conditional variant values: allow boolean (#33939)

3 files changed, 46 insertions, 17 deletions

diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index 9ff88af4df..1a22cf5c6f 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -1017,17 +1017,35 @@ class SpackSolverSetup(object):
                 values = [variant.default]
 
             for value in sorted(values):
+                if getattr(value, "when", True) is not True:  # when=True means unconditional
+                    condition_spec = spack.spec.Spec("{0}={1}".format(name, value))
+                    if value.when is False:
+                        # This value is a conflict
+                        # Cannot just prevent listing it as a possible value because it could
+                        # also come in as a possible value from the command line
+                        trigger_id = self.condition(
+                            condition_spec,
+                            name=pkg.name,
+                            msg="invalid variant value {0}={1}".format(name, value),
+                        )
+                        constraint_id = self.condition(
+                            spack.spec.Spec(),
+                            name=pkg.name,
+                            msg="empty (total) conflict constraint",
+                        )
+                        msg = "variant {0}={1} is conditionally disabled".format(name, value)
+                        self.gen.fact(fn.conflict(pkg.name, trigger_id, constraint_id, msg))
+                    else:
+                        imposed = spack.spec.Spec(value.when)
+                        imposed.name = pkg.name
+
+                        self.condition(
+                            required_spec=condition_spec,
+                            imposed_spec=imposed,
+                            name=pkg.name,
+                            msg="%s variant %s value %s when %s" % (pkg.name, name, value, when),
+                        )
                 self.gen.fact(fn.variant_possible_value(pkg.name, name, value))
-                if hasattr(value, "when"):
-                    required = spack.spec.Spec("{0}={1}".format(name, value))
-                    imposed = spack.spec.Spec(value.when)
-                    imposed.name = pkg.name
-                    self.condition(
-                        required_spec=required,
-                        imposed_spec=imposed,
-                        name=pkg.name,
-                        msg="%s variant %s value %s when %s" % (pkg.name, name, value, when),
-                    )
 
             if variant.sticky:
                 self.gen.fact(fn.variant_sticky(pkg.name, name))
diff --git a/lib/spack/spack/test/concretize.py b/lib/spack/spack/test/concretize.py
index 9afbf8f45b..55ad6a1b20 100644
--- a/lib/spack/spack/test/concretize.py
+++ b/lib/spack/spack/test/concretize.py
@@ -1481,21 +1481,25 @@ class TestConcretize(object):
         assert ver("2.7.21") == Spec("python@2.7.21").concretized().version
 
     @pytest.mark.parametrize(
-        "spec_str",
+        "spec_str,valid",
         [
-            "conditional-values-in-variant@1.62.0 cxxstd=17",
-            "conditional-values-in-variant@1.62.0 cxxstd=2a",
-            "conditional-values-in-variant@1.72.0 cxxstd=2a",
+            ("conditional-values-in-variant@1.62.0 cxxstd=17", False),
+            ("conditional-values-in-variant@1.62.0 cxxstd=2a", False),
+            ("conditional-values-in-variant@1.72.0 cxxstd=2a", False),
             # Ensure disjoint set of values work too
-            "conditional-values-in-variant@1.72.0 staging=flexpath",
+            ("conditional-values-in-variant@1.72.0 staging=flexpath", False),
+            # Ensure conditional values set False fail too
+            ("conditional-values-in-variant foo=bar", False),
+            ("conditional-values-in-variant foo=foo", True),
         ],
     )
-    def test_conditional_values_in_variants(self, spec_str):
+    def test_conditional_values_in_variants(self, spec_str, valid):
         if spack.config.get("config:concretizer") == "original":
             pytest.skip("Original concretizer doesn't resolve conditional values in variants")
 
         s = Spec(spec_str)
-        with pytest.raises((RuntimeError, spack.error.UnsatisfiableSpecError)):
+        raises = pytest.raises((RuntimeError, spack.error.UnsatisfiableSpecError))
+        with llnl.util.lang.nullcontext() if valid else raises:
             s.concretize()
 
     def test_conditional_values_in_conditional_variant(self):
diff --git a/var/spack/repos/builtin.mock/packages/conditional-values-in-variant/package.py b/var/spack/repos/builtin.mock/packages/conditional-values-in-variant/package.py
index 788141565d..3dedabe7b2 100644
--- a/var/spack/repos/builtin.mock/packages/conditional-values-in-variant/package.py
+++ b/var/spack/repos/builtin.mock/packages/conditional-values-in-variant/package.py
@@ -38,3 +38,10 @@ class ConditionalValuesInVariant(Package):
         values=any_combination_of(conditional("flexpath", "dataspaces", when="@1.73.0:")),
         description="Enable dataspaces and/or flexpath staging transports",
     )
+
+    variant(
+        "foo",
+        default="foo",
+        values=(conditional("foo", when=True), conditional("bar", when=False)),
+        description="Variant with default condition false",
+    )