == other.parents  # avoid ancestors here
             and self.compilers == other.compilers
             and self.generation == other.generation
+            and self.cpu_part == other.cpu_part
         )
 
     @coerce_target_names
@@ -143,7 +145,8 @@ def __repr__(self):
         cls_name = self.__class__.__name__
         fmt = (
             cls_name + "({0.name!r}, {0.parents!r}, {0.vendor!r}, "
-            "{0.features!r}, {0.compilers!r}, {0.generation!r})"
+            "{0.features!r}, {0.compilers!r}, generation={0.generation!r}, "
+            "cpu_part={0.cpu_part!r})"
         )
         return fmt.format(self)
 
@@ -190,6 +193,7 @@ def to_dict(self):
             "generation": self.generation,
             "parents": [str(x) for x in self.parents],
             "compilers": self.compilers,
+            "cpupart": self.cpu_part,
         }
 
     @staticmethod
@@ -202,6 +206,7 @@ def from_dict(data) -> "Microarchitecture":
             features=set(data["features"]),
             compilers=data.get("compilers", {}),
             generation=data.get("generation", 0),
+            cpu_part=data.get("cpupart", ""),
         )
 
     def optimization_flags(self, compiler, version):
@@ -360,8 +365,11 @@ def fill_target_from_dict(name, data, targets):
         features = set(values["features"])
         compilers = values.get("compilers", {})
         generation = values.get("generation", 0)
+        cpu_part = values.get("cpupart", "")
 
-        targets[name] = Microarchitecture(name, parents, vendor, features, compilers, generation)
+        targets[name] = Microarchitecture(
+            name, parents, vendor, features, compilers, generation=generation, cpu_part=cpu_part
+        )
 
     known_targets = {}
     data = archspec.cpu.schema.TARGETS_JSON["microarchitectures"]

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

@@ -2225,10 +2225,14 @@
         ],
         "nvhpc": [
           {
-            "versions": "21.11:",
+            "versions": "21.11:23.8",
 	    "name": "zen3",
             "flags": "-tp {name}",
-	    "warnings": "zen4 is not fully supported by nvhpc yet, falling back to zen3"
+	    "warnings": "zen4 is not fully supported by nvhpc versions < 23.9, falling back to zen3"
+          },
+          {
+            "versions": "23.9:",
+            "flags": "-tp {name}"
           }
 	]
       }
@@ -2711,7 +2715,8 @@
             "flags": "-mcpu=thunderx2t99"
           }
         ]
-      }
+      },
+      "cpupart": "0x0af"
     },
     "a64fx": {
       "from": ["armv8.2a"],
@@ -2779,7 +2784,8 @@
             "flags": "-march=armv8.2-a+crc+crypto+fp16+sve"
           }
         ]
-      }
+      },
+      "cpupart": "0x001"
     },
     "cortex_a72": {
       "from": ["aarch64"],
@@ -2816,7 +2822,8 @@
                   "flags" : "-mcpu=cortex-a72"
               }
           ]
-      }
+      },
+      "cpupart": "0xd08"
     },
     "neoverse_n1": {
       "from": ["cortex_a72", "armv8.2a"],
@@ -2902,7 +2909,8 @@
                   "flags": "-tp {name}"
               }
           ]
-      }
+      },
+      "cpupart": "0xd0c"
     },
     "neoverse_v1": {
       "from": ["neoverse_n1", "armv8.4a"],
@@ -2926,8 +2934,6 @@
           "lrcpc",
           "dcpop",
           "sha3",
-          "sm3",
-          "sm4",
           "asimddp",
           "sha512",
           "sve",
@@ -3028,7 +3034,8 @@
                   "flags": "-tp {name}"
               }
           ]
-      }
+      },
+      "cpupart": "0xd40"
     },
     "neoverse_v2": {
       "from": ["neoverse_n1", "armv9.0a"],
@@ -3052,13 +3059,10 @@
 	  "lrcpc",
 	  "dcpop",
 	  "sha3",
-	  "sm3",
-	  "sm4",
 	  "asimddp",
 	  "sha512",
 	  "sve",
 	  "asimdfhm",
-	  "dit",
 	  "uscat",
 	  "ilrcpc",
 	  "flagm",
@@ -3066,18 +3070,12 @@
 	  "sb",
 	  "dcpodp",
 	  "sve2",
-	  "sveaes",
-	  "svepmull",
-	  "svebitperm",
-	  "svesha3",
-	  "svesm4",
 	  "flagm2",
 	  "frint",
 	  "svei8mm",
 	  "svebf16",
 	  "i8mm",
-	  "bf16",
-	  "dgh"
+	  "bf16"
       ],
       "compilers" : {
           "gcc": [
@@ -3102,15 +3100,19 @@
                   "flags" : "-march=armv8.5-a+sve -mtune=cortex-a76"
               },
               {
-                  "versions": "10.0:11.99",
+                  "versions": "10.0:11.3.99",
                   "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16 -mtune=cortex-a77"
               },
+	      {
+                  "versions": "11.4:11.99",
+                  "flags" : "-mcpu=neoverse-v2"
+              },
               {
-                  "versions": "12.0:12.99",
+                  "versions": "12.0:12.2.99",
                   "flags" : "-march=armv9-a+i8mm+bf16 -mtune=cortex-a710"
               },
 	      {
-                  "versions": "13.0:",
+                  "versions": "12.3:",
                   "flags" : "-mcpu=neoverse-v2"
               }
           ],
@@ -3145,7 +3147,113 @@
                   "flags": "-tp {name}"
               }
           ]
-      }
+      },
+      "cpupart": "0xd4f"
+    },
+    "neoverse_n2": {
+      "from": ["neoverse_n1", "armv9.0a"],
+      "vendor": "ARM",
+      "features": [
+          "fp",
+	  "asimd",
+	  "evtstrm",
+	  "aes",
+	  "pmull",
+	  "sha1",
+	  "sha2",
+	  "crc32",
+	  "atomics",
+	  "fphp",
+	  "asimdhp",
+	  "cpuid",
+	  "asimdrdm",
+	  "jscvt",
+	  "fcma",
+	  "lrcpc",
+	  "dcpop",
+	  "sha3",
+	  "asimddp",
+	  "sha512",
+	  "sve",
+	  "asimdfhm",
+	  "uscat",
+	  "ilrcpc",
+	  "flagm",
+	  "ssbs",
+	  "sb",
+	  "dcpodp",
+	  "sve2",
+	  "flagm2",
+	  "frint",
+	  "svei8mm",
+	  "svebf16",
+	  "i8mm",
+	  "bf16"
+      ],
+      "compilers" : {
+          "gcc": [
+              {
+                  "versions": "4.8:5.99",
+                  "flags": "-march=armv8-a"
+              },
+              {
+                  "versions": "6:6.99",
+                  "flags" : "-march=armv8.1-a"
+              },
+              {
+                  "versions": "7.0:7.99",
+                  "flags" : "-march=armv8.2-a -mtune=cortex-a72"
+              },
+              {
+                  "versions": "8.0:8.99",
+                  "flags" : "-march=armv8.4-a+sve -mtune=cortex-a72"
+              },
+              {
+                  "versions": "9.0:9.99",
+                  "flags" : "-march=armv8.5-a+sve -mtune=cortex-a76"
+              },
+              {
+                  "versions": "10.0:10.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16 -mtune=cortex-a77"
+              },
+              {
+                  "versions": "11.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "clang" : [
+              {
+                  "versions": "9.0:10.99",
+                  "flags" : "-march=armv8.5-a+sve"
+              },
+              {
+                  "versions": "11.0:13.99",
+                  "flags" : "-march=armv8.5-a+sve+sve2+i8mm+bf16"
+              },
+              {
+                  "versions": "14.0:15.99",
+                  "flags" : "-march=armv9-a+i8mm+bf16"
+              },
+              {
+                  "versions": "16.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "arm" : [
+              {
+                  "versions": "23.04.0:",
+                  "flags" : "-mcpu=neoverse-n2"
+              }
+          ],
+          "nvhpc" : [
+              {
+                  "versions": "23.3:",
+                  "name": "neoverse-n1",
+                  "flags": "-tp {name}"
+              }
+          ]
+      },
+      "cpupart": "0xd49"
     },
     "m1": {
       "from": ["armv8.4a"],
@@ -3211,7 +3319,8 @@
             "flags" : "-mcpu=apple-m1"
           }
         ]
-      }
+      },
+      "cpupart": "0x022"
     },
     "m2": {
       "from": ["m1", "armv8.5a"],
@@ -3289,7 +3398,8 @@
             "flags" : "-mcpu=apple-m2"
           }
         ]
-      }
+      },
+      "cpupart": "0x032"
     },
     "arm": {
       "from": [],

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

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

lib/spack/external/patches/distro.patch

@@ -0,0 +1,45 @@
+diff --git a/lib/spack/external/_vendoring/distro/distro.py b/lib/spack/external/_vendoring/distro/distro.py
+index 89e1868047..50c3b18d4d 100644
+--- a/lib/spack/external/_vendoring/distro/distro.py
++++ b/lib/spack/external/_vendoring/distro/distro.py
+@@ -1265,27 +1265,29 @@ def _distro_release_info(self) -> Dict[str, str]:
+             match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
+         else:
+             try:
+-                basenames = [
+-                    basename
+-                    for basename in os.listdir(self.etc_dir)
+-                    if basename not in _DISTRO_RELEASE_IGNORE_BASENAMES
+-                    and os.path.isfile(os.path.join(self.etc_dir, basename))
+-                ]
++                with os.scandir(self.etc_dir) as it:
++                    etc_files = [
++                        p.path for p in it
++                        if p.is_file() and p.name not in _DISTRO_RELEASE_IGNORE_BASENAMES
++                    ]
+                 # We sort for repeatability in cases where there are multiple
+                 # distro specific files; e.g. CentOS, Oracle, Enterprise all
+                 # containing `redhat-release` on top of their own.
+-                basenames.sort()
++                etc_files.sort()
+             except OSError:
+                 # This may occur when /etc is not readable but we can't be
+                 # sure about the *-release files. Check common entries of
+                 # /etc for information. If they turn out to not be there the
+                 # error is handled in `_parse_distro_release_file()`.
+-                basenames = _DISTRO_RELEASE_BASENAMES
+-            for basename in basenames:
+-                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(basename)
++                etc_files = [
++                    os.path.join(self.etc_dir, basename)
++                    for basename in _DISTRO_RELEASE_BASENAMES
++                ]
++
++            for filepath in etc_files:
++                match = _DISTRO_RELEASE_BASENAME_PATTERN.match(os.path.basename(filepath))
+                 if match is None:
+                     continue
+-                filepath = os.path.join(self.etc_dir, basename)
+                 distro_info = self._parse_distro_release_file(filepath)
+                 # The name is always present if the pattern matches.
+                 if "name" not in distro_info:

lib/spack/external/patches/jsonschema.patch

@@ -13,3 +13,191 @@ index 6b630cdfbb..1791fe7fbf 100644
 -__version__ = metadata.version("jsonschema")
 +
 +__version__ = "3.2.0"
+diff --git a/lib/spack/external/_vendoring/jsonschema/_format.py b/lib/spack/external/_vendoring/jsonschema/_format.py
+index 281a7cfcff..29061e3661 100644
+--- a/lib/spack/external/_vendoring/jsonschema/_format.py
++++ b/lib/spack/external/_vendoring/jsonschema/_format.py
+@@ -231,96 +231,6 @@ def is_host_name(instance):
+     return True
+ 
+ 
+-try:
+-    # The built-in `idna` codec only implements RFC 3890, so we go elsewhere.
+-    import idna
+-except ImportError:
+-    pass
+-else:
+-    @_checks_drafts(draft7="idn-hostname", raises=idna.IDNAError)
+-    def is_idn_host_name(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        idna.encode(instance)
+-        return True
+-
+-
+-try:
+-    import rfc3987
+-except ImportError:
+-    try:
+-        from rfc3986_validator import validate_rfc3986
+-    except ImportError:
+-        pass
+-    else:
+-        @_checks_drafts(name="uri")
+-        def is_uri(instance):
+-            if not isinstance(instance, str_types):
+-                return True
+-            return validate_rfc3986(instance, rule="URI")
+-
+-        @_checks_drafts(
+-            draft6="uri-reference",
+-            draft7="uri-reference",
+-            raises=ValueError,
+-        )
+-        def is_uri_reference(instance):
+-            if not isinstance(instance, str_types):
+-                return True
+-            return validate_rfc3986(instance, rule="URI_reference")
+-
+-else:
+-    @_checks_drafts(draft7="iri", raises=ValueError)
+-    def is_iri(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return rfc3987.parse(instance, rule="IRI")
+-
+-    @_checks_drafts(draft7="iri-reference", raises=ValueError)
+-    def is_iri_reference(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return rfc3987.parse(instance, rule="IRI_reference")
+-
+-    @_checks_drafts(name="uri", raises=ValueError)
+-    def is_uri(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return rfc3987.parse(instance, rule="URI")
+-
+-    @_checks_drafts(
+-        draft6="uri-reference",
+-        draft7="uri-reference",
+-        raises=ValueError,
+-    )
+-    def is_uri_reference(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return rfc3987.parse(instance, rule="URI_reference")
+-
+-
+-try:
+-    from strict_rfc3339 import validate_rfc3339
+-except ImportError:
+-    try:
+-        from rfc3339_validator import validate_rfc3339
+-    except ImportError:
+-        validate_rfc3339 = None
+-
+-if validate_rfc3339:
+-    @_checks_drafts(name="date-time")
+-    def is_datetime(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return validate_rfc3339(instance)
+-
+-    @_checks_drafts(draft7="time")
+-    def is_time(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return is_datetime("1970-01-01T" + instance)
+-
+-
+ @_checks_drafts(name="regex", raises=re.error)
+ def is_regex(instance):
+     if not isinstance(instance, str_types):
+@@ -340,86 +250,3 @@ def is_draft3_time(instance):
+     if not isinstance(instance, str_types):
+         return True
+     return datetime.datetime.strptime(instance, "%H:%M:%S")
+-
+-
+-try:
+-    import webcolors
+-except ImportError:
+-    pass
+-else:
+-    def is_css_color_code(instance):
+-        return webcolors.normalize_hex(instance)
+-
+-    @_checks_drafts(draft3="color", raises=(ValueError, TypeError))
+-    def is_css21_color(instance):
+-        if (
+-            not isinstance(instance, str_types) or
+-            instance.lower() in webcolors.css21_names_to_hex
+-        ):
+-            return True
+-        return is_css_color_code(instance)
+-
+-    def is_css3_color(instance):
+-        if instance.lower() in webcolors.css3_names_to_hex:
+-            return True
+-        return is_css_color_code(instance)
+-
+-
+-try:
+-    import jsonpointer
+-except ImportError:
+-    pass
+-else:
+-    @_checks_drafts(
+-        draft6="json-pointer",
+-        draft7="json-pointer",
+-        raises=jsonpointer.JsonPointerException,
+-    )
+-    def is_json_pointer(instance):
+-        if not isinstance(instance, str_types):
+-            return True
+-        return jsonpointer.JsonPointer(instance)
+-
+-    # TODO: I don't want to maintain this, so it
+-    #       needs to go either into jsonpointer (pending
+-    #       https://github.com/stefankoegl/python-json-pointer/issues/34) or
+-    #       into a new external library.
+-    @_checks_drafts(
+-        draft7="relative-json-pointer",
+-        raises=jsonpointer.JsonPointerException,
+-    )
+-    def is_relative_json_pointer(instance):
+-        # Definition taken from:
+-        # https://tools.ietf.org/html/draft-handrews-relative-json-pointer-01#section-3
+-        if not isinstance(instance, str_types):
+-            return True
+-        non_negative_integer, rest = [], ""
+-        for i, character in enumerate(instance):
+-            if character.isdigit():
+-                non_negative_integer.append(character)
+-                continue
+-
+-            if not non_negative_integer:
+-                return False
+-
+-            rest = instance[i:]
+-            break
+-        return (rest == "#") or jsonpointer.JsonPointer(rest)
+-
+-
+-try:
+-    import uritemplate.exceptions
+-except ImportError:
+-    pass
+-else:
+-    @_checks_drafts(
+-        draft6="uri-template",
+-        draft7="uri-template",
+-        raises=uritemplate.exceptions.InvalidTemplate,
+-    )
+-    def is_uri_template(
+-        instance,
+-        template_validator=uritemplate.Validator().force_balanced_braces(),
+-    ):
+-        template = uritemplate.URITemplate(instance)
+-        return template_validator.validate(template)

lib/spack/llnl/util/filesystem.py

@@ -1624,6 +1624,12 @@ def remove_linked_tree(path):
             shutil.rmtree(os.path.realpath(path), **kwargs)
             os.unlink(path)
         else:
+            if sys.platform == "win32":
+                # Adding this prefix allows shutil to remove long paths on windows
+                # https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry
+                long_path_pfx = "\\\\?\\"
+                if not path.startswith(long_path_pfx):
+                    path = long_path_pfx + path
             shutil.rmtree(path, **kwargs)
 
 

lib/spack/llnl/util/lang.py

@@ -6,7 +6,6 @@
 import collections.abc
 import contextlib
 import functools
-import inspect
 import itertools
 import os
 import re
@@ -16,7 +15,7 @@
 from typing import Any, Callable, Iterable, List, Tuple
 
 # Ignore emacs backups when listing modules
-ignore_modules = [r"^\.#", "~$"]
+ignore_modules = r"^\.#|~$"
 
 
 def index_by(objects, *funcs):
@@ -84,20 +83,6 @@ def index_by(objects, *funcs):
     return result
 
 
-def caller_locals():
-    """This will return the locals of the *parent* of the caller.
-    This allows a function to insert variables into its caller's
-    scope.  Yes, this is some black magic, and yes it's useful
-    for implementing things like depends_on and provides.
-    """
-    # Passing zero here skips line context for speed.
-    stack = inspect.stack(0)
-    try:
-        return stack[2][0].f_locals
-    finally:
-        del stack
-
-
 def attr_setdefault(obj, name, value):
     """Like dict.setdefault, but for objects."""
     if not hasattr(obj, name):
@@ -105,15 +90,6 @@ def attr_setdefault(obj, name, value):
     return getattr(obj, name)
 
 
-def has_method(cls, name):
-    for base in inspect.getmro(cls):
-        if base is object:
-            continue
-        if name in base.__dict__:
-            return True
-    return False
-
-
 def union_dicts(*dicts):
     """Use update() to combine all dicts into one.
 
@@ -178,19 +154,22 @@ def list_modules(directory, **kwargs):
     order."""
     list_directories = kwargs.setdefault("directories", True)
 
-    for name in os.listdir(directory):
-        if name == "__init__.py":
-            continue
+    ignore = re.compile(ignore_modules)
 
-        path = os.path.join(directory, name)
-        if list_directories and os.path.isdir(path):
-            init_py = os.path.join(path, "__init__.py")
-            if os.path.isfile(init_py):
-                yield name
+    with os.scandir(directory) as it:
+        for entry in it:
+            if entry.name == "__init__.py" or entry.name == "__pycache__":
+                continue
 
-        elif name.endswith(".py"):
-            if not any(re.search(pattern, name) for pattern in ignore_modules):
-                yield re.sub(".py$", "", name)
+            if (
+                list_directories
+                and entry.is_dir()
+                and os.path.isfile(os.path.join(entry.path, "__init__.py"))
+            ):
+                yield entry.name
+
+            elif entry.name.endswith(".py") and entry.is_file() and not ignore.search(entry.name):
+                yield entry.name[:-3]  # strip .py
 
 
 def decorator_with_or_without_args(decorator):
@@ -237,8 +216,8 @@ def setter(name, value):
         value.__name__ = name
         setattr(cls, name, value)
 
-    if not has_method(cls, "_cmp_key"):
-        raise TypeError("'%s' doesn't define _cmp_key()." % cls.__name__)
+    if not hasattr(cls, "_cmp_key"):
+        raise TypeError(f"'{cls.__name__}' doesn't define _cmp_key().")
 
     setter("__eq__", lambda s, o: (s is o) or (o is not None and s._cmp_key() == o._cmp_key()))
     setter("__lt__", lambda s, o: o is not None and s._cmp_key() < o._cmp_key())
@@ -388,8 +367,8 @@ def cd_fun():
         TypeError: If the class does not have a ``_cmp_iter`` method
 
     """
-    if not has_method(cls, "_cmp_iter"):
-        raise TypeError("'%s' doesn't define _cmp_iter()." % cls.__name__)
+    if not hasattr(cls, "_cmp_iter"):
+        raise TypeError(f"'{cls.__name__}' doesn't define _cmp_iter().")
 
     # comparison operators are implemented in terms of lazy_eq and lazy_lt
     def eq(self, other):

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

@@ -10,6 +10,7 @@
 import errno
 import io
 import multiprocessing
+import multiprocessing.connection
 import os
 import re
 import select

lib/spack/spack/abi.py

@@ -1,131 +0,0 @@
-# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
-# Spack Project Developers. See the top-level COPYRIGHT file for details.
-#
-# SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-import os
-
-from llnl.util.lang import memoized
-
-import spack.spec
-import spack.version
-from spack.compilers.clang import Clang
-from spack.util.executable import Executable, ProcessError
-
-
-class ABI:
-    """This class provides methods to test ABI compatibility between specs.
-    The current implementation is rather rough and could be improved."""
-
-    def architecture_compatible(
-        self, target: spack.spec.Spec, constraint: spack.spec.Spec
-    ) -> bool:
-        """Return true if architecture of target spec is ABI compatible
-        to the architecture of constraint spec. If either the target
-        or constraint specs have no architecture, target is also defined
-        as architecture ABI compatible to constraint."""
-        return (
-            not target.architecture
-            or not constraint.architecture
-            or target.architecture.intersects(constraint.architecture)
-        )
-
-    @memoized
-    def _gcc_get_libstdcxx_version(self, version):
-        """Returns gcc ABI compatibility info by getting the library version of
-        a compiler's libstdc++ or libgcc_s"""
-        from spack.build_environment import dso_suffix
-
-        spec = spack.spec.CompilerSpec("gcc", version)
-        compilers = spack.compilers.compilers_for_spec(spec)
-        if not compilers:
-            return None
-        compiler = compilers[0]
-        rungcc = None
-        libname = None
-        output = None
-        if compiler.cxx:
-            rungcc = Executable(compiler.cxx)
-            libname = "libstdc++." + dso_suffix
-        elif compiler.cc:
-            rungcc = Executable(compiler.cc)
-            libname = "libgcc_s." + dso_suffix
-        else:
-            return None
-        try:
-            # Some gcc's are actually clang and don't respond properly to
-            # --print-file-name (they just print the filename, not the
-            # full path).  Ignore these and expect them to be handled as clang.
-            if Clang.default_version(rungcc.exe[0]) != "unknown":
-                return None
-
-            output = rungcc("--print-file-name=%s" % libname, output=str)
-        except ProcessError:
-            return None
-        if not output:
-            return None
-        libpath = os.path.realpath(output.strip())
-        if not libpath:
-            return None
-        return os.path.basename(libpath)
-
-    @memoized
-    def _gcc_compiler_compare(self, pversion, cversion):
-        """Returns true iff the gcc version pversion and cversion
-        are ABI compatible."""
-        plib = self._gcc_get_libstdcxx_version(pversion)
-        clib = self._gcc_get_libstdcxx_version(cversion)
-        if not plib or not clib:
-            return False
-        return plib == clib
-
-    def _intel_compiler_compare(
-        self, pversion: spack.version.ClosedOpenRange, cversion: spack.version.ClosedOpenRange
-    ) -> bool:
-        """Returns true iff the intel version pversion and cversion
-        are ABI compatible"""
-
-        # Test major and minor versions.  Ignore build version.
-        pv = pversion.lo
-        cv = cversion.lo
-        return pv.up_to(2) == cv.up_to(2)
-
-    def compiler_compatible(
-        self, parent: spack.spec.Spec, child: spack.spec.Spec, loose: bool = False
-    ) -> bool:
-        """Return true if compilers for parent and child are ABI compatible."""
-        if not parent.compiler or not child.compiler:
-            return True
-
-        if parent.compiler.name != child.compiler.name:
-            # Different compiler families are assumed ABI incompatible
-            return False
-
-        if loose:
-            return True
-
-        # TODO: Can we move the specialized ABI matching stuff
-        # TODO: into compiler classes?
-        for pversion in parent.compiler.versions:
-            for cversion in child.compiler.versions:
-                # For a few compilers use specialized comparisons.
-                # Otherwise match on version match.
-                if pversion.intersects(cversion):
-                    return True
-                elif parent.compiler.name == "gcc" and self._gcc_compiler_compare(
-                    pversion, cversion
-                ):
-                    return True
-                elif parent.compiler.name == "intel" and self._intel_compiler_compare(
-                    pversion, cversion
-                ):
-                    return True
-        return False
-
-    def compatible(
-        self, target: spack.spec.Spec, constraint: spack.spec.Spec, loose: bool = False
-    ) -> bool:
-        """Returns true if target spec is ABI compatible to constraint spec"""
-        return self.architecture_compatible(target, constraint) and self.compiler_compatible(
-            target, constraint, loose=loose
-        )

lib/spack/spack/audit.py

@@ -39,9 +39,9 @@ def _search_duplicate_compilers(error_cls):
 import collections
 import collections.abc
 import glob
-import inspect
 import io
 import itertools
+import os
 import pathlib
 import pickle
 import re
@@ -210,6 +210,11 @@ def _search_duplicate_compilers(error_cls):
     group="configs", tag="CFG-PACKAGES", description="Sanity checks on packages.yaml", kwargs=()
 )
 
+#: Sanity checks on packages.yaml
+config_repos = AuditClass(
+    group="configs", tag="CFG-REPOS", description="Sanity checks on repositories", kwargs=()
+)
+
 
 @config_packages
 def _search_duplicate_specs_in_externals(error_cls):
@@ -367,6 +372,27 @@ def _ensure_all_virtual_packages_have_default_providers(error_cls):
     ]
 
 
+@config_repos
+def _ensure_no_folders_without_package_py(error_cls):
+    """Check that we don't leave any folder without a package.py in repos"""
+    errors = []
+    for repository in spack.repo.PATH.repos:
+        missing = []
+        for entry in os.scandir(repository.packages_path):
+            if not entry.is_dir():
+                continue
+            package_py = pathlib.Path(entry.path) / spack.repo.package_file_name
+            if not package_py.exists():
+                missing.append(entry.path)
+        if missing:
+            summary = (
+                f"The '{repository.namespace}' repository misses a package.py file"
+                f" in the following folders"
+            )
+            errors.append(error_cls(summary=summary, details=[f"{x}" for x in missing]))
+    return errors
+
+
 def _make_config_error(config_data, summary, error_cls):
     s = io.StringIO()
     s.write("Occurring in the following file:\n")
@@ -498,7 +524,7 @@ def _search_for_reserved_attributes_names_in_packages(pkgs, error_cls):
         name_definitions = collections.defaultdict(list)
         pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
 
-        for cls_item in inspect.getmro(pkg_cls):
+        for cls_item in pkg_cls.__mro__:
             for name in RESERVED_NAMES:
                 current_value = cls_item.__dict__.get(name)
                 if current_value is None:
@@ -527,7 +553,7 @@ def _ensure_all_package_names_are_lowercase(pkgs, error_cls):
     badname_regex, errors = re.compile(r"[_A-Z]"), []
     for pkg_name in pkgs:
         if badname_regex.search(pkg_name):
-            error_msg = "Package name '{}' is either lowercase or conatine '_'".format(pkg_name)
+            error_msg = f"Package name '{pkg_name}' should be lowercase and must not contain '_'"
             errors.append(error_cls(error_msg, []))
     return errors
 

lib/spack/spack/bootstrap/_common.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 """Common basic functions used through the spack.bootstrap package"""
 import fnmatch
+import importlib
 import os.path
 import re
 import sys
@@ -28,7 +29,7 @@
 
 def _python_import(module: str) -> bool:
     try:
-        __import__(module)
+        importlib.import_module(module)
     except ImportError:
         return False
     return True

lib/spack/spack/bootstrap/clingo.py

@@ -0,0 +1,154 @@
+# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+"""Bootstrap concrete specs for clingo
+
+Spack uses clingo to concretize specs. When clingo itself needs to be bootstrapped from sources,
+we need to rely on another mechanism to get a concrete spec that fits the current host.
+
+This module contains the logic to get a concrete spec for clingo, starting from a prototype
+JSON file for a similar platform.
+"""
+import pathlib
+import sys
+from typing import Dict, Optional, Tuple
+
+import archspec.cpu
+
+import spack.compiler
+import spack.compilers
+import spack.platforms
+import spack.spec
+import spack.traverse
+
+from .config import spec_for_current_python
+
+
+class ClingoBootstrapConcretizer:
+    def __init__(self, configuration):
+        self.host_platform = spack.platforms.host()
+        self.host_os = self.host_platform.operating_system("frontend")
+        self.host_target = archspec.cpu.host().family
+        self.host_architecture = spack.spec.ArchSpec.frontend_arch()
+        self.host_architecture.target = str(self.host_target)
+        self.host_compiler = self._valid_compiler_or_raise()
+        self.host_python = self.python_external_spec()
+        if str(self.host_platform) == "linux":
+            self.host_libc = self.libc_external_spec()
+
+        self.external_cmake, self.external_bison = self._externals_from_yaml(configuration)
+
+    def _valid_compiler_or_raise(self) -> "spack.compiler.Compiler":
+        if str(self.host_platform) == "linux":
+            compiler_name = "gcc"
+        elif str(self.host_platform) == "darwin":
+            compiler_name = "apple-clang"
+        elif str(self.host_platform) == "windows":
+            compiler_name = "msvc"
+        elif str(self.host_platform) == "freebsd":
+            compiler_name = "clang"
+        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
+        )
+        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)
+        return candidates[0]
+
+    def _externals_from_yaml(
+        self, configuration: "spack.config.Configuration"
+    ) -> Tuple[Optional["spack.spec.Spec"], Optional["spack.spec.Spec"]]:
+        packages_yaml = configuration.get("packages")
+        requirements = {"cmake": "@3.20:", "bison": "@2.5:"}
+        selected: Dict[str, Optional["spack.spec.Spec"]] = {"cmake": None, "bison": None}
+        for pkg_name in ["cmake", "bison"]:
+            if pkg_name not in packages_yaml:
+                continue
+
+            candidates = packages_yaml[pkg_name].get("externals", [])
+            for candidate in candidates:
+                s = spack.spec.Spec(candidate["spec"], external_path=candidate["prefix"])
+                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
+
+                selected[pkg_name] = self._external_spec(s)
+                break
+        return selected["cmake"], selected["bison"]
+
+    def prototype_path(self) -> pathlib.Path:
+        """Path to a prototype concrete specfile for clingo"""
+        parent_dir = pathlib.Path(__file__).parent
+        result = parent_dir / "prototypes" / f"clingo-{self.host_platform}-{self.host_target}.json"
+        if str(self.host_platform) == "linux":
+            # Using aarch64 as a fallback, since it has gnuconfig (x86_64 doesn't have it)
+            if not result.exists():
+                result = parent_dir / "prototypes" / f"clingo-{self.host_platform}-aarch64.json"
+
+        elif str(self.host_platform) == "freebsd":
+            result = parent_dir / "prototypes" / f"clingo-{self.host_platform}-amd64.json"
+
+        elif not result.exists():
+            raise RuntimeError(f"Cannot bootstrap clingo from sources on {self.host_platform}")
+
+        return result
+
+    def concretize(self) -> "spack.spec.Spec":
+        # Read the prototype and mark it NOT concrete
+        s = spack.spec.Spec.from_specfile(str(self.prototype_path()))
+        s._mark_concrete(False)
+
+        # 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
+
+        for edge in spack.traverse.traverse_edges([s], cover="edges"):
+            if edge.spec.name == "python":
+                edge.spec = self.host_python
+
+            if edge.spec.name == "bison" and self.external_bison:
+                edge.spec = self.external_bison
+
+            if edge.spec.name == "cmake" and self.external_cmake:
+                edge.spec = self.external_cmake
+
+            if "libc" in edge.virtuals:
+                edge.spec = self.host_libc
+
+        s._finalize_concretization()
+
+        # Work around the fact that the installer calls Spec.dependents() and
+        # we modified edges inconsistently
+        return s.copy()
+
+    def python_external_spec(self) -> "spack.spec.Spec":
+        """Python external spec corresponding to the current running interpreter"""
+        result = spack.spec.Spec(spec_for_current_python(), external_path=sys.exec_prefix)
+        return self._external_spec(result)
+
+    def libc_external_spec(self) -> "spack.spec.Spec":
+        result = self.host_compiler.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] = []
+        return spack.spec.parse_with_version_concrete(initial_spec)

lib/spack/spack/bootstrap/config.py

@@ -143,11 +143,7 @@ def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
 def _add_compilers_if_missing() -> None:
     arch = spack.spec.ArchSpec.frontend_arch()
     if not spack.compilers.compilers_for_arch(arch):
-        new_compilers = spack.compilers.find_new_compilers(
-            mixed_toolchain=sys.platform == "darwin"
-        )
-        if new_compilers:
-            spack.compilers.add_compilers_to_config(new_compilers)
+        spack.compilers.find_compilers()
 
 
 @contextlib.contextmanager
@@ -156,7 +152,7 @@ def _ensure_bootstrap_configuration() -> Generator:
     bootstrap_store_path = store_path()
     user_configuration = _read_and_sanitize_configuration()
     with spack.environment.no_active_environment():
-        with spack.platforms.prevent_cray_detection(), spack.platforms.use_platform(
+        with spack.platforms.use_platform(
             spack.platforms.real_host()
         ), spack.repo.use_repositories(spack.paths.packages_path):
             # Default configuration scopes excluding command line

lib/spack/spack/bootstrap/core.py

@@ -54,6 +54,7 @@
 import spack.version
 
 from ._common import _executables_in_store, _python_import, _root_spec, _try_import_from_store
+from .clingo import ClingoBootstrapConcretizer
 from .config import spack_python_interpreter, spec_for_current_python
 
 #: Name of the file containing metadata about the bootstrapping source
@@ -268,15 +269,13 @@ def try_import(self, module: str, abstract_spec_str: str) -> bool:
 
         # Try to build and install from sources
         with spack_python_interpreter():
-            # Add hint to use frontend operating system on Cray
-            concrete_spec = spack.spec.Spec(abstract_spec_str + " ^" + spec_for_current_python())
-
             if module == "clingo":
-                # TODO: remove when the old concretizer is deprecated  # pylint: disable=fixme
-                concrete_spec._old_concretize(  # pylint: disable=protected-access
-                    deprecation_warning=False
-                )
+                bootstrapper = ClingoBootstrapConcretizer(configuration=spack.config.CONFIG)
+                concrete_spec = bootstrapper.concretize()
             else:
+                concrete_spec = spack.spec.Spec(
+                    abstract_spec_str + " ^" + spec_for_current_python()
+                )
                 concrete_spec.concretize()
 
         msg = "[BOOTSTRAP MODULE {0}] Try installing '{1}' from sources"
@@ -303,14 +302,7 @@ def try_search_path(self, executables: Tuple[str], abstract_spec_str: str) -> bo
         # might reduce compilation time by a fair amount
         _add_externals_if_missing()
 
-        concrete_spec = spack.spec.Spec(abstract_spec_str)
-        if concrete_spec.name == "patchelf":
-            concrete_spec._old_concretize(  # pylint: disable=protected-access
-                deprecation_warning=False
-            )
-        else:
-            concrete_spec.concretize()
-
+        concrete_spec = spack.spec.Spec(abstract_spec_str).concretized()
         msg = "[BOOTSTRAP] Try installing '{0}' from sources"
         tty.debug(msg.format(abstract_spec_str))
         with spack.config.override(self.mirror_scope):

lib/spack/spack/bootstrap/status.py

@@ -124,7 +124,7 @@ def _development_requirements() -> List[RequiredResponseType]:
     # Ensure we trigger environment modifications if we have an environment
     if BootstrapEnvironment.spack_yaml().exists():
         with BootstrapEnvironment() as env:
-            env.update_syspath_and_environ()
+            env.load()
 
     return [
         _required_executable(

lib/spack/spack/build_environment.py

@@ -457,9 +457,12 @@ def set_wrapper_variables(pkg, env):
     env.set(SPACK_DEBUG_LOG_ID, pkg.spec.format("{name}-{hash:7}"))
     env.set(SPACK_DEBUG_LOG_DIR, spack.main.spack_working_dir)
 
-    # Find ccache binary and hand it to build environment
     if spack.config.get("config:ccache"):
+        # Enable ccache in the compiler wrapper
         env.set(SPACK_CCACHE_BINARY, spack.util.executable.which_string("ccache", required=True))
+    else:
+        # Avoid cache pollution if a build system forces `ccache <compiler wrapper invocation>`.
+        env.set("CCACHE_DISABLE", "1")
 
     # Gather information about various types of dependencies
     link_deps = set(pkg.spec.traverse(root=False, deptype=("link")))
@@ -552,7 +555,7 @@ def set_package_py_globals(pkg, context: Context = Context.BUILD):
     """Populate the Python module of a package with some useful global names.
     This makes things easier for package writers.
     """
-    module = ModuleChangePropagator(pkg)
+    module = SetPackageGlobals(pkg)
 
     if context == Context.BUILD:
         module.std_cmake_args = spack.build_systems.cmake.CMakeBuilder.std_args(pkg)
@@ -1013,7 +1016,7 @@ def set_all_package_py_globals(self):
                 # setting globals for those.
                 if id(spec) not in self.nodes_in_subdag:
                     continue
-                dependent_module = ModuleChangePropagator(spec.package)
+                dependent_module = SetPackageGlobals(spec.package)
                 pkg.setup_dependent_package(dependent_module, spec)
                 dependent_module.propagate_changes_to_mro()
 
@@ -1540,7 +1543,7 @@ def write_log_summary(out, log_type, log, last=None):
         out.write(make_log_context(warnings))
 
 
-class ModuleChangePropagator:
+class SetPackageGlobals:
     """Wrapper class to accept changes to a package.py Python module, and propagate them in the
     MRO of the package.
 
@@ -1548,41 +1551,22 @@ class ModuleChangePropagator:
     "setup_dependent_package" function during build environment setup.
     """
 
-    _PROTECTED_NAMES = ("package", "current_module", "modules_in_mro", "_set_attributes")
-
-    def __init__(self, package):
-        self._set_self_attributes("package", package)
-        self._set_self_attributes("current_module", package.module)
-
+    def __init__(self, package: spack.package_base.PackageBase) -> None:
         #: Modules for the classes in the MRO up to PackageBase
         modules_in_mro = []
-        for cls in inspect.getmro(type(package)):
-            module = cls.module
-
-            if module == self.current_module:
-                continue
-
-            if module == spack.package_base:
+        for cls in package.__class__.__mro__:
+            module = getattr(cls, "module", None)
+            if module is None or module is spack.package_base:
                 break
-
             modules_in_mro.append(module)
-        self._set_self_attributes("modules_in_mro", modules_in_mro)
-        self._set_self_attributes("_set_attributes", {})
 
-    def _set_self_attributes(self, key, value):
-        super().__setattr__(key, value)
+        super().__setattr__("modules_in_mro", modules_in_mro)
 
     def __getattr__(self, item):
-        return getattr(self.current_module, item)
+        return getattr(self.modules_in_mro[0], item)
 
     def __setattr__(self, key, value):
-        if key in ModuleChangePropagator._PROTECTED_NAMES:
-            msg = f'Cannot set attribute "{key}" in ModuleMonkeyPatcher'
-            return AttributeError(msg)
-
-        setattr(self.current_module, key, value)
-        self._set_attributes[key] = value
-
-    def propagate_changes_to_mro(self):
-        for module_in_mro in self.modules_in_mro:
-            module_in_mro.__dict__.update(self._set_attributes)
+        if key == "modules_in_mro":
+            raise AttributeError(f'Cannot set attribute "{key}" in ModuleMonkeyPatcher')
+        for module in self.modules_in_mro:
+            setattr(module, key, value)

lib/spack/spack/build_systems/autotools.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 import os
 import os.path
 import stat
@@ -15,6 +14,7 @@
 import spack.build_environment
 import spack.builder
 import spack.package_base
+from spack.build_environment import SetPackageGlobals
 from spack.directives import build_system, conflicts, depends_on
 from spack.multimethod import when
 from spack.operating_systems.mac_os import macos_version
@@ -549,13 +549,12 @@ def autoreconf(self, pkg, spec, prefix):
         tty.warn("*        a custom AUTORECONF phase in the package       *")
         tty.warn("*********************************************************")
         with fs.working_dir(self.configure_directory):
-            m = inspect.getmodule(self.pkg)
             # This line is what is needed most of the time
             # --install, --verbose, --force
             autoreconf_args = ["-ivf"]
             autoreconf_args += self.autoreconf_search_path_args
             autoreconf_args += self.autoreconf_extra_args
-            m.autoreconf(*autoreconf_args)
+            self.pkg.module.autoreconf(*autoreconf_args)
 
     @property
     def autoreconf_search_path_args(self):
@@ -579,7 +578,7 @@ def set_configure_or_die(self):
             raise RuntimeError(msg.format(self.configure_directory))
 
         # Monkey-patch the configure script in the corresponding module
-        inspect.getmodule(self.pkg).configure = Executable(self.configure_abs_path)
+        SetPackageGlobals(self.pkg).configure = Executable(self.configure_abs_path)
 
     def configure_args(self):
         """Return the list of all the arguments that must be passed to configure,
@@ -596,7 +595,7 @@ def configure(self, pkg, spec, prefix):
         options += self.configure_args()
 
         with fs.working_dir(self.build_directory, create=True):
-            inspect.getmodule(self.pkg).configure(*options)
+            pkg.module.configure(*options)
 
     def build(self, pkg, spec, prefix):
         """Run "make" on the build targets specified by the builder."""
@@ -604,12 +603,12 @@ def build(self, pkg, spec, prefix):
         params = ["V=1"]
         params += self.build_targets
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make(*params)
+            pkg.module.make(*params)
 
     def install(self, pkg, spec, prefix):
         """Run "make" on the install targets specified by the builder."""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make(*self.install_targets)
+            pkg.module.make(*self.install_targets)
 
     spack.builder.run_after("build")(execute_build_time_tests)
 

lib/spack/spack/build_systems/cargo.py

@@ -3,8 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-import inspect
-
 import llnl.util.filesystem as fs
 
 import spack.builder
@@ -72,9 +70,7 @@ def check_args(self):
     def build(self, pkg, spec, prefix):
         """Runs ``cargo install`` in the source directory"""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(pkg).cargo(
-                "install", "--root", "out", "--path", ".", *self.build_args
-            )
+            pkg.module.cargo("install", "--root", "out", "--path", ".", *self.build_args)
 
     def install(self, pkg, spec, prefix):
         """Copy build files into package prefix."""
@@ -86,4 +82,4 @@ def install(self, pkg, spec, prefix):
     def check(self):
         """Run "cargo test"."""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).cargo("test", *self.check_args)
+            self.pkg.module.cargo("test", *self.check_args)

lib/spack/spack/build_systems/cmake.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import collections.abc
-import inspect
 import os
 import pathlib
 import platform
@@ -539,24 +538,24 @@ def cmake(self, pkg, spec, prefix):
         options += self.cmake_args()
         options.append(os.path.abspath(self.root_cmakelists_dir))
         with fs.working_dir(self.build_directory, create=True):
-            inspect.getmodule(self.pkg).cmake(*options)
+            pkg.module.cmake(*options)
 
     def build(self, pkg, spec, prefix):
         """Make the build targets"""
         with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
-                inspect.getmodule(self.pkg).make(*self.build_targets)
+                pkg.module.make(*self.build_targets)
             elif self.generator == "Ninja":
                 self.build_targets.append("-v")
-                inspect.getmodule(self.pkg).ninja(*self.build_targets)
+                pkg.module.ninja(*self.build_targets)
 
     def install(self, pkg, spec, prefix):
         """Make the install targets"""
         with fs.working_dir(self.build_directory):
             if self.generator == "Unix Makefiles":
-                inspect.getmodule(self.pkg).make(*self.install_targets)
+                pkg.module.make(*self.install_targets)
             elif self.generator == "Ninja":
-                inspect.getmodule(self.pkg).ninja(*self.install_targets)
+                pkg.module.ninja(*self.install_targets)
 
     spack.builder.run_after("build")(execute_build_time_tests)
 

lib/spack/spack/build_systems/cuda.py

@@ -138,14 +138,14 @@ def cuda_flags(arch_list):
         conflicts("%gcc@11.2:", when="+cuda ^cuda@:11.5")
         conflicts("%gcc@12:", when="+cuda ^cuda@:11.8")
         conflicts("%gcc@13:", when="+cuda ^cuda@:12.3")
-        conflicts("%gcc@14:", when="+cuda ^cuda@:12.5")
+        conflicts("%gcc@14:", when="+cuda ^cuda@:12.6")
         conflicts("%clang@12:", when="+cuda ^cuda@:11.4.0")
         conflicts("%clang@13:", when="+cuda ^cuda@:11.5")
         conflicts("%clang@14:", when="+cuda ^cuda@:11.7")
         conflicts("%clang@15:", when="+cuda ^cuda@:12.0")
         conflicts("%clang@16:", when="+cuda ^cuda@:12.1")
         conflicts("%clang@17:", when="+cuda ^cuda@:12.3")
-        conflicts("%clang@18:", when="+cuda ^cuda@:12.5")
+        conflicts("%clang@18:", when="+cuda ^cuda@:12.6")
 
         # https://gist.github.com/ax3l/9489132#gistcomment-3860114
         conflicts("%gcc@10", when="+cuda ^cuda@:11.4.0")

lib/spack/spack/build_systems/go.py

@@ -3,8 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-import inspect
-
 import llnl.util.filesystem as fs
 
 import spack.builder
@@ -82,7 +80,7 @@ def check_args(self):
     def build(self, pkg, spec, prefix):
         """Runs ``go build`` in the source directory"""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(pkg).go("build", *self.build_args)
+            pkg.module.go("build", *self.build_args)
 
     def install(self, pkg, spec, prefix):
         """Install built binaries into prefix bin."""
@@ -95,4 +93,4 @@ def install(self, pkg, spec, prefix):
     def check(self):
         """Run ``go test .`` in the source directory"""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).go("test", *self.check_args)
+            self.pkg.module.go("test", *self.check_args)

lib/spack/spack/build_systems/makefile.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 from typing import List
 
 import llnl.util.filesystem as fs
@@ -103,12 +102,12 @@ def edit(self, pkg, spec, prefix):
     def build(self, pkg, spec, prefix):
         """Run "make" on the build targets specified by the builder."""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make(*self.build_targets)
+            pkg.module.make(*self.build_targets)
 
     def install(self, pkg, spec, prefix):
         """Run "make" on the install targets specified by the builder."""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make(*self.install_targets)
+            pkg.module.make(*self.install_targets)
 
     spack.builder.run_after("build")(execute_build_time_tests)
 

lib/spack/spack/build_systems/meson.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 import os
 from typing import List
 
@@ -195,19 +194,19 @@ def meson(self, pkg, spec, prefix):
         options += self.std_meson_args
         options += self.meson_args()
         with fs.working_dir(self.build_directory, create=True):
-            inspect.getmodule(self.pkg).meson(*options)
+            pkg.module.meson(*options)
 
     def build(self, pkg, spec, prefix):
         """Make the build targets"""
         options = ["-v"]
         options += self.build_targets
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).ninja(*options)
+            pkg.module.ninja(*options)
 
     def install(self, pkg, spec, prefix):
         """Make the install targets"""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).ninja(*self.install_targets)
+            pkg.module.ninja(*self.install_targets)
 
     spack.builder.run_after("build")(execute_build_time_tests)
 

lib/spack/spack/build_systems/msbuild.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 from typing import List  # novm
 
 import llnl.util.filesystem as fs
@@ -104,7 +103,7 @@ def msbuild_install_args(self):
     def build(self, pkg, spec, prefix):
         """Run "msbuild" on the build targets specified by the builder."""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).msbuild(
+            pkg.module.msbuild(
                 *self.std_msbuild_args,
                 *self.msbuild_args(),
                 self.define_targets(*self.build_targets),
@@ -114,6 +113,6 @@ def install(self, pkg, spec, prefix):
         """Run "msbuild" on the install targets specified by the builder.
         This is INSTALL by default"""
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).msbuild(
+            pkg.module.msbuild(
                 *self.msbuild_install_args(), self.define_targets(*self.install_targets)
             )

lib/spack/spack/build_systems/nmake.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 from typing import List  # novm
 
 import llnl.util.filesystem as fs
@@ -132,9 +131,7 @@ def build(self, pkg, spec, prefix):
         if self.makefile_name:
             opts.append("/F{}".format(self.makefile_name))
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).nmake(
-                *opts, *self.build_targets, ignore_quotes=self.ignore_quotes
-            )
+            pkg.module.nmake(*opts, *self.build_targets, ignore_quotes=self.ignore_quotes)
 
     def install(self, pkg, spec, prefix):
         """Run "nmake" on the install targets specified by the builder.
@@ -146,6 +143,4 @@ def install(self, pkg, spec, prefix):
             opts.append("/F{}".format(self.makefile_name))
         opts.append(self.define("PREFIX", fs.windows_sfn(prefix)))
         with fs.working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).nmake(
-                *opts, *self.install_targets, ignore_quotes=self.ignore_quotes
-            )
+            pkg.module.nmake(*opts, *self.install_targets, ignore_quotes=self.ignore_quotes)

lib/spack/spack/build_systems/octave.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
-
 import spack.builder
 import spack.package_base
 from spack.directives import build_system, extends
@@ -47,7 +45,7 @@ class OctaveBuilder(BaseBuilder):
 
     def install(self, pkg, spec, prefix):
         """Install the package from the archive file"""
-        inspect.getmodule(self.pkg).octave(
+        pkg.module.octave(
             "--quiet",
             "--norc",
             "--built-in-docstrings-file=/dev/null",

lib/spack/spack/build_systems/oneapi.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 """Common utilities for managing intel oneapi packages."""
-import getpass
 import os
 import platform
 import shutil
@@ -13,6 +12,7 @@
 from llnl.util.filesystem import HeaderList, LibraryList, find_libraries, join_path, mkdirp
 from llnl.util.link_tree import LinkTree
 
+import spack.util.path
 from spack.build_environment import dso_suffix
 from spack.directives import conflicts, license, redistribute, variant
 from spack.package_base import InstallError
@@ -99,7 +99,7 @@ def install_component(self, installer_path):
             # with other install depends on the userid. For root, we
             # delete the installercache before and after install. For
             # non root we redefine the HOME environment variable.
-            if getpass.getuser() == "root":
+            if spack.util.path.get_user() == "root":
                 shutil.rmtree("/var/intel/installercache", ignore_errors=True)
 
             bash = Executable("bash")
@@ -122,7 +122,7 @@ def install_component(self, installer_path):
                 self.prefix,
             )
 
-            if getpass.getuser() == "root":
+            if spack.util.path.get_user() == "root":
                 shutil.rmtree("/var/intel/installercache", ignore_errors=True)
 
         # Some installers have a bug and do not return an error code when failing

lib/spack/spack/build_systems/perl.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 import os
 from typing import Iterable
 
@@ -134,7 +133,7 @@ def build_method(self):
     def build_executable(self):
         """Returns the executable method to build the perl package"""
         if self.build_method == "Makefile.PL":
-            build_executable = inspect.getmodule(self.pkg).make
+            build_executable = self.pkg.module.make
         elif self.build_method == "Build.PL":
             build_executable = Executable(os.path.join(self.pkg.stage.source_path, "Build"))
         return build_executable
@@ -158,7 +157,7 @@ def configure(self, pkg, spec, prefix):
             options = ["Build.PL", "--install_base", prefix]
         options += self.configure_args()
 
-        inspect.getmodule(self.pkg).perl(*options)
+        pkg.module.perl(*options)
 
     # It is possible that the shebang in the Build script that is created from
     # Build.PL may be too long causing the build to fail. Patching the shebang

lib/spack/spack/build_systems/python.py

@@ -4,7 +4,6 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import functools
-import inspect
 import operator
 import os
 import re
@@ -17,7 +16,7 @@
 import llnl.util.filesystem as fs
 import llnl.util.lang as lang
 import llnl.util.tty as tty
-from llnl.util.filesystem import HeaderList, LibraryList
+from llnl.util.filesystem import HeaderList, LibraryList, join_path
 
 import spack.builder
 import spack.config
@@ -120,6 +119,12 @@ def skip_modules(self) -> Iterable[str]:
         """
         return []
 
+    @property
+    def bindir(self) -> str:
+        """Path to Python package's bindir, bin on unix like OS's Scripts on Windows"""
+        windows = self.spec.satisfies("platform=windows")
+        return join_path(self.spec.prefix, "Scripts" if windows else "bin")
+
     def view_file_conflicts(self, view, merge_map):
         """Report all file conflicts, excepting special cases for python.
         Specifically, this does not report errors for duplicate
@@ -222,7 +227,7 @@ def test_imports(self) -> None:
 
         # Make sure we are importing the installed modules,
         # not the ones in the source directory
-        python = inspect.getmodule(self).python  # type: ignore[union-attr]
+        python = self.module.python
         for module in self.import_modules:
             with test_part(
                 self,

lib/spack/spack/build_systems/qmake.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
-
 from llnl.util.filesystem import working_dir
 
 import spack.builder
@@ -66,17 +64,17 @@ def qmake_args(self):
     def qmake(self, pkg, spec, prefix):
         """Run ``qmake`` to configure the project and generate a Makefile."""
         with working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).qmake(*self.qmake_args())
+            pkg.module.qmake(*self.qmake_args())
 
     def build(self, pkg, spec, prefix):
         """Make the build targets"""
         with working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make()
+            pkg.module.make()
 
     def install(self, pkg, spec, prefix):
         """Make the install targets"""
         with working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make("install")
+            pkg.module.make("install")
 
     def check(self):
         """Search the Makefile for a ``check:`` target and runs it if found."""

lib/spack/spack/build_systems/r.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 from typing import Optional, Tuple
 
 import llnl.util.lang as lang
@@ -51,7 +50,7 @@ def install(self, pkg, spec, prefix):
 
         args.extend(["--library={0}".format(self.pkg.module.r_lib_dir), self.stage.source_path])
 
-        inspect.getmodule(self.pkg).R(*args)
+        pkg.module.R(*args)
 
 
 class RPackage(Package):

lib/spack/spack/build_systems/ruby.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import glob
-import inspect
 
 import spack.builder
 import spack.package_base
@@ -52,10 +51,10 @@ def build(self, pkg, spec, prefix):
         gemspecs = glob.glob("*.gemspec")
         rakefiles = glob.glob("Rakefile")
         if gemspecs:
-            inspect.getmodule(self.pkg).gem("build", "--norc", gemspecs[0])
+            pkg.module.gem("build", "--norc", gemspecs[0])
         elif rakefiles:
-            jobs = inspect.getmodule(self.pkg).make_jobs
-            inspect.getmodule(self.pkg).rake("package", "-j{0}".format(jobs))
+            jobs = pkg.module.make_jobs
+            pkg.module.rake("package", "-j{0}".format(jobs))
         else:
             # Some Ruby packages only ship `*.gem` files, so nothing to build
             pass
@@ -70,6 +69,6 @@ def install(self, pkg, spec, prefix):
             # if --install-dir is not used, GEM_PATH is deleted from the
             # environement, and Gems required to build native extensions will
             # not be found. Those extensions are built during `gem install`.
-            inspect.getmodule(self.pkg).gem(
+            pkg.module.gem(
                 "install", "--norc", "--ignore-dependencies", "--install-dir", prefix, gems[0]
             )

lib/spack/spack/build_systems/scons.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
-
 import spack.builder
 import spack.package_base
 from spack.directives import build_system, depends_on
@@ -63,8 +61,7 @@ def build_args(self, spec, prefix):
 
     def build(self, pkg, spec, prefix):
         """Build the package."""
-        args = self.build_args(spec, prefix)
-        inspect.getmodule(self.pkg).scons(*args)
+        pkg.module.scons(*self.build_args(spec, prefix))
 
     def install_args(self, spec, prefix):
         """Arguments to pass to install."""
@@ -72,9 +69,7 @@ def install_args(self, spec, prefix):
 
     def install(self, pkg, spec, prefix):
         """Install the package."""
-        args = self.install_args(spec, prefix)
-
-        inspect.getmodule(self.pkg).scons("install", *args)
+        pkg.module.scons("install", *self.install_args(spec, prefix))
 
     def build_test(self):
         """Run unit tests after build.

lib/spack/spack/build_systems/sip.py

@@ -2,7 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
 import os
 import re
 
@@ -86,14 +85,13 @@ def import_modules(self):
 
     def python(self, *args, **kwargs):
         """The python ``Executable``."""
-        inspect.getmodule(self).python(*args, **kwargs)
+        self.pkg.module.python(*args, **kwargs)
 
     def test_imports(self):
         """Attempts to import modules of the installed package."""
 
         # Make sure we are importing the installed modules,
         # not the ones in the source directory
-        python = inspect.getmodule(self).python
         for module in self.import_modules:
             with spack.install_test.test_part(
                 self,
@@ -101,7 +99,7 @@ def test_imports(self):
                 purpose="checking import of {0}".format(module),
                 work_dir="spack-test",
             ):
-                python("-c", "import {0}".format(module))
+                self.python("-c", "import {0}".format(module))
 
 
 @spack.builder.builder("sip")
@@ -136,7 +134,7 @@ def configure(self, pkg, spec, prefix):
         """Configure the package."""
 
         # https://www.riverbankcomputing.com/static/Docs/sip/command_line_tools.html
-        args = ["--verbose", "--target-dir", inspect.getmodule(self.pkg).python_platlib]
+        args = ["--verbose", "--target-dir", pkg.module.python_platlib]
         args.extend(self.configure_args())
 
         # https://github.com/Python-SIP/sip/commit/cb0be6cb6e9b756b8b0db3136efb014f6fb9b766
@@ -155,7 +153,7 @@ def build(self, pkg, spec, prefix):
         args = self.build_args()
 
         with working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make(*args)
+            pkg.module.make(*args)
 
     def build_args(self):
         """Arguments to pass to build."""
@@ -166,7 +164,7 @@ def install(self, pkg, spec, prefix):
         args = self.install_args()
 
         with working_dir(self.build_directory):
-            inspect.getmodule(self.pkg).make("install", *args)
+            pkg.module.make("install", *args)
 
     def install_args(self):
         """Arguments to pass to install."""

lib/spack/spack/build_systems/waf.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import inspect
-
 from llnl.util.filesystem import working_dir
 
 import spack.builder
@@ -90,11 +88,11 @@ def build_directory(self):
 
     def python(self, *args, **kwargs):
         """The python ``Executable``."""
-        inspect.getmodule(self.pkg).python(*args, **kwargs)
+        self.pkg.module.python(*args, **kwargs)
 
     def waf(self, *args, **kwargs):
         """Runs the waf ``Executable``."""
-        jobs = inspect.getmodule(self.pkg).make_jobs
+        jobs = self.pkg.module.make_jobs
 
         with working_dir(self.build_directory):
             self.python("waf", "-j{0}".format(jobs), *args, **kwargs)

lib/spack/spack/builder.py

@@ -6,12 +6,12 @@
 import collections.abc
 import copy
 import functools
-import inspect
 from typing import List, Optional, Tuple
 
 from llnl.util import lang
 
 import spack.build_environment
+import spack.multimethod
 
 #: Builder classes, as registered by the "builder" decorator
 BUILDER_CLS = {}
@@ -96,11 +96,10 @@ class hierarchy (look at AspellDictPackage for an example of that)
     Args:
         pkg (spack.package_base.PackageBase): package object for which we need a builder
     """
-    package_module = inspect.getmodule(pkg)
     package_buildsystem = buildsystem_name(pkg)
     default_builder_cls = BUILDER_CLS[package_buildsystem]
     builder_cls_name = default_builder_cls.__name__
-    builder_cls = getattr(package_module, builder_cls_name, None)
+    builder_cls = getattr(pkg.module, builder_cls_name, None)
     if builder_cls:
         return builder_cls(pkg)
 
@@ -295,7 +294,11 @@ def _decorator(fn):
         return _decorator
 
 
-class BuilderMeta(PhaseCallbacksMeta, type(collections.abc.Sequence)):  # type: ignore
+class BuilderMeta(
+    PhaseCallbacksMeta,
+    spack.multimethod.MultiMethodMeta,
+    type(collections.abc.Sequence),  # type: ignore
+):
     pass
 
 

lib/spack/spack/caches.py

@@ -9,11 +9,11 @@
 
 import llnl.util.lang
 from llnl.util.filesystem import mkdirp
-from llnl.util.symlink import symlink
 
 import spack.config
 import spack.error
 import spack.fetch_strategy
+import spack.mirror
 import spack.paths
 import spack.util.file_cache
 import spack.util.path
@@ -74,23 +74,6 @@ def store(self, fetcher, relative_dest):
         mkdirp(os.path.dirname(dst))
         fetcher.archive(dst)
 
-    def symlink(self, mirror_ref):
-        """Symlink a human readible path in our mirror to the actual
-        storage location."""
-
-        cosmetic_path = os.path.join(self.root, mirror_ref.cosmetic_path)
-        storage_path = os.path.join(self.root, mirror_ref.storage_path)
-        relative_dst = os.path.relpath(storage_path, start=os.path.dirname(cosmetic_path))
-
-        if not os.path.exists(cosmetic_path):
-            if os.path.lexists(cosmetic_path):
-                # In this case the link itself exists but it is broken: remove
-                # it and recreate it (in order to fix any symlinks broken prior
-                # to https://github.com/spack/spack/pull/13908)
-                os.unlink(cosmetic_path)
-            mkdirp(os.path.dirname(cosmetic_path))
-            symlink(relative_dst, cosmetic_path)
-
 
 #: Spack's local cache for downloaded source archives
 FETCH_CACHE: Union[spack.fetch_strategy.FsCache, llnl.util.lang.Singleton] = (

lib/spack/spack/ci.py

@@ -38,6 +38,7 @@
 import spack.paths
 import spack.repo
 import spack.spec
+import spack.stage
 import spack.util.git
 import spack.util.gpg as gpg_util
 import spack.util.spack_yaml as syaml
@@ -1107,9 +1108,10 @@ def main_script_replacements(cmd):
     if cdash_handler and cdash_handler.auth_token:
         try:
             cdash_handler.populate_buildgroup(all_job_names)
-        except (SpackError, HTTPError, URLError) as err:
+        except (SpackError, HTTPError, URLError, TimeoutError) as err:
             tty.warn(f"Problem populating buildgroup: {err}")
-    else:
+    elif cdash_config:
+        # warn only if there was actually a CDash configuration.
         tty.warn("Unable to populate buildgroup without CDash credentials")
 
     service_job_retries = {
@@ -1370,15 +1372,6 @@ def can_verify_binaries():
     return len(gpg_util.public_keys()) >= 1
 
 
-def _push_to_build_cache(spec: spack.spec.Spec, sign_binaries: bool, mirror_url: str) -> None:
-    """Unchecked version of the public API, for easier mocking"""
-    bindist.push_or_raise(
-        spec,
-        spack.mirror.Mirror.from_url(mirror_url).push_url,
-        bindist.PushOptions(force=True, unsigned=not sign_binaries),
-    )
-
-
 def push_to_build_cache(spec: spack.spec.Spec, mirror_url: str, sign_binaries: bool) -> bool:
     """Push one or more binary packages to the mirror.
 
@@ -1389,20 +1382,15 @@ def push_to_build_cache(spec: spack.spec.Spec, mirror_url: str, sign_binaries: b
         sign_binaries: If True, spack will attempt to sign binary package before pushing.
     """
     tty.debug(f"Pushing to build cache ({'signed' if sign_binaries else 'unsigned'})")
+    signing_key = bindist.select_signing_key() if sign_binaries else None
+    mirror = spack.mirror.Mirror.from_url(mirror_url)
     try:
-        _push_to_build_cache(spec, sign_binaries, mirror_url)
+        with bindist.make_uploader(mirror, signing_key=signing_key) as uploader:
+            uploader.push_or_raise([spec])
         return True
     except bindist.PushToBuildCacheError as e:
-        tty.error(str(e))
+        tty.error(f"Problem writing to {mirror_url}: {e}")
         return False
-    except Exception as e:
-        # TODO (zackgalbreath): write an adapter for boto3 exceptions so we can catch a specific
-        # exception instead of parsing str(e)...
-        msg = str(e)
-        if any(x in msg for x in ["Access Denied", "InvalidAccessKeyId"]):
-            tty.error(f"Permission problem writing to {mirror_url}: {msg}")
-            return False
-        raise
 
 
 def remove_other_mirrors(mirrors_to_keep, scope=None):
@@ -1448,10 +1436,6 @@ def copy_stage_logs_to_artifacts(job_spec: spack.spec.Spec, job_log_dir: str) ->
         job_log_dir: path into which build log should be copied
     """
     tty.debug(f"job spec: {job_spec}")
-    if not job_spec:
-        msg = f"Cannot copy stage logs: job spec ({job_spec}) is required"
-        tty.error(msg)
-        return
 
     try:
         pkg_cls = spack.repo.PATH.get_pkg_class(job_spec.name)
@@ -2083,7 +2067,7 @@ def read_broken_spec(broken_spec_url):
     """
     try:
         _, _, fs = web_util.read_from_url(broken_spec_url)
-    except (URLError, web_util.SpackWebError, HTTPError):
+    except web_util.SpackWebError:
         tty.warn(f"Unable to read broken spec from {broken_spec_url}")
         return None
 

lib/spack/spack/cmd/__init__.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import argparse
+import importlib
 import os
 import re
 import sys
@@ -114,8 +115,8 @@ def get_module(cmd_name):
 
     try:
         # Try to import the command from the built-in directory
-        module_name = "%s.%s" % (__name__, pname)
-        module = __import__(module_name, fromlist=[pname, SETUP_PARSER, DESCRIPTION], level=0)
+        module_name = f"{__name__}.{pname}"
+        module = importlib.import_module(module_name)
         tty.debug("Imported {0} from built-in commands".format(pname))
     except ImportError:
         module = spack.extensions.get_module(cmd_name)

lib/spack/spack/cmd/buildcache.py

@@ -3,28 +3,24 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import argparse
-import copy
 import glob
-import hashlib
 import json
-import multiprocessing
-import multiprocessing.pool
 import os
 import shutil
 import sys
 import tempfile
-from typing import Dict, List, Optional, Tuple, Union
+from typing import List, Tuple
 
 import llnl.util.tty as tty
 from llnl.string import plural
-from llnl.util.lang import elide_list
+from llnl.util.lang import elide_list, stable_partition
 
 import spack.binary_distribution as bindist
 import spack.cmd
 import spack.config
+import spack.deptypes as dt
 import spack.environment as ev
 import spack.error
-import spack.hash_types as ht
 import spack.mirror
 import spack.oci.oci
 import spack.oci.opener
@@ -35,28 +31,12 @@
 import spack.store
 import spack.user_environment
 import spack.util.crypto
+import spack.util.parallel
 import spack.util.url as url_util
 import spack.util.web as web_util
 from spack import traverse
-from spack.build_environment import determine_number_of_jobs
 from spack.cmd import display_specs
 from spack.cmd.common import arguments
-from spack.oci.image import (
-    Digest,
-    ImageReference,
-    default_config,
-    default_index_tag,
-    default_manifest,
-    default_tag,
-    tag_is_spec,
-)
-from spack.oci.oci import (
-    copy_missing_layers_with_retry,
-    get_manifest_and_config_with_retry,
-    list_tags,
-    upload_blob_with_retry,
-    upload_manifest_with_retry,
-)
 from spack.spec import Spec, save_dependency_specfiles
 
 description = "create, download and install binary packages"
@@ -112,6 +92,17 @@ def setup_parser(subparser: argparse.ArgumentParser):
         "Alternatively, one can decide to build a cache for only the package or only the "
         "dependencies",
     )
+    with_or_without_build_deps = push.add_mutually_exclusive_group()
+    with_or_without_build_deps.add_argument(
+        "--with-build-dependencies",
+        action="store_true",
+        help="include build dependencies in the buildcache",
+    )
+    with_or_without_build_deps.add_argument(
+        "--without-build-dependencies",
+        action="store_true",
+        help="exclude build dependencies from the buildcache",
+    )
     push.add_argument(
         "--fail-fast",
         action="store_true",
@@ -329,39 +320,6 @@ def _format_spec(spec: Spec) -> str:
     return spec.cformat("{name}{@version}{/hash:7}")
 
 
-def _progress(i: int, total: int):
-    if total > 1:
-        digits = len(str(total))
-        return f"[{i+1:{digits}}/{total}] "
-    return ""
-
-
-class NoPool:
-    def map(self, func, args):
-        return [func(a) for a in args]
-
-    def starmap(self, func, args):
-        return [func(*a) for a in args]
-
-    def __enter__(self):
-        return self
-
-    def __exit__(self, *args):
-        pass
-
-
-MaybePool = Union[multiprocessing.pool.Pool, NoPool]
-
-
-def _make_pool() -> MaybePool:
-    """Can't use threading because it's unsafe, and can't use spawned processes because of globals.
-    That leaves only forking"""
-    if multiprocessing.get_start_method() == "fork":
-        return multiprocessing.pool.Pool(determine_number_of_jobs(parallel=True))
-    else:
-        return NoPool()
-
-
 def _skip_no_redistribute_for_public(specs):
     remaining_specs = list()
     removed_specs = list()
@@ -381,6 +339,45 @@ def _skip_no_redistribute_for_public(specs):
     return remaining_specs
 
 
+class PackagesAreNotInstalledError(spack.error.SpackError):
+    """Raised when a list of specs is not installed but picked to be packaged."""
+
+    def __init__(self, specs: List[Spec]):
+        super().__init__(
+            "Cannot push non-installed packages",
+            ", ".join(elide_list([_format_spec(s) for s in specs], 5)),
+        )
+
+
+class PackageNotInstalledError(spack.error.SpackError):
+    """Raised when a spec is not installed but picked to be packaged."""
+
+
+def _specs_to_be_packaged(
+    requested: List[Spec], things_to_install: str, build_deps: bool
+) -> List[Spec]:
+    """Collect all non-external with or without roots and dependencies"""
+    if "dependencies" not in things_to_install:
+        deptype = dt.NONE
+    elif build_deps:
+        deptype = dt.ALL
+    else:
+        deptype = dt.RUN | dt.LINK | dt.TEST
+    specs = [
+        s
+        for s in traverse.traverse_nodes(
+            requested,
+            root="package" in things_to_install,
+            deptype=deptype,
+            order="breadth",
+            key=traverse.by_dag_hash,
+        )
+        if not s.external
+    ]
+    specs.reverse()
+    return specs
+
+
 def push_fn(args):
     """create a binary package and push it to a mirror"""
     if args.spec_file:
@@ -394,13 +391,8 @@ def push_fn(args):
     else:
         roots = spack.cmd.require_active_env(cmd_name="buildcache push").concrete_roots()
 
-    mirror: spack.mirror.Mirror = args.mirror
-
-    # Check if this is an OCI image.
-    try:
-        target_image = spack.oci.oci.image_from_mirror(mirror)
-    except ValueError:
-        target_image = None
+    mirror = args.mirror
+    assert isinstance(mirror, spack.mirror.Mirror)
 
     push_url = mirror.push_url
 
@@ -411,92 +403,52 @@ def push_fn(args):
         unsigned = not (args.key or args.signed)
 
     # For OCI images, we require dependencies to be pushed for now.
-    if target_image:
-        if "dependencies" not in args.things_to_install:
-            tty.die("Dependencies must be pushed for OCI images.")
-        if not unsigned:
-            tty.warn(
-                "Code signing is currently not supported for OCI images. "
-                "Use --unsigned to silence this warning."
-            )
+    if mirror.push_url.startswith("oci://") and not unsigned:
+        tty.warn(
+            "Code signing is currently not supported for OCI images. "
+            "Use --unsigned to silence this warning."
+        )
+        unsigned = True
 
-    # This is a list of installed, non-external specs.
-    specs = bindist.specs_to_be_packaged(
+    # Select a signing key, or None if unsigned.
+    signing_key = None if unsigned else (args.key or bindist.select_signing_key())
+
+    specs = _specs_to_be_packaged(
         roots,
-        root="package" in args.things_to_install,
-        dependencies="dependencies" in args.things_to_install,
+        things_to_install=args.things_to_install,
+        build_deps=args.with_build_dependencies or not args.without_build_dependencies,
     )
+
     if not args.private:
         specs = _skip_no_redistribute_for_public(specs)
 
-    # When pushing multiple specs, print the url once ahead of time, as well as how
-    # many specs are being pushed.
     if len(specs) > 1:
         tty.info(f"Selected {len(specs)} specs to push to {push_url}")
 
-    failed = []
-
-    # TODO: unify this logic in the future.
-    if target_image:
-        base_image = ImageReference.from_string(args.base_image) if args.base_image else None
-        with tempfile.TemporaryDirectory(
-            dir=spack.stage.get_stage_root()
-        ) as tmpdir, _make_pool() as pool:
-            skipped, base_images, checksums = _push_oci(
-                target_image=target_image,
-                base_image=base_image,
-                installed_specs_with_deps=specs,
-                force=args.force,
-                tmpdir=tmpdir,
-                pool=pool,
-            )
-
-            # Apart from creating manifests for each individual spec, we allow users to create a
-            # separate image tag for all root specs and their runtime dependencies.
-            if args.tag:
-                tagged_image = target_image.with_tag(args.tag)
-                # _push_oci may not populate base_images if binaries were already in the registry
-                for spec in roots:
-                    _update_base_images(
-                        base_image=base_image,
-                        target_image=target_image,
-                        spec=spec,
-                        base_image_cache=base_images,
-                    )
-                _put_manifest(base_images, checksums, tagged_image, tmpdir, None, None, *roots)
-                tty.info(f"Tagged {tagged_image}")
-
-    else:
-        skipped = []
-
-        for i, spec in enumerate(specs):
-            try:
-                bindist.push_or_raise(
-                    spec,
-                    push_url,
-                    bindist.PushOptions(
-                        force=args.force,
-                        unsigned=unsigned,
-                        key=args.key,
-                        regenerate_index=args.update_index,
-                    ),
+    # Pushing not installed specs is an error. Either fail fast or populate the error list and
+    # push installed package in best effort mode.
+    failed: List[Tuple[Spec, BaseException]] = []
+    with spack.store.STORE.db.read_transaction():
+        if any(not s.installed for s in specs):
+            specs, not_installed = stable_partition(specs, lambda s: s.installed)
+            if args.fail_fast:
+                raise PackagesAreNotInstalledError(not_installed)
+            else:
+                failed.extend(
+                    (s, PackageNotInstalledError("package not installed")) for s in not_installed
                 )
 
-                msg = f"{_progress(i, len(specs))}Pushed {_format_spec(spec)}"
-                if len(specs) == 1:
-                    msg += f" to {push_url}"
-                tty.info(msg)
-
-            except bindist.NoOverwriteException:
-                skipped.append(_format_spec(spec))
-
-            # Catch any other exception unless the fail fast option is set
-            except Exception as e:
-                if args.fail_fast or isinstance(
-                    e, (bindist.PickKeyException, bindist.NoKeyException)
-                ):
-                    raise
-                failed.append((_format_spec(spec), e))
+    with bindist.make_uploader(
+        mirror=mirror,
+        force=args.force,
+        update_index=args.update_index,
+        signing_key=signing_key,
+        base_image=args.base_image,
+    ) as uploader:
+        skipped, upload_errors = uploader.push(specs=specs)
+        failed.extend(upload_errors)
+        if not upload_errors and args.tag:
+            uploader.tag(args.tag, roots)
 
     if skipped:
         if len(specs) == 1:
@@ -519,389 +471,15 @@ def push_fn(args):
         raise spack.error.SpackError(
             f"The following {len(failed)} errors occurred while pushing specs to the buildcache",
             "\n".join(
-                elide_list([f"    {spec}: {e.__class__.__name__}: {e}" for spec, e in failed], 5)
-            ),
-        )
-
-    # Update the index if requested
-    # TODO: remove update index logic out of bindist; should be once after all specs are pushed
-    # not once per spec.
-    if target_image and len(skipped) < len(specs) and args.update_index:
-        with tempfile.TemporaryDirectory(
-            dir=spack.stage.get_stage_root()
-        ) as tmpdir, _make_pool() as pool:
-            _update_index_oci(target_image, tmpdir, pool)
-
-
-def _get_spack_binary_blob(image_ref: ImageReference) -> Optional[spack.oci.oci.Blob]:
-    """Get the spack tarball layer digests and size if it exists"""
-    try:
-        manifest, config = get_manifest_and_config_with_retry(image_ref)
-
-        return spack.oci.oci.Blob(
-            compressed_digest=Digest.from_string(manifest["layers"][-1]["digest"]),
-            uncompressed_digest=Digest.from_string(config["rootfs"]["diff_ids"][-1]),
-            size=manifest["layers"][-1]["size"],
-        )
-    except Exception:
-        return None
-
-
-def _push_single_spack_binary_blob(image_ref: ImageReference, spec: spack.spec.Spec, tmpdir: str):
-    filename = os.path.join(tmpdir, f"{spec.dag_hash()}.tar.gz")
-
-    # Create an oci.image.layer aka tarball of the package
-    compressed_tarfile_checksum, tarfile_checksum = spack.oci.oci.create_tarball(spec, filename)
-
-    blob = spack.oci.oci.Blob(
-        Digest.from_sha256(compressed_tarfile_checksum),
-        Digest.from_sha256(tarfile_checksum),
-        os.path.getsize(filename),
-    )
-
-    # Upload the blob
-    upload_blob_with_retry(image_ref, file=filename, digest=blob.compressed_digest)
-
-    # delete the file
-    os.unlink(filename)
-
-    return blob
-
-
-def _retrieve_env_dict_from_config(config: dict) -> dict:
-    """Retrieve the environment variables from the image config file.
-    Sets a default value for PATH if it is not present.
-
-    Args:
-        config (dict): The image config file.
-
-    Returns:
-        dict: The environment variables.
-    """
-    env = {"PATH": "/bin:/usr/bin"}
-
-    if "Env" in config.get("config", {}):
-        for entry in config["config"]["Env"]:
-            key, value = entry.split("=", 1)
-            env[key] = value
-    return env
-
-
-def _archspec_to_gooarch(spec: spack.spec.Spec) -> str:
-    name = spec.target.family.name
-    name_map = {"aarch64": "arm64", "x86_64": "amd64"}
-    return name_map.get(name, name)
-
-
-def _put_manifest(
-    base_images: Dict[str, Tuple[dict, dict]],
-    checksums: Dict[str, spack.oci.oci.Blob],
-    image_ref: ImageReference,
-    tmpdir: str,
-    extra_config: Optional[dict],
-    annotations: Optional[dict],
-    *specs: spack.spec.Spec,
-):
-    architecture = _archspec_to_gooarch(specs[0])
-
-    dependencies = list(
-        reversed(
-            list(
-                s
-                for s in traverse.traverse_nodes(
-                    specs, order="topo", deptype=("link", "run"), root=True
+                elide_list(
+                    [
+                        f"    {_format_spec(spec)}: {e.__class__.__name__}: {e}"
+                        for spec, e in failed
+                    ],
+                    5,
                 )
-                if not s.external
-            )
-        )
-    )
-
-    base_manifest, base_config = base_images[architecture]
-    env = _retrieve_env_dict_from_config(base_config)
-
-    # If the base image uses `vnd.docker.distribution.manifest.v2+json`, then we use that too.
-    # This is because Singularity / Apptainer is very strict about not mixing them.
-    base_manifest_mediaType = base_manifest.get(
-        "mediaType", "application/vnd.oci.image.manifest.v1+json"
-    )
-    use_docker_format = (
-        base_manifest_mediaType == "application/vnd.docker.distribution.manifest.v2+json"
-    )
-
-    spack.user_environment.environment_modifications_for_specs(*specs).apply_modifications(env)
-
-    # Create an oci.image.config file
-    config = copy.deepcopy(base_config)
-
-    # Add the diff ids of the dependencies
-    for s in dependencies:
-        config["rootfs"]["diff_ids"].append(str(checksums[s.dag_hash()].uncompressed_digest))
-
-    # Set the environment variables
-    config["config"]["Env"] = [f"{k}={v}" for k, v in env.items()]
-
-    if extra_config:
-        # From the OCI v1.0 spec:
-        # > Any extra fields in the Image JSON struct are considered implementation
-        # > specific and MUST be ignored by any implementations which are unable to
-        # > interpret them.
-        config.update(extra_config)
-
-    config_file = os.path.join(tmpdir, f"{specs[0].dag_hash()}.config.json")
-
-    with open(config_file, "w") as f:
-        json.dump(config, f, separators=(",", ":"))
-
-    config_file_checksum = Digest.from_sha256(
-        spack.util.crypto.checksum(hashlib.sha256, config_file)
-    )
-
-    # Upload the config file
-    upload_blob_with_retry(image_ref, file=config_file, digest=config_file_checksum)
-
-    manifest = {
-        "mediaType": base_manifest_mediaType,
-        "schemaVersion": 2,
-        "config": {
-            "mediaType": base_manifest["config"]["mediaType"],
-            "digest": str(config_file_checksum),
-            "size": os.path.getsize(config_file),
-        },
-        "layers": [
-            *(layer for layer in base_manifest["layers"]),
-            *(
-                {
-                    "mediaType": (
-                        "application/vnd.docker.image.rootfs.diff.tar.gzip"
-                        if use_docker_format
-                        else "application/vnd.oci.image.layer.v1.tar+gzip"
-                    ),
-                    "digest": str(checksums[s.dag_hash()].compressed_digest),
-                    "size": checksums[s.dag_hash()].size,
-                }
-                for s in dependencies
             ),
-        ],
-    }
-
-    if not use_docker_format and annotations:
-        manifest["annotations"] = annotations
-
-    # Finally upload the manifest
-    upload_manifest_with_retry(image_ref, manifest=manifest)
-
-    # delete the config file
-    os.unlink(config_file)
-
-
-def _update_base_images(
-    *,
-    base_image: Optional[ImageReference],
-    target_image: ImageReference,
-    spec: spack.spec.Spec,
-    base_image_cache: Dict[str, Tuple[dict, dict]],
-):
-    """For a given spec and base image, copy the missing layers of the base image with matching
-    arch to the registry of the target image. If no base image is specified, create a dummy
-    manifest and config file."""
-    architecture = _archspec_to_gooarch(spec)
-    if architecture in base_image_cache:
-        return
-    if base_image is None:
-        base_image_cache[architecture] = (
-            default_manifest(),
-            default_config(architecture, "linux"),
         )
-    else:
-        base_image_cache[architecture] = copy_missing_layers_with_retry(
-            base_image, target_image, architecture
-        )
-
-
-def _push_oci(
-    *,
-    target_image: ImageReference,
-    base_image: Optional[ImageReference],
-    installed_specs_with_deps: List[Spec],
-    tmpdir: str,
-    pool: MaybePool,
-    force: bool = False,
-) -> Tuple[List[str], Dict[str, Tuple[dict, dict]], Dict[str, spack.oci.oci.Blob]]:
-    """Push specs to an OCI registry
-
-    Args:
-        image_ref: The target OCI image
-        base_image: Optional base image, which will be copied to the target registry.
-        installed_specs_with_deps: The installed specs to push, excluding externals,
-            including deps, ordered from roots to leaves.
-        force: Whether to overwrite existing layers and manifests in the buildcache.
-
-    Returns:
-        A tuple consisting of the list of skipped specs already in the build cache,
-        a dictionary mapping architectures to base image manifests and configs,
-        and a dictionary mapping each spec's dag hash to a blob.
-    """
-
-    # Reverse the order
-    installed_specs_with_deps = list(reversed(installed_specs_with_deps))
-
-    # Spec dag hash -> blob
-    checksums: Dict[str, spack.oci.oci.Blob] = {}
-
-    # arch -> (manifest, config)
-    base_images: Dict[str, Tuple[dict, dict]] = {}
-
-    # Specs not uploaded because they already exist
-    skipped = []
-
-    if not force:
-        tty.info("Checking for existing specs in the buildcache")
-        to_be_uploaded = []
-
-        tags_to_check = (target_image.with_tag(default_tag(s)) for s in installed_specs_with_deps)
-        available_blobs = pool.map(_get_spack_binary_blob, tags_to_check)
-
-        for spec, maybe_blob in zip(installed_specs_with_deps, available_blobs):
-            if maybe_blob is not None:
-                checksums[spec.dag_hash()] = maybe_blob
-                skipped.append(_format_spec(spec))
-            else:
-                to_be_uploaded.append(spec)
-    else:
-        to_be_uploaded = installed_specs_with_deps
-
-    if not to_be_uploaded:
-        return skipped, base_images, checksums
-
-    tty.info(
-        f"{len(to_be_uploaded)} specs need to be pushed to "
-        f"{target_image.domain}/{target_image.name}"
-    )
-
-    # Upload blobs
-    new_blobs = pool.starmap(
-        _push_single_spack_binary_blob, ((target_image, spec, tmpdir) for spec in to_be_uploaded)
-    )
-
-    # And update the spec to blob mapping
-    for spec, blob in zip(to_be_uploaded, new_blobs):
-        checksums[spec.dag_hash()] = blob
-
-    # Copy base images if necessary
-    for spec in to_be_uploaded:
-        _update_base_images(
-            base_image=base_image,
-            target_image=target_image,
-            spec=spec,
-            base_image_cache=base_images,
-        )
-
-    def extra_config(spec: Spec):
-        spec_dict = spec.to_dict(hash=ht.dag_hash)
-        spec_dict["buildcache_layout_version"] = 1
-        spec_dict["binary_cache_checksum"] = {
-            "hash_algorithm": "sha256",
-            "hash": checksums[spec.dag_hash()].compressed_digest.digest,
-        }
-        return spec_dict
-
-    # Upload manifests
-    tty.info("Uploading manifests")
-    pool.starmap(
-        _put_manifest,
-        (
-            (
-                base_images,
-                checksums,
-                target_image.with_tag(default_tag(spec)),
-                tmpdir,
-                extra_config(spec),
-                {"org.opencontainers.image.description": spec.format()},
-                spec,
-            )
-            for spec in to_be_uploaded
-        ),
-    )
-
-    # Print the image names of the top-level specs
-    for spec in to_be_uploaded:
-        tty.info(f"Pushed {_format_spec(spec)} to {target_image.with_tag(default_tag(spec))}")
-
-    return skipped, base_images, checksums
-
-
-def _config_from_tag(image_ref: ImageReference, tag: str) -> Optional[dict]:
-    # Don't allow recursion here, since Spack itself always uploads
-    # vnd.oci.image.manifest.v1+json, not vnd.oci.image.index.v1+json
-    _, config = get_manifest_and_config_with_retry(image_ref.with_tag(tag), tag, recurse=0)
-
-    # Do very basic validation: if "spec" is a key in the config, it
-    # must be a Spec object too.
-    return config if "spec" in config else None
-
-
-def _update_index_oci(image_ref: ImageReference, tmpdir: str, pool: MaybePool) -> None:
-    tags = list_tags(image_ref)
-
-    # Fetch all image config files in parallel
-    spec_dicts = pool.starmap(
-        _config_from_tag, ((image_ref, tag) for tag in tags if tag_is_spec(tag))
-    )
-
-    # Populate the database
-    db_root_dir = os.path.join(tmpdir, "db_root")
-    db = bindist.BuildCacheDatabase(db_root_dir)
-
-    for spec_dict in spec_dicts:
-        spec = Spec.from_dict(spec_dict)
-        db.add(spec, directory_layout=None)
-        db.mark(spec, "in_buildcache", True)
-
-    # Create the index.json file
-    index_json_path = os.path.join(tmpdir, "index.json")
-    with open(index_json_path, "w") as f:
-        db._write_to_file(f)
-
-    # Create an empty config.json file
-    empty_config_json_path = os.path.join(tmpdir, "config.json")
-    with open(empty_config_json_path, "wb") as f:
-        f.write(b"{}")
-
-    # Upload the index.json file
-    index_shasum = Digest.from_sha256(spack.util.crypto.checksum(hashlib.sha256, index_json_path))
-    upload_blob_with_retry(image_ref, file=index_json_path, digest=index_shasum)
-
-    # Upload the config.json file
-    empty_config_digest = Digest.from_sha256(
-        spack.util.crypto.checksum(hashlib.sha256, empty_config_json_path)
-    )
-    upload_blob_with_retry(image_ref, file=empty_config_json_path, digest=empty_config_digest)
-
-    # Push a manifest file that references the index.json file as a layer
-    # Notice that we push this as if it is an image, which it of course is not.
-    # When the ORAS spec becomes official, we can use that instead of a fake image.
-    # For now we just use the OCI image spec, so that we don't run into issues with
-    # automatic garbage collection of blobs that are not referenced by any image manifest.
-    oci_manifest = {
-        "mediaType": "application/vnd.oci.image.manifest.v1+json",
-        "schemaVersion": 2,
-        # Config is just an empty {} file for now, and irrelevant
-        "config": {
-            "mediaType": "application/vnd.oci.image.config.v1+json",
-            "digest": str(empty_config_digest),
-            "size": os.path.getsize(empty_config_json_path),
-        },
-        # The buildcache index is the only layer, and is not a tarball, we lie here.
-        "layers": [
-            {
-                "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
-                "digest": str(index_shasum),
-                "size": os.path.getsize(index_json_path),
-            }
-        ],
-    }
-
-    upload_manifest_with_retry(image_ref.with_tag(default_index_tag), oci_manifest)
 
 
 def install_fn(args):
@@ -1182,14 +760,15 @@ def update_index(mirror: spack.mirror.Mirror, update_keys=False):
     if image_ref:
         with tempfile.TemporaryDirectory(
             dir=spack.stage.get_stage_root()
-        ) as tmpdir, _make_pool() as pool:
-            _update_index_oci(image_ref, tmpdir, pool)
+        ) as tmpdir, spack.util.parallel.make_concurrent_executor() as executor:
+            bindist._oci_update_index(image_ref, tmpdir, executor)
         return
 
     # Otherwise, assume a normal mirror.
     url = mirror.push_url
 
-    bindist.generate_package_index(url_util.join(url, bindist.build_cache_relative_path()))
+    with tempfile.TemporaryDirectory(dir=spack.stage.get_stage_root()) as tmpdir:
+        bindist._url_generate_package_index(url, tmpdir)
 
     if update_keys:
         keys_url = url_util.join(
@@ -1197,7 +776,8 @@ def update_index(mirror: spack.mirror.Mirror, update_keys=False):
         )
 
         try:
-            bindist.generate_key_index(keys_url)
+            with tempfile.TemporaryDirectory(dir=spack.stage.get_stage_root()) as tmpdir:
+                bindist.generate_key_index(keys_url, tmpdir)
         except bindist.CannotListKeys as e:
             # Do not error out if listing keys went wrong. This usually means that the _gpg path
             # does not exist. TODO: distinguish between this and other errors.

lib/spack/spack/cmd/compiler.py

@@ -50,6 +50,7 @@ def setup_parser(subparser):
         default=lambda: spack.config.default_modify_scope("compilers"),
         help="configuration scope to modify",
     )
+    arguments.add_common_arguments(find_parser, ["jobs"])
 
     # Remove
     remove_parser = sp.add_parser("remove", aliases=["rm"], help="remove compiler by spec")
@@ -78,25 +79,21 @@ def setup_parser(subparser):
 def compiler_find(args):
     """Search either $PATH or a list of paths OR MODULES for compilers and
     add them to Spack's configuration.
-
     """
-    # None signals spack.compiler.find_compilers to use its default logic
     paths = args.add_paths or None
-
-    # Below scope=None because we want new compilers that don't appear
-    # in any other configuration.
-    new_compilers = spack.compilers.find_new_compilers(
-        paths, scope=None, mixed_toolchain=args.mixed_toolchain
+    new_compilers = spack.compilers.find_compilers(
+        path_hints=paths,
+        scope=args.scope,
+        mixed_toolchain=args.mixed_toolchain,
+        max_workers=args.jobs,
     )
     if new_compilers:
-        spack.compilers.add_compilers_to_config(new_compilers, scope=args.scope)
         n = len(new_compilers)
         s = "s" if n > 1 else ""
-
-        config = spack.config.CONFIG
-        filename = config.get_config_filename(args.scope, "compilers")
-        tty.msg("Added %d new compiler%s to %s" % (n, s, filename))
-        colify(reversed(sorted(c.spec.display_str for c in new_compilers)), indent=4)
+        filename = spack.config.CONFIG.get_config_filename(args.scope, "compilers")
+        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)
+        colify(reversed(compiler_strs), indent=4)
     else:
         tty.msg("Found no new compilers")
     tty.msg("Compilers are defined in the following files:")

lib/spack/spack/cmd/create.py

@@ -6,6 +6,7 @@
 import re
 import sys
 import urllib.parse
+from typing import List
 
 import llnl.util.tty as tty
 from llnl.util.filesystem import mkdirp
@@ -14,9 +15,15 @@
 import spack.stage
 import spack.util.web
 from spack.spec import Spec
-from spack.url import UndetectableNameError, UndetectableVersionError, parse_name, parse_version
+from spack.url import (
+    UndetectableNameError,
+    UndetectableVersionError,
+    find_versions_of_archive,
+    parse_name,
+    parse_version,
+)
 from spack.util.editor import editor
-from spack.util.executable import ProcessError, which
+from spack.util.executable import which
 from spack.util.format import get_version_lines
 from spack.util.naming import mod_to_class, simplify_name, valid_fully_qualified_module_name
 
@@ -89,14 +96,20 @@ class BundlePackageTemplate:
     url_def = "    # There is no URL since there is no code to download."
     body_def = "    # There is no need for install() since there is no code."
 
-    def __init__(self, name, versions):
+    def __init__(self, name: str, versions, languages: List[str]):
         self.name = name
         self.class_name = mod_to_class(name)
         self.versions = versions
+        self.languages = languages
 
     def write(self, pkg_path):
         """Writes the new package file."""
 
+        all_deps = [f'    depends_on("{lang}", type="build")' for lang in self.languages]
+        if all_deps and self.dependencies:
+            all_deps.append("")
+        all_deps.append(self.dependencies)
+
         # Write out a template for the file
         with open(pkg_path, "w") as pkg_file:
             pkg_file.write(
@@ -106,7 +119,7 @@ def write(self, pkg_path):
                     base_class_name=self.base_class_name,
                     url_def=self.url_def,
                     versions=self.versions,
-                    dependencies=self.dependencies,
+                    dependencies="\n".join(all_deps),
                     body_def=self.body_def,
                 )
             )
@@ -125,8 +138,8 @@ def install(self, spec, prefix):
 
     url_line = '    url = "{url}"'
 
-    def __init__(self, name, url, versions):
-        super().__init__(name, versions)
+    def __init__(self, name, url, versions, languages: List[str]):
+        super().__init__(name, versions, languages)
 
         self.url_def = self.url_line.format(url=url)
 
@@ -214,13 +227,13 @@ def luarocks_args(self):
         args = []
         return args"""
 
-    def __init__(self, name, url, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name lua-lpeg`, don't rename it lua-lua-lpeg
         if not name.startswith("lua-"):
             # Make it more obvious that we are renaming the package
             tty.msg("Changing package name from {0} to lua-{0}".format(name))
             name = "lua-{0}".format(name)
-        super().__init__(name, url, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class MesonPackageTemplate(PackageTemplate):
@@ -321,14 +334,14 @@ class RacketPackageTemplate(PackageTemplate):
     # subdirectory = None
     """
 
-    def __init__(self, name, url, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name rkt-scribble`, don't rename it rkt-rkt-scribble
         if not name.startswith("rkt-"):
             # Make it more obvious that we are renaming the package
             tty.msg("Changing package name from {0} to rkt-{0}".format(name))
             name = "rkt-{0}".format(name)
         self.body_def = self.body_def.format(name[4:])
-        super().__init__(name, url, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class PythonPackageTemplate(PackageTemplate):
@@ -361,7 +374,7 @@ def config_settings(self, spec, prefix):
         settings = {}
         return settings"""
 
-    def __init__(self, name, url, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name py-numpy`, don't rename it py-py-numpy
         if not name.startswith("py-"):
             # Make it more obvious that we are renaming the package
@@ -415,7 +428,7 @@ def __init__(self, name, url, *args, **kwargs):
                 + self.url_line
             )
 
-        super().__init__(name, url, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class RPackageTemplate(PackageTemplate):
@@ -434,7 +447,7 @@ def configure_args(self):
         args = []
         return args"""
 
-    def __init__(self, name, url, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name r-rcpp`, don't rename it r-r-rcpp
         if not name.startswith("r-"):
             # Make it more obvious that we are renaming the package
@@ -454,7 +467,7 @@ def __init__(self, name, url, *args, **kwargs):
         if bioc:
             self.url_line = '    url = "{0}"\n' '    bioc = "{1}"'.format(url, r_name)
 
-        super().__init__(name, url, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class PerlmakePackageTemplate(PackageTemplate):
@@ -474,14 +487,14 @@ def configure_args(self):
         args = []
         return args"""
 
-    def __init__(self, name, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name perl-cpp`, don't rename it perl-perl-cpp
         if not name.startswith("perl-"):
             # Make it more obvious that we are renaming the package
             tty.msg("Changing package name from {0} to perl-{0}".format(name))
             name = "perl-{0}".format(name)
 
-        super().__init__(name, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class PerlbuildPackageTemplate(PerlmakePackageTemplate):
@@ -506,7 +519,7 @@ class OctavePackageTemplate(PackageTemplate):
     # FIXME: Add additional dependencies if required.
     # depends_on("octave-foo", type=("build", "run"))"""
 
-    def __init__(self, name, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name octave-splines`, don't rename it
         # octave-octave-splines
         if not name.startswith("octave-"):
@@ -514,7 +527,7 @@ def __init__(self, name, *args, **kwargs):
             tty.msg("Changing package name from {0} to octave-{0}".format(name))
             name = "octave-{0}".format(name)
 
-        super().__init__(name, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class RubyPackageTemplate(PackageTemplate):
@@ -534,7 +547,7 @@ def build(self, spec, prefix):
         # FIXME: If not needed delete this function
         pass"""
 
-    def __init__(self, name, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name ruby-numpy`, don't rename it
         # ruby-ruby-numpy
         if not name.startswith("ruby-"):
@@ -542,7 +555,7 @@ def __init__(self, name, *args, **kwargs):
             tty.msg("Changing package name from {0} to ruby-{0}".format(name))
             name = "ruby-{0}".format(name)
 
-        super().__init__(name, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 class MakefilePackageTemplate(PackageTemplate):
@@ -580,14 +593,14 @@ def configure_args(self, spec, prefix):
         args = []
         return args"""
 
-    def __init__(self, name, *args, **kwargs):
+    def __init__(self, name, url, versions, languages: List[str]):
         # If the user provided `--name py-pyqt4`, don't rename it py-py-pyqt4
         if not name.startswith("py-"):
             # Make it more obvious that we are renaming the package
             tty.msg("Changing package name from {0} to py-{0}".format(name))
             name = "py-{0}".format(name)
 
-        super().__init__(name, *args, **kwargs)
+        super().__init__(name, url, versions, languages)
 
 
 templates = {
@@ -658,8 +671,48 @@ def setup_parser(subparser):
     )
 
 
-class BuildSystemGuesser:
-    """An instance of BuildSystemGuesser provides a callable object to be used
+#: C file extensions
+C_EXT = {".c"}
+
+#: C++ file extensions
+CXX_EXT = {
+    ".C",
+    ".c++",
+    ".cc",
+    ".ccm",
+    ".cpp",
+    ".CPP",
+    ".cxx",
+    ".h++",
+    ".hh",
+    ".hpp",
+    ".hxx",
+    ".inl",
+    ".ipp",
+    ".ixx",
+    ".tcc",
+    ".tpp",
+}
+
+#: Fortran file extensions
+FORTRAN_EXT = {
+    ".f77",
+    ".F77",
+    ".f90",
+    ".F90",
+    ".f95",
+    ".F95",
+    ".f",
+    ".F",
+    ".for",
+    ".FOR",
+    ".ftn",
+    ".FTN",
+}
+
+
+class BuildSystemAndLanguageGuesser:
+    """An instance of BuildSystemAndLanguageGuesser provides a callable object to be used
     during ``spack create``. By passing this object to ``spack checksum``, we
     can take a peek at the fetched tarball and discern the build system it uses
     """
@@ -667,81 +720,119 @@ class BuildSystemGuesser:
     def __init__(self):
         """Sets the default build system."""
         self.build_system = "generic"
+        self._c = False
+        self._cxx = False
+        self._fortran = False
 
-    def __call__(self, stage, url):
+        # List of files in the archive ordered by their depth in the directory tree.
+        self._file_entries: List[str] = []
+
+    def __call__(self, archive: str, url: str) -> None:
         """Try to guess the type of build system used by a project based on
         the contents of its archive or the URL it was downloaded from."""
 
-        if url is not None:
-            # Most octave extensions are hosted on Octave-Forge:
-            #     https://octave.sourceforge.net/index.html
-            # They all have the same base URL.
-            if "downloads.sourceforge.net/octave/" in url:
-                self.build_system = "octave"
-                return
-            if url.endswith(".gem"):
-                self.build_system = "ruby"
-                return
-            if url.endswith(".whl") or ".whl#" in url:
-                self.build_system = "python"
-                return
-            if url.endswith(".rock"):
-                self.build_system = "lua"
-                return
-
-        # A list of clues that give us an idea of the build system a package
-        # uses. If the regular expression matches a file contained in the
-        # archive, the corresponding build system is assumed.
-        # NOTE: Order is important here. If a package supports multiple
-        # build systems, we choose the first match in this list.
-        clues = [
-            (r"/CMakeLists\.txt$", "cmake"),
-            (r"/NAMESPACE$", "r"),
-            (r"/Cargo\.toml$", "cargo"),
-            (r"/go\.mod$", "go"),
-            (r"/configure$", "autotools"),
-            (r"/configure\.(in|ac)$", "autoreconf"),
-            (r"/Makefile\.am$", "autoreconf"),
-            (r"/pom\.xml$", "maven"),
-            (r"/SConstruct$", "scons"),
-            (r"/waf$", "waf"),
-            (r"/pyproject.toml", "python"),
-            (r"/setup\.(py|cfg)$", "python"),
-            (r"/WORKSPACE$", "bazel"),
-            (r"/Build\.PL$", "perlbuild"),
-            (r"/Makefile\.PL$", "perlmake"),
-            (r"/.*\.gemspec$", "ruby"),
-            (r"/Rakefile$", "ruby"),
-            (r"/setup\.rb$", "ruby"),
-            (r"/.*\.pro$", "qmake"),
-            (r"/.*\.rockspec$", "lua"),
-            (r"/(GNU)?[Mm]akefile$", "makefile"),
-            (r"/DESCRIPTION$", "octave"),
-            (r"/meson\.build$", "meson"),
-            (r"/configure\.py$", "sip"),
-        ]
-
         # Peek inside the compressed file.
-        if stage.archive_file.endswith(".zip") or ".zip#" in stage.archive_file:
+        if archive.endswith(".zip") or ".zip#" in archive:
             try:
                 unzip = which("unzip")
-                output = unzip("-lq", stage.archive_file, output=str)
-            except ProcessError:
+                assert unzip is not None
+                output = unzip("-lq", archive, output=str)
+            except Exception:
                 output = ""
         else:
             try:
                 tar = which("tar")
-                output = tar("--exclude=*/*/*", "-tf", stage.archive_file, output=str)
-            except ProcessError:
+                assert tar is not None
+                output = tar("tf", archive, output=str)
+            except Exception:
                 output = ""
-        lines = output.splitlines()
+        self._file_entries[:] = output.splitlines()
 
-        # Determine the build system based on the files contained
-        # in the archive.
-        for pattern, bs in clues:
-            if any(re.search(pattern, line) for line in lines):
-                self.build_system = bs
-                break
+        # Files closest to the root should be considered first when determining build system.
+        self._file_entries.sort(key=lambda p: p.count("/"))
+
+        self._determine_build_system(url)
+        self._determine_language()
+
+    def _determine_build_system(self, url: str) -> None:
+        # Most octave extensions are hosted on Octave-Forge:
+        #     https://octave.sourceforge.net/index.html
+        # They all have the same base URL.
+        if "downloads.sourceforge.net/octave/" in url:
+            self.build_system = "octave"
+        elif url.endswith(".gem"):
+            self.build_system = "ruby"
+        elif url.endswith(".whl") or ".whl#" in url:
+            self.build_system = "python"
+        elif url.endswith(".rock"):
+            self.build_system = "lua"
+        elif self._file_entries:
+            # A list of clues that give us an idea of the build system a package
+            # uses. If the regular expression matches a file contained in the
+            # archive, the corresponding build system is assumed.
+            # NOTE: Order is important here. If a package supports multiple
+            # build systems, we choose the first match in this list.
+            clues = [
+                (re.compile(pattern), build_system)
+                for pattern, build_system in (
+                    (r"/CMakeLists\.txt$", "cmake"),
+                    (r"/NAMESPACE$", "r"),
+                    (r"/Cargo\.toml$", "cargo"),
+                    (r"/go\.mod$", "go"),
+                    (r"/configure$", "autotools"),
+                    (r"/configure\.(in|ac)$", "autoreconf"),
+                    (r"/Makefile\.am$", "autoreconf"),
+                    (r"/pom\.xml$", "maven"),
+                    (r"/SConstruct$", "scons"),
+                    (r"/waf$", "waf"),
+                    (r"/pyproject.toml", "python"),
+                    (r"/setup\.(py|cfg)$", "python"),
+                    (r"/WORKSPACE$", "bazel"),
+                    (r"/Build\.PL$", "perlbuild"),
+                    (r"/Makefile\.PL$", "perlmake"),
+                    (r"/.*\.gemspec$", "ruby"),
+                    (r"/Rakefile$", "ruby"),
+                    (r"/setup\.rb$", "ruby"),
+                    (r"/.*\.pro$", "qmake"),
+                    (r"/.*\.rockspec$", "lua"),
+                    (r"/(GNU)?[Mm]akefile$", "makefile"),
+                    (r"/DESCRIPTION$", "octave"),
+                    (r"/meson\.build$", "meson"),
+                    (r"/configure\.py$", "sip"),
+                )
+            ]
+
+            # Determine the build system based on the files contained in the archive.
+            for file in self._file_entries:
+                for pattern, build_system in clues:
+                    if pattern.search(file):
+                        self.build_system = build_system
+                        return
+
+    def _determine_language(self):
+        for entry in self._file_entries:
+            _, ext = os.path.splitext(entry)
+
+            if not self._c and ext in C_EXT:
+                self._c = True
+            elif not self._cxx and ext in CXX_EXT:
+                self._cxx = True
+            elif not self._fortran and ext in FORTRAN_EXT:
+                self._fortran = True
+
+            if self._c and self._cxx and self._fortran:
+                return
+
+    @property
+    def languages(self) -> List[str]:
+        langs: List[str] = []
+        if self._c:
+            langs.append("c")
+        if self._cxx:
+            langs.append("cxx")
+        if self._fortran:
+            langs.append("fortran")
+        return langs
 
 
 def get_name(name, url):
@@ -811,7 +902,7 @@ def get_url(url):
 def get_versions(args, name):
     """Returns a list of versions and hashes for a package.
 
-    Also returns a BuildSystemGuesser object.
+    Also returns a BuildSystemAndLanguageGuesser object.
 
     Returns default values if no URL is provided.
 
@@ -820,7 +911,7 @@ def get_versions(args, name):
         name (str): The name of the package
 
     Returns:
-        tuple: versions and hashes, and a BuildSystemGuesser object
+        tuple: versions and hashes, and a BuildSystemAndLanguageGuesser object
     """
 
     # Default version with hash
@@ -834,7 +925,7 @@ def get_versions(args, name):
     # version("1.2.4")"""
 
     # Default guesser
-    guesser = BuildSystemGuesser()
+    guesser = BuildSystemAndLanguageGuesser()
 
     valid_url = True
     try:
@@ -847,7 +938,7 @@ def get_versions(args, name):
     if args.url is not None and args.template != "bundle" and valid_url:
         # Find available versions
         try:
-            url_dict = spack.url.find_versions_of_archive(args.url)
+            url_dict = find_versions_of_archive(args.url)
             if len(url_dict) > 1 and not args.batch and sys.stdin.isatty():
                 url_dict_filtered = spack.stage.interactive_version_filter(url_dict)
                 if url_dict_filtered is None:
@@ -874,7 +965,7 @@ def get_versions(args, name):
     return versions, guesser
 
 
-def get_build_system(template, url, guesser):
+def get_build_system(template: str, url: str, guesser: BuildSystemAndLanguageGuesser) -> str:
     """Determine the build system template.
 
     If a template is specified, always use that. Otherwise, if a URL
@@ -882,11 +973,10 @@ def get_build_system(template, url, guesser):
     build system it uses. Otherwise, use a generic template by default.
 
     Args:
-        template (str): ``--template`` argument given to ``spack create``
-        url (str): ``url`` argument given to ``spack create``
-        args (argparse.Namespace): The arguments given to ``spack create``
-        guesser (BuildSystemGuesser): The first_stage_function given to
-            ``spack checksum`` which records the build system it detects
+        template: ``--template`` argument given to ``spack create``
+        url: ``url`` argument given to ``spack create``
+        guesser: The first_stage_function given to ``spack checksum`` which records the build
+            system it detects
 
     Returns:
         str: The name of the build system template to use
@@ -960,7 +1050,7 @@ def create(parser, args):
     build_system = get_build_system(args.template, url, guesser)
 
     # Create the package template object
-    constr_args = {"name": name, "versions": versions}
+    constr_args = {"name": name, "versions": versions, "languages": guesser.languages}
     package_class = templates[build_system]
     if package_class != BundlePackageTemplate:
         constr_args["url"] = url

lib/spack/spack/cmd/debug.py

@@ -6,6 +6,7 @@
 import os
 import platform
 import re
+import sys
 from datetime import datetime
 from glob import glob
 
@@ -62,9 +63,10 @@ def create_db_tarball(args):
 
     base = os.path.basename(str(spack.store.STORE.root))
     transform_args = []
+    # Currently --transform and -s are not supported by Windows native tar
     if "GNU" in tar("--version", output=str):
         transform_args = ["--transform", "s/^%s/%s/" % (base, tarball_name)]
-    else:
+    elif sys.platform != "win32":
         transform_args = ["-s", "/^%s/%s/" % (base, tarball_name)]
 
     wd = os.path.dirname(str(spack.store.STORE.root))
@@ -90,7 +92,6 @@ def report(args):
     print("* **Spack:**", get_version())
     print("* **Python:**", platform.python_version())
     print("* **Platform:**", architecture)
-    print("* **Concretizer:**", spack.config.get("config:concretizer"))
 
 
 def debug(parser, args):

lib/spack/spack/cmd/develop.py

@@ -10,8 +10,10 @@
 import spack.cmd
 import spack.config
 import spack.fetch_strategy
+import spack.package_base
 import spack.repo
 import spack.spec
+import spack.stage
 import spack.util.path
 import spack.version
 from spack.cmd.common import arguments
@@ -62,7 +64,7 @@ def change_fn(section):
     spack.config.change_or_add("develop", find_fn, change_fn)
 
 
-def _retrieve_develop_source(spec, abspath):
+def _retrieve_develop_source(spec: spack.spec.Spec, abspath: str) -> None:
     # "steal" the source code via staging API. We ask for a stage
     # to be created, then copy it afterwards somewhere else. It would be
     # better if we can create the `source_path` directly into its final
@@ -71,13 +73,13 @@ def _retrieve_develop_source(spec, abspath):
     # We construct a package class ourselves, rather than asking for
     # Spec.package, since Spec only allows this when it is concrete
     package = pkg_cls(spec)
-    source_stage = package.stage[0]
+    source_stage: spack.stage.Stage = package.stage[0]
     if isinstance(source_stage.fetcher, spack.fetch_strategy.GitFetchStrategy):
         source_stage.fetcher.get_full_repo = True
         # If we retrieved this version before and cached it, we may have
         # done so without cloning the full git repo; likewise, any
         # mirror might store an instance with truncated history.
-        source_stage.disable_mirrors()
+        source_stage.default_fetcher_only = True
 
     source_stage.fetcher.set_package(package)
     package.stage.steal_source(abspath)

lib/spack/spack/cmd/env.py

@@ -468,32 +468,30 @@ def env_remove(args):
     This removes an environment managed by Spack. Directory environments
     and manifests embedded in repositories should be removed manually.
     """
-    read_envs = []
+    remove_envs = []
     valid_envs = []
     bad_envs = []
-    invalid_envs = []
 
     for env_name in ev.all_environment_names():
         try:
             env = ev.read(env_name)
-            valid_envs.append(env_name)
+            valid_envs.append(env)
 
             if env_name in args.rm_env:
-                read_envs.append(env)
+                remove_envs.append(env)
         except (spack.config.ConfigFormatError, ev.SpackEnvironmentConfigError):
-            invalid_envs.append(env_name)
-
             if env_name in args.rm_env:
                 bad_envs.append(env_name)
 
-        # Check if env is linked to another before trying to remove
-        for name in valid_envs:
+    # Check if remove_env is included from another env before trying to remove
+    for env in valid_envs:
+        for remove_env in remove_envs:
             # don't check if environment is included to itself
-            if name == env_name:
+            if env.name == remove_env.name:
                 continue
-            environ = ev.Environment(ev.root(name))
-            if ev.root(env_name) in environ.included_concrete_envs:
-                msg = f'Environment "{env_name}" is being used by environment "{name}"'
+
+            if remove_env.path in env.included_concrete_envs:
+                msg = f'Environment "{remove_env.name}" is being used by environment "{env.name}"'
                 if args.force:
                     tty.warn(msg)
                 else:
@@ -506,7 +504,7 @@ def env_remove(args):
         if not answer:
             tty.die("Will not remove any environments")
 
-    for env in read_envs:
+    for env in remove_envs:
         name = env.name
         if env.active:
             tty.die(f"Environment {name} can't be removed while activated.")

lib/spack/spack/cmd/gpg.py

@@ -5,10 +5,12 @@
 
 import argparse
 import os
+import tempfile
 
 import spack.binary_distribution
 import spack.mirror
 import spack.paths
+import spack.stage
 import spack.util.gpg
 import spack.util.url
 from spack.cmd.common import arguments
@@ -115,6 +117,7 @@ def setup_parser(subparser):
         help="URL of the mirror where keys will be published",
     )
     publish.add_argument(
+        "--update-index",
         "--rebuild-index",
         action="store_true",
         default=False,
@@ -220,9 +223,10 @@ def gpg_publish(args):
     elif args.mirror_url:
         mirror = spack.mirror.Mirror(args.mirror_url, args.mirror_url)
 
-    spack.binary_distribution.push_keys(
-        mirror, keys=args.keys, regenerate_index=args.rebuild_index
-    )
+    with tempfile.TemporaryDirectory(dir=spack.stage.get_stage_root()) as tmpdir:
+        spack.binary_distribution._url_push_keys(
+            mirror, keys=args.keys, tmpdir=tmpdir, update_index=args.update_index
+        )
 
 
 def gpg(parser, args):

lib/spack/spack/cmd/info.py

@@ -502,7 +502,7 @@ def print_licenses(pkg, args):
 
 def info(parser, args):
     spec = spack.spec.Spec(args.package)
-    pkg_cls = spack.repo.PATH.get_pkg_class(spec.name)
+    pkg_cls = spack.repo.PATH.get_pkg_class(spec.fullname)
     pkg = pkg_cls(spec)
 
     # Output core package information

lib/spack/spack/cmd/versions.py

@@ -23,11 +23,6 @@ def setup_parser(subparser):
     output.add_argument(
         "-s", "--safe", action="store_true", help="only list safe versions of the package"
     )
-    output.add_argument(
-        "--safe-only",
-        action="store_true",
-        help="[deprecated] only list safe versions of the package",
-    )
     output.add_argument(
         "-r", "--remote", action="store_true", help="only list remote versions of the package"
     )
@@ -47,17 +42,13 @@ def versions(parser, args):
 
     safe_versions = pkg.versions
 
-    if args.safe_only:
-        tty.warn('"--safe-only" is deprecated. Use "--safe" instead.')
-        args.safe = args.safe_only
-
     if not (args.remote or args.new):
         if sys.stdout.isatty():
             tty.msg("Safe versions (already checksummed):")
 
         if not safe_versions:
             if sys.stdout.isatty():
-                tty.warn("Found no versions for {0}".format(pkg.name))
+                tty.warn(f"Found no versions for {pkg.name}")
                 tty.debug("Manually add versions to the package.")
         else:
             colify(sorted(safe_versions, reverse=True), indent=2)
@@ -83,12 +74,12 @@ def versions(parser, args):
     if not remote_versions:
         if sys.stdout.isatty():
             if not fetched_versions:
-                tty.warn("Found no versions for {0}".format(pkg.name))
+                tty.warn(f"Found no versions for {pkg.name}")
                 tty.debug(
                     "Check the list_url and list_depth attributes of "
                     "the package to help Spack find versions."
                 )
             else:
-                tty.warn("Found no unchecksummed versions for {0}".format(pkg.name))
+                tty.warn(f"Found no unchecksummed versions for {pkg.name}")
     else:
         colify(sorted(remote_versions, reverse=True), indent=2)

lib/spack/spack/compiler.py

@@ -29,6 +29,9 @@
 
 __all__ = ["Compiler"]
 
+PATH_INSTANCE_VARS = ["cc", "cxx", "f77", "fc"]
+FLAG_INSTANCE_VARS = ["cflags", "cppflags", "cxxflags", "fflags"]
+
 
 @llnl.util.lang.memoized
 def _get_compiler_version_output(compiler_path, version_arg, ignore_errors=()):
@@ -700,6 +703,30 @@ def compiler_environment(self):
             os.environ.clear()
             os.environ.update(backup_env)
 
+    def to_dict(self):
+        flags_dict = {fname: " ".join(fvals) for fname, fvals in self.flags.items()}
+        flags_dict.update(
+            {attr: getattr(self, attr, None) for attr in FLAG_INSTANCE_VARS if hasattr(self, attr)}
+        )
+        result = {
+            "spec": str(self.spec),
+            "paths": {attr: getattr(self, attr, None) for attr in PATH_INSTANCE_VARS},
+            "flags": flags_dict,
+            "operating_system": str(self.operating_system),
+            "target": str(self.target),
+            "modules": self.modules or [],
+            "environment": self.environment or {},
+            "extra_rpaths": self.extra_rpaths or [],
+        }
+
+        if self.enable_implicit_rpaths is not None:
+            result["implicit_rpaths"] = self.enable_implicit_rpaths
+
+        if self.alias:
+            result["alias"] = self.alias
+
+        return result
+
 
 class CompilerAccessError(spack.error.SpackError):
     def __init__(self, compiler, paths):

lib/spack/spack/compilers/__init__.py

@@ -6,12 +6,11 @@
 """This module contains functions related to finding compilers on the
 system and configuring Spack to use multiple compilers.
 """
-import collections
-import itertools
-import multiprocessing.pool
+import importlib
 import os
+import sys
 import warnings
-from typing import Dict, List, Optional, Tuple
+from typing import Dict, List, Optional
 
 import archspec.cpu
 
@@ -22,16 +21,15 @@
 import spack.compiler
 import spack.config
 import spack.error
-import spack.operating_systems
 import spack.paths
 import spack.platforms
+import spack.repo
 import spack.spec
 import spack.version
+from spack.operating_systems import windows_os
 from spack.util.environment import get_path
 from spack.util.naming import mod_to_class
 
-_path_instance_vars = ["cc", "cxx", "f77", "fc"]
-_flags_instance_vars = ["cflags", "cppflags", "cxxflags", "fflags"]
 _other_instance_vars = [
     "modules",
     "operating_system",
@@ -63,6 +61,10 @@
 }
 
 
+#: Tag used to identify packages providing a compiler
+COMPILER_TAG = "compiler"
+
+
 def pkg_spec_for_compiler(cspec):
     """Return the spec of the package that provides the compiler."""
     for spec, package in _compiler_to_pkg.items():
@@ -85,29 +87,7 @@ def converter(cspec_like, *args, **kwargs):
 
 def _to_dict(compiler):
     """Return a dict version of compiler suitable to insert in YAML."""
-    d = {}
-    d["spec"] = str(compiler.spec)
-    d["paths"] = dict((attr, getattr(compiler, attr, None)) for attr in _path_instance_vars)
-    d["flags"] = dict((fname, " ".join(fvals)) for fname, fvals in compiler.flags.items())
-    d["flags"].update(
-        dict(
-            (attr, getattr(compiler, attr, None))
-            for attr in _flags_instance_vars
-            if hasattr(compiler, attr)
-        )
-    )
-    d["operating_system"] = str(compiler.operating_system)
-    d["target"] = str(compiler.target)
-    d["modules"] = compiler.modules or []
-    d["environment"] = compiler.environment or {}
-    d["extra_rpaths"] = compiler.extra_rpaths or []
-    if compiler.enable_implicit_rpaths is not None:
-        d["implicit_rpaths"] = compiler.enable_implicit_rpaths
-
-    if compiler.alias:
-        d["alias"] = compiler.alias
-
-    return {"compiler": d}
+    return {"compiler": compiler.to_dict()}
 
 
 def get_compiler_config(
@@ -127,7 +107,7 @@ def get_compiler_config(
         # Do not init config because there is a non-empty scope
         return config
 
-    _init_compiler_config(configuration, scope=scope)
+    find_compilers(scope=scope)
     config = configuration.get("compilers", scope=scope)
     return config
 
@@ -136,125 +116,8 @@ def get_compiler_config_from_packages(
     configuration: "spack.config.Configuration", *, scope: Optional[str] = None
 ) -> List[Dict]:
     """Return the compiler configuration from packages.yaml"""
-    config = configuration.get("packages", scope=scope)
-    if not config:
-        return []
-
-    packages = []
-    compiler_package_names = supported_compilers() + list(package_name_to_compiler_name.keys())
-    for name, entry in config.items():
-        if name not in compiler_package_names:
-            continue
-        externals_config = entry.get("externals", None)
-        if not externals_config:
-            continue
-        packages.extend(_compiler_config_from_package_config(externals_config))
-
-    return packages
-
-
-def _compiler_config_from_package_config(config):
-    compilers = []
-    for entry in config:
-        compiler = _compiler_config_from_external(entry)
-        if compiler:
-            compilers.append(compiler)
-
-    return compilers
-
-
-def _compiler_config_from_external(config):
-    extra_attributes_key = "extra_attributes"
-    compilers_key = "compilers"
-    c_key, cxx_key, fortran_key = "c", "cxx", "fortran"
-
-    # Allow `@x.y.z` instead of `@=x.y.z`
-    spec = spack.spec.parse_with_version_concrete(config["spec"])
-
-    compiler_spec = spack.spec.CompilerSpec(
-        package_name_to_compiler_name.get(spec.name, spec.name), spec.version
-    )
-
-    err_header = f"The external spec '{spec}' cannot be used as a compiler"
-
-    # If extra_attributes is not there I might not want to use this entry as a compiler,
-    # therefore just leave a debug message, but don't be loud with a warning.
-    if extra_attributes_key not in config:
-        tty.debug(f"[{__file__}] {err_header}: missing the '{extra_attributes_key}' key")
-        return None
-    extra_attributes = config[extra_attributes_key]
-
-    # If I have 'extra_attributes' warn if 'compilers' is missing, or we don't have a C compiler
-    if compilers_key not in extra_attributes:
-        warnings.warn(
-            f"{err_header}: missing the '{compilers_key}' key under '{extra_attributes_key}'"
-        )
-        return None
-    attribute_compilers = extra_attributes[compilers_key]
-
-    if c_key not in attribute_compilers:
-        warnings.warn(
-            f"{err_header}: missing the C compiler path under "
-            f"'{extra_attributes_key}:{compilers_key}'"
-        )
-        return None
-    c_compiler = attribute_compilers[c_key]
-
-    # C++ and Fortran compilers are not mandatory, so let's just leave a debug trace
-    if cxx_key not in attribute_compilers:
-        tty.debug(f"[{__file__}] The external spec {spec} does not have a C++ compiler")
-
-    if fortran_key not in attribute_compilers:
-        tty.debug(f"[{__file__}] The external spec {spec} does not have a Fortran compiler")
-
-    # compilers format has cc/fc/f77, externals format has "c/fortran"
-    paths = {
-        "cc": c_compiler,
-        "cxx": attribute_compilers.get(cxx_key, None),
-        "fc": attribute_compilers.get(fortran_key, None),
-        "f77": attribute_compilers.get(fortran_key, None),
-    }
-
-    if not spec.architecture:
-        host_platform = spack.platforms.host()
-        operating_system = host_platform.operating_system("default_os")
-        target = host_platform.target("default_target").microarchitecture
-    else:
-        target = spec.architecture.target
-        if not target:
-            target = spack.platforms.host().target("default_target")
-        target = target.microarchitecture
-
-        operating_system = spec.os
-        if not operating_system:
-            host_platform = spack.platforms.host()
-            operating_system = host_platform.operating_system("default_os")
-
-    compiler_entry = {
-        "compiler": {
-            "spec": str(compiler_spec),
-            "paths": paths,
-            "flags": extra_attributes.get("flags", {}),
-            "operating_system": str(operating_system),
-            "target": str(target.family),
-            "modules": config.get("modules", []),
-            "environment": extra_attributes.get("environment", {}),
-            "extra_rpaths": extra_attributes.get("extra_rpaths", []),
-            "implicit_rpaths": extra_attributes.get("implicit_rpaths", None),
-        }
-    }
-    return compiler_entry
-
-
-def _init_compiler_config(
-    configuration: "spack.config.Configuration", *, scope: Optional[str]
-) -> None:
-    """Compiler search used when Spack has no compilers."""
-    compilers = find_compilers()
-    compilers_dict = []
-    for compiler in compilers:
-        compilers_dict.append(_to_dict(compiler))
-    configuration.set("compilers", compilers_dict, scope=scope)
+    packages_yaml = configuration.get("packages", scope=scope)
+    return CompilerConfigFactory.from_packages_yaml(packages_yaml)
 
 
 def compiler_config_files():
@@ -278,9 +141,7 @@ def add_compilers_to_config(compilers, scope=None):
         compilers: a list of Compiler objects.
         scope: configuration scope to modify.
     """
-    compiler_config = get_compiler_config(
-        configuration=spack.config.CONFIG, scope=scope, init_config=False
-    )
+    compiler_config = get_compiler_config(configuration=spack.config.CONFIG, scope=scope)
     for compiler in compilers:
         if not compiler.cc:
             tty.debug(f"{compiler.spec} does not have a C compiler")
@@ -329,9 +190,7 @@ def _remove_compiler_from_scope(compiler_spec, scope):
          True if one or more compiler entries were actually removed, False otherwise
     """
     assert scope is not None, "a specific scope is needed when calling this function"
-    compiler_config = get_compiler_config(
-        configuration=spack.config.CONFIG, scope=scope, init_config=False
-    )
+    compiler_config = get_compiler_config(configuration=spack.config.CONFIG, scope=scope)
     filtered_compiler_config = [
         compiler_entry
         for compiler_entry in compiler_config
@@ -380,79 +239,77 @@ def all_compiler_specs(scope=None, init_config=True):
 
 
 def find_compilers(
-    path_hints: Optional[List[str]] = None, *, mixed_toolchain=False
+    path_hints: Optional[List[str]] = None,
+    *,
+    scope: Optional[str] = None,
+    mixed_toolchain: bool = False,
+    max_workers: Optional[int] = None,
 ) -> List["spack.compiler.Compiler"]:
-    """Return the list of compilers found in the paths given as arguments.
+    """Searches for compiler in the paths given as argument. If any new compiler is found, the
+    configuration is updated, and the list of new compiler objects is returned.
 
     Args:
         path_hints: list of path hints where to look for. A sensible default based on the ``PATH``
             environment variable will be used if the value is None
+        scope: configuration scope to modify
         mixed_toolchain: allow mixing compilers from different toolchains if otherwise missing for
             a certain language
+        max_workers: number of processes used to search for compilers
     """
+    import spack.detection
+
+    known_compilers = set(all_compilers(init_config=False))
+
     if path_hints is None:
         path_hints = get_path("PATH")
     default_paths = fs.search_paths_for_executables(*path_hints)
+    if sys.platform == "win32":
+        default_paths.extend(windows_os.WindowsOs().compiler_search_paths)
+    compiler_pkgs = spack.repo.PATH.packages_with_tags(COMPILER_TAG, full=True)
 
-    # To detect the version of the compilers, we dispatch a certain number
-    # of function calls to different workers. Here we construct the list
-    # of arguments for each call.
-    arguments = []
-    for o in all_os_classes():
-        search_paths = getattr(o, "compiler_search_paths", default_paths)
-        arguments.extend(arguments_to_detect_version_fn(o, search_paths))
-
-    # Here we map the function arguments to the corresponding calls
-    tp = multiprocessing.pool.ThreadPool()
-    try:
-        detected_versions = tp.map(detect_version, arguments)
-    finally:
-        tp.close()
-
-    def valid_version(item: Tuple[Optional[DetectVersionArgs], Optional[str]]) -> bool:
-        value, error = item
-        if error is None:
-            return True
-        try:
-            # This will fail on Python 2.6 if a non ascii
-            # character is in the error
-            tty.debug(error)
-        except UnicodeEncodeError:
-            pass
-        return False
-
-    def remove_errors(
-        item: Tuple[Optional[DetectVersionArgs], Optional[str]]
-    ) -> DetectVersionArgs:
-        value, _ = item
-        assert value is not None
-        return value
-
-    return make_compiler_list(
-        [remove_errors(detected) for detected in detected_versions if valid_version(detected)],
-        mixed_toolchain=mixed_toolchain,
+    detected_packages = spack.detection.by_path(
+        compiler_pkgs, path_hints=default_paths, max_workers=max_workers
     )
 
+    valid_compilers = {}
+    for name, detected in detected_packages.items():
+        compilers = [x for x in detected if CompilerConfigFactory.from_external_spec(x.spec)]
+        if not compilers:
+            continue
+        valid_compilers[name] = compilers
 
-def find_new_compilers(
-    path_hints: Optional[List[str]] = None,
-    scope: Optional[str] = None,
-    *,
-    mixed_toolchain: bool = False,
-):
-    """Same as ``find_compilers`` but return only the compilers that are not
-    already in compilers.yaml.
+    def _has_fortran_compilers(x):
+        if "compilers" not in x.spec.extra_attributes:
+            return False
 
-    Args:
-        path_hints: list of path hints where to look for. A sensible default based on the ``PATH``
-            environment variable will be used if the value is None
-        scope: scope to look for a compiler. If None consider the merged configuration.
-        mixed_toolchain: allow mixing compilers from different toolchains if otherwise missing for
-            a certain language
-    """
-    compilers = find_compilers(path_hints, mixed_toolchain=mixed_toolchain)
+        return "fortran" in x.spec.extra_attributes["compilers"]
 
-    return select_new_compilers(compilers, scope)
+    if mixed_toolchain:
+        gccs = [x for x in valid_compilers.get("gcc", []) if _has_fortran_compilers(x)]
+        if gccs:
+            best_gcc = sorted(
+                gccs, key=lambda x: spack.spec.parse_with_version_concrete(x.spec).version
+            )[-1]
+            gfortran = best_gcc.spec.extra_attributes["compilers"]["fortran"]
+            for name in ("llvm", "apple-clang"):
+                if name not in valid_compilers:
+                    continue
+                candidates = valid_compilers[name]
+                for candidate in candidates:
+                    if _has_fortran_compilers(candidate):
+                        continue
+                    candidate.spec.extra_attributes["compilers"]["fortran"] = gfortran
+
+    new_compilers = []
+    for name, detected in valid_compilers.items():
+        for config in CompilerConfigFactory.from_specs([x.spec for x in detected]):
+            c = _compiler_from_config_entry(config["compiler"])
+            if c in known_compilers:
+                continue
+            new_compilers.append(c)
+
+    add_compilers_to_config(new_compilers, scope=scope)
+    return new_compilers
 
 
 def select_new_compilers(compilers, scope=None):
@@ -462,7 +319,9 @@ def select_new_compilers(compilers, scope=None):
     compilers_not_in_config = []
     for c in compilers:
         arch_spec = spack.spec.ArchSpec((None, c.operating_system, c.target))
-        same_specs = compilers_for_spec(c.spec, arch_spec, scope=scope, init_config=False)
+        same_specs = compilers_for_spec(
+            c.spec, arch_spec=arch_spec, scope=scope, init_config=False
+        )
         if not same_specs:
             compilers_not_in_config.append(c)
 
@@ -510,8 +369,9 @@ def replace_apple_clang(name):
     return [replace_apple_clang(name) for name in all_compiler_module_names()]
 
 
+@llnl.util.lang.memoized
 def all_compiler_module_names() -> List[str]:
-    return [name for name in llnl.util.lang.list_modules(spack.paths.compilers_path)]
+    return list(llnl.util.lang.list_modules(spack.paths.compilers_path))
 
 
 @_auto_compiler_spec
@@ -531,7 +391,12 @@ def find(compiler_spec, scope=None, init_config=True):
 def find_specs_by_arch(compiler_spec, arch_spec, scope=None, init_config=True):
     """Return specs of available compilers that match the supplied
     compiler spec.  Return an empty list if nothing found."""
-    return [c.spec for c in compilers_for_spec(compiler_spec, arch_spec, scope, True, init_config)]
+    return [
+        c.spec
+        for c in compilers_for_spec(
+            compiler_spec, arch_spec=arch_spec, scope=scope, init_config=init_config
+        )
+    ]
 
 
 def all_compilers(scope=None, init_config=True):
@@ -553,14 +418,11 @@ def all_compilers_from(configuration, scope=None, init_config=True):
 
 
 @_auto_compiler_spec
-def compilers_for_spec(
-    compiler_spec, arch_spec=None, scope=None, use_cache=True, init_config=True
-):
+def compilers_for_spec(compiler_spec, *, arch_spec=None, scope=None, init_config=True):
     """This gets all compilers that satisfy the supplied CompilerSpec.
     Returns an empty list if none are found.
     """
     config = all_compilers_config(spack.config.CONFIG, scope=scope, init_config=init_config)
-
     matches = set(find(compiler_spec, scope, init_config))
     compilers = []
     for cspec in matches:
@@ -569,7 +431,7 @@ def compilers_for_spec(
 
 
 def compilers_for_arch(arch_spec, scope=None):
-    config = all_compilers_config(spack.config.CONFIG, scope=scope)
+    config = all_compilers_config(spack.config.CONFIG, scope=scope, init_config=False)
     return list(get_compilers(config, arch_spec=arch_spec))
 
 
@@ -601,13 +463,15 @@ def compiler_from_dict(items):
     os = items.get("operating_system", None)
     target = items.get("target", None)
 
-    if not ("paths" in items and all(n in items["paths"] for n in _path_instance_vars)):
+    if not (
+        "paths" in items and all(n in items["paths"] for n in spack.compiler.PATH_INSTANCE_VARS)
+    ):
         raise InvalidCompilerConfigurationError(cspec)
 
     cls = class_for_compiler_name(cspec.name)
 
     compiler_paths = []
-    for c in _path_instance_vars:
+    for c in spack.compiler.PATH_INSTANCE_VARS:
         compiler_path = items["paths"][c]
         if compiler_path != "None":
             compiler_paths.append(compiler_path)
@@ -766,7 +630,7 @@ def class_for_compiler_name(compiler_name):
         submodule_name = compiler_name.replace("-", "_")
 
     module_name = ".".join(["spack", "compilers", submodule_name])
-    module_obj = __import__(module_name, fromlist=[None])
+    module_obj = importlib.import_module(module_name)
     cls = getattr(module_obj, mod_to_class(compiler_name))
 
     # make a note of the name in the module so we can get to it easily.
@@ -775,272 +639,10 @@ def class_for_compiler_name(compiler_name):
     return cls
 
 
-def all_os_classes():
-    """
-    Return the list of classes for all operating systems available on
-    this platform
-    """
-    classes = []
-
-    platform = spack.platforms.host()
-    for os_class in platform.operating_sys.values():
-        classes.append(os_class)
-
-    return classes
-
-
 def all_compiler_types():
     return [class_for_compiler_name(c) for c in supported_compilers()]
 
 
-#: Gathers the attribute values by which a detected compiler is considered
-#: unique in Spack.
-#:
-#:  - os: the operating system
-#:  - compiler_name: the name of the compiler (e.g. 'gcc', 'clang', etc.)
-#:  - version: the version of the compiler
-#:
-CompilerID = collections.namedtuple("CompilerID", ["os", "compiler_name", "version"])
-
-#: Variations on a matched compiler name
-NameVariation = collections.namedtuple("NameVariation", ["prefix", "suffix"])
-
-#: Groups together the arguments needed by `detect_version`. The four entries
-#: in the tuple are:
-#:
-#: - id: An instance of the CompilerID named tuple (version can be set to None
-#:       as it will be detected later)
-#: - variation: a NameVariation for file being tested
-#: - language: compiler language being tested (one of 'cc', 'cxx', 'fc', 'f77')
-#: - path: full path to the executable being tested
-#:
-DetectVersionArgs = collections.namedtuple(
-    "DetectVersionArgs", ["id", "variation", "language", "path"]
-)
-
-
-def arguments_to_detect_version_fn(
-    operating_system: spack.operating_systems.OperatingSystem, paths: List[str]
-) -> List[DetectVersionArgs]:
-    """Returns a list of DetectVersionArgs tuples to be used in a
-    corresponding function to detect compiler versions.
-
-    The ``operating_system`` instance can customize the behavior of this
-    function by providing a method called with the same name.
-
-    Args:
-        operating_system: the operating system on which we are looking for compilers
-        paths: paths to search for compilers
-
-    Returns:
-        List of DetectVersionArgs tuples. Each item in the list will be later
-        mapped to the corresponding function call to detect the version of the
-        compilers in this OS.
-    """
-
-    def _default(search_paths: List[str]) -> List[DetectVersionArgs]:
-        command_arguments: List[DetectVersionArgs] = []
-        files_to_be_tested = fs.files_in(*search_paths)
-        for compiler_name in supported_compilers_for_host_platform():
-            compiler_cls = class_for_compiler_name(compiler_name)
-
-            for language in ("cc", "cxx", "f77", "fc"):
-                # Select only the files matching a regexp
-                for (file, full_path), regexp in itertools.product(
-                    files_to_be_tested, compiler_cls.search_regexps(language)
-                ):
-                    match = regexp.match(file)
-                    if match:
-                        compiler_id = CompilerID(operating_system, compiler_name, None)
-                        detect_version_args = DetectVersionArgs(
-                            id=compiler_id,
-                            variation=NameVariation(*match.groups()),
-                            language=language,
-                            path=full_path,
-                        )
-                        command_arguments.append(detect_version_args)
-
-        return command_arguments
-
-    fn = getattr(operating_system, "arguments_to_detect_version_fn", _default)
-    return fn(paths)
-
-
-def detect_version(
-    detect_version_args: DetectVersionArgs,
-) -> Tuple[Optional[DetectVersionArgs], Optional[str]]:
-    """Computes the version of a compiler and adds it to the information
-    passed as input.
-
-    As this function is meant to be executed by worker processes it won't
-    raise any exception but instead will return a (value, error) tuple that
-    needs to be checked by the code dispatching the calls.
-
-    Args:
-        detect_version_args: information on the compiler for which we should detect the version.
-
-    Returns:
-        A ``(DetectVersionArgs, error)`` tuple. If ``error`` is ``None`` the
-        version of the compiler was computed correctly and the first argument
-        of the tuple will contain it. Otherwise ``error`` is a string
-        containing an explanation on why the version couldn't be computed.
-    """
-
-    def _default(fn_args):
-        compiler_id = fn_args.id
-        language = fn_args.language
-        compiler_cls = class_for_compiler_name(compiler_id.compiler_name)
-        path = fn_args.path
-
-        # Get compiler names and the callback to detect their versions
-        callback = getattr(compiler_cls, f"{language}_version")
-
-        try:
-            version = callback(path)
-            if version and str(version).strip() and version != "unknown":
-                value = fn_args._replace(id=compiler_id._replace(version=version))
-                return value, None
-
-            error = f"Couldn't get version for compiler {path}".format(path)
-        except spack.util.executable.ProcessError as e:
-            error = f"Couldn't get version for compiler {path}\n" + str(e)
-        except spack.util.executable.ProcessTimeoutError as e:
-            error = f"Couldn't get version for compiler {path}\n" + str(e)
-        except Exception as e:
-            # Catching "Exception" here is fine because it just
-            # means something went wrong running a candidate executable.
-            error = "Error while executing candidate compiler {0}" "\n{1}: {2}".format(
-                path, e.__class__.__name__, str(e)
-            )
-        return None, error
-
-    operating_system = detect_version_args.id.os
-    fn = getattr(operating_system, "detect_version", _default)
-    return fn(detect_version_args)
-
-
-def make_compiler_list(
-    detected_versions: List[DetectVersionArgs], mixed_toolchain: bool = False
-) -> List["spack.compiler.Compiler"]:
-    """Process a list of detected versions and turn them into a list of
-    compiler specs.
-
-    Args:
-        detected_versions: list of DetectVersionArgs containing a valid version
-        mixed_toolchain: allow mixing compilers from different toolchains if langauge is missing
-
-    Returns:
-        list: list of Compiler objects
-    """
-    group_fn = lambda x: (x.id, x.variation, x.language)
-    sorted_compilers = sorted(detected_versions, key=group_fn)
-
-    # Gather items in a dictionary by the id, name variation and language
-    compilers_d: Dict[CompilerID, Dict[NameVariation, dict]] = {}
-    for sort_key, group in itertools.groupby(sorted_compilers, key=group_fn):
-        compiler_id, name_variation, language = sort_key
-        by_compiler_id = compilers_d.setdefault(compiler_id, {})
-        by_name_variation = by_compiler_id.setdefault(name_variation, {})
-        by_name_variation[language] = next(x.path for x in group)
-
-    def _default_make_compilers(cmp_id, paths):
-        operating_system, compiler_name, version = cmp_id
-        compiler_cls = class_for_compiler_name(compiler_name)
-        spec = spack.spec.CompilerSpec(compiler_cls.name, f"={version}")
-        paths = [paths.get(x, None) for x in ("cc", "cxx", "f77", "fc")]
-        # TODO: johnwparent - revist the following line as per discussion at:
-        # https://github.com/spack/spack/pull/33385/files#r1040036318
-        target = archspec.cpu.host()
-        compiler = compiler_cls(spec, operating_system, str(target.family), paths)
-        return [compiler]
-
-    # For compilers with the same compiler id:
-    #
-    # - Prefer with C compiler to without
-    # - Prefer with C++ compiler to without
-    # - Prefer no variations to variations (e.g., clang to clang-gpu)
-    #
-    sort_fn = lambda variation: (
-        "cc" not in by_compiler_id[variation],  # None last
-        "cxx" not in by_compiler_id[variation],  # None last
-        getattr(variation, "prefix", None),
-        getattr(variation, "suffix", None),
-    )
-
-    # Flatten to a list of compiler id, primary variation and compiler dictionary
-    flat_compilers: List[Tuple[CompilerID, NameVariation, dict]] = []
-    for compiler_id, by_compiler_id in compilers_d.items():
-        ordered = sorted(by_compiler_id, key=sort_fn)
-        selected_variation = ordered[0]
-        selected = by_compiler_id[selected_variation]
-
-        # Fill any missing parts from subsequent entries (without mixing toolchains)
-        for lang in ["cxx", "f77", "fc"]:
-            if lang not in selected:
-                next_lang = next(
-                    (by_compiler_id[v][lang] for v in ordered if lang in by_compiler_id[v]), None
-                )
-                if next_lang:
-                    selected[lang] = next_lang
-
-        flat_compilers.append((compiler_id, selected_variation, selected))
-
-    # Next, fill out the blanks of missing compilers by creating a mixed toolchain (if requested)
-    if mixed_toolchain:
-        make_mixed_toolchain(flat_compilers)
-
-    # Finally, create the compiler list
-    compilers: List["spack.compiler.Compiler"] = []
-    for compiler_id, _, compiler in flat_compilers:
-        make_compilers = getattr(compiler_id.os, "make_compilers", _default_make_compilers)
-        candidates = make_compilers(compiler_id, compiler)
-        compilers.extend(x for x in candidates if x.cc is not None)
-
-    return compilers
-
-
-def make_mixed_toolchain(compilers: List[Tuple[CompilerID, NameVariation, dict]]) -> None:
-    """Add missing compilers across toolchains when they are missing for a particular language.
-    This currently only adds the most sensible gfortran to (apple)-clang if it doesn't have a
-    fortran compiler (no flang)."""
-
-    # First collect the clangs that are missing a fortran compiler
-    clangs_without_flang = [
-        (id, variation, compiler)
-        for id, variation, compiler in compilers
-        if id.compiler_name in ("clang", "apple-clang")
-        and "f77" not in compiler
-        and "fc" not in compiler
-    ]
-    if not clangs_without_flang:
-        return
-
-    # Filter on GCCs with fortran compiler
-    gccs_with_fortran = [
-        (id, variation, compiler)
-        for id, variation, compiler in compilers
-        if id.compiler_name == "gcc" and "f77" in compiler and "fc" in compiler
-    ]
-
-    # Sort these GCCs by "best variation" (no prefix / suffix first)
-    gccs_with_fortran.sort(
-        key=lambda x: (getattr(x[1], "prefix", None), getattr(x[1], "suffix", None))
-    )
-
-    # Attach the optimal GCC fortran compiler to the clangs that don't have one
-    for clang_id, _, clang_compiler in clangs_without_flang:
-        gcc_compiler = next(
-            (gcc[2] for gcc in gccs_with_fortran if gcc[0].os == clang_id.os), None
-        )
-
-        if not gcc_compiler:
-            continue
-
-        # Update the fc / f77 entries
-        clang_compiler["f77"] = gcc_compiler["f77"]
-        clang_compiler["fc"] = gcc_compiler["fc"]
-
-
 def is_mixed_toolchain(compiler):
     """Returns True if the current compiler is a mixed toolchain,
     False otherwise.
@@ -1087,20 +689,164 @@ def name_matches(name, name_list):
     return False
 
 
+_EXTRA_ATTRIBUTES_KEY = "extra_attributes"
+_COMPILERS_KEY = "compilers"
+_C_KEY = "c"
+_CXX_KEY, _FORTRAN_KEY = "cxx", "fortran"
+
+
+class CompilerConfigFactory:
+    """Class aggregating all ways of constructing a list of compiler config entries."""
+
+    @staticmethod
+    def from_specs(specs: List["spack.spec.Spec"]) -> List[dict]:
+        result = []
+        compiler_package_names = supported_compilers() + list(package_name_to_compiler_name.keys())
+        for s in specs:
+            if s.name not in compiler_package_names:
+                continue
+
+            candidate = CompilerConfigFactory.from_external_spec(s)
+            if candidate is None:
+                continue
+
+            result.append(candidate)
+        return result
+
+    @staticmethod
+    def from_packages_yaml(packages_yaml) -> List[dict]:
+        compiler_specs = []
+        compiler_package_names = supported_compilers() + list(package_name_to_compiler_name.keys())
+        for name, entry in packages_yaml.items():
+            if name not in compiler_package_names:
+                continue
+
+            externals_config = entry.get("externals", None)
+            if not externals_config:
+                continue
+
+            current_specs = []
+            for current_external in externals_config:
+                compiler = CompilerConfigFactory._spec_from_external_config(current_external)
+                if compiler:
+                    current_specs.append(compiler)
+            compiler_specs.extend(current_specs)
+
+        return CompilerConfigFactory.from_specs(compiler_specs)
+
+    @staticmethod
+    def _spec_from_external_config(config):
+        # Allow `@x.y.z` instead of `@=x.y.z`
+        err_header = f"The external spec '{config['spec']}' cannot be used as a compiler"
+        # If extra_attributes is not there I might not want to use this entry as a compiler,
+        # therefore just leave a debug message, but don't be loud with a warning.
+        if _EXTRA_ATTRIBUTES_KEY not in config:
+            tty.debug(f"[{__file__}] {err_header}: missing the '{_EXTRA_ATTRIBUTES_KEY}' key")
+            return None
+        extra_attributes = config[_EXTRA_ATTRIBUTES_KEY]
+        result = spack.spec.Spec(
+            str(spack.spec.parse_with_version_concrete(config["spec"])),
+            external_modules=config.get("modules"),
+        )
+        result.extra_attributes = extra_attributes
+        return result
+
+    @staticmethod
+    def from_external_spec(spec: "spack.spec.Spec") -> Optional[dict]:
+        spec = spack.spec.parse_with_version_concrete(spec)
+        extra_attributes = getattr(spec, _EXTRA_ATTRIBUTES_KEY, None)
+        if extra_attributes is None:
+            return None
+
+        paths = CompilerConfigFactory._extract_compiler_paths(spec)
+        if paths is None:
+            return None
+
+        compiler_spec = spack.spec.CompilerSpec(
+            package_name_to_compiler_name.get(spec.name, spec.name), spec.version
+        )
+
+        operating_system, target = CompilerConfigFactory._extract_os_and_target(spec)
+
+        compiler_entry = {
+            "compiler": {
+                "spec": str(compiler_spec),
+                "paths": paths,
+                "flags": extra_attributes.get("flags", {}),
+                "operating_system": str(operating_system),
+                "target": str(target.family),
+                "modules": getattr(spec, "external_modules", []),
+                "environment": extra_attributes.get("environment", {}),
+                "extra_rpaths": extra_attributes.get("extra_rpaths", []),
+                "implicit_rpaths": extra_attributes.get("implicit_rpaths", None),
+            }
+        }
+        return compiler_entry
+
+    @staticmethod
+    def _extract_compiler_paths(spec: "spack.spec.Spec") -> Optional[Dict[str, str]]:
+        err_header = f"The external spec '{spec}' cannot be used as a compiler"
+        extra_attributes = spec.extra_attributes
+        # If I have 'extra_attributes' warn if 'compilers' is missing,
+        # or we don't have a C compiler
+        if _COMPILERS_KEY not in extra_attributes:
+            warnings.warn(
+                f"{err_header}: missing the '{_COMPILERS_KEY}' key under '{_EXTRA_ATTRIBUTES_KEY}'"
+            )
+            return None
+        attribute_compilers = extra_attributes[_COMPILERS_KEY]
+
+        if _C_KEY not in attribute_compilers:
+            warnings.warn(
+                f"{err_header}: missing the C compiler path under "
+                f"'{_EXTRA_ATTRIBUTES_KEY}:{_COMPILERS_KEY}'"
+            )
+            return None
+        c_compiler = attribute_compilers[_C_KEY]
+
+        # C++ and Fortran compilers are not mandatory, so let's just leave a debug trace
+        if _CXX_KEY not in attribute_compilers:
+            tty.debug(f"[{__file__}] The external spec {spec} does not have a C++ compiler")
+
+        if _FORTRAN_KEY not in attribute_compilers:
+            tty.debug(f"[{__file__}] The external spec {spec} does not have a Fortran compiler")
+
+        # compilers format has cc/fc/f77, externals format has "c/fortran"
+        return {
+            "cc": c_compiler,
+            "cxx": attribute_compilers.get(_CXX_KEY, None),
+            "fc": attribute_compilers.get(_FORTRAN_KEY, None),
+            "f77": attribute_compilers.get(_FORTRAN_KEY, None),
+        }
+
+    @staticmethod
+    def _extract_os_and_target(spec: "spack.spec.Spec"):
+        if not spec.architecture:
+            host_platform = spack.platforms.host()
+            operating_system = host_platform.operating_system("default_os")
+            target = host_platform.target("default_target").microarchitecture
+        else:
+            target = spec.architecture.target
+            if not target:
+                target = spack.platforms.host().target("default_target")
+            target = target.microarchitecture
+
+            operating_system = spec.os
+            if not operating_system:
+                host_platform = spack.platforms.host()
+                operating_system = host_platform.operating_system("default_os")
+        return operating_system, target
+
+
 class InvalidCompilerConfigurationError(spack.error.SpackError):
     def __init__(self, compiler_spec):
         super().__init__(
-            'Invalid configuration for [compiler "%s"]: ' % compiler_spec,
-            "Compiler configuration must contain entries for all compilers: %s"
-            % _path_instance_vars,
+            f'Invalid configuration for [compiler "{compiler_spec}"]: ',
+            f"Compiler configuration must contain entries for "
+            f"all compilers: {spack.compiler.PATH_INSTANCE_VARS}",
         )
 
 
-class NoCompilersError(spack.error.SpackError):
-    def __init__(self):
-        super().__init__("Spack could not find any compilers!")
-
-
 class UnknownCompilerError(spack.error.SpackError):
     def __init__(self, compiler_name):
         super().__init__("Spack doesn't support the requested compiler: {0}".format(compiler_name))
@@ -1111,25 +857,3 @@ def __init__(self, compiler_spec, target):
         super().__init__(
             "No compilers for operating system %s satisfy spec %s" % (target, compiler_spec)
         )
-
-
-class CompilerDuplicateError(spack.error.SpackError):
-    def __init__(self, compiler_spec, arch_spec):
-        config_file_to_duplicates = get_compiler_duplicates(compiler_spec, arch_spec)
-        duplicate_table = list((x, len(y)) for x, y in config_file_to_duplicates.items())
-        descriptor = lambda num: "time" if num == 1 else "times"
-        duplicate_msg = lambda cfgfile, count: "{0}: {1} {2}".format(
-            cfgfile, str(count), descriptor(count)
-        )
-        msg = (
-            "Compiler configuration contains entries with duplicate"
-            + " specification ({0}, {1})".format(compiler_spec, arch_spec)
-            + " in the following files:\n\t"
-            + "\n\t".join(duplicate_msg(x, y) for x, y in duplicate_table)
-        )
-        super().__init__(msg)
-
-
-class CompilerSpecInsufficientlySpecificError(spack.error.SpackError):
-    def __init__(self, compiler_spec):
-        super().__init__("Multiple compilers satisfy spec %s" % compiler_spec)

lib/spack/spack/compilers/msvc.py

@@ -223,6 +223,30 @@ def get_oneapi_root(pth: str):
             )
         self.msvc_compiler_environment = CmdCall(*env_cmds)
 
+    @property
+    def cxx11_flag(self):
+        return "/std:c++11"
+
+    @property
+    def cxx14_flag(self):
+        return "/std:c++14"
+
+    @property
+    def cxx17_flag(self):
+        return "/std:c++17"
+
+    @property
+    def cxx20_flag(self):
+        return "/std:c++20"
+
+    @property
+    def c11_flag(self):
+        return "/std:c11"
+
+    @property
+    def c17_flag(self):
+        return "/std:c17"
+
     @property
     def msvc_version(self):
         """This is the VCToolset version *NOT* the actual version of the cl compiler

lib/spack/spack/concretize.py

@@ -2,31 +2,12 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
 """
-Functions here are used to take abstract specs and make them concrete.
-For example, if a spec asks for a version between 1.8 and 1.9, these
-functions might take will take the most recent 1.9 version of the
-package available.  Or, if the user didn't specify a compiler for a
-spec, then this will assign a compiler to the spec based on defaults
-or user preferences.
-
-TODO: make this customizable and allow users to configure
-      concretization  policies.
+(DEPRECATED) Used to contain the code for the original concretizer
 """
-import functools
-import platform
-import tempfile
 from contextlib import contextmanager
 from itertools import chain
-from typing import Union
 
-import archspec.cpu
-
-import llnl.util.lang
-import llnl.util.tty as tty
-
-import spack.abi
 import spack.compilers
 import spack.config
 import spack.environment
@@ -37,639 +18,20 @@
 import spack.target
 import spack.tengine
 import spack.util.path
-import spack.variant as vt
-from spack.package_prefs import PackagePrefs, is_spec_buildable, spec_externals
-from spack.version import ClosedOpenRange, VersionList, ver
-
-#: impements rudimentary logic for ABI compatibility
-_abi: Union[spack.abi.ABI, llnl.util.lang.Singleton] = llnl.util.lang.Singleton(
-    lambda: spack.abi.ABI()
-)
-
-
-@functools.total_ordering
-class reverse_order:
-    """Helper for creating key functions.
-
-    This is a wrapper that inverts the sense of the natural
-    comparisons on the object.
-    """
-
-    def __init__(self, value):
-        self.value = value
-
-    def __eq__(self, other):
-        return other.value == self.value
-
-    def __lt__(self, other):
-        return other.value < self.value
 
 
 class Concretizer:
-    """You can subclass this class to override some of the default
-    concretization strategies, or you can override all of them.
-    """
+    """(DEPRECATED) Only contains logic to enable/disable compiler existence checks."""
 
     #: Controls whether we check that compiler versions actually exist
     #: during concretization. Used for testing and for mirror creation
     check_for_compiler_existence = None
 
-    #: Packages that the old concretizer cannot deal with correctly, and cannot build anyway.
-    #: Those will not be considered as providers for virtuals.
-    non_buildable_packages = {"glibc", "musl"}
-
-    def __init__(self, abstract_spec=None):
+    def __init__(self):
         if Concretizer.check_for_compiler_existence is None:
             Concretizer.check_for_compiler_existence = not spack.config.get(
                 "config:install_missing_compilers", False
             )
-        self.abstract_spec = abstract_spec
-        self._adjust_target_answer_generator = None
-
-    def concretize_develop(self, spec):
-        """
-        Add ``dev_path=*`` variant to packages built from local source.
-        """
-        env = spack.environment.active_environment()
-        dev_info = env.dev_specs.get(spec.name, {}) if env else {}
-        if not dev_info:
-            return False
-
-        path = spack.util.path.canonicalize_path(dev_info["path"], default_wd=env.path)
-
-        if "dev_path" in spec.variants:
-            assert spec.variants["dev_path"].value == path
-            changed = False
-        else:
-            spec.variants.setdefault("dev_path", vt.SingleValuedVariant("dev_path", path))
-            changed = True
-        changed |= spec.constrain(dev_info["spec"])
-        return changed
-
-    def _valid_virtuals_and_externals(self, spec):
-        """Returns a list of candidate virtual dep providers and external
-        packages that coiuld be used to concretize a spec.
-
-        Preferred specs come first in the list.
-        """
-        # First construct a list of concrete candidates to replace spec with.
-        candidates = [spec]
-        pref_key = lambda spec: 0  # no-op pref key
-
-        if spec.virtual:
-            candidates = [
-                s
-                for s in spack.repo.PATH.providers_for(spec)
-                if s.name not in self.non_buildable_packages
-            ]
-            if not candidates:
-                raise spack.error.UnsatisfiableProviderSpecError(candidates[0], spec)
-
-            # Find nearest spec in the DAG (up then down) that has prefs.
-            spec_w_prefs = find_spec(
-                spec, lambda p: PackagePrefs.has_preferred_providers(p.name, spec.name), spec
-            )  # default to spec itself.
-
-            # Create a key to sort candidates by the prefs we found
-            pref_key = PackagePrefs(spec_w_prefs.name, "providers", spec.name)
-
-        # For each candidate package, if it has externals, add those
-        # to the usable list.  if it's not buildable, then *only* add
-        # the externals.
-        usable = []
-        for cspec in candidates:
-            if is_spec_buildable(cspec):
-                usable.append(cspec)
-
-            externals = spec_externals(cspec)
-            for ext in externals:
-                if ext.intersects(spec):
-                    usable.append(ext)
-
-        # If nothing is in the usable list now, it's because we aren't
-        # allowed to build anything.
-        if not usable:
-            raise NoBuildError(spec)
-
-        # Use a sort key to order the results
-        return sorted(
-            usable,
-            key=lambda spec: (
-                not spec.external,  # prefer externals
-                pref_key(spec),  # respect prefs
-                spec.name,  # group by name
-                reverse_order(spec.versions),  # latest version
-                spec,  # natural order
-            ),
-        )
-
-    def choose_virtual_or_external(self, spec: spack.spec.Spec):
-        """Given a list of candidate virtual and external packages, try to
-        find one that is most ABI compatible.
-        """
-        candidates = self._valid_virtuals_and_externals(spec)
-        if not candidates:
-            return candidates
-
-        # Find the nearest spec in the dag that has a compiler.  We'll
-        # use that spec to calibrate compiler compatibility.
-        abi_exemplar = find_spec(spec, lambda x: x.compiler)
-        if abi_exemplar is None:
-            abi_exemplar = spec.root
-
-        # Sort candidates from most to least compatibility.
-        #   We reverse because True > False.
-        #   Sort is stable, so candidates keep their order.
-        return sorted(
-            candidates,
-            reverse=True,
-            key=lambda spec: (
-                _abi.compatible(spec, abi_exemplar, loose=True),
-                _abi.compatible(spec, abi_exemplar),
-            ),
-        )
-
-    def concretize_version(self, spec):
-        """If the spec is already concrete, return.  Otherwise take
-        the preferred version from spackconfig, and default to the package's
-        version if there are no available versions.
-
-        TODO: In many cases we probably want to look for installed
-              versions of each package and use an installed version
-              if we can link to it.  The policy implemented here will
-              tend to rebuild a lot of stuff becasue it will prefer
-              a compiler in the spec to any compiler already-
-              installed things were built with.  There is likely
-              some better policy that finds some middle ground
-              between these two extremes.
-        """
-        # return if already concrete.
-        if spec.versions.concrete:
-            return False
-
-        # List of versions we could consider, in sorted order
-        pkg_versions = spec.package_class.versions
-        usable = [v for v in pkg_versions if any(v.intersects(sv) for sv in spec.versions)]
-
-        yaml_prefs = PackagePrefs(spec.name, "version")
-
-        # The keys below show the order of precedence of factors used
-        # to select a version when concretizing.  The item with
-        # the "largest" key will be selected.
-        #
-        # NOTE: When COMPARING VERSIONS, the '@develop' version is always
-        #       larger than other versions.  BUT when CONCRETIZING,
-        #       the largest NON-develop version is selected by default.
-        keyfn = lambda v: (
-            # ------- Special direction from the user
-            # Respect order listed in packages.yaml
-            -yaml_prefs(v),
-            # The preferred=True flag (packages or packages.yaml or both?)
-            pkg_versions.get(v).get("preferred", False),
-            # ------- Regular case: use latest non-develop version by default.
-            # Avoid @develop version, which would otherwise be the "largest"
-            # in straight version comparisons
-            not v.isdevelop(),
-            # Compare the version itself
-            # This includes the logic:
-            #    a) develop > everything (disabled by "not v.isdevelop() above)
-            #    b) numeric > non-numeric
-            #    c) Numeric or string comparison
-            v,
-        )
-        usable.sort(key=keyfn, reverse=True)
-
-        if usable:
-            spec.versions = ver([usable[0]])
-        else:
-            # We don't know of any SAFE versions that match the given
-            # spec.  Grab the spec's versions and grab the highest
-            # *non-open* part of the range of versions it specifies.
-            # Someone else can raise an error if this happens,
-            # e.g. when we go to fetch it and don't know how.  But it
-            # *might* work.
-            if not spec.versions or spec.versions == VersionList([":"]):
-                raise NoValidVersionError(spec)
-            else:
-                last = spec.versions[-1]
-                if isinstance(last, ClosedOpenRange):
-                    range_as_version = VersionList([last]).concrete_range_as_version
-                    if range_as_version:
-                        spec.versions = ver([range_as_version])
-                    else:
-                        raise NoValidVersionError(spec)
-                else:
-                    spec.versions = ver([last])
-
-        return True  # Things changed
-
-    def concretize_architecture(self, spec):
-        """If the spec is empty provide the defaults of the platform. If the
-        architecture is not a string type, then check if either the platform,
-        target or operating system are concretized. If any of the fields are
-        changed then return True. If everything is concretized (i.e the
-        architecture attribute is a namedtuple of classes) then return False.
-        If the target is a string type, then convert the string into a
-        concretized architecture. If it has no architecture and the root of the
-        DAG has an architecture, then use the root otherwise use the defaults
-        on the platform.
-        """
-        # ensure type safety for the architecture
-        if spec.architecture is None:
-            spec.architecture = spack.spec.ArchSpec()
-
-        if spec.architecture.concrete:
-            return False
-
-        # Get platform of nearest spec with a platform, including spec
-        # If spec has a platform, easy
-        if spec.architecture.platform:
-            new_plat = spack.platforms.by_name(spec.architecture.platform)
-        else:
-            # Else if anyone else has a platform, take the closest one
-            # Search up, then down, along build/link deps first
-            # Then any nearest. Algorithm from compilerspec search
-            platform_spec = find_spec(spec, lambda x: x.architecture and x.architecture.platform)
-            if platform_spec:
-                new_plat = spack.platforms.by_name(platform_spec.architecture.platform)
-            else:
-                # If no platform anywhere in this spec, grab the default
-                new_plat = spack.platforms.host()
-
-        # Get nearest spec with relevant platform and an os
-        # Generally, same algorithm as finding platform, except we only
-        # consider specs that have a platform
-        if spec.architecture.os:
-            new_os = spec.architecture.os
-        else:
-            new_os_spec = find_spec(
-                spec,
-                lambda x: (
-                    x.architecture
-                    and x.architecture.platform == str(new_plat)
-                    and x.architecture.os
-                ),
-            )
-            if new_os_spec:
-                new_os = new_os_spec.architecture.os
-            else:
-                new_os = new_plat.operating_system("default_os")
-
-        # Get the nearest spec with relevant platform and a target
-        # Generally, same algorithm as finding os
-        curr_target = None
-        if spec.architecture.target:
-            curr_target = spec.architecture.target
-        if spec.architecture.target and spec.architecture.target_concrete:
-            new_target = spec.architecture.target
-        else:
-            new_target_spec = find_spec(
-                spec,
-                lambda x: (
-                    x.architecture
-                    and x.architecture.platform == str(new_plat)
-                    and x.architecture.target
-                    and x.architecture.target != curr_target
-                ),
-            )
-            if new_target_spec:
-                if curr_target:
-                    # constrain one target by the other
-                    new_target_arch = spack.spec.ArchSpec(
-                        (None, None, new_target_spec.architecture.target)
-                    )
-                    curr_target_arch = spack.spec.ArchSpec((None, None, curr_target))
-                    curr_target_arch.constrain(new_target_arch)
-                    new_target = curr_target_arch.target
-                else:
-                    new_target = new_target_spec.architecture.target
-            else:
-                # To get default platform, consider package prefs
-                if PackagePrefs.has_preferred_targets(spec.name):
-                    new_target = self.target_from_package_preferences(spec)
-                else:
-                    new_target = new_plat.target("default_target")
-                if curr_target:
-                    # convert to ArchSpec to compare satisfaction
-                    new_target_arch = spack.spec.ArchSpec((None, None, str(new_target)))
-                    curr_target_arch = spack.spec.ArchSpec((None, None, str(curr_target)))
-
-                    if not new_target_arch.intersects(curr_target_arch):
-                        # new_target is an incorrect guess based on preferences
-                        # and/or default
-                        valid_target_ranges = str(curr_target).split(",")
-                        for target_range in valid_target_ranges:
-                            t_min, t_sep, t_max = target_range.partition(":")
-                            if not t_sep:
-                                new_target = t_min
-                                break
-                            elif t_max:
-                                new_target = t_max
-                                break
-                            elif t_min:
-                                # TODO: something better than picking first
-                                new_target = t_min
-                                break
-
-        # Construct new architecture, compute whether spec changed
-        arch_spec = (str(new_plat), str(new_os), str(new_target))
-        new_arch = spack.spec.ArchSpec(arch_spec)
-        spec_changed = new_arch != spec.architecture
-        spec.architecture = new_arch
-        return spec_changed
-
-    def target_from_package_preferences(self, spec):
-        """Returns the preferred target from the package preferences if
-        there's any.
-
-        Args:
-            spec: abstract spec to be concretized
-        """
-        target_prefs = PackagePrefs(spec.name, "target")
-        target_specs = [spack.spec.Spec("target=%s" % tname) for tname in archspec.cpu.TARGETS]
-
-        def tspec_filter(s):
-            # Filter target specs by whether the architecture
-            # family is the current machine type. This ensures
-            # we only consider x86_64 targets when on an
-            # x86_64 machine, etc. This may need to change to
-            # enable setting cross compiling as a default
-            target = archspec.cpu.TARGETS[str(s.architecture.target)]
-            arch_family_name = target.family.name
-            return arch_family_name == platform.machine()
-
-        # Sort filtered targets by package prefs
-        target_specs = list(filter(tspec_filter, target_specs))
-        target_specs.sort(key=target_prefs)
-        new_target = target_specs[0].architecture.target
-        return new_target
-
-    def concretize_variants(self, spec):
-        """If the spec already has variants filled in, return.  Otherwise, add
-        the user preferences from packages.yaml or the default variants from
-        the package specification.
-        """
-        changed = False
-        preferred_variants = PackagePrefs.preferred_variants(spec.name)
-        pkg_cls = spec.package_class
-        for name, entry in pkg_cls.variants.items():
-            variant, when = entry
-            var = spec.variants.get(name, None)
-            if var and "*" in var:
-                # remove variant wildcard before concretizing
-                # wildcard cannot be combined with other variables in a
-                # multivalue variant, a concrete variant cannot have the value
-                # wildcard, and a wildcard does not constrain a variant
-                spec.variants.pop(name)
-            if name not in spec.variants and any(spec.satisfies(w) for w in when):
-                changed = True
-                if name in preferred_variants:
-                    spec.variants[name] = preferred_variants.get(name)
-                else:
-                    spec.variants[name] = variant.make_default()
-            if name in spec.variants and not any(spec.satisfies(w) for w in when):
-                raise vt.InvalidVariantForSpecError(name, when, spec)
-
-        return changed
-
-    def concretize_compiler(self, spec):
-        """If the spec already has a compiler, we're done.  If not, then take
-        the compiler used for the nearest ancestor with a compiler
-        spec and use that.  If the ancestor's compiler is not
-        concrete, then used the preferred compiler as specified in
-        spackconfig.
-
-        Intuition: Use the spackconfig default if no package that depends on
-        this one has a strict compiler requirement.  Otherwise, try to
-        build with the compiler that will be used by libraries that
-        link to this one, to maximize compatibility.
-        """
-        # Pass on concretizing the compiler if the target or operating system
-        # is not yet determined
-        if not spec.architecture.concrete:
-            # We haven't changed, but other changes need to happen before we
-            # continue. `return True` here to force concretization to keep
-            # running.
-            return True
-
-        # Only use a matching compiler if it is of the proper style
-        # Takes advantage of the proper logic already existing in
-        # compiler_for_spec Should think whether this can be more
-        # efficient
-        def _proper_compiler_style(cspec, aspec):
-            compilers = spack.compilers.compilers_for_spec(cspec, arch_spec=aspec)
-            # If the spec passed as argument is concrete we want to check
-            # the versions match exactly
-            if (
-                cspec.concrete
-                and compilers
-                and cspec.version not in [c.version for c in compilers]
-            ):
-                return []
-
-            return compilers
-
-        if spec.compiler and spec.compiler.concrete:
-            if self.check_for_compiler_existence and not _proper_compiler_style(
-                spec.compiler, spec.architecture
-            ):
-                _compiler_concretization_failure(spec.compiler, spec.architecture)
-            return False
-
-        # Find another spec that has a compiler, or the root if none do
-        other_spec = spec if spec.compiler else find_spec(spec, lambda x: x.compiler, spec.root)
-        other_compiler = other_spec.compiler
-        assert other_spec
-
-        # Check if the compiler is already fully specified
-        if other_compiler and other_compiler.concrete:
-            if self.check_for_compiler_existence and not _proper_compiler_style(
-                other_compiler, spec.architecture
-            ):
-                _compiler_concretization_failure(other_compiler, spec.architecture)
-            spec.compiler = other_compiler
-            return True
-
-        if other_compiler:  # Another node has abstract compiler information
-            compiler_list = spack.compilers.find_specs_by_arch(other_compiler, spec.architecture)
-            if not compiler_list:
-                # We don't have a matching compiler installed
-                if not self.check_for_compiler_existence:
-                    # Concretize compiler spec versions as a package to build
-                    cpkg_spec = spack.compilers.pkg_spec_for_compiler(other_compiler)
-                    self.concretize_version(cpkg_spec)
-                    spec.compiler = spack.spec.CompilerSpec(
-                        other_compiler.name, cpkg_spec.versions
-                    )
-                    return True
-                else:
-                    # No compiler with a satisfactory spec was found
-                    raise UnavailableCompilerVersionError(other_compiler, spec.architecture)
-        else:
-            # We have no hints to go by, grab any compiler
-            compiler_list = spack.compilers.all_compiler_specs()
-            if not compiler_list:
-                # Spack has no compilers.
-                raise spack.compilers.NoCompilersError()
-
-        # By default, prefer later versions of compilers
-        compiler_list = sorted(compiler_list, key=lambda x: (x.name, x.version), reverse=True)
-        ppk = PackagePrefs(other_spec.name, "compiler")
-        matches = sorted(compiler_list, key=ppk)
-
-        # copy concrete version into other_compiler
-        try:
-            spec.compiler = next(
-                c for c in matches if _proper_compiler_style(c, spec.architecture)
-            ).copy()
-        except StopIteration:
-            # No compiler with a satisfactory spec has a suitable arch
-            _compiler_concretization_failure(other_compiler, spec.architecture)
-
-        assert spec.compiler.concrete
-        return True  # things changed.
-
-    def concretize_compiler_flags(self, spec):
-        """
-        The compiler flags are updated to match those of the spec whose
-        compiler is used, defaulting to no compiler flags in the spec.
-        Default specs set at the compiler level will still be added later.
-        """
-        # Pass on concretizing the compiler flags if the target or operating
-        # system is not set.
-        if not spec.architecture.concrete:
-            # We haven't changed, but other changes need to happen before we
-            # continue. `return True` here to force concretization to keep
-            # running.
-            return True
-
-        compiler_match = lambda other: (
-            spec.compiler == other.compiler and spec.architecture == other.architecture
-        )
-
-        ret = False
-        for flag in spack.spec.FlagMap.valid_compiler_flags():
-            if flag not in spec.compiler_flags:
-                spec.compiler_flags[flag] = list()
-            try:
-                nearest = next(
-                    p
-                    for p in spec.traverse(direction="parents")
-                    if (compiler_match(p) and (p is not spec) and flag in p.compiler_flags)
-                )
-                nearest_flags = nearest.compiler_flags.get(flag, [])
-                flags = spec.compiler_flags.get(flag, [])
-                if set(nearest_flags) - set(flags):
-                    spec.compiler_flags[flag] = list(llnl.util.lang.dedupe(nearest_flags + flags))
-                    ret = True
-            except StopIteration:
-                pass
-
-        # Include the compiler flag defaults from the config files
-        # This ensures that spack will detect conflicts that stem from a change
-        # in default compiler flags.
-        try:
-            compiler = spack.compilers.compiler_for_spec(spec.compiler, spec.architecture)
-        except spack.compilers.NoCompilerForSpecError:
-            if self.check_for_compiler_existence:
-                raise
-            return ret
-        for flag in compiler.flags:
-            config_flags = compiler.flags.get(flag, [])
-            flags = spec.compiler_flags.get(flag, [])
-            spec.compiler_flags[flag] = list(llnl.util.lang.dedupe(config_flags + flags))
-            if set(config_flags) - set(flags):
-                ret = True
-
-        return ret
-
-    def adjust_target(self, spec):
-        """Adjusts the target microarchitecture if the compiler is too old
-        to support the default one.
-
-        Args:
-            spec: spec to be concretized
-
-        Returns:
-            True if spec was modified, False otherwise
-        """
-        # To minimize the impact on performance this function will attempt
-        # to adjust the target only at the very first call once necessary
-        # information is set. It will just return False on subsequent calls.
-        # The way this is achieved is by initializing a generator and making
-        # this function return the next answer.
-        if not (spec.architecture and spec.architecture.concrete):
-            # Not ready, but keep going because we have work to do later
-            return True
-
-        def _make_only_one_call(spec):
-            yield self._adjust_target(spec)
-            while True:
-                yield False
-
-        if self._adjust_target_answer_generator is None:
-            self._adjust_target_answer_generator = _make_only_one_call(spec)
-
-        return next(self._adjust_target_answer_generator)
-
-    def _adjust_target(self, spec):
-        """Assumes that the architecture and the compiler have been
-        set already and checks if the current target microarchitecture
-        is the default and can be optimized by the compiler.
-
-        If not, downgrades the microarchitecture until a suitable one
-        is found. If none can be found raise an error.
-
-        Args:
-            spec: spec to be concretized
-
-        Returns:
-            True if any modification happened, False otherwise
-        """
-        import archspec.cpu
-
-        # Try to adjust the target only if it is the default
-        # target for this platform
-        current_target = spec.architecture.target
-        current_platform = spack.platforms.by_name(spec.architecture.platform)
-
-        default_target = current_platform.target("default_target")
-        if PackagePrefs.has_preferred_targets(spec.name):
-            default_target = self.target_from_package_preferences(spec)
-
-        if current_target != default_target or (
-            self.abstract_spec
-            and self.abstract_spec.architecture
-            and self.abstract_spec.architecture.concrete
-        ):
-            return False
-
-        try:
-            current_target.optimization_flags(spec.compiler)
-        except archspec.cpu.UnsupportedMicroarchitecture:
-            microarchitecture = current_target.microarchitecture
-            for ancestor in microarchitecture.ancestors:
-                candidate = None
-                try:
-                    candidate = spack.target.Target(ancestor)
-                    candidate.optimization_flags(spec.compiler)
-                except archspec.cpu.UnsupportedMicroarchitecture:
-                    continue
-
-                if candidate is not None:
-                    msg = (
-                        "{0.name}@{0.version} cannot build optimized "
-                        'binaries for "{1}". Using best target possible: '
-                        '"{2}"'
-                    )
-                    msg = msg.format(spec.compiler, current_target, candidate)
-                    tty.warn(msg)
-                    spec.architecture.target = candidate
-                    return True
-            else:
-                raise
-
-        return False
 
 
 @contextmanager
@@ -719,19 +81,6 @@ def find_spec(spec, condition, default=None):
     return default  # Nothing matched the condition; return default.
 
 
-def _compiler_concretization_failure(compiler_spec, arch):
-    # Distinguish between the case that there are compilers for
-    # the arch but not with the given compiler spec and the case that
-    # there are no compilers for the arch at all
-    if not spack.compilers.compilers_for_arch(arch):
-        available_os_targets = set(
-            (c.operating_system, c.target) for c in spack.compilers.all_compilers()
-        )
-        raise NoCompilersForArchError(arch, available_os_targets)
-    else:
-        raise UnavailableCompilerVersionError(compiler_spec, arch)
-
-
 def concretize_specs_together(*abstract_specs, **kwargs):
     """Given a number of specs as input, tries to concretize them together.
 
@@ -744,12 +93,6 @@ def concretize_specs_together(*abstract_specs, **kwargs):
     Returns:
         List of concretized specs
     """
-    if spack.config.get("config:concretizer", "clingo") == "original":
-        return _concretize_specs_together_original(*abstract_specs, **kwargs)
-    return _concretize_specs_together_new(*abstract_specs, **kwargs)
-
-
-def _concretize_specs_together_new(*abstract_specs, **kwargs):
     import spack.solver.asp
 
     allow_deprecated = spack.config.get("config:deprecated", False)
@@ -760,51 +103,6 @@ def _concretize_specs_together_new(*abstract_specs, **kwargs):
     return [s.copy() for s in result.specs]
 
 
-def _concretize_specs_together_original(*abstract_specs, **kwargs):
-    abstract_specs = [spack.spec.Spec(s) for s in abstract_specs]
-    tmpdir = tempfile.mkdtemp()
-    builder = spack.repo.MockRepositoryBuilder(tmpdir)
-    # Split recursive specs, as it seems the concretizer has issue
-    # respecting conditions on dependents expressed like
-    # depends_on('foo ^bar@1.0'), see issue #11160
-    split_specs = [
-        dep.copy(deps=False) for spec1 in abstract_specs for dep in spec1.traverse(root=True)
-    ]
-    builder.add_package(
-        "concretizationroot", dependencies=[(str(x), None, None) for x in split_specs]
-    )
-
-    with spack.repo.use_repositories(builder.root, override=False):
-        # Spec from a helper package that depends on all the abstract_specs
-        concretization_root = spack.spec.Spec("concretizationroot")
-        concretization_root.concretize(tests=kwargs.get("tests", False))
-        # Retrieve the direct dependencies
-        concrete_specs = [concretization_root[spec.name].copy() for spec in abstract_specs]
-
-    return concrete_specs
-
-
-class NoCompilersForArchError(spack.error.SpackError):
-    def __init__(self, arch, available_os_targets):
-        err_msg = (
-            "No compilers found"
-            " for operating system %s and target %s."
-            "\nIf previous installations have succeeded, the"
-            " operating system may have been updated." % (arch.os, arch.target)
-        )
-
-        available_os_target_strs = list()
-        for operating_system, t in available_os_targets:
-            os_target_str = "%s-%s" % (operating_system, t) if t else operating_system
-            available_os_target_strs.append(os_target_str)
-        err_msg += (
-            "\nCompilers are defined for the following"
-            " operating systems and targets:\n\t" + "\n\t".join(available_os_target_strs)
-        )
-
-        super().__init__(err_msg, "Run 'spack compiler find' to add compilers.")
-
-
 class UnavailableCompilerVersionError(spack.error.SpackError):
     """Raised when there is no available compiler that satisfies a
     compiler spec."""
@@ -820,37 +118,3 @@ def __init__(self, compiler_spec, arch=None):
             "'spack compilers' to see which compilers are already recognized"
             " by spack.",
         )
-
-
-class NoValidVersionError(spack.error.SpackError):
-    """Raised when there is no way to have a concrete version for a
-    particular spec."""
-
-    def __init__(self, spec):
-        super().__init__(
-            "There are no valid versions for %s that match '%s'" % (spec.name, spec.versions)
-        )
-
-
-class InsufficientArchitectureInfoError(spack.error.SpackError):
-    """Raised when details on architecture cannot be collected from the
-    system"""
-
-    def __init__(self, spec, archs):
-        super().__init__(
-            "Cannot determine necessary architecture information for '%s': %s"
-            % (spec.name, str(archs))
-        )
-
-
-class NoBuildError(spack.error.SpecError):
-    """Raised when a package is configured with the buildable option False, but
-    no satisfactory external versions can be found
-    """
-
-    def __init__(self, spec):
-        msg = (
-            "The spec\n    '%s'\n    is configured as not buildable, "
-            "and no matching external installs were found"
-        )
-        super().__init__(msg % spec)

lib/spack/spack/config.py

@@ -99,7 +99,6 @@
         "dirty": False,
         "build_jobs": min(16, cpus_available()),
         "build_stage": "$tempdir/spack-stage",
-        "concretizer": "clingo",
         "license_dir": spack.paths.default_license_dir,
     }
 }
@@ -1091,7 +1090,7 @@ def validate(
 
 
 def read_config_file(
-    filename: str, schema: Optional[YamlConfigDict] = None
+    path: str, schema: Optional[YamlConfigDict] = None
 ) -> Optional[YamlConfigDict]:
     """Read a YAML configuration file.
 
@@ -1101,21 +1100,9 @@ def read_config_file(
     # to preserve flexibility in calling convention (don't need to provide
     # schema when it's not necessary) while allowing us to validate against a
     # known schema when the top-level key could be incorrect.
-
-    if not os.path.exists(filename):
-        # Ignore nonexistent files.
-        tty.debug(f"Skipping nonexistent config path {filename}", level=3)
-        return None
-
-    elif not os.path.isfile(filename):
-        raise ConfigFileError(f"Invalid configuration. {filename} exists but is not a file.")
-
-    elif not os.access(filename, os.R_OK):
-        raise ConfigFileError(f"Config file is not readable: {filename}")
-
     try:
-        tty.debug(f"Reading config from file {filename}")
-        with open(filename) as f:
+        with open(path) as f:
+            tty.debug(f"Reading config from file {path}")
             data = syaml.load_config(f)
 
         if data:
@@ -1126,15 +1113,20 @@ def read_config_file(
 
         return data
 
-    except StopIteration:
-        raise ConfigFileError(f"Config file is empty or is not a valid YAML dict: {filename}")
+    except FileNotFoundError:
+        # Ignore nonexistent files.
+        tty.debug(f"Skipping nonexistent config path {path}", level=3)
+        return None
+
+    except OSError as e:
+        raise ConfigFileError(f"Path is not a file or is not readable: {path}: {str(e)}") from e
+
+    except StopIteration as e:
+        raise ConfigFileError(f"Config file is empty or is not a valid YAML dict: {path}") from e
 
     except syaml.SpackYAMLError as e:
         raise ConfigFileError(str(e)) from e
 
-    except OSError as e:
-        raise ConfigFileError(f"Error reading configuration file {filename}: {str(e)}") from e
-
 
 def _override(string: str) -> bool:
     """Test if a spack YAML string is an override.

lib/spack/spack/detection/common.py

@@ -45,7 +45,9 @@ def __reduce__(self):
     def restore(
         spec_str: str, prefix: str, extra_attributes: Optional[Dict[str, str]]
     ) -> "DetectedPackage":
-        spec = spack.spec.Spec.from_detection(spec_str=spec_str, extra_attributes=extra_attributes)
+        spec = spack.spec.Spec.from_detection(
+            spec_str=spec_str, external_path=prefix, extra_attributes=extra_attributes
+        )
         return DetectedPackage(spec=spec, prefix=prefix)
 
 
@@ -136,10 +138,10 @@ def path_to_dict(search_paths: List[str]):
     # entry overrides later entries
     for search_path in reversed(search_paths):
         try:
-            for lib in os.listdir(search_path):
-                lib_path = os.path.join(search_path, lib)
-                if llnl.util.filesystem.is_readable_file(lib_path):
-                    path_to_lib[lib_path] = lib
+            with os.scandir(search_path) as entries:
+                path_to_lib.update(
+                    {entry.path: entry.name for entry in entries if entry.is_file()}
+                )
         except OSError as e:
             msg = f"cannot scan '{search_path}' for external software: {str(e)}"
             llnl.util.tty.debug(msg)
@@ -239,7 +241,7 @@ def update_configuration(
         external_entries = pkg_config.get("externals", [])
         assert not isinstance(external_entries, bool), "unexpected value for external entry"
 
-        all_new_specs.extend([spack.spec.Spec(x["spec"]) for x in external_entries])
+        all_new_specs.extend([x.spec for x in new_entries])
         if buildable is False:
             pkg_config["buildable"] = False
         pkg_to_cfg[package_name] = pkg_config

lib/spack/spack/detection/path.py

@@ -12,7 +12,7 @@
 import re
 import sys
 import warnings
-from typing import Dict, List, Optional, Set, Tuple, Type
+from typing import Dict, Iterable, List, Optional, Set, Tuple, Type
 
 import llnl.util.filesystem
 import llnl.util.lang
@@ -62,7 +62,7 @@ def common_windows_package_paths(pkg_cls=None) -> List[str]:
 
 def file_identifier(path):
     s = os.stat(path)
-    return (s.st_dev, s.st_ino)
+    return s.st_dev, s.st_ino
 
 
 def executables_in_path(path_hints: List[str]) -> Dict[str, str]:
@@ -80,6 +80,8 @@ def executables_in_path(path_hints: List[str]) -> Dict[str, str]:
             constructed based on the PATH environment variable.
     """
     search_paths = llnl.util.filesystem.search_paths_for_executables(*path_hints)
+    # Make use we don't doubly list /usr/lib and /lib etc
+    search_paths = list(llnl.util.lang.dedupe(search_paths, key=file_identifier))
     return path_to_dict(search_paths)
 
 
@@ -187,7 +189,7 @@ def libraries_in_windows_paths(path_hints: Optional[List[str]] = None) -> Dict[s
     return path_to_dict(search_paths)
 
 
-def _group_by_prefix(paths: Set[str]) -> Dict[str, Set[str]]:
+def _group_by_prefix(paths: List[str]) -> Dict[str, Set[str]]:
     groups = collections.defaultdict(set)
     for p in paths:
         groups[os.path.dirname(p)].add(p)
@@ -243,7 +245,9 @@ def detect_specs(
             return []
 
         result = []
-        for candidate_path, items_in_prefix in sorted(_group_by_prefix(set(paths)).items()):
+        for candidate_path, items_in_prefix in _group_by_prefix(
+            llnl.util.lang.dedupe(paths)
+        ).items():
             # TODO: multiple instances of a package can live in the same
             # prefix, and a package implementation can return multiple specs
             # for one prefix, but without additional details (e.g. about the
@@ -299,19 +303,17 @@ def detect_specs(
         return result
 
     def find(
-        self, *, pkg_name: str, initial_guess: Optional[List[str]] = None
+        self, *, pkg_name: str, repository, initial_guess: Optional[List[str]] = None
     ) -> List[DetectedPackage]:
         """For a given package, returns a list of detected specs.
 
         Args:
             pkg_name: package being detected
-            initial_guess: initial list of paths to search from the caller
-                           if None, default paths are searched. If this
-                           is an empty list, nothing will be searched.
+            repository: repository to retrieve the package
+            initial_guess: initial list of paths to search from the caller if None, default paths
+                are searched. If this is an empty list, nothing will be searched.
         """
-        import spack.repo
-
-        pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
+        pkg_cls = repository.get_pkg_class(pkg_name)
         patterns = self.search_patterns(pkg=pkg_cls)
         if not patterns:
             return []
@@ -335,13 +337,10 @@ def search_patterns(self, *, pkg: Type["spack.package_base.PackageBase"]) -> Lis
 
     def candidate_files(self, *, patterns: List[str], paths: List[str]) -> List[str]:
         executables_by_path = executables_in_path(path_hints=paths)
-        patterns = [re.compile(x) for x in patterns]
-        result = []
-        for compiled_re in patterns:
-            for path, exe in executables_by_path.items():
-                if compiled_re.search(exe):
-                    result.append(path)
-        return list(sorted(set(result)))
+        joined_pattern = re.compile(r"|".join(patterns))
+        result = [path for path, exe in executables_by_path.items() if joined_pattern.search(exe)]
+        result.sort()
+        return result
 
     def prefix_from_path(self, *, path: str) -> str:
         result = executable_prefix(path)
@@ -385,7 +384,7 @@ def prefix_from_path(self, *, path: str) -> str:
 
 
 def by_path(
-    packages_to_search: List[str],
+    packages_to_search: Iterable[str],
     *,
     path_hints: Optional[List[str]] = None,
     max_workers: Optional[int] = None,
@@ -399,19 +398,28 @@ def by_path(
         path_hints: initial list of paths to be searched
         max_workers: maximum number of workers to search for packages in parallel
     """
+    import spack.repo
+
     # TODO: Packages should be able to define both .libraries and .executables in the future
     # TODO: determine_spec_details should get all relevant libraries and executables in one call
     executables_finder, libraries_finder = ExecutablesFinder(), LibrariesFinder()
     detected_specs_by_package: Dict[str, Tuple[concurrent.futures.Future, ...]] = {}
 
     result = collections.defaultdict(list)
+    repository = spack.repo.PATH.ensure_unwrapped()
     with concurrent.futures.ProcessPoolExecutor(max_workers=max_workers) as executor:
         for pkg in packages_to_search:
             executable_future = executor.submit(
-                executables_finder.find, pkg_name=pkg, initial_guess=path_hints
+                executables_finder.find,
+                pkg_name=pkg,
+                initial_guess=path_hints,
+                repository=repository,
             )
             library_future = executor.submit(
-                libraries_finder.find, pkg_name=pkg, initial_guess=path_hints
+                libraries_finder.find,
+                pkg_name=pkg,
+                initial_guess=path_hints,
+                repository=repository,
             )
             detected_specs_by_package[pkg] = executable_future, library_future
 

lib/spack/spack/detection/test.py

@@ -104,7 +104,9 @@ def _create_executable_scripts(self, mock_executables: MockExecutables) -> List[
     @property
     def expected_specs(self) -> List[spack.spec.Spec]:
         return [
-            spack.spec.Spec.from_detection(item.spec, extra_attributes=item.extra_attributes)
+            spack.spec.Spec.from_detection(
+                item.spec, external_path=self.tmpdir.name, extra_attributes=item.extra_attributes
+            )
             for item in self.test.results
         ]
 

lib/spack/spack/directives.py

@@ -32,10 +32,9 @@ class OpenMpi(Package):
 """
 import collections
 import collections.abc
-import functools
 import os.path
 import re
-from typing import TYPE_CHECKING, Any, Callable, List, Optional, Set, Tuple, Union
+from typing import TYPE_CHECKING, Any, Callable, List, Optional, Tuple, Union
 
 import llnl.util.lang
 import llnl.util.tty.color
@@ -48,6 +47,7 @@ class OpenMpi(Package):
 import spack.util.crypto
 import spack.variant
 from spack.dependency import Dependency
+from spack.directives_meta import DirectiveError, DirectiveMeta
 from spack.fetch_strategy import from_kwargs
 from spack.resource import Resource
 from spack.version import (
@@ -80,22 +80,6 @@ class OpenMpi(Package):
     "redistribute",
 ]
 
-#: These are variant names used by Spack internally; packages can't use them
-reserved_names = [
-    "arch",
-    "architecture",
-    "dev_path",
-    "namespace",
-    "operating_system",
-    "os",
-    "patches",
-    "platform",
-    "target",
-]
-
-#: Names of possible directives. This list is mostly populated using the @directive decorator.
-#: Some directives leverage others and in that case are not automatically added.
-directive_names = ["build_system"]
 
 _patch_order_index = 0
 
@@ -155,219 +139,6 @@ def _make_when_spec(value: WhenType) -> Optional["spack.spec.Spec"]:
     return spack.spec.Spec(value)
 
 
-class DirectiveMeta(type):
-    """Flushes the directives that were temporarily stored in the staging
-    area into the package.
-    """
-
-    # Set of all known directives
-    _directive_dict_names: Set[str] = set()
-    _directives_to_be_executed: List[str] = []
-    _when_constraints_from_context: List[str] = []
-    _default_args: List[dict] = []
-
-    def __new__(cls, name, bases, attr_dict):
-        # Initialize the attribute containing the list of directives
-        # to be executed. Here we go reversed because we want to execute
-        # commands:
-        # 1. in the order they were defined
-        # 2. following the MRO
-        attr_dict["_directives_to_be_executed"] = []
-        for base in reversed(bases):
-            try:
-                directive_from_base = base._directives_to_be_executed
-                attr_dict["_directives_to_be_executed"].extend(directive_from_base)
-            except AttributeError:
-                # The base class didn't have the required attribute.
-                # Continue searching
-                pass
-
-        # De-duplicates directives from base classes
-        attr_dict["_directives_to_be_executed"] = [
-            x for x in llnl.util.lang.dedupe(attr_dict["_directives_to_be_executed"])
-        ]
-
-        # Move things to be executed from module scope (where they
-        # are collected first) to class scope
-        if DirectiveMeta._directives_to_be_executed:
-            attr_dict["_directives_to_be_executed"].extend(
-                DirectiveMeta._directives_to_be_executed
-            )
-            DirectiveMeta._directives_to_be_executed = []
-
-        return super(DirectiveMeta, cls).__new__(cls, name, bases, attr_dict)
-
-    def __init__(cls, name, bases, attr_dict):
-        # The instance is being initialized: if it is a package we must ensure
-        # that the directives are called to set it up.
-
-        if "spack.pkg" in cls.__module__:
-            # Ensure the presence of the dictionaries associated with the directives.
-            # All dictionaries are defaultdicts that create lists for missing keys.
-            for d in DirectiveMeta._directive_dict_names:
-                setattr(cls, d, {})
-
-            # Lazily execute directives
-            for directive in cls._directives_to_be_executed:
-                directive(cls)
-
-            # Ignore any directives executed *within* top-level
-            # directives by clearing out the queue they're appended to
-            DirectiveMeta._directives_to_be_executed = []
-
-        super(DirectiveMeta, cls).__init__(name, bases, attr_dict)
-
-    @staticmethod
-    def push_to_context(when_spec):
-        """Add a spec to the context constraints."""
-        DirectiveMeta._when_constraints_from_context.append(when_spec)
-
-    @staticmethod
-    def pop_from_context():
-        """Pop the last constraint from the context"""
-        return DirectiveMeta._when_constraints_from_context.pop()
-
-    @staticmethod
-    def push_default_args(default_args):
-        """Push default arguments"""
-        DirectiveMeta._default_args.append(default_args)
-
-    @staticmethod
-    def pop_default_args():
-        """Pop default arguments"""
-        return DirectiveMeta._default_args.pop()
-
-    @staticmethod
-    def directive(dicts=None):
-        """Decorator for Spack directives.
-
-        Spack directives allow you to modify a package while it is being
-        defined, e.g. to add version or dependency information.  Directives
-        are one of the key pieces of Spack's package "language", which is
-        embedded in python.
-
-        Here's an example directive:
-
-        .. code-block:: python
-
-            @directive(dicts='versions')
-            version(pkg, ...):
-                ...
-
-        This directive allows you write:
-
-        .. code-block:: python
-
-            class Foo(Package):
-                version(...)
-
-        The ``@directive`` decorator handles a couple things for you:
-
-          1. Adds the class scope (pkg) as an initial parameter when
-             called, like a class method would.  This allows you to modify
-             a package from within a directive, while the package is still
-             being defined.
-
-          2. It automatically adds a dictionary called "versions" to the
-             package so that you can refer to pkg.versions.
-
-        The ``(dicts='versions')`` part ensures that ALL packages in Spack
-        will have a ``versions`` attribute after they're constructed, and
-        that if no directive actually modified it, it will just be an
-        empty dict.
-
-        This is just a modular way to add storage attributes to the
-        Package class, and it's how Spack gets information from the
-        packages to the core.
-        """
-        global directive_names
-
-        if isinstance(dicts, str):
-            dicts = (dicts,)
-
-        if not isinstance(dicts, collections.abc.Sequence):
-            message = "dicts arg must be list, tuple, or string. Found {0}"
-            raise TypeError(message.format(type(dicts)))
-
-        # Add the dictionary names if not already there
-        DirectiveMeta._directive_dict_names |= set(dicts)
-
-        # This decorator just returns the directive functions
-        def _decorator(decorated_function):
-            directive_names.append(decorated_function.__name__)
-
-            @functools.wraps(decorated_function)
-            def _wrapper(*args, **_kwargs):
-                # First merge default args with kwargs
-                kwargs = dict()
-                for default_args in DirectiveMeta._default_args:
-                    kwargs.update(default_args)
-                kwargs.update(_kwargs)
-
-                # Inject when arguments from the context
-                if DirectiveMeta._when_constraints_from_context:
-                    # Check that directives not yet supporting the when= argument
-                    # are not used inside the context manager
-                    if decorated_function.__name__ == "version":
-                        msg = (
-                            'directive "{0}" cannot be used within a "when"'
-                            ' context since it does not support a "when=" '
-                            "argument"
-                        )
-                        msg = msg.format(decorated_function.__name__)
-                        raise DirectiveError(msg)
-
-                    when_constraints = [
-                        spack.spec.Spec(x) for x in DirectiveMeta._when_constraints_from_context
-                    ]
-                    if kwargs.get("when"):
-                        when_constraints.append(spack.spec.Spec(kwargs["when"]))
-                    when_spec = spack.spec.merge_abstract_anonymous_specs(*when_constraints)
-
-                    kwargs["when"] = when_spec
-
-                # If any of the arguments are executors returned by a
-                # directive passed as an argument, don't execute them
-                # lazily. Instead, let the called directive handle them.
-                # This allows nested directive calls in packages.  The
-                # caller can return the directive if it should be queued.
-                def remove_directives(arg):
-                    directives = DirectiveMeta._directives_to_be_executed
-                    if isinstance(arg, (list, tuple)):
-                        # Descend into args that are lists or tuples
-                        for a in arg:
-                            remove_directives(a)
-                    else:
-                        # Remove directives args from the exec queue
-                        remove = next((d for d in directives if d is arg), None)
-                        if remove is not None:
-                            directives.remove(remove)
-
-                # Nasty, but it's the best way I can think of to avoid
-                # side effects if directive results are passed as args
-                remove_directives(args)
-                remove_directives(list(kwargs.values()))
-
-                # A directive returns either something that is callable on a
-                # package or a sequence of them
-                result = decorated_function(*args, **kwargs)
-
-                # ...so if it is not a sequence make it so
-                values = result
-                if not isinstance(values, collections.abc.Sequence):
-                    values = (values,)
-
-                DirectiveMeta._directives_to_be_executed.extend(values)
-
-                # wrapped function returns same result as original so
-                # that we can nest directives
-                return result
-
-            return _wrapper
-
-        return _decorator
-
-
 SubmoduleCallback = Callable[["spack.package_base.PackageBase"], Union[str, List[str], bool]]
 directive = DirectiveMeta.directive
 
@@ -846,7 +617,7 @@ def format_error(msg, pkg):
         msg += " @*r{{[{0}, variant '{1}']}}"
         return llnl.util.tty.color.colorize(msg.format(pkg.name, name))
 
-    if name in reserved_names:
+    if name in spack.variant.reserved_names:
 
         def _raise_reserved_name(pkg):
             msg = "The name '%s' is reserved by Spack" % name
@@ -1110,10 +881,6 @@ def _execute_languages(pkg: "spack.package_base.PackageBase"):
     return _execute_languages
 
 
-class DirectiveError(spack.error.SpackError):
-    """This is raised when something is wrong with a package directive."""
-
-
 class DependencyError(DirectiveError):
     """This is raised when a dependency specification is invalid."""
 

lib/spack/spack/directives_meta.py

@@ -0,0 +1,234 @@
+# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+import collections.abc
+import functools
+from typing import List, Set
+
+import llnl.util.lang
+
+import spack.error
+import spack.spec
+
+#: Names of possible directives. This list is mostly populated using the @directive decorator.
+#: Some directives leverage others and in that case are not automatically added.
+directive_names = ["build_system"]
+
+
+class DirectiveMeta(type):
+    """Flushes the directives that were temporarily stored in the staging
+    area into the package.
+    """
+
+    # Set of all known directives
+    _directive_dict_names: Set[str] = set()
+    _directives_to_be_executed: List[str] = []
+    _when_constraints_from_context: List[str] = []
+    _default_args: List[dict] = []
+
+    def __new__(cls, name, bases, attr_dict):
+        # Initialize the attribute containing the list of directives
+        # to be executed. Here we go reversed because we want to execute
+        # commands:
+        # 1. in the order they were defined
+        # 2. following the MRO
+        attr_dict["_directives_to_be_executed"] = []
+        for base in reversed(bases):
+            try:
+                directive_from_base = base._directives_to_be_executed
+                attr_dict["_directives_to_be_executed"].extend(directive_from_base)
+            except AttributeError:
+                # The base class didn't have the required attribute.
+                # Continue searching
+                pass
+
+        # De-duplicates directives from base classes
+        attr_dict["_directives_to_be_executed"] = [
+            x for x in llnl.util.lang.dedupe(attr_dict["_directives_to_be_executed"])
+        ]
+
+        # Move things to be executed from module scope (where they
+        # are collected first) to class scope
+        if DirectiveMeta._directives_to_be_executed:
+            attr_dict["_directives_to_be_executed"].extend(
+                DirectiveMeta._directives_to_be_executed
+            )
+            DirectiveMeta._directives_to_be_executed = []
+
+        return super(DirectiveMeta, cls).__new__(cls, name, bases, attr_dict)
+
+    def __init__(cls, name, bases, attr_dict):
+        # The instance is being initialized: if it is a package we must ensure
+        # that the directives are called to set it up.
+
+        if "spack.pkg" in cls.__module__:
+            # Ensure the presence of the dictionaries associated with the directives.
+            # All dictionaries are defaultdicts that create lists for missing keys.
+            for d in DirectiveMeta._directive_dict_names:
+                setattr(cls, d, {})
+
+            # Lazily execute directives
+            for directive in cls._directives_to_be_executed:
+                directive(cls)
+
+            # Ignore any directives executed *within* top-level
+            # directives by clearing out the queue they're appended to
+            DirectiveMeta._directives_to_be_executed = []
+
+        super(DirectiveMeta, cls).__init__(name, bases, attr_dict)
+
+    @staticmethod
+    def push_to_context(when_spec):
+        """Add a spec to the context constraints."""
+        DirectiveMeta._when_constraints_from_context.append(when_spec)
+
+    @staticmethod
+    def pop_from_context():
+        """Pop the last constraint from the context"""
+        return DirectiveMeta._when_constraints_from_context.pop()
+
+    @staticmethod
+    def push_default_args(default_args):
+        """Push default arguments"""
+        DirectiveMeta._default_args.append(default_args)
+
+    @staticmethod
+    def pop_default_args():
+        """Pop default arguments"""
+        return DirectiveMeta._default_args.pop()
+
+    @staticmethod
+    def directive(dicts=None):
+        """Decorator for Spack directives.
+
+        Spack directives allow you to modify a package while it is being
+        defined, e.g. to add version or dependency information.  Directives
+        are one of the key pieces of Spack's package "language", which is
+        embedded in python.
+
+        Here's an example directive:
+
+        .. code-block:: python
+
+            @directive(dicts='versions')
+            version(pkg, ...):
+                ...
+
+        This directive allows you write:
+
+        .. code-block:: python
+
+            class Foo(Package):
+                version(...)
+
+        The ``@directive`` decorator handles a couple things for you:
+
+          1. Adds the class scope (pkg) as an initial parameter when
+             called, like a class method would.  This allows you to modify
+             a package from within a directive, while the package is still
+             being defined.
+
+          2. It automatically adds a dictionary called "versions" to the
+             package so that you can refer to pkg.versions.
+
+        The ``(dicts='versions')`` part ensures that ALL packages in Spack
+        will have a ``versions`` attribute after they're constructed, and
+        that if no directive actually modified it, it will just be an
+        empty dict.
+
+        This is just a modular way to add storage attributes to the
+        Package class, and it's how Spack gets information from the
+        packages to the core.
+        """
+        global directive_names
+
+        if isinstance(dicts, str):
+            dicts = (dicts,)
+
+        if not isinstance(dicts, collections.abc.Sequence):
+            message = "dicts arg must be list, tuple, or string. Found {0}"
+            raise TypeError(message.format(type(dicts)))
+
+        # Add the dictionary names if not already there
+        DirectiveMeta._directive_dict_names |= set(dicts)
+
+        # This decorator just returns the directive functions
+        def _decorator(decorated_function):
+            directive_names.append(decorated_function.__name__)
+
+            @functools.wraps(decorated_function)
+            def _wrapper(*args, **_kwargs):
+                # First merge default args with kwargs
+                kwargs = dict()
+                for default_args in DirectiveMeta._default_args:
+                    kwargs.update(default_args)
+                kwargs.update(_kwargs)
+
+                # Inject when arguments from the context
+                if DirectiveMeta._when_constraints_from_context:
+                    # Check that directives not yet supporting the when= argument
+                    # are not used inside the context manager
+                    if decorated_function.__name__ == "version":
+                        msg = (
+                            'directive "{0}" cannot be used within a "when"'
+                            ' context since it does not support a "when=" '
+                            "argument"
+                        )
+                        msg = msg.format(decorated_function.__name__)
+                        raise DirectiveError(msg)
+
+                    when_constraints = [
+                        spack.spec.Spec(x) for x in DirectiveMeta._when_constraints_from_context
+                    ]
+                    if kwargs.get("when"):
+                        when_constraints.append(spack.spec.Spec(kwargs["when"]))
+                    when_spec = spack.spec.merge_abstract_anonymous_specs(*when_constraints)
+
+                    kwargs["when"] = when_spec
+
+                # If any of the arguments are executors returned by a
+                # directive passed as an argument, don't execute them
+                # lazily. Instead, let the called directive handle them.
+                # This allows nested directive calls in packages.  The
+                # caller can return the directive if it should be queued.
+                def remove_directives(arg):
+                    directives = DirectiveMeta._directives_to_be_executed
+                    if isinstance(arg, (list, tuple)):
+                        # Descend into args that are lists or tuples
+                        for a in arg:
+                            remove_directives(a)
+                    else:
+                        # Remove directives args from the exec queue
+                        remove = next((d for d in directives if d is arg), None)
+                        if remove is not None:
+                            directives.remove(remove)
+
+                # Nasty, but it's the best way I can think of to avoid
+                # side effects if directive results are passed as args
+                remove_directives(args)
+                remove_directives(list(kwargs.values()))
+
+                # A directive returns either something that is callable on a
+                # package or a sequence of them
+                result = decorated_function(*args, **kwargs)
+
+                # ...so if it is not a sequence make it so
+                values = result
+                if not isinstance(values, collections.abc.Sequence):
+                    values = (values,)
+
+                DirectiveMeta._directives_to_be_executed.extend(values)
+
+                # wrapped function returns same result as original so
+                # that we can nest directives
+                return result
+
+            return _wrapper
+
+        return _decorator
+
+
+class DirectiveError(spack.error.SpackError):
+    """This is raised when something is wrong with a package directive."""

lib/spack/spack/environment/environment.py

@@ -1214,7 +1214,6 @@ def scope_name(self):
     def include_concrete_envs(self):
         """Copy and save the included envs' specs internally"""
 
-        lockfile_meta = None
         root_hash_seen = set()
         concrete_hash_seen = set()
         self.included_concrete_spec_data = {}
@@ -1225,37 +1224,26 @@ def include_concrete_envs(self):
                 raise SpackEnvironmentError(f"Unable to find env at {env_path}")
 
             env = Environment(env_path)
-
-            with open(env.lock_path) as f:
-                lockfile_as_dict = env._read_lockfile(f)
-
-            # Lockfile_meta must match each env and use at least format version 5
-            if lockfile_meta is None:
-                lockfile_meta = lockfile_as_dict["_meta"]
-            elif lockfile_meta != lockfile_as_dict["_meta"]:
-                raise SpackEnvironmentError("All lockfile _meta values must match")
-            elif lockfile_meta["lockfile-version"] < 5:
-                raise SpackEnvironmentError("The lockfile format must be at version 5 or higher")
+            self.included_concrete_spec_data[env_path] = {"roots": [], "concrete_specs": {}}
 
             # Copy unique root specs from env
-            self.included_concrete_spec_data[env_path] = {"roots": []}
-            for root_dict in lockfile_as_dict["roots"]:
+            for root_dict in env._concrete_roots_dict():
                 if root_dict["hash"] not in root_hash_seen:
                     self.included_concrete_spec_data[env_path]["roots"].append(root_dict)
                     root_hash_seen.add(root_dict["hash"])
 
             # Copy unique concrete specs from env
-            for concrete_spec in lockfile_as_dict["concrete_specs"]:
-                if concrete_spec not in concrete_hash_seen:
-                    self.included_concrete_spec_data[env_path].update(
-                        {"concrete_specs": lockfile_as_dict["concrete_specs"]}
+            for dag_hash, spec_details in env._concrete_specs_dict().items():
+                if dag_hash not in concrete_hash_seen:
+                    self.included_concrete_spec_data[env_path]["concrete_specs"].update(
+                        {dag_hash: spec_details}
                     )
-                    concrete_hash_seen.add(concrete_spec)
+                    concrete_hash_seen.add(dag_hash)
 
-            if "include_concrete" in lockfile_as_dict.keys():
-                self.included_concrete_spec_data[env_path]["include_concrete"] = lockfile_as_dict[
-                    "include_concrete"
-                ]
+            # Copy transitive include data
+            transitive = env.included_concrete_spec_data
+            if transitive:
+                self.included_concrete_spec_data[env_path]["include_concrete"] = transitive
 
         self._read_lockfile_dict(self._to_lockfile_dict())
         self.write()
@@ -1644,9 +1632,8 @@ def _concretize_separately(self, tests=False):
                 i += 1
 
         # Ensure we don't try to bootstrap clingo in parallel
-        if spack.config.get("config:concretizer", "clingo") == "clingo":
-            with spack.bootstrap.ensure_bootstrap_configuration():
-                spack.bootstrap.ensure_clingo_importable_or_raise()
+        with spack.bootstrap.ensure_bootstrap_configuration():
+            spack.bootstrap.ensure_clingo_importable_or_raise()
 
         # Ensure all the indexes have been built or updated, since
         # otherwise the processes in the pool may timeout on waiting
@@ -1657,7 +1644,7 @@ def _concretize_separately(self, tests=False):
 
         # Ensure we have compilers in compilers.yaml to avoid that
         # processes try to write the config file in parallel
-        _ = spack.compilers.get_compiler_config(spack.config.CONFIG, init_config=True)
+        _ = spack.compilers.all_compilers_config(spack.config.CONFIG)
 
         # Early return if there is nothing to do
         if len(args) == 0:
@@ -2174,16 +2161,23 @@ def _get_environment_specs(self, recurse_dependencies=True):
 
         return specs
 
-    def _to_lockfile_dict(self):
-        """Create a dictionary to store a lockfile for this environment."""
+    def _concrete_specs_dict(self):
         concrete_specs = {}
         for s in traverse.traverse_nodes(self.specs_by_hash.values(), key=traverse.by_dag_hash):
             spec_dict = s.node_dict_with_hashes(hash=ht.dag_hash)
             # Assumes no legacy formats, since this was just created.
             spec_dict[ht.dag_hash.name] = s.dag_hash()
             concrete_specs[s.dag_hash()] = spec_dict
+        return concrete_specs
 
+    def _concrete_roots_dict(self):
         hash_spec_list = zip(self.concretized_order, self.concretized_user_specs)
+        return [{"hash": h, "spec": str(s)} for h, s in hash_spec_list]
+
+    def _to_lockfile_dict(self):
+        """Create a dictionary to store a lockfile for this environment."""
+        concrete_specs = self._concrete_specs_dict()
+        root_specs = self._concrete_roots_dict()
 
         spack_dict = {"version": spack.spack_version}
         spack_commit = spack.main.get_spack_commit()
@@ -2204,7 +2198,7 @@ def _to_lockfile_dict(self):
             # spack version information
             "spack": spack_dict,
             # users specs + hashes are the 'roots' of the environment
-            "roots": [{"hash": h, "spec": str(s)} for h, s in hash_spec_list],
+            "roots": root_specs,
             # Concrete specs by hash, including dependencies
             "concrete_specs": concrete_specs,
         }

lib/spack/spack/fetch_strategy.py

@@ -30,6 +30,7 @@
 import shutil
 import urllib.error
 import urllib.parse
+import urllib.request
 from pathlib import PurePath
 from typing import List, Optional
 
@@ -53,7 +54,7 @@
 import spack.version
 import spack.version.git_ref_lookup
 from spack.util.compression import decompressor_for
-from spack.util.executable import CommandNotFoundError, which
+from spack.util.executable import CommandNotFoundError, Executable, which
 
 #: List of all fetch strategies, created by FetchStrategy metaclass.
 all_strategies = []
@@ -245,38 +246,30 @@ class URLFetchStrategy(FetchStrategy):
 
     # these are checksum types. The generic 'checksum' is deprecated for
     # specific hash names, but we need it for backward compatibility
-    optional_attrs = list(crypto.hashes.keys()) + ["checksum"]
+    optional_attrs = [*crypto.hashes.keys(), "checksum"]
 
-    def __init__(self, url=None, checksum=None, **kwargs):
+    def __init__(self, *, url: str, checksum: Optional[str] = None, **kwargs) -> None:
         super().__init__(**kwargs)
 
-        # Prefer values in kwargs to the positionals.
-        self.url = kwargs.get("url", url)
+        self.url = url
         self.mirrors = kwargs.get("mirrors", [])
 
         # digest can be set as the first argument, or from an explicit
         # kwarg by the hash name.
-        self.digest = kwargs.get("checksum", checksum)
+        self.digest: Optional[str] = checksum
         for h in self.optional_attrs:
             if h in kwargs:
                 self.digest = kwargs[h]
 
-        self.expand_archive = kwargs.get("expand", True)
-        self.extra_options = kwargs.get("fetch_options", {})
-        self._curl = None
-
-        self.extension = kwargs.get("extension", None)
-
-        if not self.url:
-            raise ValueError("URLFetchStrategy requires a url for fetching.")
+        self.expand_archive: bool = kwargs.get("expand", True)
+        self.extra_options: dict = kwargs.get("fetch_options", {})
+        self._curl: Optional[Executable] = None
+        self.extension: Optional[str] = kwargs.get("extension", None)
 
     @property
-    def curl(self):
+    def curl(self) -> Executable:
         if not self._curl:
-            try:
-                self._curl = which("curl", required=True)
-            except CommandNotFoundError as exc:
-                tty.error(str(exc))
+            self._curl = web_util.require_curl()
         return self._curl
 
     def source_id(self):
@@ -297,27 +290,23 @@ def candidate_urls(self):
     @_needs_stage
     def fetch(self):
         if self.archive_file:
-            tty.debug("Already downloaded {0}".format(self.archive_file))
+            tty.debug(f"Already downloaded {self.archive_file}")
             return
 
-        url = None
-        errors = []
+        errors: List[Exception] = []
         for url in self.candidate_urls:
-            if not web_util.url_exists(url):
-                tty.debug("URL does not exist: " + url)
-                continue
-
             try:
                 self._fetch_from_url(url)
                 break
             except FailedDownloadError as e:
-                errors.append(str(e))
-
-        for msg in errors:
-            tty.debug(msg)
+                errors.extend(e.exceptions)
+        else:
+            raise FailedDownloadError(*errors)
 
         if not self.archive_file:
-            raise FailedDownloadError(url)
+            raise FailedDownloadError(
+                RuntimeError(f"Missing archive {self.archive_file} after fetching")
+            )
 
     def _fetch_from_url(self, url):
         if spack.config.get("config:url_fetch_method") == "curl":
@@ -336,27 +325,28 @@ def _check_headers(self, headers):
     @_needs_stage
     def _fetch_urllib(self, url):
         save_file = self.stage.save_filename
-        tty.msg("Fetching {0}".format(url))
 
-        # Run urllib but grab the mime type from the http headers
+        request = urllib.request.Request(url, headers={"User-Agent": web_util.SPACK_USER_AGENT})
+
         try:
-            url, headers, response = web_util.read_from_url(url)
-        except web_util.SpackWebError as e:
+            response = web_util.urlopen(request)
+        except (TimeoutError, urllib.error.URLError) as e:
             # clean up archive on failure.
             if self.archive_file:
                 os.remove(self.archive_file)
             if os.path.lexists(save_file):
                 os.remove(save_file)
-            msg = "urllib failed to fetch with error {0}".format(e)
-            raise FailedDownloadError(url, msg)
+            raise FailedDownloadError(e) from e
+
+        tty.msg(f"Fetching {url}")
 
         if os.path.lexists(save_file):
             os.remove(save_file)
 
-        with open(save_file, "wb") as _open_file:
-            shutil.copyfileobj(response, _open_file)
+        with open(save_file, "wb") as f:
+            shutil.copyfileobj(response, f)
 
-        self._check_headers(str(headers))
+        self._check_headers(str(response.headers))
 
     @_needs_stage
     def _fetch_curl(self, url):
@@ -365,7 +355,7 @@ def _fetch_curl(self, url):
         if self.stage.save_filename:
             save_file = self.stage.save_filename
             partial_file = self.stage.save_filename + ".part"
-        tty.msg("Fetching {0}".format(url))
+        tty.msg(f"Fetching {url}")
         if partial_file:
             save_args = [
                 "-C",
@@ -405,8 +395,8 @@ def _fetch_curl(self, url):
 
             try:
                 web_util.check_curl_code(curl.returncode)
-            except spack.error.FetchError as err:
-                raise spack.fetch_strategy.FailedDownloadError(url, str(err))
+            except spack.error.FetchError as e:
+                raise FailedDownloadError(e) from e
 
         self._check_headers(headers)
 
@@ -473,7 +463,7 @@ def check(self):
         """Check the downloaded archive against a checksum digest.
         No-op if this stage checks code out of a repository."""
         if not self.digest:
-            raise NoDigestError("Attempt to check URLFetchStrategy with no digest.")
+            raise NoDigestError(f"Attempt to check {self.__class__.__name__} with no digest.")
 
         verify_checksum(self.archive_file, self.digest)
 
@@ -484,8 +474,8 @@ def reset(self):
         """
         if not self.archive_file:
             raise NoArchiveFileError(
-                "Tried to reset URLFetchStrategy before fetching",
-                "Failed on reset() for URL %s" % self.url,
+                f"Tried to reset {self.__class__.__name__} before fetching",
+                f"Failed on reset() for URL{self.url}",
             )
 
         # Remove everything but the archive from the stage
@@ -498,14 +488,10 @@ def reset(self):
         self.expand()
 
     def __repr__(self):
-        url = self.url if self.url else "no url"
-        return "%s<%s>" % (self.__class__.__name__, url)
+        return f"{self.__class__.__name__}<{self.url}>"
 
     def __str__(self):
-        if self.url:
-            return self.url
-        else:
-            return "[no url]"
+        return self.url
 
 
 @fetcher
@@ -518,7 +504,7 @@ def fetch(self):
 
         # check whether the cache file exists.
         if not os.path.isfile(path):
-            raise NoCacheError("No cache of %s" % path)
+            raise NoCacheError(f"No cache of {path}")
 
         # remove old symlink if one is there.
         filename = self.stage.save_filename
@@ -528,8 +514,8 @@ def fetch(self):
         # Symlink to local cached archive.
         symlink(path, filename)
 
-        # Remove link if checksum fails, or subsequent fetchers
-        # will assume they don't need to download.
+        # Remove link if checksum fails, or subsequent fetchers will assume they don't need to
+        # download.
         if self.digest:
             try:
                 self.check()
@@ -538,12 +524,12 @@ def fetch(self):
                 raise
 
         # Notify the user how we fetched.
-        tty.msg("Using cached archive: {0}".format(path))
+        tty.msg(f"Using cached archive: {path}")
 
 
 class OCIRegistryFetchStrategy(URLFetchStrategy):
-    def __init__(self, url=None, checksum=None, **kwargs):
-        super().__init__(url, checksum, **kwargs)
+    def __init__(self, *, url: str, checksum: Optional[str] = None, **kwargs):
+        super().__init__(url=url, checksum=checksum, **kwargs)
 
         self._urlopen = kwargs.get("_urlopen", spack.oci.opener.urlopen)
 
@@ -554,13 +540,13 @@ def fetch(self):
 
         try:
             response = self._urlopen(self.url)
-        except urllib.error.URLError as e:
+        except (TimeoutError, urllib.error.URLError) as e:
             # clean up archive on failure.
             if self.archive_file:
                 os.remove(self.archive_file)
             if os.path.lexists(file):
                 os.remove(file)
-            raise FailedDownloadError(self.url, f"Failed to fetch {self.url}: {e}") from e
+            raise FailedDownloadError(e) from e
 
         if os.path.lexists(file):
             os.remove(file)
@@ -588,18 +574,18 @@ def __init__(self, **kwargs):
         # Set a URL based on the type of fetch strategy.
         self.url = kwargs.get(self.url_attr, None)
         if not self.url:
-            raise ValueError("%s requires %s argument." % (self.__class__, self.url_attr))
+            raise ValueError(f"{self.__class__} requires {self.url_attr} argument.")
 
         for attr in self.optional_attrs:
             setattr(self, attr, kwargs.get(attr, None))
 
     @_needs_stage
     def check(self):
-        tty.debug("No checksum needed when fetching with {0}".format(self.url_attr))
+        tty.debug(f"No checksum needed when fetching with {self.url_attr}")
 
     @_needs_stage
     def expand(self):
-        tty.debug("Source fetched with %s is already expanded." % self.url_attr)
+        tty.debug(f"Source fetched with {self.url_attr} is already expanded.")
 
     @_needs_stage
     def archive(self, destination, *, exclude: Optional[str] = None):
@@ -619,10 +605,10 @@ def archive(self, destination, *, exclude: Optional[str] = None):
             )
 
     def __str__(self):
-        return "VCS: %s" % self.url
+        return f"VCS: {self.url}"
 
     def __repr__(self):
-        return "%s<%s>" % (self.__class__, self.url)
+        return f"{self.__class__}<{self.url}>"
 
 
 @fetcher
@@ -725,11 +711,17 @@ class GitFetchStrategy(VCSFetchStrategy):
         "submodules",
         "get_full_repo",
         "submodules_delete",
+        "git_sparse_paths",
     ]
 
     git_version_re = r"git version (\S+)"
 
     def __init__(self, **kwargs):
+
+        self.commit: Optional[str] = None
+        self.tag: Optional[str] = None
+        self.branch: Optional[str] = None
+
         # Discards the keywords in kwargs that may conflict with the next call
         # to __init__
         forwarded_args = copy.copy(kwargs)
@@ -740,6 +732,7 @@ def __init__(self, **kwargs):
         self.submodules = kwargs.get("submodules", False)
         self.submodules_delete = kwargs.get("submodules_delete", False)
         self.get_full_repo = kwargs.get("get_full_repo", False)
+        self.git_sparse_paths = kwargs.get("git_sparse_paths", None)
 
     @property
     def git_version(self):
@@ -777,68 +770,71 @@ def git(self):
 
     @property
     def cachable(self):
-        return self.cache_enabled and bool(self.commit or self.tag)
+        return self.cache_enabled and bool(self.commit)
 
     def source_id(self):
-        return self.commit or self.tag
+        # TODO: tree-hash would secure download cache and mirrors, commit only secures checkouts.
+        return self.commit
 
     def mirror_id(self):
-        repo_ref = self.commit or self.tag or self.branch
-        if repo_ref:
+        if self.commit:
             repo_path = urllib.parse.urlparse(self.url).path
-            result = os.path.sep.join(["git", repo_path, repo_ref])
+            result = os.path.sep.join(["git", repo_path, self.commit])
             return result
 
     def _repo_info(self):
         args = ""
-
         if self.commit:
-            args = " at commit {0}".format(self.commit)
+            args = f" at commit {self.commit}"
         elif self.tag:
-            args = " at tag {0}".format(self.tag)
+            args = f" at tag {self.tag}"
         elif self.branch:
-            args = " on branch {0}".format(self.branch)
+            args = f" on branch {self.branch}"
 
-        return "{0}{1}".format(self.url, args)
+        return f"{self.url}{args}"
 
     @_needs_stage
     def fetch(self):
         if self.stage.expanded:
-            tty.debug("Already fetched {0}".format(self.stage.source_path))
+            tty.debug(f"Already fetched {self.stage.source_path}")
             return
 
-        self.clone(commit=self.commit, branch=self.branch, tag=self.tag)
+        if self.git_sparse_paths:
+            self._sparse_clone_src()
+        else:
+            self._clone_src()
+        self.submodule_operations()
 
-    def clone(self, dest=None, commit=None, branch=None, tag=None, bare=False):
+    def bare_clone(self, dest: str) -> None:
         """
-        Clone a repository to a path.
+        Execute a bare clone for metadata only
 
-        This method handles cloning from git, but does not require a stage.
-
-        Arguments:
-            dest (str or None): The path into which the code is cloned. If None,
-                requires a stage and uses the stage's source path.
-            commit (str or None): A commit to fetch from the remote. Only one of
-                commit, branch, and tag may be non-None.
-            branch (str or None): A branch to fetch from the remote.
-            tag (str or None): A tag to fetch from the remote.
-            bare (bool): Execute a "bare" git clone (--bare option to git)
+        Requires a destination since bare cloning does not provide source
+        and shouldn't be used for staging.
         """
         # Default to spack source path
-        dest = dest or self.stage.source_path
-        tty.debug("Cloning git repository: {0}".format(self._repo_info()))
+        tty.debug(f"Cloning git repository: {self._repo_info()}")
 
         git = self.git
         debug = spack.config.get("config:debug")
 
-        if bare:
-            # We don't need to worry about which commit/branch/tag is checked out
-            clone_args = ["clone", "--bare"]
-            if not debug:
-                clone_args.append("--quiet")
-            clone_args.extend([self.url, dest])
-            git(*clone_args)
-        elif commit:
+        # We don't need to worry about which commit/branch/tag is checked out
+        clone_args = ["clone", "--bare"]
+        if not debug:
+            clone_args.append("--quiet")
+        clone_args.extend([self.url, dest])
+        git(*clone_args)
+
+    def _clone_src(self) -> None:
+        """Clone a repository to a path using git."""
+        # Default to spack source path
+        dest = self.stage.source_path
+        tty.debug(f"Cloning git repository: {self._repo_info()}")
+
+        git = self.git
+        debug = spack.config.get("config:debug")
+
+        if self.commit:
             # Need to do a regular clone and check out everything if
             # they asked for a particular commit.
             clone_args = ["clone", self.url]
@@ -857,7 +853,7 @@ def clone(self, dest=None, commit=None, branch=None, tag=None, bare=False):
                 )
 
             with working_dir(dest):
-                checkout_args = ["checkout", commit]
+                checkout_args = ["checkout", self.commit]
                 if not debug:
                     checkout_args.insert(1, "--quiet")
                 git(*checkout_args)
@@ -869,10 +865,10 @@ def clone(self, dest=None, commit=None, branch=None, tag=None, bare=False):
                 args.append("--quiet")
 
             # If we want a particular branch ask for it.
-            if branch:
-                args.extend(["--branch", branch])
-            elif tag and self.git_version >= spack.version.Version("1.8.5.2"):
-                args.extend(["--branch", tag])
+            if self.branch:
+                args.extend(["--branch", self.branch])
+            elif self.tag and self.git_version >= spack.version.Version("1.8.5.2"):
+                args.extend(["--branch", self.tag])
 
             # Try to be efficient if we're using a new enough git.
             # This checks out only one branch's history
@@ -904,7 +900,7 @@ def clone(self, dest=None, commit=None, branch=None, tag=None, bare=False):
                 # For tags, be conservative and check them out AFTER
                 # cloning.  Later git versions can do this with clone
                 # --branch, but older ones fail.
-                if tag and self.git_version < spack.version.Version("1.8.5.2"):
+                if self.tag and self.git_version < spack.version.Version("1.8.5.2"):
                     # pull --tags returns a "special" error code of 1 in
                     # older versions that we have to ignore.
                     # see: https://github.com/git/git/commit/19d122b
@@ -917,6 +913,79 @@ def clone(self, dest=None, commit=None, branch=None, tag=None, bare=False):
                     git(*pull_args, ignore_errors=1)
                     git(*co_args)
 
+    def _sparse_clone_src(self, **kwargs):
+        """Use git's sparse checkout feature to clone portions of a git repository"""
+        dest = self.stage.source_path
+        git = self.git
+
+        if self.git_version < spack.version.Version("2.26.0"):
+            # technically this should be supported for 2.25, but bumping for OS issues
+            # see https://github.com/spack/spack/issues/45771
+            # code paths exist where the package is not set.  Assure some indentifier for the
+            # package that was configured  for sparse checkout exists in the error message
+            identifier = str(self.url)
+            if self.package:
+                identifier += f" ({self.package.name})"
+            tty.warn(
+                (
+                    f"{identifier} is configured for git sparse-checkout "
+                    "but the git version is too old to support sparse cloning. "
+                    "Cloning the full repository instead."
+                )
+            )
+            self._clone_src()
+        else:
+            # default to depth=2 to allow for retention of some git properties
+            depth = kwargs.get("depth", 2)
+            needs_fetch = self.branch or self.tag
+            git_ref = self.branch or self.tag or self.commit
+
+            assert git_ref
+
+            clone_args = ["clone"]
+
+            if needs_fetch:
+                clone_args.extend(["--branch", git_ref])
+
+            if self.get_full_repo:
+                clone_args.append("--no-single-branch")
+            else:
+                clone_args.append("--single-branch")
+
+            clone_args.extend(
+                [f"--depth={depth}", "--no-checkout", "--filter=blob:none", self.url]
+            )
+
+            sparse_args = ["sparse-checkout", "set"]
+
+            if callable(self.git_sparse_paths):
+                sparse_args.extend(self.git_sparse_paths())
+            else:
+                sparse_args.extend([p for p in self.git_sparse_paths])
+
+            sparse_args.append("--cone")
+
+            checkout_args = ["checkout", git_ref]
+
+            if not spack.config.get("config:debug"):
+                clone_args.insert(1, "--quiet")
+                checkout_args.insert(1, "--quiet")
+
+            with temp_cwd():
+                git(*clone_args)
+                repo_name = get_single_file(".")
+                if self.stage:
+                    self.stage.srcdir = repo_name
+                shutil.move(repo_name, dest)
+
+            with working_dir(dest):
+                git(*sparse_args)
+                git(*checkout_args)
+
+    def submodule_operations(self):
+        dest = self.stage.source_path
+        git = self.git
+
         if self.submodules_delete:
             with working_dir(dest):
                 for submodule_to_delete in self.submodules_delete:
@@ -969,7 +1038,7 @@ def protocol_supports_shallow_clone(self):
         return not (self.url.startswith("http://") or self.url.startswith("/"))
 
     def __str__(self):
-        return "[git] {0}".format(self._repo_info())
+        return f"[git] {self._repo_info()}"
 
 
 @fetcher
@@ -1293,7 +1362,7 @@ def reset(self):
             shutil.move(scrubbed, source_path)
 
     def __str__(self):
-        return "[hg] %s" % self.url
+        return f"[hg] {self.url}"
 
 
 @fetcher
@@ -1302,45 +1371,20 @@ class S3FetchStrategy(URLFetchStrategy):
 
     url_attr = "s3"
 
-    def __init__(self, *args, **kwargs):
-        try:
-            super().__init__(*args, **kwargs)
-        except ValueError:
-            if not kwargs.get("url"):
-                raise ValueError("S3FetchStrategy requires a url for fetching.")
-
     @_needs_stage
     def fetch(self):
-        if self.archive_file:
-            tty.debug("Already downloaded {0}".format(self.archive_file))
-            return
-
-        parsed_url = urllib.parse.urlparse(self.url)
-        if parsed_url.scheme != "s3":
-            raise spack.error.FetchError("S3FetchStrategy can only fetch from s3:// urls.")
-
-        tty.debug("Fetching {0}".format(self.url))
-
-        basename = os.path.basename(parsed_url.path)
-
-        with working_dir(self.stage.path):
-            _, headers, stream = web_util.read_from_url(self.url)
-
-            with open(basename, "wb") as f:
-                shutil.copyfileobj(stream, f)
-
-            content_type = web_util.get_header(headers, "Content-type")
-
-        if content_type == "text/html":
-            warn_content_type_mismatch(self.archive_file or "the archive")
-
-        if self.stage.save_filename:
-            llnl.util.filesystem.rename(
-                os.path.join(self.stage.path, basename), self.stage.save_filename
+        if not self.url.startswith("s3://"):
+            raise spack.error.FetchError(
+                f"{self.__class__.__name__} can only fetch from s3:// urls."
             )
-
+        if self.archive_file:
+            tty.debug(f"Already downloaded {self.archive_file}")
+            return
+        self._fetch_urllib(self.url)
         if not self.archive_file:
-            raise FailedDownloadError(self.url)
+            raise FailedDownloadError(
+                RuntimeError(f"Missing archive {self.archive_file} after fetching")
+            )
 
 
 @fetcher
@@ -1349,43 +1393,22 @@ class GCSFetchStrategy(URLFetchStrategy):
 
     url_attr = "gs"
 
-    def __init__(self, *args, **kwargs):
-        try:
-            super().__init__(*args, **kwargs)
-        except ValueError:
-            if not kwargs.get("url"):
-                raise ValueError("GCSFetchStrategy requires a url for fetching.")
-
     @_needs_stage
     def fetch(self):
+        if not self.url.startswith("gs"):
+            raise spack.error.FetchError(
+                f"{self.__class__.__name__} can only fetch from gs:// urls."
+            )
         if self.archive_file:
-            tty.debug("Already downloaded {0}".format(self.archive_file))
+            tty.debug(f"Already downloaded {self.archive_file}")
             return
 
-        parsed_url = urllib.parse.urlparse(self.url)
-        if parsed_url.scheme != "gs":
-            raise spack.error.FetchError("GCSFetchStrategy can only fetch from gs:// urls.")
-
-        tty.debug("Fetching {0}".format(self.url))
-
-        basename = os.path.basename(parsed_url.path)
-
-        with working_dir(self.stage.path):
-            _, headers, stream = web_util.read_from_url(self.url)
-
-            with open(basename, "wb") as f:
-                shutil.copyfileobj(stream, f)
-
-            content_type = web_util.get_header(headers, "Content-type")
-
-        if content_type == "text/html":
-            warn_content_type_mismatch(self.archive_file or "the archive")
-
-        if self.stage.save_filename:
-            os.rename(os.path.join(self.stage.path, basename), self.stage.save_filename)
+        self._fetch_urllib(self.url)
 
         if not self.archive_file:
-            raise FailedDownloadError(self.url)
+            raise FailedDownloadError(
+                RuntimeError(f"Missing archive {self.archive_file} after fetching")
+            )
 
 
 @fetcher
@@ -1394,7 +1417,7 @@ class FetchAndVerifyExpandedFile(URLFetchStrategy):
     as well as after expanding it."""
 
     def __init__(self, url, archive_sha256: str, expanded_sha256: str):
-        super().__init__(url, archive_sha256)
+        super().__init__(url=url, checksum=archive_sha256)
         self.expanded_sha256 = expanded_sha256
 
     def expand(self):
@@ -1436,14 +1459,14 @@ def stable_target(fetcher):
     return False
 
 
-def from_url(url):
+def from_url(url: str) -> URLFetchStrategy:
     """Given a URL, find an appropriate fetch strategy for it.
     Currently just gives you a URLFetchStrategy that uses curl.
 
     TODO: make this return appropriate fetch strategies for other
           types of URLs.
     """
-    return URLFetchStrategy(url)
+    return URLFetchStrategy(url=url)
 
 
 def from_kwargs(**kwargs):
@@ -1512,10 +1535,12 @@ def _check_version_attributes(fetcher, pkg, version):
 def _extrapolate(pkg, version):
     """Create a fetcher from an extrapolated URL for this version."""
     try:
-        return URLFetchStrategy(pkg.url_for_version(version), fetch_options=pkg.fetch_options)
+        return URLFetchStrategy(url=pkg.url_for_version(version), fetch_options=pkg.fetch_options)
     except spack.package_base.NoURLError:
-        msg = "Can't extrapolate a URL for version %s " "because package %s defines no URLs"
-        raise ExtrapolationError(msg % (version, pkg.name))
+        raise ExtrapolationError(
+            f"Can't extrapolate a URL for version {version} because "
+            f"package {pkg.name} defines no URLs"
+        )
 
 
 def _from_merged_attrs(fetcher, pkg, version):
@@ -1532,8 +1557,11 @@ def _from_merged_attrs(fetcher, pkg, version):
     attrs["fetch_options"] = pkg.fetch_options
     attrs.update(pkg.versions[version])
 
-    if fetcher.url_attr == "git" and hasattr(pkg, "submodules"):
-        attrs.setdefault("submodules", pkg.submodules)
+    if fetcher.url_attr == "git":
+        pkg_attr_list = ["submodules", "git_sparse_paths"]
+        for pkg_attr in pkg_attr_list:
+            if hasattr(pkg, pkg_attr):
+                attrs.setdefault(pkg_attr, getattr(pkg, pkg_attr))
 
     return fetcher(**attrs)
 
@@ -1628,11 +1656,9 @@ def for_package_version(pkg, version=None):
     raise InvalidArgsError(pkg, version, **args)
 
 
-def from_url_scheme(url, *args, **kwargs):
+def from_url_scheme(url: str, **kwargs) -> FetchStrategy:
     """Finds a suitable FetchStrategy by matching its url_attr with the scheme
     in the given url."""
-
-    url = kwargs.get("url", url)
     parsed_url = urllib.parse.urlparse(url, scheme="file")
 
     scheme_mapping = kwargs.get("scheme_mapping") or {
@@ -1649,11 +1675,9 @@ def from_url_scheme(url, *args, **kwargs):
     for fetcher in all_strategies:
         url_attr = getattr(fetcher, "url_attr", None)
         if url_attr and url_attr == scheme:
-            return fetcher(url, *args, **kwargs)
+            return fetcher(url=url, **kwargs)
 
-    raise ValueError(
-        'No FetchStrategy found for url with scheme: "{SCHEME}"'.format(SCHEME=parsed_url.scheme)
-    )
+    raise ValueError(f'No FetchStrategy found for url with scheme: "{parsed_url.scheme}"')
 
 
 def from_list_url(pkg):
@@ -1678,7 +1702,9 @@ def from_list_url(pkg):
                     )
 
                 # construct a fetcher
-                return URLFetchStrategy(url_from_list, checksum, fetch_options=pkg.fetch_options)
+                return URLFetchStrategy(
+                    url=url_from_list, checksum=checksum, fetch_options=pkg.fetch_options
+                )
             except KeyError as e:
                 tty.debug(e)
                 tty.msg("Cannot find version %s in url_list" % pkg.version)
@@ -1706,10 +1732,10 @@ def store(self, fetcher, relative_dest):
         mkdirp(os.path.dirname(dst))
         fetcher.archive(dst)
 
-    def fetcher(self, target_path, digest, **kwargs):
+    def fetcher(self, target_path: str, digest: Optional[str], **kwargs) -> CacheURLFetchStrategy:
         path = os.path.join(self.root, target_path)
         url = url_util.path_to_file_url(path)
-        return CacheURLFetchStrategy(url, digest, **kwargs)
+        return CacheURLFetchStrategy(url=url, checksum=digest, **kwargs)
 
     def destroy(self):
         shutil.rmtree(self.root, ignore_errors=True)
@@ -1722,9 +1748,9 @@ class NoCacheError(spack.error.FetchError):
 class FailedDownloadError(spack.error.FetchError):
     """Raised when a download fails."""
 
-    def __init__(self, url, msg=""):
-        super().__init__("Failed to fetch file from URL: %s" % url, msg)
-        self.url = url
+    def __init__(self, *exceptions: Exception):
+        super().__init__("Failed to download")
+        self.exceptions = exceptions
 
 
 class NoArchiveFileError(spack.error.FetchError):

lib/spack/spack/hash_types.py

@@ -37,6 +37,12 @@ def __call__(self, spec):
         """Run this hash on the provided spec."""
         return spec.spec_hash(self)
 
+    def __repr__(self):
+        return (
+            f"SpecHashDescriptor(depflag={self.depflag!r}, "
+            f"package_hash={self.package_hash!r}, name={self.name!r}, override={self.override!r})"
+        )
+
 
 #: Spack's deployment hash. Includes all inputs that can affect how a package is built.
 dag_hash = SpecHashDescriptor(depflag=dt.BUILD | dt.LINK | dt.RUN, package_hash=True, name="hash")

lib/spack/spack/hooks/__init__.py

@@ -20,6 +20,7 @@
 systems (e.g. modules, lmod, etc.) or to add other custom
 features.
 """
+import importlib
 
 from llnl.util.lang import ensure_last, list_modules
 
@@ -46,11 +47,7 @@ def _populate_hooks(cls):
 
         for name in relative_names:
             module_name = __name__ + "." + name
-            # When importing a module from a package, __import__('A.B', ...)
-            # returns package A when 'fromlist' is empty. If fromlist is not
-            # empty it returns the submodule B instead
-            # See: https://stackoverflow.com/a/2725668/771663
-            module_obj = __import__(module_name, fromlist=[None])
+            module_obj = importlib.import_module(module_name)
             cls._hooks.append((module_name, module_obj))
 
     @property

lib/spack/spack/hooks/autopush.py

@@ -23,9 +23,7 @@ def post_install(spec, explicit):
 
     # Push the package to all autopush mirrors
     for mirror in spack.mirror.MirrorCollection(binary=True, autopush=True).values():
-        bindist.push_or_raise(
-            spec,
-            mirror.push_url,
-            bindist.PushOptions(force=True, regenerate_index=False, unsigned=not mirror.signed),
-        )
+        signing_key = bindist.select_signing_key() if mirror.signed else None
+        with bindist.make_uploader(mirror=mirror, force=True, signing_key=signing_key) as uploader:
+            uploader.push_or_raise([spec])
         tty.msg(f"{spec.name}: Pushed to build cache: '{mirror.name}'")

lib/spack/spack/install_test.py

@@ -757,6 +757,10 @@ def test_process(pkg: Pb, kwargs):
             pkg.tester.status(pkg.spec.name, TestStatus.SKIPPED)
             return
 
+        # Make sure properly named build-time test methods actually run as
+        # stand-alone tests.
+        pkg.run_tests = True
+
         # run test methods from the package and all virtuals it provides
         v_names = virtuals(pkg)
         test_specs = [pkg.spec] + [spack.spec.Spec(v_name) for v_name in sorted(v_names)]

lib/spack/spack/installer.py

@@ -1611,9 +1611,7 @@ def _add_tasks(self, request: BuildRequest, all_deps):
 
     def _add_compiler_package_to_config(self, pkg: "spack.package_base.PackageBase") -> None:
         compiler_search_prefix = getattr(pkg, "compiler_search_prefix", pkg.spec.prefix)
-        spack.compilers.add_compilers_to_config(
-            spack.compilers.find_compilers([compiler_search_prefix])
-        )
+        spack.compilers.find_compilers([compiler_search_prefix])
 
     def _install_task(self, task: BuildTask, install_status: InstallStatus) -> None:
         """

lib/spack/spack/mirror.py

@@ -21,6 +21,7 @@
 from typing import List, Optional, Union
 
 import llnl.url
+import llnl.util.symlink
 import llnl.util.tty as tty
 from llnl.util.filesystem import mkdirp
 
@@ -30,6 +31,7 @@
 import spack.fetch_strategy
 import spack.mirror
 import spack.oci.image
+import spack.repo
 import spack.spec
 import spack.util.path
 import spack.util.spack_json as sjson
@@ -426,51 +428,74 @@ def _determine_extension(fetcher):
     return ext
 
 
-class MirrorReference:
-    """A ``MirrorReference`` stores the relative paths where you can store a
-    package/resource in a mirror directory.
+class MirrorLayout:
+    """A ``MirrorLayout`` object describes the relative path of a mirror entry."""
 
-    The appropriate storage location is given by ``storage_path``. The
-    ``cosmetic_path`` property provides a reference that a human could generate
-    themselves based on reading the details of the package.
-
-    A user can iterate over a ``MirrorReference`` object to get all the
-    possible names that might be used to refer to the resource in a mirror;
-    this includes names generated by previous naming schemes that are no-longer
-    reported by ``storage_path`` or ``cosmetic_path``.
-    """
-
-    def __init__(self, cosmetic_path, global_path=None):
-        self.global_path = global_path
-        self.cosmetic_path = cosmetic_path
-
-    @property
-    def storage_path(self):
-        if self.global_path:
-            return self.global_path
-        else:
-            return self.cosmetic_path
+    def __init__(self, path: str) -> None:
+        self.path = path
 
     def __iter__(self):
-        if self.global_path:
-            yield self.global_path
-        yield self.cosmetic_path
+        """Yield all paths including aliases where the resource can be found."""
+        yield self.path
+
+    def make_alias(self, root: str) -> None:
+        """Make the entry ``root / self.path`` available under a human readable alias"""
+        pass
 
 
-class OCIImageLayout:
-    """Follow the OCI Image Layout Specification to archive blobs
+class DefaultLayout(MirrorLayout):
+    def __init__(self, alias_path: str, digest_path: Optional[str] = None) -> None:
+        # When we have a digest, it is used as the primary storage location. If not, then we use
+        # the human-readable alias. In case of mirrors of a VCS checkout, we currently do not have
+        # a digest, that's why an alias is required and a digest optional.
+        super().__init__(path=digest_path or alias_path)
+        self.alias = alias_path
+        self.digest_path = digest_path
 
-    Paths are of the form `blobs/<algorithm>/<digest>`
-    """
+    def make_alias(self, root: str) -> None:
+        """Symlink a human readible path in our mirror to the actual storage location."""
+        # We already use the human-readable path as the main storage location.
+        if not self.digest_path:
+            return
+
+        alias, digest = os.path.join(root, self.alias), os.path.join(root, self.digest_path)
+
+        alias_dir = os.path.dirname(alias)
+        relative_dst = os.path.relpath(digest, start=alias_dir)
+
+        mkdirp(alias_dir)
+        tmp = f"{alias}.tmp"
+        llnl.util.symlink.symlink(relative_dst, tmp)
+
+        try:
+            os.rename(tmp, alias)
+        except OSError:
+            # Clean up the temporary if possible
+            try:
+                os.unlink(tmp)
+            except OSError:
+                pass
+            raise
+
+    def __iter__(self):
+        if self.digest_path:
+            yield self.digest_path
+        yield self.alias
+
+
+class OCILayout(MirrorLayout):
+    """Follow the OCI Image Layout Specification to archive blobs where paths are of the form
+    ``blobs/<algorithm>/<digest>``"""
 
     def __init__(self, digest: spack.oci.image.Digest) -> None:
-        self.storage_path = os.path.join("blobs", digest.algorithm, digest.digest)
-
-    def __iter__(self):
-        yield self.storage_path
+        super().__init__(os.path.join("blobs", digest.algorithm, digest.digest))
 
 
-def mirror_archive_paths(fetcher, per_package_ref, spec=None):
+def default_mirror_layout(
+    fetcher: "spack.fetch_strategy.FetchStrategy",
+    per_package_ref: str,
+    spec: Optional["spack.spec.Spec"] = None,
+) -> MirrorLayout:
     """Returns a ``MirrorReference`` object which keeps track of the relative
     storage path of the resource associated with the specified ``fetcher``."""
     ext = None
@@ -494,7 +519,7 @@ def mirror_archive_paths(fetcher, per_package_ref, spec=None):
     if global_ref and ext:
         global_ref += ".%s" % ext
 
-    return MirrorReference(per_package_ref, global_ref)
+    return DefaultLayout(per_package_ref, global_ref)
 
 
 def get_all_versions(specs):

lib/spack/spack/multimethod.py

@@ -25,14 +25,11 @@
 so package authors should use their judgement.
 """
 import functools
-import inspect
 from contextlib import contextmanager
 
-from llnl.util.lang import caller_locals
-
-import spack.directives
+import spack.directives_meta
 import spack.error
-from spack.spec import Spec
+import spack.spec
 
 
 class MultiMethodMeta(type):
@@ -135,7 +132,7 @@ def __call__(self, package_or_builder_self, *args, **kwargs):
         # its superclasses for successive calls. We don't have that
         # information within `SpecMultiMethod`, because it is not
         # associated with the package class.
-        for cls in inspect.getmro(package_or_builder_self.__class__)[1:]:
+        for cls in package_or_builder_self.__class__.__mro__[1:]:
             superself = cls.__dict__.get(self.__name__, None)
 
             if isinstance(superself, SpecMultiMethod):
@@ -165,9 +162,9 @@ def __init__(self, condition):
             condition (str): condition to be met
         """
         if isinstance(condition, bool):
-            self.spec = Spec() if condition else None
+            self.spec = spack.spec.Spec() if condition else None
         else:
-            self.spec = Spec(condition)
+            self.spec = spack.spec.Spec(condition)
 
     def __call__(self, method):
         """This annotation lets packages declare multiple versions of
@@ -229,11 +226,9 @@ def install(self, prefix):
            platform-specific versions.  There's not much we can do to get
            around this because of the way decorators work.
         """
-        # In Python 2, Get the first definition of the method in the
-        # calling scope by looking at the caller's locals. In Python 3,
-        # we handle this using MultiMethodMeta.__prepare__.
-        if MultiMethodMeta._locals is None:
-            MultiMethodMeta._locals = caller_locals()
+        assert (
+            MultiMethodMeta._locals is not None
+        ), "cannot use multimethod, missing MultiMethodMeta metaclass?"
 
         # Create a multimethod with this name if there is not one already
         original_method = MultiMethodMeta._locals.get(method.__name__)
@@ -266,17 +261,17 @@ def __enter__(self):
         and add their constraint to whatever may be already present in the directive
         `when=` argument.
         """
-        spack.directives.DirectiveMeta.push_to_context(str(self.spec))
+        spack.directives_meta.DirectiveMeta.push_to_context(str(self.spec))
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        spack.directives.DirectiveMeta.pop_from_context()
+        spack.directives_meta.DirectiveMeta.pop_from_context()
 
 
 @contextmanager
 def default_args(**kwargs):
-    spack.directives.DirectiveMeta.push_default_args(kwargs)
+    spack.directives_meta.DirectiveMeta.push_default_args(kwargs)
     yield
-    spack.directives.DirectiveMeta.pop_default_args()
+    spack.directives_meta.DirectiveMeta.pop_default_args()
 
 
 class MultiMethodError(spack.error.SpackError):

lib/spack/spack/oci/oci.py

@@ -6,7 +6,6 @@
 import hashlib
 import json
 import os
-import time
 import urllib.error
 import urllib.parse
 import urllib.request
@@ -43,11 +42,6 @@ def create_tarball(spec: spack.spec.Spec, tarfile_path):
     return spack.binary_distribution._do_create_tarball(tarfile_path, spec.prefix, buildinfo)
 
 
-def _log_upload_progress(digest: Digest, size: int, elapsed: float):
-    elapsed = max(elapsed, 0.001)  # guard against division by zero
-    tty.info(f"Uploaded {digest} ({elapsed:.2f}s, {size / elapsed / 1024 / 1024:.2f} MB/s)")
-
-
 def with_query_param(url: str, param: str, value: str) -> str:
     """Add a query parameter to a URL
 
@@ -141,8 +135,6 @@ def upload_blob(
     if not force and blob_exists(ref, digest, _urlopen):
         return False
 
-    start = time.time()
-
     with open(file, "rb") as f:
         file_size = os.fstat(f.fileno()).st_size
 
@@ -167,7 +159,6 @@ def upload_blob(
 
         # Created the blob in one go.
         if response.status == 201:
-            _log_upload_progress(digest, file_size, time.time() - start)
             return True
 
         # Otherwise, do another PUT request.
@@ -191,8 +182,6 @@ def upload_blob(
 
         spack.oci.opener.ensure_status(request, response, 201)
 
-    # print elapsed time and # MB/s
-    _log_upload_progress(digest, file_size, time.time() - start)
     return True
 
 
@@ -401,15 +390,12 @@ def make_stage(
 ) -> spack.stage.Stage:
     _urlopen = _urlopen or spack.oci.opener.urlopen
     fetch_strategy = spack.fetch_strategy.OCIRegistryFetchStrategy(
-        url, checksum=digest.digest, _urlopen=_urlopen
+        url=url, checksum=digest.digest, _urlopen=_urlopen
     )
     # Use blobs/<alg>/<encoded> as the cache path, which follows
     # the OCI Image Layout Specification. What's missing though,
     # is the `oci-layout` and `index.json` files, which are
     # required by the spec.
     return spack.stage.Stage(
-        fetch_strategy,
-        mirror_paths=spack.mirror.OCIImageLayout(digest),
-        name=digest.digest,
-        keep=keep,
+        fetch_strategy, mirror_paths=spack.mirror.OCILayout(digest), name=digest.digest, keep=keep
     )

lib/spack/spack/package_base.py

@@ -15,7 +15,7 @@
 import functools
 import glob
 import hashlib
-import inspect
+import importlib
 import io
 import os
 import re
@@ -197,13 +197,12 @@ def __init__(cls, name, bases, attr_dict):
         # that "foo" was a possible executable.
 
         # If a package has the executables or libraries  attribute then it's
-        # assumed to be detectable
+        # assumed to be detectable. Add a tag, so finding them is faster
         if hasattr(cls, "executables") or hasattr(cls, "libraries"):
-            # Append a tag to each detectable package, so that finding them is faster
-            if not hasattr(cls, "tags"):
-                setattr(cls, "tags", [DetectablePackageMeta.TAG])
-            elif DetectablePackageMeta.TAG not in cls.tags:
-                cls.tags.append(DetectablePackageMeta.TAG)
+            # To add the tag, we need to copy the tags attribute, and attach it to
+            # the current class. We don't use append, since it might modify base classes,
+            # if "tags" is retrieved following the MRO.
+            cls.tags = getattr(cls, "tags", []) + [DetectablePackageMeta.TAG]
 
             @classmethod
             def platform_executables(cls):
@@ -246,10 +245,7 @@ def determine_spec_details(cls, prefix, objs_in_prefix):
                         if version_str:
                             objs_by_version[version_str].append(obj)
                     except Exception as e:
-                        msg = (
-                            "An error occurred when trying to detect " 'the version of "{0}" [{1}]'
-                        )
-                        tty.debug(msg.format(obj, str(e)))
+                        tty.debug(f"Cannot detect the version of '{obj}' [{str(e)}]")
 
                 specs = []
                 for version_str, objs in objs_by_version.items():
@@ -262,27 +258,23 @@ def determine_spec_details(cls, prefix, objs_in_prefix):
                         if isinstance(variant, str):
                             variant = (variant, {})
                         variant_str, extra_attributes = variant
-                        spec_str = "{0}@{1} {2}".format(cls.name, version_str, variant_str)
+                        spec_str = f"{cls.name}@{version_str} {variant_str}"
 
                         # Pop a few reserved keys from extra attributes, since
                         # they have a different semantics
                         external_path = extra_attributes.pop("prefix", None)
                         external_modules = extra_attributes.pop("modules", None)
                         try:
-                            spec = spack.spec.Spec(
+                            spec = spack.spec.Spec.from_detection(
                                 spec_str,
                                 external_path=external_path,
                                 external_modules=external_modules,
+                                extra_attributes=extra_attributes,
                             )
                         except Exception as e:
-                            msg = 'Parsing failed [spec_str="{0}", error={1}]'
-                            tty.debug(msg.format(spec_str, str(e)))
+                            tty.debug(f'Parsing failed [spec_str="{spec_str}", error={str(e)}]')
                         else:
-                            specs.append(
-                                spack.spec.Spec.from_detection(
-                                    spec, extra_attributes=extra_attributes
-                                )
-                            )
+                            specs.append(spec)
 
                 return sorted(specs)
 
@@ -741,7 +733,7 @@ def __init__(self, spec):
             raise ValueError(msg.format(self))
 
         # init internal variables
-        self._stage = None
+        self._stage: Optional[StageComposite] = None
         self._fetcher = None
         self._tester: Optional["PackageTest"] = None
 
@@ -869,7 +861,7 @@ def module(cls):
         We use this to add variables to package modules.  This makes
         install() methods easier to write (e.g., can call configure())
         """
-        return __import__(cls.__module__, fromlist=[cls.__name__])
+        return importlib.import_module(cls.__module__)
 
     @classproperty
     def namespace(cls):
@@ -885,7 +877,7 @@ def fullname(cls):
     def fullnames(cls):
         """Fullnames for this package and any packages from which it inherits."""
         fullnames = []
-        for cls in inspect.getmro(cls):
+        for cls in cls.__mro__:
             namespace = getattr(cls, "namespace", None)
             if namespace:
                 fullnames.append("%s.%s" % (namespace, cls.name))
@@ -1099,9 +1091,10 @@ def _make_resource_stage(self, root_stage, resource):
             root=root_stage,
             resource=resource,
             name=self._resource_stage(resource),
-            mirror_paths=spack.mirror.mirror_archive_paths(
+            mirror_paths=spack.mirror.default_mirror_layout(
                 resource.fetcher, os.path.join(self.name, pretty_resource_name)
             ),
+            mirrors=spack.mirror.MirrorCollection(source=True).values(),
             path=self.path,
         )
 
@@ -1113,7 +1106,7 @@ def _make_root_stage(self, fetcher):
         # Construct a mirror path (TODO: get this out of package.py)
         format_string = "{name}-{version}"
         pretty_name = self.spec.format_path(format_string)
-        mirror_paths = spack.mirror.mirror_archive_paths(
+        mirror_paths = spack.mirror.default_mirror_layout(
             fetcher, os.path.join(self.name, pretty_name), self.spec
         )
         # Construct a path where the stage should build..
@@ -1122,6 +1115,7 @@ def _make_root_stage(self, fetcher):
         stage = Stage(
             fetcher,
             mirror_paths=mirror_paths,
+            mirrors=spack.mirror.MirrorCollection(source=True).values(),
             name=stage_name,
             path=self.path,
             search_fn=self._download_search,
@@ -1178,7 +1172,7 @@ def stage(self):
         return self._stage
 
     @stage.setter
-    def stage(self, stage):
+    def stage(self, stage: StageComposite):
         """Allow a stage object to be set to override the default."""
         self._stage = stage
 
@@ -1748,7 +1742,7 @@ def _has_make_target(self, target):
             bool: True if 'target' is found, else False
         """
         # Prevent altering LC_ALL for 'make' outside this function
-        make = copy.deepcopy(inspect.getmodule(self).make)
+        make = copy.deepcopy(self.module.make)
 
         # Use English locale for missing target message comparison
         make.add_default_env("LC_ALL", "C")
@@ -1798,7 +1792,7 @@ def _if_make_target_execute(self, target, *args, **kwargs):
         """
         if self._has_make_target(target):
             # Execute target
-            inspect.getmodule(self).make(target, *args, **kwargs)
+            self.module.make(target, *args, **kwargs)
 
     def _has_ninja_target(self, target):
         """Checks to see if 'target' is a valid target in a Ninja build script.
@@ -1809,7 +1803,7 @@ def _has_ninja_target(self, target):
         Returns:
             bool: True if 'target' is found, else False
         """
-        ninja = inspect.getmodule(self).ninja
+        ninja = self.module.ninja
 
         # Check if we have a Ninja build script
         if not os.path.exists("build.ninja"):
@@ -1838,7 +1832,7 @@ def _if_ninja_target_execute(self, target, *args, **kwargs):
         """
         if self._has_ninja_target(target):
             # Execute target
-            inspect.getmodule(self).ninja(target, *args, **kwargs)
+            self.module.ninja(target, *args, **kwargs)
 
     def _get_needed_resources(self):
         # We use intersects here cause it would also work if self.spec is abstract

lib/spack/spack/package_prefs.py

@@ -5,10 +5,11 @@
 import stat
 import warnings
 
+import spack.config
 import spack.error
 import spack.repo
+import spack.spec
 from spack.config import ConfigError
-from spack.util.path import canonicalize_path
 from spack.version import Version
 
 _lesser_spec_types = {"compiler": spack.spec.CompilerSpec, "version": Version}
@@ -154,44 +155,6 @@ def preferred_variants(cls, pkg_name):
         )
 
 
-def spec_externals(spec):
-    """Return a list of external specs (w/external directory path filled in),
-    one for each known external installation.
-    """
-    # break circular import.
-    from spack.util.module_cmd import path_from_modules  # noqa: F401
-
-    def _package(maybe_abstract_spec):
-        pkg_cls = spack.repo.PATH.get_pkg_class(spec.name)
-        return pkg_cls(maybe_abstract_spec)
-
-    allpkgs = spack.config.get("packages")
-    names = set([spec.name])
-    names |= set(vspec.name for vspec in _package(spec).virtuals_provided)
-
-    external_specs = []
-    for name in names:
-        pkg_config = allpkgs.get(name, {})
-        pkg_externals = pkg_config.get("externals", [])
-        for entry in pkg_externals:
-            spec_str = entry["spec"]
-            external_path = entry.get("prefix", None)
-            if external_path:
-                external_path = canonicalize_path(external_path)
-            external_modules = entry.get("modules", None)
-            external_spec = spack.spec.Spec.from_detection(
-                spack.spec.Spec(
-                    spec_str, external_path=external_path, external_modules=external_modules
-                ),
-                extra_attributes=entry.get("extra_attributes", {}),
-            )
-            if external_spec.intersects(spec):
-                external_specs.append(external_spec)
-
-    # Defensively copy returned specs
-    return [s.copy() for s in external_specs]
-
-
 def is_spec_buildable(spec):
     """Return true if the spec is configured as buildable"""
     allpkgs = spack.config.get("packages")

lib/spack/spack/patch.py

@@ -4,7 +4,6 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import hashlib
-import inspect
 import os
 import os.path
 import pathlib
@@ -185,8 +184,8 @@ def __init__(
         # search mro to look for the file
         abs_path: Optional[str] = None
         # At different times we call FilePatch on instances and classes
-        pkg_cls = pkg if inspect.isclass(pkg) else pkg.__class__
-        for cls in inspect.getmro(pkg_cls):  # type: ignore
+        pkg_cls = pkg if isinstance(pkg, type) else pkg.__class__
+        for cls in pkg_cls.__mro__:  # type: ignore
             if not hasattr(cls, "module"):
                 # We've gone too far up the MRO
                 break
@@ -319,18 +318,19 @@ def stage(self) -> "spack.stage.Stage":
                 self.url, archive_sha256=self.archive_sha256, expanded_sha256=self.sha256
             )
         else:
-            fetcher = fs.URLFetchStrategy(self.url, sha256=self.sha256, expand=False)
+            fetcher = fs.URLFetchStrategy(url=self.url, sha256=self.sha256, expand=False)
 
         # The same package can have multiple patches with the same name but
         # with different contents, therefore apply a subset of the hash.
         name = "{0}-{1}".format(os.path.basename(self.url), fetch_digest[:7])
 
         per_package_ref = os.path.join(self.owner.split(".")[-1], name)
-        mirror_ref = spack.mirror.mirror_archive_paths(fetcher, per_package_ref)
+        mirror_ref = spack.mirror.default_mirror_layout(fetcher, per_package_ref)
         self._stage = spack.stage.Stage(
             fetcher,
             name=f"{spack.stage.stage_prefix}patch-{fetch_digest}",
             mirror_paths=mirror_ref,
+            mirrors=spack.mirror.MirrorCollection(source=True).values(),
         )
         return self._stage
 

lib/spack/spack/platforms/__init__.py

@@ -4,7 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import contextlib
 
-from ._functions import _host, by_name, platforms, prevent_cray_detection, reset
+from ._functions import _host, by_name, platforms, reset
 from ._platform import Platform
 from .darwin import Darwin
 from .freebsd import FreeBSD
@@ -23,7 +23,6 @@
     "host",
     "by_name",
     "reset",
-    "prevent_cray_detection",
 ]
 
 #: The "real" platform of the host running Spack. This should not be changed

lib/spack/spack/platforms/_functions.py

@@ -2,12 +2,8 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import contextlib
-
 import llnl.util.lang
 
-import spack.util.environment
-
 from .darwin import Darwin
 from .freebsd import FreeBSD
 from .linux import Linux
@@ -57,14 +53,3 @@ def by_name(name):
     """
     platform_cls = cls_by_name(name)
     return platform_cls() if platform_cls else None
-
-
-@contextlib.contextmanager
-def prevent_cray_detection():
-    """Context manager that prevents the detection of the Cray platform"""
-    reset()
-    try:
-        with spack.util.environment.set_env(MODULEPATH=""):
-            yield
-    finally:
-        reset()

lib/spack/spack/repo.py

@@ -149,12 +149,12 @@ def current_repository(self, value):
     @contextlib.contextmanager
     def switch_repo(self, substitute: "RepoType"):
         """Switch the current repository list for the duration of the context manager."""
-        old = self.current_repository
+        old = self._repo
         try:
-            self.current_repository = substitute
+            self._repo = substitute
             yield
         finally:
-            self.current_repository = old
+            self._repo = old
 
     def find_spec(self, fullname, python_path, target=None):
         # "target" is not None only when calling importlib.reload()
@@ -365,9 +365,9 @@ def __init__(self, namespace):
 
     def __getattr__(self, name):
         """Getattr lazily loads modules if they're not already loaded."""
-        submodule = self.__package__ + "." + name
+        submodule = f"{self.__package__}.{name}"
         try:
-            setattr(self, name, __import__(submodule))
+            setattr(self, name, importlib.import_module(submodule))
         except ImportError:
             msg = "'{0}' object has no attribute {1}"
             raise AttributeError(msg.format(type(self), name))
@@ -683,7 +683,7 @@ class RepoPath:
     def __init__(
         self,
         *repos: Union[str, "Repo"],
-        cache: "spack.caches.FileCacheType",
+        cache: Optional["spack.caches.FileCacheType"],
         overrides: Optional[Dict[str, Any]] = None,
     ) -> None:
         self.repos: List[Repo] = []
@@ -696,6 +696,7 @@ def __init__(
         for repo in repos:
             try:
                 if isinstance(repo, str):
+                    assert cache is not None, "cache must hold a value, when repo is a string"
                     repo = Repo(repo, cache=cache, overrides=overrides)
                 repo.finder(self)
                 self.put_last(repo)
@@ -707,6 +708,10 @@ def __init__(
                     f"    spack repo rm {repo}",
                 )
 
+    def ensure_unwrapped(self) -> "RepoPath":
+        """Ensure we unwrap this object from any dynamic wrapper (like Singleton)"""
+        return self
+
     def put_first(self, repo: "Repo") -> None:
         """Add repo first in the search path."""
         if isinstance(repo, RepoPath):
@@ -930,6 +935,16 @@ def is_virtual_safe(self, pkg_name: str) -> bool:
     def __contains__(self, pkg_name):
         return self.exists(pkg_name)
 
+    def marshal(self):
+        return (self.repos,)
+
+    @staticmethod
+    def unmarshal(repos):
+        return RepoPath(*repos, cache=None)
+
+    def __reduce__(self):
+        return RepoPath.unmarshal, self.marshal()
+
 
 class Repo:
     """Class representing a package repository in the filesystem.
@@ -1266,7 +1281,7 @@ def get_pkg_class(self, pkg_name: str) -> Type["spack.package_base.PackageBase"]
             raise RepoError(msg) from e
 
         cls = getattr(module, class_name)
-        if not inspect.isclass(cls):
+        if not isinstance(cls, type):
             tty.die(f"{pkg_name}.{class_name} is not a class")
 
         # Clear any prior changes to class attributes in case the class was loaded from the
@@ -1319,6 +1334,20 @@ def __repr__(self) -> str:
     def __contains__(self, pkg_name: str) -> bool:
         return self.exists(pkg_name)
 
+    @staticmethod
+    def unmarshal(root, cache, overrides):
+        """Helper method to unmarshal keyword arguments"""
+        return Repo(root, cache=cache, overrides=overrides)
+
+    def marshal(self):
+        cache = self._cache
+        if isinstance(cache, llnl.util.lang.Singleton):
+            cache = cache.instance
+        return self.root, cache, self.overrides
+
+    def __reduce__(self):
+        return Repo.unmarshal, self.marshal()
+
 
 RepoType = Union[Repo, RepoPath]
 

lib/spack/spack/schema/compilers.py

@@ -11,6 +11,26 @@
 
 import spack.schema.environment
 
+flags: Dict[str, Any] = {
+    "type": "object",
+    "additionalProperties": False,
+    "properties": {
+        "cflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+        "cxxflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+        "fflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+        "cppflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+        "ldflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+        "ldlibs": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+    },
+}
+
+
+extra_rpaths: Dict[str, Any] = {"type": "array", "default": [], "items": {"type": "string"}}
+
+implicit_rpaths: Dict[str, Any] = {
+    "anyOf": [{"type": "array", "items": {"type": "string"}}, {"type": "boolean"}]
+}
+
 #: Properties for inclusion in other schemas
 properties: Dict[str, Any] = {
     "compilers": {
@@ -35,18 +55,7 @@
                                 "fc": {"anyOf": [{"type": "string"}, {"type": "null"}]},
                             },
                         },
-                        "flags": {
-                            "type": "object",
-                            "additionalProperties": False,
-                            "properties": {
-                                "cflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                                "cxxflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                                "fflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                                "cppflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                                "ldflags": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                                "ldlibs": {"anyOf": [{"type": "string"}, {"type": "null"}]},
-                            },
-                        },
+                        "flags": flags,
                         "spec": {"type": "string"},
                         "operating_system": {"type": "string"},
                         "target": {"type": "string"},
@@ -54,18 +63,9 @@
                         "modules": {
                             "anyOf": [{"type": "string"}, {"type": "null"}, {"type": "array"}]
                         },
-                        "implicit_rpaths": {
-                            "anyOf": [
-                                {"type": "array", "items": {"type": "string"}},
-                                {"type": "boolean"},
-                            ]
-                        },
+                        "implicit_rpaths": implicit_rpaths,
                         "environment": spack.schema.environment.definition,
-                        "extra_rpaths": {
-                            "type": "array",
-                            "default": [],
-                            "items": {"type": "string"},
-                        },
+                        "extra_rpaths": extra_rpaths,
                     },
                 }
             },

lib/spack/spack/schema/config.py

@@ -84,7 +84,6 @@
             "build_language": {"type": "string"},
             "build_jobs": {"type": "integer", "minimum": 1},
             "ccache": {"type": "boolean"},
-            "concretizer": {"type": "string", "enum": ["original", "clingo"]},
             "db_lock_timeout": {"type": "integer", "minimum": 1},
             "package_lock_timeout": {
                 "anyOf": [{"type": "integer", "minimum": 1}, {"type": "null"}]
@@ -98,9 +97,9 @@
             "aliases": {"type": "object", "patternProperties": {r"\w[\w-]*": {"type": "string"}}},
         },
         "deprecatedProperties": {
-            "properties": ["terminal_title"],
-            "message": "config:terminal_title has been replaced by "
-            "install_status and is ignored",
+            "properties": ["concretizer"],
+            "message": "Spack supports only clingo as a concretizer from v0.23. "
+            "The config:concretizer config option is ignored.",
             "error": False,
         },
     }

lib/spack/spack/schema/packages.py

@@ -11,6 +11,8 @@
 
 import spack.schema.environment
 
+from .compilers import extra_rpaths, flags, implicit_rpaths
+
 permissions = {
     "type": "object",
     "additionalProperties": False,
@@ -184,7 +186,16 @@
                                     "type": "object",
                                     "additionalProperties": True,
                                     "properties": {
-                                        "environment": spack.schema.environment.definition
+                                        "compilers": {
+                                            "type": "object",
+                                            "patternProperties": {
+                                                r"(^\w[\w-]*)": {"type": "string"}
+                                            },
+                                        },
+                                        "environment": spack.schema.environment.definition,
+                                        "extra_rpaths": extra_rpaths,
+                                        "implicit_rpaths": implicit_rpaths,
+                                        "flags": flags,
                                     },
                                 },
                             },

lib/spack/spack/solver/asp.py

@@ -32,7 +32,6 @@
 import spack.config
 import spack.config as sc
 import spack.deptypes as dt
-import spack.directives
 import spack.environment as ev
 import spack.error
 import spack.package_base
@@ -285,16 +284,14 @@ def _create_counter(specs: List[spack.spec.Spec], tests: bool):
     return NoDuplicatesCounter(specs, tests=tests)
 
 
-def all_compilers_in_config(configuration):
-    return spack.compilers.all_compilers_from(configuration)
-
-
 def all_libcs() -> Set[spack.spec.Spec]:
     """Return a set of all libc specs targeted by any configured compiler. If none, fall back to
     libc determined from the current Python process if dynamically linked."""
 
     libcs = {
-        c.default_libc for c in all_compilers_in_config(spack.config.CONFIG) if c.default_libc
+        c.default_libc
+        for c in spack.compilers.all_compilers_from(spack.config.CONFIG)
+        if c.default_libc
     }
 
     if libcs:
@@ -613,7 +610,7 @@ def _external_config_with_implicit_externals(configuration):
     if not using_libc_compatibility():
         return packages_yaml
 
-    for compiler in all_compilers_in_config(configuration):
+    for compiler in spack.compilers.all_compilers_from(configuration):
         libc = compiler.default_libc
         if libc:
             entry = {"spec": f"{libc} %{compiler.spec}", "prefix": libc.external_path}
@@ -1880,8 +1877,7 @@ def _spec_clauses(
 
                 # validate variant value only if spec not concrete
                 if not spec.concrete:
-                    reserved_names = spack.directives.reserved_names
-                    if not spec.virtual and vname not in reserved_names:
+                    if not spec.virtual and vname not in spack.variant.reserved_names:
                         pkg_cls = self.pkg_class(spec.name)
                         try:
                             variant_def, _ = pkg_cls.variants[vname]
@@ -3002,7 +2998,7 @@ class CompilerParser:
 
     def __init__(self, configuration) -> None:
         self.compilers: Set[KnownCompiler] = set()
-        for c in all_compilers_in_config(configuration):
+        for c in spack.compilers.all_compilers_from(configuration):
             if using_libc_compatibility() and not c_compiler_runs(c):
                 tty.debug(
                     f"the C compiler {c.cc} does not exist, or does not run correctly."
@@ -3466,7 +3462,7 @@ def reorder_flags(self):
         """
         # reverse compilers so we get highest priority compilers that share a spec
         compilers = dict(
-            (c.spec, c) for c in reversed(all_compilers_in_config(spack.config.CONFIG))
+            (c.spec, c) for c in reversed(spack.compilers.all_compilers_from(spack.config.CONFIG))
         )
         cmd_specs = dict((s.name, s) for spec in self._command_line_specs for s in spec.traverse())
 

lib/spack/spack/spec.py

@@ -51,6 +51,7 @@
 import collections
 import collections.abc
 import enum
+import io
 import itertools
 import os
 import pathlib
@@ -70,7 +71,6 @@
 import spack.compiler
 import spack.compilers
 import spack.config
-import spack.dependency as dp
 import spack.deptypes as dt
 import spack.error
 import spack.hash_types as ht
@@ -1428,7 +1428,7 @@ def __init__(
         # init an empty spec that matches anything.
         self.name = None
         self.versions = vn.VersionList(":")
-        self.variants = vt.VariantMap(self)
+        self.variants = VariantMap(self)
         self.architecture = None
         self.compiler = None
         self.compiler_flags = FlagMap(self)
@@ -1640,7 +1640,7 @@ def _add_flag(self, name, value, propagate):
         Known flags currently include "arch"
         """
 
-        if propagate and name in spack.directives.reserved_names:
+        if propagate and name in vt.reserved_names:
             raise UnsupportedPropagationError(
                 f"Propagation with '==' is not supported for '{name}'."
             )
@@ -2578,22 +2578,27 @@ def from_signed_json(stream):
         return Spec.from_dict(extracted_json)
 
     @staticmethod
-    def from_detection(spec_str, extra_attributes=None):
+    def from_detection(
+        spec_str: str,
+        *,
+        external_path: str,
+        external_modules: Optional[List[str]] = None,
+        extra_attributes: Optional[Dict] = None,
+    ) -> "Spec":
         """Construct a spec from a spec string determined during external
         detection and attach extra attributes to it.
 
         Args:
-            spec_str (str): spec string
-            extra_attributes (dict): dictionary containing extra attributes
-
-        Returns:
-            spack.spec.Spec: external spec
+            spec_str: spec string
+            external_path: prefix of the external spec
+            external_modules: optional module files to be loaded when the external spec is used
+            extra_attributes: dictionary containing extra attributes
         """
-        s = Spec(spec_str)
+        s = Spec(spec_str, external_path=external_path, external_modules=external_modules)
         extra_attributes = syaml.sorted_dict(extra_attributes or {})
         # This is needed to be able to validate multi-valued variants,
         # otherwise they'll still be abstract in the context of detection.
-        vt.substitute_abstract_variants(s)
+        substitute_abstract_variants(s)
         s.extra_attributes = extra_attributes
         return s
 
@@ -2615,294 +2620,6 @@ def validate_detection(self):
         validate_fn = getattr(pkg_cls, "validate_detected_spec", lambda x, y: None)
         validate_fn(self, self.extra_attributes)
 
-    def _concretize_helper(self, concretizer, presets=None, visited=None):
-        """Recursive helper function for concretize().
-        This concretizes everything bottom-up.  As things are
-        concretized, they're added to the presets, and ancestors
-        will prefer the settings of their children.
-        """
-        if presets is None:
-            presets = {}
-        if visited is None:
-            visited = set()
-
-        if self.name in visited:
-            return False
-
-        if self.concrete:
-            visited.add(self.name)
-            return False
-
-        changed = False
-
-        # Concretize deps first -- this is a bottom-up process.
-        for name in sorted(self._dependencies):
-            # WARNING: This function is an implementation detail of the
-            # WARNING: original concretizer. Since with that greedy
-            # WARNING: algorithm we don't allow multiple nodes from
-            # WARNING: the same package in a DAG, here we hard-code
-            # WARNING: using index 0 i.e. we assume that we have only
-            # WARNING: one edge from package "name"
-            changed |= self._dependencies[name][0].spec._concretize_helper(
-                concretizer, presets, visited
-            )
-
-        if self.name in presets:
-            changed |= self.constrain(presets[self.name])
-        else:
-            # Concretize virtual dependencies last.  Because they're added
-            # to presets below, their constraints will all be merged, but we'll
-            # still need to select a concrete package later.
-            if not self.virtual:
-                changed |= any(
-                    (
-                        concretizer.concretize_develop(self),  # special variant
-                        concretizer.concretize_architecture(self),
-                        concretizer.concretize_compiler(self),
-                        concretizer.adjust_target(self),
-                        # flags must be concretized after compiler
-                        concretizer.concretize_compiler_flags(self),
-                        concretizer.concretize_version(self),
-                        concretizer.concretize_variants(self),
-                    )
-                )
-            presets[self.name] = self
-
-        visited.add(self.name)
-        return changed
-
-    def _replace_with(self, concrete):
-        """Replace this virtual spec with a concrete spec."""
-        assert self.virtual
-        virtuals = (self.name,)
-        for dep_spec in itertools.chain.from_iterable(self._dependents.values()):
-            dependent = dep_spec.parent
-            depflag = dep_spec.depflag
-
-            # remove self from all dependents, unless it is already removed
-            if self.name in dependent._dependencies:
-                del dependent._dependencies.edges[self.name]
-
-            # add the replacement, unless it is already a dep of dependent.
-            if concrete.name not in dependent._dependencies:
-                dependent._add_dependency(concrete, depflag=depflag, virtuals=virtuals)
-            else:
-                dependent.edges_to_dependencies(name=concrete.name)[0].update_virtuals(
-                    virtuals=virtuals
-                )
-
-    def _expand_virtual_packages(self, concretizer):
-        """Find virtual packages in this spec, replace them with providers,
-        and normalize again to include the provider's (potentially virtual)
-        dependencies.  Repeat until there are no virtual deps.
-
-        Precondition: spec is normalized.
-
-        .. todo::
-
-           If a provider depends on something that conflicts with
-           other dependencies in the spec being expanded, this can
-           produce a conflicting spec.  For example, if mpich depends
-           on hwloc@:1.3 but something in the spec needs hwloc1.4:,
-           then we should choose an MPI other than mpich.  Cases like
-           this are infrequent, but should implement this before it is
-           a problem.
-        """
-        # Make an index of stuff this spec already provides
-        self_index = spack.provider_index.ProviderIndex(
-            repository=spack.repo.PATH, specs=self.traverse(), restrict=True
-        )
-        changed = False
-        done = False
-
-        while not done:
-            done = True
-            for spec in list(self.traverse()):
-                replacement = None
-                if spec.external:
-                    continue
-                if spec.virtual:
-                    replacement = self._find_provider(spec, self_index)
-                    if replacement:
-                        # TODO: may break if in-place on self but
-                        # shouldn't happen if root is traversed first.
-                        spec._replace_with(replacement)
-                        done = False
-                        break
-
-                if not replacement:
-                    # Get a list of possible replacements in order of
-                    # preference.
-                    candidates = concretizer.choose_virtual_or_external(spec)
-
-                    # Try the replacements in order, skipping any that cause
-                    # satisfiability problems.
-                    for replacement in candidates:
-                        if replacement is spec:
-                            break
-
-                        # Replace spec with the candidate and normalize
-                        copy = self.copy()
-                        copy[spec.name]._dup(replacement, deps=False)
-
-                        try:
-                            # If there are duplicate providers or duplicate
-                            # provider deps, consolidate them and merge
-                            # constraints.
-                            copy.normalize(force=True)
-                            break
-                        except spack.error.SpecError:
-                            # On error, we'll try the next replacement.
-                            continue
-
-                # If replacement is external then trim the dependencies
-                if replacement.external:
-                    if spec._dependencies:
-                        for dep in spec.dependencies():
-                            del dep._dependents.edges[spec.name]
-                        changed = True
-                        spec.clear_dependencies()
-                    replacement.clear_dependencies()
-                    replacement.architecture = self.architecture
-
-                # TODO: could this and the stuff in _dup be cleaned up?
-                def feq(cfield, sfield):
-                    return (not cfield) or (cfield == sfield)
-
-                if replacement is spec or (
-                    feq(replacement.name, spec.name)
-                    and feq(replacement.versions, spec.versions)
-                    and feq(replacement.compiler, spec.compiler)
-                    and feq(replacement.architecture, spec.architecture)
-                    and feq(replacement._dependencies, spec._dependencies)
-                    and feq(replacement.variants, spec.variants)
-                    and feq(replacement.external_path, spec.external_path)
-                    and feq(replacement.external_modules, spec.external_modules)
-                ):
-                    continue
-                # Refine this spec to the candidate. This uses
-                # replace_with AND dup so that it can work in
-                # place. TODO: make this more efficient.
-                if spec.virtual:
-                    spec._replace_with(replacement)
-                    changed = True
-                if spec._dup(replacement, deps=False, cleardeps=False):
-                    changed = True
-
-                self_index.update(spec)
-                done = False
-                break
-
-        return changed
-
-    def _old_concretize(self, tests=False, deprecation_warning=True):
-        """A spec is concrete if it describes one build of a package uniquely.
-        This will ensure that this spec is concrete.
-
-        Args:
-            tests (list or bool): list of packages that will need test
-                dependencies, or True/False for test all/none
-            deprecation_warning (bool): enable or disable the deprecation
-                warning for the old concretizer
-
-        If this spec could describe more than one version, variant, or build
-        of a package, this will add constraints to make it concrete.
-
-        Some rigorous validation and checks are also performed on the spec.
-        Concretizing ensures that it is self-consistent and that it's
-        consistent with requirements of its packages. See flatten() and
-        normalize() for more details on this.
-        """
-        import spack.concretize
-
-        # Add a warning message to inform users that the original concretizer
-        # will be removed
-        if deprecation_warning:
-            msg = (
-                "the original concretizer is currently being used.\n\tUpgrade to "
-                '"clingo" at your earliest convenience. The original concretizer '
-                "will be removed from Spack in a future version."
-            )
-            warnings.warn(msg)
-
-        self.replace_hash()
-
-        if not self.name:
-            raise spack.error.SpecError("Attempting to concretize anonymous spec")
-
-        if self._concrete:
-            return
-
-        # take the spec apart once before starting the main concretization loop and resolving
-        # deps, but don't break dependencies during concretization as the spec is built.
-        user_spec_deps = self.flat_dependencies(disconnect=True)
-
-        changed = True
-        force = False
-        concretizer = spack.concretize.Concretizer(self.copy())
-        while changed:
-            changes = (
-                self.normalize(force, tests, user_spec_deps, disconnect=False),
-                self._expand_virtual_packages(concretizer),
-                self._concretize_helper(concretizer),
-            )
-            changed = any(changes)
-            force = True
-
-        visited_user_specs = set()
-        for dep in self.traverse():
-            visited_user_specs.add(dep.name)
-            pkg_cls = spack.repo.PATH.get_pkg_class(dep.name)
-            visited_user_specs.update(pkg_cls(dep).provided_virtual_names())
-
-        extra = set(user_spec_deps.keys()).difference(visited_user_specs)
-        if extra:
-            raise InvalidDependencyError(self.name, extra)
-
-        Spec.inject_patches_variant(self)
-
-        for s in self.traverse():
-            # TODO: Refactor this into a common method to build external specs
-            # TODO: or turn external_path into a lazy property
-            Spec.ensure_external_path_if_external(s)
-
-        # assign hashes and mark concrete
-        self._finalize_concretization()
-
-        # If any spec in the DAG is deprecated, throw an error
-        Spec.ensure_no_deprecated(self)
-
-        # Update externals as needed
-        for dep in self.traverse():
-            if dep.external:
-                dep.package.update_external_dependencies()
-
-        # Now that the spec is concrete we should check if
-        # there are declared conflicts
-        #
-        # TODO: this needs rethinking, as currently we can only express
-        # TODO: internal configuration conflicts within one package.
-        matches = []
-        for x in self.traverse():
-            if x.external:
-                # external specs are already built, don't worry about whether
-                # it's possible to build that configuration with Spack
-                continue
-
-            for when_spec, conflict_list in x.package_class.conflicts.items():
-                if x.satisfies(when_spec):
-                    for conflict_spec, msg in conflict_list:
-                        if x.satisfies(conflict_spec):
-                            when = when_spec.copy()
-                            when.name = x.name
-                            matches.append((x, conflict_spec, when, msg))
-        if matches:
-            raise ConflictsInSpecError(self, matches)
-
-        # Check if we can produce an optimized binary (will throw if
-        # there are declared inconsistencies)
-        self.architecture.target.optimization_flags(self.compiler)
-
     def _patches_assigned(self):
         """Whether patches have been assigned to this spec by the concretizer."""
         # FIXME: _patches_in_order_of_appearance is attached after concretization
@@ -3032,7 +2749,13 @@ def ensure_no_deprecated(root):
             msg += "    For each package listed, choose another spec\n"
             raise SpecDeprecatedError(msg)
 
-    def _new_concretize(self, tests=False):
+    def concretize(self, tests: Union[bool, List[str]] = False) -> None:
+        """Concretize the current spec.
+
+        Args:
+            tests: if False disregard 'test' dependencies, if a list of names activate them for
+                the packages in the list, if True activate 'test' dependencies for all packages.
+        """
         import spack.solver.asp
 
         self.replace_hash()
@@ -3066,19 +2789,6 @@ def _new_concretize(self, tests=False):
         concretized = answer[node]
         self._dup(concretized)
 
-    def concretize(self, tests=False):
-        """Concretize the current spec.
-
-        Args:
-            tests (bool or list): if False disregard 'test' dependencies,
-                if a list of names activate them for the packages in the list,
-                if True activate 'test' dependencies for all packages.
-        """
-        if spack.config.get("config:concretizer", "clingo") == "clingo":
-            self._new_concretize(tests)
-        else:
-            self._old_concretize(tests)
-
     def _mark_root_concrete(self, value=True):
         """Mark just this spec (not dependencies) concrete."""
         if (not value) and self.concrete and self.installed:
@@ -3182,34 +2892,6 @@ def concretized(self, tests=False):
         clone.concretize(tests=tests)
         return clone
 
-    def flat_dependencies(self, disconnect: bool = False):
-        """Build DependencyMap of all of this spec's dependencies with their constraints merged.
-
-        Arguments:
-            disconnect: if True, disconnect all dependents and dependencies among nodes in this
-                spec's DAG.
-        """
-        flat_deps = {}
-        deptree = self.traverse(root=False)
-
-        for spec in deptree:
-            if spec.name not in flat_deps:
-                flat_deps[spec.name] = spec
-            else:
-                try:
-                    flat_deps[spec.name].constrain(spec)
-                except spack.error.UnsatisfiableSpecError as e:
-                    # DAG contains two instances of the same package with inconsistent constraints.
-                    raise InconsistentSpecError("Invalid Spec DAG: %s" % e.message) from e
-
-        if disconnect:
-            for spec in flat_deps.values():
-                if not spec.concrete:
-                    spec.clear_edges()
-            self.clear_dependencies()
-
-        return flat_deps
-
     def index(self, deptype="all"):
         """Return a dictionary that points to all the dependencies in this
         spec.
@@ -3219,312 +2901,6 @@ def index(self, deptype="all"):
             dm[spec.name].append(spec)
         return dm
 
-    def _evaluate_dependency_conditions(self, name):
-        """Evaluate all the conditions on a dependency with this name.
-
-        Args:
-            name (str): name of dependency to evaluate conditions on.
-
-        Returns:
-            (Dependency): new Dependency object combining all constraints.
-
-        If the package depends on <name> in the current spec
-        configuration, return the constrained dependency and
-        corresponding dependency types.
-
-        If no conditions are True (and we don't depend on it), return
-        ``(None, None)``.
-        """
-        vt.substitute_abstract_variants(self)
-        # evaluate when specs to figure out constraints on the dependency.
-        dep = None
-        for when_spec, deps_by_name in self.package_class.dependencies.items():
-            if not self.satisfies(when_spec):
-                continue
-
-            for dep_name, dependency in deps_by_name.items():
-                if dep_name != name:
-                    continue
-
-                if dep is None:
-                    dep = dp.Dependency(Spec(self.name), Spec(name), depflag=0)
-                try:
-                    dep.merge(dependency)
-                except spack.error.UnsatisfiableSpecError as e:
-                    e.message = (
-                        "Conflicting conditional dependencies for spec"
-                        "\n\n\t{0}\n\n"
-                        "Cannot merge constraint"
-                        "\n\n\t{1}\n\n"
-                        "into"
-                        "\n\n\t{2}".format(self, dependency.spec, dep.spec)
-                    )
-                    raise e
-
-        return dep
-
-    def _find_provider(self, vdep, provider_index):
-        """Find provider for a virtual spec in the provider index.
-        Raise an exception if there is a conflicting virtual
-        dependency already in this spec.
-        """
-        assert spack.repo.PATH.is_virtual_safe(vdep.name), vdep
-
-        # note that this defensively copies.
-        providers = provider_index.providers_for(vdep)
-
-        # If there is a provider for the vpkg, then use that instead of
-        # the virtual package.
-        if providers:
-            # Remove duplicate providers that can concretize to the same
-            # result.
-            for provider in providers:
-                for spec in providers:
-                    if spec is not provider and provider.intersects(spec):
-                        providers.remove(spec)
-            # Can't have multiple providers for the same thing in one spec.
-            if len(providers) > 1:
-                raise MultipleProviderError(vdep, providers)
-            return providers[0]
-        else:
-            # The user might have required something insufficient for
-            # pkg_dep -- so we'll get a conflict.  e.g., user asked for
-            # mpi@:1.1 but some package required mpi@2.1:.
-            required = provider_index.providers_for(vdep.name)
-            if len(required) > 1:
-                raise MultipleProviderError(vdep, required)
-            elif required:
-                raise UnsatisfiableProviderSpecError(required[0], vdep)
-
-    def _merge_dependency(self, dependency, visited, spec_deps, provider_index, tests):
-        """Merge dependency information from a Package into this Spec.
-
-        Args:
-            dependency (Dependency): dependency metadata from a package;
-                this is typically the result of merging *all* matching
-                dependency constraints from the package.
-            visited (set): set of dependency nodes already visited by
-                ``normalize()``.
-            spec_deps (dict): ``dict`` of all dependencies from the spec
-                being normalized.
-            provider_index (dict): ``provider_index`` of virtual dep
-                providers in the ``Spec`` as normalized so far.
-
-        NOTE: Caller should assume that this routine owns the
-        ``dependency`` parameter, i.e., it needs to be a copy of any
-        internal structures.
-
-        This is the core of ``normalize()``.  There are some basic steps:
-
-          * If dep is virtual, evaluate whether it corresponds to an
-            existing concrete dependency, and merge if so.
-
-          * If it's real and it provides some virtual dep, see if it provides
-            what some virtual dependency wants and merge if so.
-
-          * Finally, if none of the above, merge dependency and its
-            constraints into this spec.
-
-        This method returns True if the spec was changed, False otherwise.
-
-        """
-        changed = False
-        dep = dependency.spec
-
-        # If it's a virtual dependency, try to find an existing
-        # provider in the spec, and merge that.
-        virtuals = ()
-        if spack.repo.PATH.is_virtual_safe(dep.name):
-            virtuals = (dep.name,)
-            visited.add(dep.name)
-            provider = self._find_provider(dep, provider_index)
-            if provider:
-                dep = provider
-        else:
-            index = spack.provider_index.ProviderIndex(
-                repository=spack.repo.PATH, specs=[dep], restrict=True
-            )
-            items = list(spec_deps.items())
-            for name, vspec in items:
-                if not spack.repo.PATH.is_virtual_safe(vspec.name):
-                    continue
-
-                if index.providers_for(vspec):
-                    vspec._replace_with(dep)
-                    del spec_deps[vspec.name]
-                    changed = True
-                else:
-                    required = index.providers_for(vspec.name)
-                    if required:
-                        raise UnsatisfiableProviderSpecError(required[0], dep)
-            provider_index.update(dep)
-
-        # If the spec isn't already in the set of dependencies, add it.
-        # Note: dep is always owned by this method. If it's from the
-        # caller, it's a copy from _evaluate_dependency_conditions. If it
-        # comes from a vdep, it's a defensive copy from _find_provider.
-        if dep.name not in spec_deps:
-            if self.concrete:
-                return False
-
-            spec_deps[dep.name] = dep
-            changed = True
-        else:
-            # merge package/vdep information into spec
-            try:
-                tty.debug("{0} applying constraint {1}".format(self.name, str(dep)))
-                changed |= spec_deps[dep.name].constrain(dep)
-            except spack.error.UnsatisfiableSpecError as e:
-                fmt = "An unsatisfiable {0}".format(e.constraint_type)
-                fmt += " constraint has been detected for spec:"
-                fmt += "\n\n{0}\n\n".format(spec_deps[dep.name].tree(indent=4))
-                fmt += "while trying to concretize the partial spec:"
-                fmt += "\n\n{0}\n\n".format(self.tree(indent=4))
-                fmt += "{0} requires {1} {2} {3}, but spec asked for {4}"
-
-                e.message = fmt.format(
-                    self.name, dep.name, e.constraint_type, e.required, e.provided
-                )
-
-                raise
-
-        # Add merged spec to my deps and recurse
-        spec_dependency = spec_deps[dep.name]
-        if dep.name not in self._dependencies:
-            self._add_dependency(spec_dependency, depflag=dependency.depflag, virtuals=virtuals)
-
-        changed |= spec_dependency._normalize_helper(visited, spec_deps, provider_index, tests)
-        return changed
-
-    def _normalize_helper(self, visited, spec_deps, provider_index, tests):
-        """Recursive helper function for _normalize."""
-        if self.name in visited:
-            return False
-        visited.add(self.name)
-
-        # If we descend into a virtual spec, there's nothing more
-        # to normalize.  Concretize will finish resolving it later.
-        if self.virtual or self.external:
-            return False
-
-        # Avoid recursively adding constraints for already-installed packages:
-        # these may include build dependencies which are not needed for this
-        # install (since this package is already installed).
-        if self.concrete and self.installed:
-            return False
-
-        # Combine constraints from package deps with constraints from
-        # the spec, until nothing changes.
-        any_change = False
-        changed = True
-
-        while changed:
-            changed = False
-            for dep_name in self.package_class.dependency_names():
-                # Do we depend on dep_name?  If so pkg_dep is not None.
-                dep = self._evaluate_dependency_conditions(dep_name)
-
-                # If dep is a needed dependency, merge it.
-                if dep:
-                    merge = (
-                        # caller requested test dependencies
-                        tests is True
-                        or (tests and self.name in tests)
-                        or
-                        # this is not a test-only dependency
-                        (dep.depflag & ~dt.TEST)
-                    )
-
-                    if merge:
-                        changed |= self._merge_dependency(
-                            dep, visited, spec_deps, provider_index, tests
-                        )
-            any_change |= changed
-
-        return any_change
-
-    def normalize(self, force=False, tests=False, user_spec_deps=None, disconnect=True):
-        """When specs are parsed, any dependencies specified are hanging off
-        the root, and ONLY the ones that were explicitly provided are there.
-        Normalization turns a partial flat spec into a DAG, where:
-
-        1. Known dependencies of the root package are in the DAG.
-        2. Each node's dependencies dict only contains its known direct
-           deps.
-        3. There is only ONE unique spec for each package in the DAG.
-
-           * This includes virtual packages.  If there a non-virtual
-             package that provides a virtual package that is in the spec,
-             then we replace the virtual package with the non-virtual one.
-
-        TODO: normalize should probably implement some form of cycle
-        detection, to ensure that the spec is actually a DAG.
-        """
-        if not self.name:
-            raise spack.error.SpecError("Attempting to normalize anonymous spec")
-
-        # Set _normal and _concrete to False when forced
-        if force and not self._concrete:
-            self._normal = False
-
-        if self._normal:
-            return False
-
-        # Ensure first that all packages & compilers in the DAG exist.
-        self.validate_or_raise()
-        # Clear the DAG and collect all dependencies in the DAG, which will be
-        # reapplied as constraints. All dependencies collected this way will
-        # have been created by a previous execution of 'normalize'.
-        # A dependency extracted here will only be reintegrated if it is
-        # discovered to apply according to _normalize_helper, so
-        # user-specified dependencies are recorded separately in case they
-        # refer to specs which take several normalization passes to
-        # materialize.
-        all_spec_deps = self.flat_dependencies(disconnect=disconnect)
-
-        if user_spec_deps:
-            for name, spec in user_spec_deps.items():
-                if not name:
-                    msg = "Attempted to normalize anonymous dependency spec"
-                    msg += " %s" % spec
-                    raise InvalidSpecDetected(msg)
-                if name not in all_spec_deps:
-                    all_spec_deps[name] = spec
-                else:
-                    all_spec_deps[name].constrain(spec)
-
-        # Initialize index of virtual dependency providers if
-        # concretize didn't pass us one already
-        provider_index = spack.provider_index.ProviderIndex(
-            repository=spack.repo.PATH, specs=[s for s in all_spec_deps.values()], restrict=True
-        )
-
-        # traverse the package DAG and fill out dependencies according
-        # to package files & their 'when' specs
-        visited = set()
-
-        any_change = self._normalize_helper(visited, all_spec_deps, provider_index, tests)
-
-        # remove any leftover dependents outside the spec from, e.g., pruning externals
-        valid = {id(spec) for spec in all_spec_deps.values()} | {id(self)}
-        for spec in all_spec_deps.values():
-            remove = [dep for dep in spec.dependents() if id(dep) not in valid]
-            for dep in remove:
-                del spec._dependents.edges[dep.name]
-                del dep._dependencies.edges[spec.name]
-
-        # Mark the spec as normal once done.
-        self._normal = True
-        return any_change
-
-    def normalized(self):
-        """
-        Return a normalized copy of this spec without modifying this spec.
-        """
-        clone = self.copy()
-        clone.normalize()
-        return clone
-
     def validate_or_raise(self):
         """Checks that names and values in this spec are real. If they're not,
         it will raise an appropriate exception.
@@ -3545,7 +2921,7 @@ def validate_or_raise(self):
             # Ensure correctness of variants (if the spec is not virtual)
             if not spec.virtual:
                 Spec.ensure_valid_variants(spec)
-                vt.substitute_abstract_variants(spec)
+                substitute_abstract_variants(spec)
 
     @staticmethod
     def ensure_valid_variants(spec):
@@ -3565,9 +2941,7 @@ def ensure_valid_variants(spec):
         pkg_variants = pkg_cls.variants
         # reserved names are variants that may be set on any package
         # but are not necessarily recorded by the package's class
-        not_existing = set(spec.variants) - (
-            set(pkg_variants) | set(spack.directives.reserved_names)
-        )
+        not_existing = set(spec.variants) - (set(pkg_variants) | set(vt.reserved_names))
         if not_existing:
             raise vt.UnknownVariantError(spec, not_existing)
 
@@ -4516,7 +3890,7 @@ def format_attribute(match_object: Match) -> str:
                 if part.startswith("_"):
                     raise SpecFormatStringError("Attempted to format private attribute")
                 else:
-                    if part == "variants" and isinstance(current, vt.VariantMap):
+                    if part == "variants" and isinstance(current, VariantMap):
                         # subscript instead of getattr for variant names
                         current = current[part]
                     else:
@@ -4971,9 +4345,155 @@ def attach_git_version_lookup(self):
                 v.attach_lookup(spack.version.git_ref_lookup.GitRefLookup(self.fullname))
 
 
-def parse_with_version_concrete(string: str, compiler: bool = False):
+class VariantMap(lang.HashableMap):
+    """Map containing variant instances. New values can be added only
+    if the key is not already present."""
+
+    def __init__(self, spec: Spec):
+        super().__init__()
+        self.spec = spec
+
+    def __setitem__(self, name, vspec):
+        # Raise a TypeError if vspec is not of the right type
+        if not isinstance(vspec, vt.AbstractVariant):
+            raise TypeError(
+                "VariantMap accepts only values of variant types "
+                f"[got {type(vspec).__name__} instead]"
+            )
+
+        # Raise an error if the variant was already in this map
+        if name in self.dict:
+            msg = 'Cannot specify variant "{0}" twice'.format(name)
+            raise vt.DuplicateVariantError(msg)
+
+        # Raise an error if name and vspec.name don't match
+        if name != vspec.name:
+            raise KeyError(
+                f'Inconsistent key "{name}", must be "{vspec.name}" to ' "match VariantSpec"
+            )
+
+        # Set the item
+        super().__setitem__(name, vspec)
+
+    def substitute(self, vspec):
+        """Substitutes the entry under ``vspec.name`` with ``vspec``.
+
+        Args:
+            vspec: variant spec to be substituted
+        """
+        if vspec.name not in self:
+            raise KeyError(f"cannot substitute a key that does not exist [{vspec.name}]")
+
+        # Set the item
+        super().__setitem__(vspec.name, vspec)
+
+    def satisfies(self, other):
+        return all(k in self and self[k].satisfies(other[k]) for k in other)
+
+    def intersects(self, other):
+        return all(self[k].intersects(other[k]) for k in other if k in self)
+
+    def constrain(self, other: "VariantMap") -> bool:
+        """Add all variants in other that aren't in self to self. Also constrain all multi-valued
+        variants that are already present. Return True iff self changed"""
+        if other.spec is not None and other.spec._concrete:
+            for k in self:
+                if k not in other:
+                    raise vt.UnsatisfiableVariantSpecError(self[k], "<absent>")
+
+        changed = False
+        for k in other:
+            if k in self:
+                # If they are not compatible raise an error
+                if not self[k].compatible(other[k]):
+                    raise vt.UnsatisfiableVariantSpecError(self[k], other[k])
+                # If they are compatible merge them
+                changed |= self[k].constrain(other[k])
+            else:
+                # If it is not present copy it straight away
+                self[k] = other[k].copy()
+                changed = True
+
+        return changed
+
+    @property
+    def concrete(self):
+        """Returns True if the spec is concrete in terms of variants.
+
+        Returns:
+            bool: True or False
+        """
+        return self.spec._concrete or all(v in self for v in self.spec.package_class.variants)
+
+    def copy(self) -> "VariantMap":
+        clone = VariantMap(self.spec)
+        for name, variant in self.items():
+            clone[name] = variant.copy()
+        return clone
+
+    def __str__(self):
+        if not self:
+            return ""
+
+        # print keys in order
+        sorted_keys = sorted(self.keys())
+
+        # Separate boolean variants from key-value pairs as they print
+        # differently. All booleans go first to avoid ' ~foo' strings that
+        # break spec reuse in zsh.
+        bool_keys = []
+        kv_keys = []
+        for key in sorted_keys:
+            bool_keys.append(key) if isinstance(self[key].value, bool) else kv_keys.append(key)
+
+        # add spaces before and after key/value variants.
+        string = io.StringIO()
+
+        for key in bool_keys:
+            string.write(str(self[key]))
+
+        for key in kv_keys:
+            string.write(" ")
+            string.write(str(self[key]))
+
+        return string.getvalue()
+
+
+def substitute_abstract_variants(spec: Spec):
+    """Uses the information in `spec.package` to turn any variant that needs
+    it into a SingleValuedVariant.
+
+    This method is best effort. All variants that can be substituted will be
+    substituted before any error is raised.
+
+    Args:
+        spec: spec on which to operate the substitution
+    """
+    # This method needs to be best effort so that it works in matrix exlusion
+    # in $spack/lib/spack/spack/spec_list.py
+    failed = []
+    for name, v in spec.variants.items():
+        if name == "dev_path":
+            spec.variants.substitute(vt.SingleValuedVariant(name, v._original_value))
+            continue
+        elif name in vt.reserved_names:
+            continue
+        elif name not in spec.package_class.variants:
+            failed.append(name)
+            continue
+        pkg_variant, _ = spec.package_class.variants[name]
+        new_variant = pkg_variant.make_variant(v._original_value)
+        pkg_variant.validate_or_raise(new_variant, spec.package_class)
+        spec.variants.substitute(new_variant)
+
+    # Raise all errors at once
+    if failed:
+        raise vt.UnknownVariantError(spec, failed)
+
+
+def parse_with_version_concrete(spec_like: Union[str, Spec], compiler: bool = False):
     """Same as Spec(string), but interprets @x as @=x"""
-    s: Union[CompilerSpec, Spec] = CompilerSpec(string) if compiler else Spec(string)
+    s: Union[CompilerSpec, Spec] = CompilerSpec(spec_like) if compiler else Spec(spec_like)
     interpreted_version = s.versions.concrete_range_as_version
     if interpreted_version:
         s.versions = vn.VersionList([interpreted_version])

lib/spack/spack/spec_list.py

@@ -5,6 +5,7 @@
 import itertools
 from typing import List
 
+import spack.spec
 import spack.variant
 from spack.error import SpackError
 from spack.spec import Spec
@@ -225,7 +226,7 @@ def _expand_matrix_constraints(matrix_config):
         # Catch exceptions because we want to be able to operate on
         # abstract specs without needing package information
         try:
-            spack.variant.substitute_abstract_variants(test_spec)
+            spack.spec.substitute_abstract_variants(test_spec)
         except spack.variant.UnknownVariantError:
             pass
 

lib/spack/spack/stage.py

@@ -13,7 +13,7 @@
 import stat
 import sys
 import tempfile
-from typing import Callable, Dict, Iterable, Optional, Set
+from typing import Callable, Dict, Generator, Iterable, List, Optional, Set
 
 import llnl.string
 import llnl.util.lang
@@ -40,6 +40,7 @@
 import spack.resource
 import spack.spec
 import spack.stage
+import spack.util.crypto
 import spack.util.lock
 import spack.util.path as sup
 import spack.util.pattern as pattern
@@ -351,8 +352,10 @@ class Stage(LockableStagingDir):
     def __init__(
         self,
         url_or_fetch_strategy,
+        *,
         name=None,
-        mirror_paths=None,
+        mirror_paths: Optional[spack.mirror.MirrorLayout] = None,
+        mirrors: Optional[Iterable[spack.mirror.Mirror]] = None,
         keep=False,
         path=None,
         lock=True,
@@ -361,36 +364,30 @@ def __init__(
         """Create a stage object.
         Parameters:
           url_or_fetch_strategy
-              URL of the archive to be downloaded into this stage, OR
-              a valid FetchStrategy.
+              URL of the archive to be downloaded into this stage, OR a valid FetchStrategy.
 
           name
-              If a name is provided, then this stage is a named stage
-              and will persist between runs (or if you construct another
-              stage object later).  If name is not provided, then this
+              If a name is provided, then this stage is a named stage and will persist between runs
+              (or if you construct another stage object later).  If name is not provided, then this
               stage will be given a unique name automatically.
 
           mirror_paths
-              If provided, Stage will search Spack's mirrors for
-              this archive at each of the provided relative mirror paths
-              before using the default fetch strategy.
+              If provided, Stage will search Spack's mirrors for this archive at each of the
+              provided relative mirror paths before using the default fetch strategy.
 
           keep
-              By default, when used as a context manager, the Stage
-              is deleted on exit when no exceptions are raised.
-              Pass True to keep the stage intact even if no
-              exceptions are raised.
+              By default, when used as a context manager, the Stage is deleted on exit when no
+              exceptions are raised. Pass True to keep the stage intact even if no exceptions are
+              raised.
 
          path
               If provided, the stage path to use for associated builds.
 
          lock
-              True if the stage directory file lock is to be used, False
-              otherwise.
+              True if the stage directory file lock is to be used, False otherwise.
 
          search_fn
-              The search function that provides the fetch strategy
-              instance.
+              The search function that provides the fetch strategy instance.
         """
         super().__init__(name, path, keep, lock)
 
@@ -406,30 +403,37 @@ def __init__(
         # self.fetcher can change with mirrors.
         self.default_fetcher = self.fetcher
         self.search_fn = search_fn
-        # used for mirrored archives of repositories.
-        self.skip_checksum_for_mirror = True
+        # If we fetch from a mirror, but the original data is from say git, we can currently not
+        # prove that they are equal (we don't even have a tree hash in package.py). This bool is
+        # used to skip checksum verification and instead warn the user.
+        if isinstance(self.default_fetcher, fs.URLFetchStrategy):
+            self.skip_checksum_for_mirror = not bool(self.default_fetcher.digest)
+        else:
+            self.skip_checksum_for_mirror = True
 
         self.srcdir = None
 
-        self.mirror_paths = mirror_paths
+        self.mirror_layout = mirror_paths
+        self.mirrors = list(mirrors) if mirrors else []
+        # Allow users the disable both mirrors and download cache
+        self.default_fetcher_only = False
 
     @property
     def expected_archive_files(self):
         """Possible archive file paths."""
-        paths = []
         fnames = []
         expanded = True
         if isinstance(self.default_fetcher, fs.URLFetchStrategy):
             expanded = self.default_fetcher.expand_archive
             fnames.append(url_util.default_download_filename(self.default_fetcher.url))
 
-        if self.mirror_paths:
-            fnames.extend(os.path.basename(x) for x in self.mirror_paths)
+        if self.mirror_layout:
+            fnames.append(os.path.basename(self.mirror_layout.path))
 
-        paths.extend(os.path.join(self.path, f) for f in fnames)
+        paths = [os.path.join(self.path, f) for f in fnames]
         if not expanded:
-            # If the download file is not compressed, the "archive" is a
-            # single file placed in Stage.source_path
+            # If the download file is not compressed, the "archive" is a single file placed in
+            # Stage.source_path
             paths.extend(os.path.join(self.source_path, f) for f in fnames)
 
         return paths
@@ -462,104 +466,84 @@ def source_path(self):
         """Returns the well-known source directory path."""
         return os.path.join(self.path, _source_path_subdir)
 
-    def disable_mirrors(self):
-        """The Stage will not attempt to look for the associated fetcher
-        target in any of Spack's mirrors (including the local download cache).
-        """
-        self.mirror_paths = []
-
-    def fetch(self, mirror_only=False, err_msg=None):
-        """Retrieves the code or archive
-
-        Args:
-            mirror_only (bool): only fetch from a mirror
-            err_msg (str or None): the error message to display if all fetchers
-                fail or ``None`` for the default fetch failure message
-        """
-        fetchers = []
+    def _generate_fetchers(self, mirror_only=False) -> Generator[fs.FetchStrategy, None, None]:
+        fetchers: List[fs.FetchStrategy] = []
         if not mirror_only:
             fetchers.append(self.default_fetcher)
 
+        # If this archive is normally fetched from a URL, then use the same digest.
+        if isinstance(self.default_fetcher, fs.URLFetchStrategy):
+            digest = self.default_fetcher.digest
+            expand = self.default_fetcher.expand_archive
+            extension = self.default_fetcher.extension
+        else:
+            digest = None
+            expand = True
+            extension = None
+
         # TODO: move mirror logic out of here and clean it up!
         # TODO: Or @alalazo may have some ideas about how to use a
         # TODO: CompositeFetchStrategy here.
-        self.skip_checksum_for_mirror = True
-        if self.mirror_paths:
-            # Join URLs of mirror roots with mirror paths. Because
-            # urljoin() will strip everything past the final '/' in
-            # the root, so we add a '/' if it is not present.
-            mirror_urls = [
-                url_util.join(mirror.fetch_url, rel_path)
-                for mirror in spack.mirror.MirrorCollection(source=True).values()
-                if not mirror.fetch_url.startswith("oci://")
-                for rel_path in self.mirror_paths
-            ]
-
-            # If this archive is normally fetched from a tarball URL,
-            # then use the same digest.  `spack mirror` ensures that
-            # the checksum will be the same.
-            digest = None
-            expand = True
-            extension = None
-            if isinstance(self.default_fetcher, fs.URLFetchStrategy):
-                digest = self.default_fetcher.digest
-                expand = self.default_fetcher.expand_archive
-                extension = self.default_fetcher.extension
-
-            # Have to skip the checksum for things archived from
-            # repositories.  How can this be made safer?
-            self.skip_checksum_for_mirror = not bool(digest)
-
+        if not self.default_fetcher_only and self.mirror_layout and self.mirrors:
             # Add URL strategies for all the mirrors with the digest
             # Insert fetchers in the order that the URLs are provided.
-            for url in reversed(mirror_urls):
-                fetchers.insert(
-                    0, fs.from_url_scheme(url, digest, expand=expand, extension=extension)
+            fetchers[:0] = (
+                fs.from_url_scheme(
+                    url_util.join(mirror.fetch_url, self.mirror_layout.path),
+                    checksum=digest,
+                    expand=expand,
+                    extension=extension,
                 )
+                for mirror in self.mirrors
+                if not mirror.fetch_url.startswith("oci://")  # no support for mirrors yet
+            )
 
-            if self.default_fetcher.cachable:
-                for rel_path in reversed(list(self.mirror_paths)):
-                    cache_fetcher = spack.caches.FETCH_CACHE.fetcher(
-                        rel_path, digest, expand=expand, extension=extension
-                    )
-                    fetchers.insert(0, cache_fetcher)
+        if not self.default_fetcher_only and self.mirror_layout and self.default_fetcher.cachable:
+            fetchers.insert(
+                0,
+                spack.caches.FETCH_CACHE.fetcher(
+                    self.mirror_layout.path, digest, expand=expand, extension=extension
+                ),
+            )
 
-        def generate_fetchers():
-            for fetcher in fetchers:
-                yield fetcher
-            # The search function may be expensive, so wait until now to
-            # call it so the user can stop if a prior fetcher succeeded
-            if self.search_fn and not mirror_only:
-                dynamic_fetchers = self.search_fn()
-                for fetcher in dynamic_fetchers:
-                    yield fetcher
+        yield from fetchers
 
-        def print_errors(errors):
-            for msg in errors:
-                tty.debug(msg)
+        # The search function may be expensive, so wait until now to call it so the user can stop
+        # if a prior fetcher succeeded
+        if self.search_fn and not mirror_only:
+            yield from self.search_fn()
 
-        errors = []
-        for fetcher in generate_fetchers():
+    def fetch(self, mirror_only: bool = False, err_msg: Optional[str] = None) -> None:
+        """Retrieves the code or archive
+
+        Args:
+            mirror_only: only fetch from a mirror
+            err_msg: the error message to display if all fetchers fail or ``None`` for the default
+                fetch failure message
+        """
+        errors: List[str] = []
+        for fetcher in self._generate_fetchers(mirror_only):
             try:
                 fetcher.stage = self
                 self.fetcher = fetcher
                 self.fetcher.fetch()
                 break
-            except spack.fetch_strategy.NoCacheError:
+            except fs.NoCacheError:
                 # Don't bother reporting when something is not cached.
                 continue
+            except fs.FailedDownloadError as f:
+                errors.extend(f"{fetcher}: {e.__class__.__name__}: {e}" for e in f.exceptions)
+                continue
             except spack.error.SpackError as e:
-                errors.append("Fetching from {0} failed.".format(fetcher))
-                tty.debug(e)
+                errors.append(f"{fetcher}: {e.__class__.__name__}: {e}")
                 continue
         else:
-            print_errors(errors)
-
             self.fetcher = self.default_fetcher
-            default_msg = "All fetchers failed for {0}".format(self.name)
-            raise spack.error.FetchError(err_msg or default_msg, None)
-
-        print_errors(errors)
+            if err_msg:
+                raise spack.error.FetchError(err_msg)
+            raise spack.error.FetchError(
+                f"All fetchers failed for {self.name}", "\n".join(f"    {e}" for e in errors)
+            )
 
     def steal_source(self, dest):
         """Copy the source_path directory in its entirety to directory dest
@@ -597,56 +581,60 @@ def steal_source(self, dest):
         self.destroy()
 
     def check(self):
-        """Check the downloaded archive against a checksum digest.
-        No-op if this stage checks code out of a repository."""
+        """Check the downloaded archive against a checksum digest."""
         if self.fetcher is not self.default_fetcher and self.skip_checksum_for_mirror:
+            cache = isinstance(self.fetcher, fs.CacheURLFetchStrategy)
+            if cache:
+                secure_msg = "your download cache is in a secure location"
+            else:
+                secure_msg = "you trust this mirror and have a secure connection"
             tty.warn(
-                "Fetching from mirror without a checksum!",
-                "This package is normally checked out from a version "
-                "control system, but it has been archived on a spack "
-                "mirror.  This means we cannot know a checksum for the "
-                "tarball in advance. Be sure that your connection to "
-                "this mirror is secure!",
+                f"Using {'download cache' if cache else 'a mirror'} instead of version control",
+                "The required sources are normally checked out from a version control system, "
+                f"but have been archived {'in download cache' if cache else 'on a mirror'}: "
+                f"{self.fetcher}. Spack lacks a tree hash to verify the integrity of this "
+                f"archive. Make sure {secure_msg}.",
             )
         elif spack.config.get("config:checksum"):
             self.fetcher.check()
 
     def cache_local(self):
-        spack.caches.FETCH_CACHE.store(self.fetcher, self.mirror_paths.storage_path)
+        spack.caches.FETCH_CACHE.store(self.fetcher, self.mirror_layout.path)
 
-    def cache_mirror(self, mirror, stats):
+    def cache_mirror(
+        self, mirror: spack.caches.MirrorCache, stats: spack.mirror.MirrorStats
+    ) -> None:
         """Perform a fetch if the resource is not already cached
 
         Arguments:
-            mirror (spack.caches.MirrorCache): the mirror to cache this Stage's
-                resource in
-            stats (spack.mirror.MirrorStats): this is updated depending on whether the
-                caching operation succeeded or failed
+            mirror: the mirror to cache this Stage's resource in
+            stats: this is updated depending on whether the caching operation succeeded or failed
         """
         if isinstance(self.default_fetcher, fs.BundleFetchStrategy):
-            # BundleFetchStrategy has no source to fetch. The associated
-            # fetcher does nothing but the associated stage may still exist.
-            # There is currently no method available on the fetcher to
-            # distinguish this ('cachable' refers to whether the fetcher
-            # refers to a resource with a fixed ID, which is not the same
-            # concept as whether there is anything to fetch at all) so we
-            # must examine the type of the fetcher.
+            # BundleFetchStrategy has no source to fetch. The associated fetcher does nothing but
+            # the associated stage may still exist. There is currently no method available on the
+            # fetcher to distinguish this ('cachable' refers to whether the fetcher refers to a
+            # resource with a fixed ID, which is not the same concept as whether there is anything
+            # to fetch at all) so we must examine the type of the fetcher.
             return
 
-        if mirror.skip_unstable_versions and not fs.stable_target(self.default_fetcher):
+        elif mirror.skip_unstable_versions and not fs.stable_target(self.default_fetcher):
             return
 
-        absolute_storage_path = os.path.join(mirror.root, self.mirror_paths.storage_path)
+        elif not self.mirror_layout:
+            return
+
+        absolute_storage_path = os.path.join(mirror.root, self.mirror_layout.path)
 
         if os.path.exists(absolute_storage_path):
             stats.already_existed(absolute_storage_path)
         else:
             self.fetch()
             self.check()
-            mirror.store(self.fetcher, self.mirror_paths.storage_path)
+            mirror.store(self.fetcher, self.mirror_layout.path)
             stats.added(absolute_storage_path)
 
-        mirror.symlink(self.mirror_paths)
+        self.mirror_layout.make_alias(mirror.root)
 
     def expand_archive(self):
         """Changes to the stage directory and attempt to expand the downloaded
@@ -654,9 +642,9 @@ def expand_archive(self):
         downloaded."""
         if not self.expanded:
             self.fetcher.expand()
-            tty.debug("Created stage in {0}".format(self.path))
+            tty.debug(f"Created stage in {self.path}")
         else:
-            tty.debug("Already staged {0} in {1}".format(self.name, self.path))
+            tty.debug(f"Already staged {self.name} in {self.path}")
 
     def restage(self):
         """Removes the expanded archive path if it exists, then re-expands
@@ -1175,20 +1163,22 @@ def _fetch_and_checksum(url, options, keep_stage, action_fn=None):
     try:
         url_or_fs = url
         if options:
-            url_or_fs = fs.URLFetchStrategy(url, fetch_options=options)
+            url_or_fs = fs.URLFetchStrategy(url=url, fetch_options=options)
 
         with Stage(url_or_fs, keep=keep_stage) as stage:
             # Fetch the archive
             stage.fetch()
-            if action_fn is not None:
+            archive = stage.archive_file
+            assert archive is not None, f"Archive not found for {url}"
+            if action_fn is not None and archive:
                 # Only run first_stage_function the first time,
                 # no need to run it every time
-                action_fn(stage, url)
+                action_fn(archive, url)
 
             # Checksum the archive and add it to the list
-            checksum = spack.util.crypto.checksum(hashlib.sha256, stage.archive_file)
+            checksum = spack.util.crypto.checksum(hashlib.sha256, archive)
         return checksum, None
-    except FailedDownloadError:
+    except fs.FailedDownloadError:
         return None, f"[WORKER] Failed to fetch {url}"
     except Exception as e:
         return None, f"[WORKER] Something failed on {url}, skipping.  ({e})"
@@ -1208,7 +1198,3 @@ class RestageError(StageError):
 
 class VersionFetchError(StageError):
     """Raised when we can't determine a URL to fetch a package."""
-
-
-# Keep this in namespace for convenience
-FailedDownloadError = fs.FailedDownloadError