From 4c9de6f6d56f1f1c295e58537993d71921930186 Mon Sep 17 00:00:00 2001
From: "Olivier Wilkinson (reivilibre)" <oliverw@matrix.org>
Date: Wed, 5 Jul 2023 12:04:39 +0100
Subject: [PATCH] Revert to `Type[Model]` to keep type variable constrained;
 add type ignores to work around mypy deficiency

---
 synapse/config/_util.py   | 6 +++---
 synapse/config/workers.py | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/synapse/config/_util.py b/synapse/config/_util.py
index 6c97cd2772dc..0de58c00cc26 100644
--- a/synapse/config/_util.py
+++ b/synapse/config/_util.py
@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Any, Dict, TypeVar
+from typing import Any, Dict, TypeVar, Type
 
 import jsonschema
 from pydantic import BaseModel, ValidationError, parse_obj_as
@@ -75,7 +75,7 @@ def json_error_to_config_error(
 # for what I suspect is the wrong reason.
 def parse_and_validate_mapping(
     config: Any,
-    model_type: TypeAlias,
+    model_type: Type[Model],
 ) -> Dict[str, Model]:
     """Parse `config` as a mapping from strings to a given `Model` type.
     Args:
@@ -89,7 +89,7 @@ def parse_and_validate_mapping(
     try:
         # type-ignore: mypy doesn't like constructing `Dict[str, model_type]` because
         # `model_type` is a runtime variable. Pydantic is fine with this.
-        instances = parse_obj_as(Dict[str, model_type], config)
+        instances = parse_obj_as(Dict[str, model_type], config)  # type: ignore
     except ValidationError as e:
         raise ConfigError(str(e)) from e
     return instances
diff --git a/synapse/config/workers.py b/synapse/config/workers.py
index bc4d3a9f619d..75181aae450d 100644
--- a/synapse/config/workers.py
+++ b/synapse/config/workers.py
@@ -279,9 +279,10 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
                     % MAIN_PROCESS_INSTANCE_MAP_NAME
                 )
 
+        # type-ignore: the expression `Union[A, B]` is not a Type[Union[A, B]] currently
         self.instance_map: Dict[
             str, InstanceLocationConfig
-        ] = parse_and_validate_mapping(instance_map, InstanceLocationConfig)
+        ] = parse_and_validate_mapping(instance_map, InstanceLocationConfig)  # type: ignore
 
         # Map from type of streams to source, c.f. WriterLocations.
         writers = config.get("stream_writers") or {}