Fixed return annotation of __aexit__ (#913)

Author: Enegg

docs/versionhistory.rst

@@ -12,6 +12,9 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
   this prevents an OSError on the ``ProactorEventLoop``.
   (`#896 <https://github.com/agronholm/anyio/pull/896>`_; PR by @graingert)
 - Fixed ``anyio.Path.copy()`` and ``anyio.Path.copy_into()`` failing on Python 3.14.0a7
+- Fixed return annotation of ``__aexit__`` on async context managers. CMs which can
+  suppress exceptions should return ``bool``, or ``None`` otherwise.
+  (`#913 <https://github.com/agronholm/anyio/pull/913>`_; PR by @Enegg)
 
 **4.9.0**
 

src/anyio/_backends/_asyncio.py

@@ -726,7 +726,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         try:
             if exc_val is not None:
                 self.cancel_scope.cancel()

src/anyio/_core/_synchronization.py

@@ -505,7 +505,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> None:
         raise NotImplementedError
 
     @property
@@ -630,7 +630,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> None:
         return await self._limiter.__aexit__(exc_type, exc_val, exc_tb)
 
     @property

src/anyio/abc/_sockets.py

@@ -35,7 +35,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> None:
         return None
 
 

src/anyio/abc/_tasks.py

@@ -97,5 +97,5 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         """Exit the task group context waiting for all tasks to finish."""

src/anyio/from_thread.py

@@ -163,7 +163,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         await self.stop()
         return await self._task_group.__aexit__(exc_type, exc_val, exc_tb)