modules: remove default symlink on uninstall (#36454)

When app is uninstalled, if it matches a default, then remove the
default symlink targeting its modulefile.

Until now, when a default were uninstalled, the default symlink were
left pointing to a nonexistent modulefile.

lib/spack/spack/modules/common.py

@@ -935,6 +935,7 @@ def remove(self):
         if os.path.exists(mod_file):
             try:
                 os.remove(mod_file)  # Remove the module file
+                self.remove_module_defaults()  # Remove default targeting module file
                 os.removedirs(
                     os.path.dirname(mod_file)
                 )  # Remove all the empty directories from the leaf up
@@ -942,6 +943,18 @@ def remove(self):
                 # removedirs throws OSError on first non-empty directory found
                 pass
 
+    def remove_module_defaults(self):
+        if not any(self.spec.satisfies(default) for default in self.conf.defaults):
+            return
+
+        # This spec matches a default, symlink needs to be removed as we remove the module
+        # file it targets.
+        default_symlink = os.path.join(os.path.dirname(self.layout.filename), "default")
+        try:
+            os.unlink(default_symlink)
+        except OSError:
+            pass
+
 
 @contextlib.contextmanager
 def disable_modules():

lib/spack/spack/test/modules/common.py

@@ -77,6 +77,9 @@ def test_modules_default_symlink(
     assert os.path.islink(link_path)
     assert os.readlink(link_path) == mock_module_filename
 
+    generator.remove()
+    assert not os.path.lexists(link_path)
+
 
 class MockDb(object):
     def __init__(self, db_ids, spec_hash_to_db):