async102 not applicable to asyncio (#393)

* async102 not applicable to asyncio

* update tests to reflect async102 changes

* Apply suggestions from code review

minor fixes

---------

Co-authored-by: John Litborn <11260241+jakkdl@users.noreply.github.com>

Author: RomanValov

docs/changelog.rst

@@ -4,6 +4,10 @@ Changelog
 
 `CalVer, YY.month.patch <https://calver.org/>`_
 
+25.7.1
+======
+- :ref:`ASYNC102 <async102>` no longer triggered for asyncio due to different cancellation semantics it uses.
+
 25.5.3
 ======
 - :ref:`ASYNC115 <async115>` and :ref:`ASYNC116 <async116>` now also checks kwargs.

docs/rules.rst

@@ -24,8 +24,8 @@ _`ASYNC101` : yield-in-cancel-scope
 _`ASYNC102` : await-in-finally-or-cancelled
     ``await`` inside ``finally``, :ref:`cancelled-catching <cancelled>` ``except:``, or ``__aexit__`` must have shielded :ref:`cancel scope <cancel_scope>` with timeout.
     If not, the async call will immediately raise a new cancellation, suppressing any cancellation that was caught.
+    Not applicable to asyncio due to edge-based cancellation semantics it uses as opposed to level-based used by trio and anyio.
     See :ref:`ASYNC120 <async120>` for the general case where other exceptions might get suppressed.
-    This is currently not able to detect asyncio shields.
 
 ASYNC103 : no-reraise-cancelled
     :ref:`cancelled`-catching exception that does not reraise the exception.

docs/usage.rst

@@ -33,7 +33,7 @@ adding the following to your ``.pre-commit-config.yaml``:
    minimum_pre_commit_version: '2.9.0'
    repos:
    - repo: https://github.com/python-trio/flake8-async
-     rev: 25.5.3
+     rev: 25.7.1
      hooks:
        - id: flake8-async
          # args: ["--enable=ASYNC100,ASYNC112", "--disable=", "--autofix=ASYNC"]

flake8_async/__init__.py

@@ -38,7 +38,7 @@
 
 
 # CalVer: YY.month.patch, e.g. first release of July 2022 == "22.7.1"
-__version__ = "25.5.3"
+__version__ = "25.7.1"
 
 
 # taken from https://github.com/Zac-HD/shed

flake8_async/visitors/visitor102_120.py

@@ -74,7 +74,8 @@ def async_call_checker(
             # non-critical exception handlers have the statement name set to "except"
             if self._critical_scope.name == "except":
                 self._potential_120.append((node, self._critical_scope))
-            else:
+            # not applicable to asyncio due to different cancellation semantics it uses
+            elif self.library != ("asyncio",):
                 self.error(node, self._critical_scope, error_code="ASYNC102")
 
     def visit_Raise(self, node: ast.Raise):
@@ -84,10 +85,7 @@ def visit_Raise(self, node: ast.Raise):
 
     def is_safe_aclose_call(self, node: ast.Await) -> bool:
         return (
-            # don't mark calls safe in asyncio-only files
-            # a more defensive option would be `asyncio not in self.library`
-            self.library != ("asyncio",)
-            and isinstance(node.value, ast.Call)
+            isinstance(node.value, ast.Call)
             # only known safe if no arguments
             and not node.value.args
             and not node.value.keywords

tests/eval_files/async102.py

@@ -1,6 +1,6 @@
 # type: ignore
 # ARG --enable=ASYNC102,ASYNC120
-# NOASYNCIO # TODO: support asyncio shields
+# ASYNCIO_NO_ERROR  # ASYNC102 not applicable to asyncio
 from contextlib import asynccontextmanager
 
 import trio
@@ -310,3 +310,38 @@ async def foo_nested_cs():
 # treat __aexit__ as a critical scope
 async def __aexit__():
     await foo()  # error: 4, Statement("__aexit__", lineno-1)
+
+
+# exclude `finally: await x.aclose()` with no arguments
+async def foo_aclose_noargs():
+    # no type tracking in this check, we allow any call that looks like
+    # `await [...].aclose()`
+    x = None
+
+    try:
+        ...
+    except BaseException:
+        await x.aclose()
+        await x.y.aclose()
+    finally:
+        await x.aclose()
+        await x.y.aclose()
+
+
+# should still raise errors if there's args, as that indicates it's a non-standard aclose
+async def foo():
+    # no type tracking in this check
+    x = None
+
+    try:
+        ...
+    except BaseException:
+        await x.aclose(foo)  # ASYNC102: 8, Statement("BaseException", lineno-1)
+        await x.aclose(bar=foo)  # ASYNC102: 8, Statement("BaseException", lineno-2)
+        await x.aclose(*foo)  # ASYNC102: 8, Statement("BaseException", lineno-3)
+        await x.aclose(None)  # ASYNC102: 8, Statement("BaseException", lineno-4)
+    finally:
+        await x.aclose(foo)  # ASYNC102: 8, Statement("try/finally", lineno-8)
+        await x.aclose(bar=foo)  # ASYNC102: 8, Statement("try/finally", lineno-9)
+        await x.aclose(*foo)  # ASYNC102: 8, Statement("try/finally", lineno-10)
+        await x.aclose(None)  # ASYNC102: 8, Statement("try/finally", lineno-11)

tests/eval_files/async102_aclose.py

@@ -1,9 +1,9 @@
 # type: ignore
+# this test will raise the same errors with trio, despite trio.get_cancelled_exc_class not existing
+# marked not to run the tests though as error messages will only refer to anyio
 # NOTRIO
-# NOASYNCIO
+# ASYNCIO_NO_ERROR  # ASYNC102 not applicable to asyncio
 # BASE_LIBRARY anyio
-# this test will raise the same errors with trio/asyncio, despite [trio|asyncio].get_cancelled_exc_class not existing
-# marked not to run the tests though as error messages will only refer to anyio
 import anyio
 from anyio import get_cancelled_exc_class