async102 & async120 no longer requires cancelscope to have a timeout

docs/changelog.rst

@@ -4,6 +4,10 @@ Changelog
 
 `CalVer, YY.month.patch <https://calver.org/>`_
 
+25.5.2
+======
+- :ref:`ASYNC120 <async120>` no longer requires cancel scopes to have a timeout. https://github.com/python-trio/flake8-async/issues/272
+
 25.5.1
 ======
 - Fixed :ref:`ASYNC113 <async113>` false alarms if the ``start_soon`` calls are in a nursery cm that was closed before the yield point.

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: 25.5.1
+     rev: 25.5.2
      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__ = "25.5.1"
+__version__ = "25.5.2"
 
 
 # taken from https://github.com/Zac-HD/shed

flake8_async/visitors/visitor102_120.py

@@ -40,16 +40,6 @@ def __init__(self, node: ast.Call, funcname: str):
             self.funcname = funcname
             self.variable_name: str | None = None
             self.shielded: bool = False
-            self.has_timeout: bool = True
-
-            # scope.shielded is assigned to in visit_Assign
-
-            if self.funcname == "CancelScope":
-                self.has_timeout = False
-                for kw in node.keywords:
-                    # note: sets to True even if timeout is explicitly set to inf
-                    if kw.arg == "deadline":
-                        self.has_timeout = True
 
             # trio 0.27 adds shield parameter to all scope helpers
             if self.funcname in cancel_scope_names:
@@ -79,7 +69,7 @@ def async_call_checker(
         self, node: ast.Await | ast.AsyncFor | ast.AsyncWith
     ) -> None:
         if self._critical_scope is not None and not any(
-            cm.has_timeout and cm.shielded for cm in self._trio_context_managers
+            cm.shielded for cm in self._trio_context_managers
         ):
             # non-critical exception handlers have the statement name set to "except"
             if self._critical_scope.name == "except":

tests/eval_files/async102.py

@@ -100,8 +100,9 @@ async def foo():
     try:
         pass
     finally:
+        # it's now fine to have a shield and no timeout
         with trio.CancelScope(shield=True):
-            await foo()  # error: 12, Statement("try/finally", lineno-4)
+            await foo()
     try:
         pass
     finally:

tests/eval_files/async120.py

@@ -121,3 +121,13 @@ async def foobar():
             await foo()
 
         raise
+
+
+# shielded but no timeout no longer triggers async120
+# https://github.com/python-trio/flake8-async/issues/272
+async def foo_shield_no_timeout():
+    try:
+        ...
+    finally:
+        with trio.CancelScope(shield=True):
+            await foo()