bugfix: env concretize after remove (#37877)

lib/spack/spack/environment/environment.py

@@ -1351,6 +1351,10 @@ def concretize(self, force=False, tests=False):
             self.concretized_order = []
             self.specs_by_hash = {}
 
+        # Remove concrete specs that no longer correlate to a user spec
+        for spec in set(self.concretized_user_specs) - set(self.user_specs):
+            self.deconcretize(spec)
+
         # Pick the right concretization strategy
         if self.unify == "when_possible":
             return self._concretize_together_where_possible(tests=tests)
@@ -1364,6 +1368,16 @@ def concretize(self, force=False, tests=False):
         msg = "concretization strategy not implemented [{0}]"
         raise SpackEnvironmentError(msg.format(self.unify))
 
+    def deconcretize(self, spec):
+        # spec has to be a root of the environment
+        index = self.concretized_user_specs.index(spec)
+        dag_hash = self.concretized_order.pop(index)
+        del self.concretized_user_specs[index]
+
+        # If this was the only user spec that concretized to this concrete spec, remove it
+        if dag_hash not in self.concretized_order:
+            del self.specs_by_hash[dag_hash]
+
     def _get_specs_to_concretize(
         self,
     ) -> Tuple[Set[spack.spec.Spec], Set[spack.spec.Spec], List[spack.spec.Spec]]:

lib/spack/spack/test/cmd/env.py

@@ -390,6 +390,19 @@ def test_remove_after_concretize():
     assert not any(s.name == "mpileaks" for s in env_specs)
 
 
+def test_remove_before_concretize():
+    e = ev.create("test")
+    e.unify = True
+
+    e.add("mpileaks")
+    e.concretize()
+
+    e.remove("mpileaks")
+    e.concretize()
+
+    assert not list(e.concretized_specs())
+
+
 def test_remove_command():
     env("create", "test")
     assert "test" in env("list")