allow lists and dicts since we get them for free

This reverts commit 48c15d2f6be8a0bd88428e015ea41a8c814130f8.

lib/spack/spack/repo.py

@@ -1362,6 +1362,41 @@ def get_pkg_class(self, pkg_name):
         if not inspect.isclass(cls):
             tty.die("%s.%s is not a class" % (pkg_name, class_name))
 
+        new_cfg_settings = (
+            spack.config.get("packages").get(pkg_name, {}).get("package_attributes", {})
+        )
+
+        overidden_attrs = getattr(cls, "overidden_attrs", {})
+        attrs_exclusively_from_config = getattr(cls, "attrs_exclusively_from_config", [])
+        # Clear any prior changes to class attributes in case the config has
+        # since changed
+        for key, val in overidden_attrs.items():
+            setattr(cls, key, val)
+        for key in attrs_exclusively_from_config:
+            delattr(cls, key)
+
+        # Keep track of every class attribute that is overidden by the config:
+        # if the config changes between calls to this method, we make sure to
+        # restore the original config values (in case the new config no longer
+        # sets attributes that it used to)
+        new_overidden_attrs = {}
+        new_attrs_exclusively_from_config = set()
+        for key, val in new_cfg_settings.items():
+            if hasattr(cls, key):
+                new_overidden_attrs[key] = getattr(cls, key)
+            else:
+                new_attrs_exclusively_from_config.add(key)
+
+            setattr(cls, key, val)
+        if new_overidden_attrs:
+            setattr(cls, "overidden_attrs", dict(new_overidden_attrs))
+        elif hasattr(cls, "overidden_attrs"):
+            delattr(cls, "overidden_attrs")
+        if new_attrs_exclusively_from_config:
+            setattr(cls, "attrs_exclusively_from_config", new_attrs_exclusively_from_config)
+        elif hasattr(cls, "attrs_exclusively_from_config"):
+            delattr(cls, "attrs_exclusively_from_config")
+
         return cls
 
     def __str__(self):

lib/spack/spack/schema/packages.py

@@ -82,6 +82,15 @@
                             },
                         },
                     },
+                    # If 'get_full_repo' is promoted to a Package-level
+                    # attribute, it could be useful to set it here
+                    "package_attributes": {
+                        "type": "object",
+                        "additionalProperties": False,
+                        "patternProperties": {
+                            r"\w+": {},
+                        },
+                    },
                     "providers": {
                         "type": "object",
                         "default": {},

lib/spack/spack/test/concretize_preferences.py

@@ -179,6 +179,43 @@ def test_preferred_providers(self):
         spec = concretize("mpileaks")
         assert "zmpi" in spec
 
+    def test_config_set_pkg_property_url(self, mutable_mock_repo):
+        """Test setting an attribute that is explicitly-handled in the schema"""
+        update_packages(
+            "mpileaks",
+            "package_attributes",
+            {"url": "http://www.somewhereelse.com/mpileaks-1.0.tar.gz"},
+        )
+        spec = concretize("mpileaks")
+        assert spec.package.fetcher[0].url == "http://www.somewhereelse.com/mpileaks-2.3.tar.gz"
+
+        update_packages("mpileaks", "package_attributes", {})
+        spec = concretize("mpileaks")
+        assert spec.package.fetcher[0].url == "http://www.llnl.gov/mpileaks-2.3.tar.gz"
+
+    def test_config_set_pkg_property_new(self, mutable_mock_repo):
+        """Test that you can set arbitrary attributes on the Package class"""
+        update_packages(
+            "mpileaks",
+            "package_attributes",
+            {"x": 1, "y": True, "z": "yesterday"},
+        )
+        spec = concretize("mpileaks")
+        assert spec.package.x == 1
+        assert spec.package.y is True
+        assert spec.package.z == "yesterday"
+
+        update_packages("mpileaks", "package_attributes", {})
+        spec = concretize("mpileaks")
+        with pytest.raises(AttributeError):
+            spec.package.x
+
+    def test_config_set_pkg_property_collection_unsupported(self, mutable_mock_repo):
+        """Test that an error is raised if you attempt to assign a list value"""
+        update_packages("mpileaks", "package_attributes", {"x": ["a", "b"]})
+        with pytest.raises(ConfigError):
+            concretize("mpileaks")
+
     def test_preferred(self):
         """ "Test packages with some version marked as preferred=True"""
         spec = Spec("python")