Merge branch 'develop' into rei/gsfg_1

3 files changed, 16 insertions, 4 deletions

diff --git a/synapse/logging/context.py b/synapse/logging/context.py
index bdc0187743..d8ae3188b7 100644
--- a/synapse/logging/context.py
+++ b/synapse/logging/context.py
@@ -220,7 +220,7 @@ class _Sentinel:
         self.scope = None
         self.tag = None
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "sentinel"
 
     def copy_to(self, record):
@@ -241,7 +241,7 @@ class _Sentinel:
     def record_event_fetch(self, event_count):
         pass
 
-    def __bool__(self):
+    def __bool__(self) -> Literal[False]:
         return False
 
 
diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 5276c4bfcc..20d23a4260 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -807,6 +807,14 @@ def trace(func=None, opname=None):
                         result.addCallbacks(call_back, err_back)
 
                     else:
+                        if inspect.isawaitable(result):
+                            logger.error(
+                                "@trace may not have wrapped %s correctly! "
+                                "The function is not async but returned a %s.",
+                                func.__qualname__,
+                                type(result).__name__,
+                            )
+
                         scope.__exit__(None, None, None)
 
                     return result
diff --git a/synapse/logging/utils.py b/synapse/logging/utils.py
index 08895e72ee..4a01b902c2 100644
--- a/synapse/logging/utils.py
+++ b/synapse/logging/utils.py
@@ -16,6 +16,7 @@
 import logging
 from functools import wraps
 from inspect import getcallargs
+from typing import Callable, TypeVar, cast
 
 _TIME_FUNC_ID = 0
 
@@ -41,7 +42,10 @@ def _log_debug_as_f(f, msg, msg_args):
         logger.handle(record)
 
 
-def log_function(f):
+F = TypeVar("F", bound=Callable)
+
+
+def log_function(f: F) -> F:
     """Function decorator that logs every call to that function."""
     func_name = f.__name__
 
@@ -69,4 +73,4 @@ def log_function(f):
         return f(*args, **kwargs)
 
     wrapped.__name__ = func_name
-    return wrapped
+    return cast(F, wrapped)