gh-110686: Fix pattern matching with runtime_checkable protocols (#290

)

CHANGELOG.md

@@ -5,6 +5,8 @@
   signature of `typing.NewType.__call__`. Patch by Alex Waygood.
 - `typing.deprecated` now gives a better error message if you pass a non-`str`
   argument to the `msg` parameter. Patch by Alex Waygood.
+- Exclude `__match_args__` from `Protocol` members,
+  this is a backport of https://github.com/python/cpython/pull/110683
 
 # Release 4.8.0 (September 17, 2023)
 

src/test_typing_extensions.py

@@ -2521,6 +2521,39 @@ class Bad: pass
         self.assertNotIsInstance(Other(), Concrete)
         self.assertIsInstance(NT(1, 2), Position)
 
+    def test_runtime_checkable_with_match_args(self):
+        @runtime_checkable
+        class P_regular(Protocol):
+            x: int
+            y: int
+
+        @runtime_checkable
+        class P_match(Protocol):
+            __match_args__ = ("x", "y")
+            x: int
+            y: int
+
+        class Regular:
+            def __init__(self, x: int, y: int):
+                self.x = x
+                self.y = y
+
+        class WithMatch:
+            __match_args__ = ("x", "y", "z")
+            def __init__(self, x: int, y: int, z: int):
+                self.x = x
+                self.y = y
+                self.z = z
+
+        class Nope: ...
+
+        self.assertIsInstance(Regular(1, 2), P_regular)
+        self.assertIsInstance(Regular(1, 2), P_match)
+        self.assertIsInstance(WithMatch(1, 2, 3), P_regular)
+        self.assertIsInstance(WithMatch(1, 2, 3), P_match)
+        self.assertNotIsInstance(Nope(), P_regular)
+        self.assertNotIsInstance(Nope(), P_match)
+
     def test_protocols_isinstance_init(self):
         T = TypeVar('T')
         @runtime_checkable
@@ -5062,12 +5095,12 @@ def test_typing_extensions_defers_when_possible(self):
             exclude |= {'final', 'Any', 'NewType'}
         if sys.version_info < (3, 12):
             exclude |= {
-                'Protocol', 'SupportsAbs', 'SupportsBytes',
+                'SupportsAbs', 'SupportsBytes',
                 'SupportsComplex', 'SupportsFloat', 'SupportsIndex', 'SupportsInt',
                 'SupportsRound', 'Unpack',
             }
         if sys.version_info < (3, 13):
-            exclude |= {'NamedTuple', 'TypedDict', 'is_typeddict'}
+            exclude |= {'NamedTuple', 'Protocol', 'TypedDict', 'is_typeddict'}
         for item in typing_extensions.__all__:
             if item not in exclude and hasattr(typing, item):
                 self.assertIs(

src/typing_extensions.py

@@ -473,6 +473,7 @@ def clear_overloads():
     "__orig_bases__", "__module__", "_MutableMapping__marker", "__doc__",
     "__subclasshook__", "__orig_class__", "__init__", "__new__",
     "__protocol_attrs__", "__callable_proto_members_only__",
+    "__match_args__",
 }
 
 if sys.version_info >= (3, 9):
@@ -503,9 +504,9 @@ def _caller(depth=2):
         return None
 
 
-# The performance of runtime-checkable protocols is significantly improved on Python 3.12,
-# so we backport the 3.12 version of Protocol to Python <=3.11
-if sys.version_info >= (3, 12):
+# `__match_args__` attribute was removed from protocol members in 3.13,
+# we want to backport this change to older Python versions.
+if sys.version_info >= (3, 13):
     Protocol = typing.Protocol
 else:
     def _allow_reckless_class_checks(depth=3):