Fix __exit__ return type of various context managers

docs/versionhistory.rst

@@ -11,6 +11,8 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
   (`#836 <https://github.com/agronholm/anyio/pull/836>`_; PR by @graingert)
 - Fixed ``AssertionError`` when using ``nest-asyncio``
   (`#840 <https://github.com/agronholm/anyio/issues/840>`_)
+- Fixed return type annotation of various context managers' ``__exit__`` method
+  (`#847 <https://github.com/agronholm/anyio/issues/847>`_)
 
 **4.7.0**
 

src/anyio/_backends/_asyncio.py

@@ -449,7 +449,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         del exc_tb
 
         if not self._active:
@@ -2116,7 +2116,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> None:
         for sig in self._handled_signals:
             self._loop.remove_signal_handler(sig)
         return None

src/anyio/_backends/_trio.py

@@ -132,8 +132,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
-        # https://github.com/python-trio/trio-typing/pull/79
+    ) -> bool:
         return self.__original.__exit__(exc_type, exc_val, exc_tb)
 
     def cancel(self) -> None:
@@ -186,7 +185,7 @@ async def __aexit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         try:
             return await self._nursery_manager.__aexit__(exc_type, exc_val, exc_tb)
         except BaseExceptionGroup as exc:

src/anyio/_core/_synchronization.py

@@ -728,6 +728,6 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> None:
         self._guarded = False
         return None

src/anyio/_core/_tasks.py

@@ -88,7 +88,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None:
+    ) -> bool:
         raise NotImplementedError