commit variant concretizes and check is commit

lib/spack/spack/solver/asp.py

@@ -3173,6 +3173,7 @@ def setup(
 
         self.gen.h1("Special variants")
         self.define_auto_variant("dev_path", multi=False)
+        self.define_auto_variant("commit", multi=False)
         self.define_auto_variant("patches", multi=True)
 
         self.gen.h1("Develop specs")
@@ -4140,6 +4141,10 @@ def build_specs(self, function_tuples):
                         spack.version.git_ref_lookup.GitRefLookup(spec.fullname)
                     )
 
+        # check for commits mush happen after all version adaptations are complete
+        for s in self._specs.values():
+            _specs_with_commits(s)
+
         specs = self.execute_explicit_splices()
         return specs
 
@@ -4266,6 +4271,37 @@ def _ensure_external_path_if_external(spec: spack.spec.Spec) -> None:
     )
 
 
+def _specs_with_commits(spec):
+    has_commit_var = "commit" in spec.variants
+    has_git_version = isinstance(spec.version, vn.GitVersion)
+
+    if not (has_commit_var or has_git_version):
+        return
+
+    # Specs with commit variants
+    # - variant value satsifies commit regex
+    # - paired to a GitVersion or can create GitVersion from version that was selected
+    # - variant value should match GitVersion's commit value
+    if has_commit_var:
+        invalid_commit_msg = (
+            f"Internal Error: {spec.name}'s assigned commit {spec.variants['commit'].value}"
+            " does not meet commit syntax requirements."
+        )
+
+        # TODO probably want a more specific function just for sha validation
+        assert vn.is_git_version(spec.variants["commit"].value), invalid_commit_msg
+
+    # Specs with GitVersions
+    # - must have a commit variant, or add it here
+    # - must have a commit on the GitVersion (enforce after look up implemented)
+    if has_git_version:
+        if not spec.version.commit_sha:
+            # TODO(psakiev) this will be a failure when commit look up is automated
+            return
+
+        spec.variants["commit"] = vt.SingleValuedVariant("commit", spec.version.commit_sha)
+
+
 def _develop_specs_from_env(spec, env):
     dev_info = env.dev_specs.get(spec.name, {}) if env else {}
     if not dev_info:

lib/spack/spack/spec.py

@@ -4615,7 +4615,7 @@ def substitute_abstract_variants(spec: Spec):
     # in $spack/lib/spack/spack/spec_list.py
     unknown = []
     for name, v in spec.variants.items():
-        if name == "dev_path":
+        if name in ("dev_path", "commit"):
             spec.variants.substitute(vt.SingleValuedVariant(name, v._original_value))
             continue
         elif name in vt.reserved_names:

lib/spack/spack/variant.py

@@ -24,6 +24,7 @@
 reserved_names = [
     "arch",
     "architecture",
+    "commit",
     "dev_path",
     "namespace",
     "operating_system",