Fix crash on weird decorators

Author: Zac-HD

CHANGELOG.md

@@ -1,6 +1,9 @@
 # Changelog
 *[CalVer, YY.month.patch](https://calver.org/)*
 
+## 22.9.2
+- Fix a crash on nontrivial decorator expressions (calls, PEP-614) and document behavior.
+
 ## 22.9.1
 - Add `--no-checkpoint-warning-decorators` option, to disable missing-checkpoint warnings for certain decorated functions.
 

README.md

@@ -40,6 +40,8 @@ pip install flake8-trio
 ## Configuration
 `no-checkpoint-warning-decorators`: Specify a list of decorators to disable checkpointing checks for, turning off TRIO107 and TRIO108 warnings for functions decorated with any decorator matching any in the list. Matching is done with [fnmatch](https://docs.python.org/3/library/fnmatch.html). Defaults to disabling for `asynccontextmanager`.
 
+Decorators-to-match must be identifiers or dotted names only (not PEP-614 expressions), and will match against the name only - e.g. `foo.bar` matches `foo.bar`, `foo.bar()`, and `foo.bar(args, here)`, etc.
+
 For example:
 ```
 [flake8]

flake8_trio.py

@@ -29,7 +29,7 @@
 from flake8.options.manager import OptionManager
 
 # CalVer: YY.month.patch, e.g. first release of July 2022 == "22.7.1"
-__version__ = "22.9.1"
+__version__ = "22.9.2"
 
 
 Error_codes = {
@@ -208,14 +208,22 @@ def has_decorator(decorator_list: List[ast.expr], *names: str):
 
 # matches the full decorator name against fnmatch pattern
 def fnmatch_decorator(decorator_list: List[ast.expr], *patterns: str):
-    def construct_name(expr: ast.expr) -> str:
+    def construct_name(expr: ast.expr) -> Optional[str]:
+        if isinstance(expr, ast.Call):
+            expr = expr.func
         if isinstance(expr, ast.Name):
             return expr.id
-        assert isinstance(expr, ast.Attribute)
-        return construct_name(expr.value) + "." + expr.attr
+        elif isinstance(expr, ast.Attribute):
+            attr = construct_name(expr.value)
+            assert attr is not None
+            return attr + "." + expr.attr
+        # See https://peps.python.org/pep-0614/ - we don't handle everything
+        return None  # pragma: no cover  # impossible on Python 3.8
 
     for decorator in decorator_list:
         qualified_decorator_name = construct_name(decorator)
+        if qualified_decorator_name is None:
+            continue  # pragma: no cover  # impossible on Python 3.8
         for pattern in patterns:
             if fnmatch(qualified_decorator_name, pattern.lstrip("@")):
                 return True

tests/test_decorator.py

@@ -1,7 +1,9 @@
 import ast
+import sys
 from argparse import Namespace
 from typing import Tuple
 
+import pytest
 from flake8.main.application import Application
 
 from flake8_trio import Error_codes, Plugin, Statement, fnmatch_decorator
@@ -69,6 +71,19 @@ def test_at():
     assert wrap(("foo.bar",), "@foo.bar")
 
 
+def test_calls():
+    assert wrap(("foo()",), "@foo")
+    assert wrap(("foo(1, 2, *x, **y)",), "@foo")
+    assert wrap(("foo.bar()",), "@foo.bar")
+    assert wrap(("foo.bar(1, 2, *x, **y)",), "@foo.bar")
+
+
+@pytest.mark.skipif(sys.version_info[:2] < (3, 9), reason="not yet supported")
+def test_pep614():
+    # Just don't crash and we'll be good.
+    assert not wrap(("(any, expression, we, like)",), "no match here")
+
+
 def test_plugin():
     tree = dec_list("app.route")
     plugin = Plugin(tree)