Fix a minor bug in pytype's expansion of Protocol[T].

Inheriting from Protocol[T] is a shorthand for inheriting from both Protocol
and Generic[T]. We were handling this case properly for typing.Protocol but not
for typing_extensions.Protocol.

Context: python/typeshed#5172
PiperOrigin-RevId: 366414389

Author: rchen152

pytype/pyi/classdef.py

@@ -12,6 +12,7 @@
 from typed_ast import ast3
 
 
+_PROTOCOL_ALIASES = ("typing.Protocol", "typing_extensions.Protocol")
 _TYPED_DICT_ALIASES = ("typing.TypedDict", "typing_extensions.TypedDict")
 
 
@@ -101,4 +102,4 @@ def check_for_duplicate_defs(methods, constants, aliases) -> None:
 
 def _is_parameterized_protocol(t) -> bool:
   return (isinstance(t, pytd.GenericType) and
-          t.base_type.name == "typing.Protocol")
+          pytd_utils.MatchesFullName(t.base_type, _PROTOCOL_ALIASES))

pytype/pyi/parser_test.py

@@ -1496,6 +1496,26 @@ class Foo(Protocol[T]): ...
       class Foo(Protocol, Generic[T]): ...
     """)
 
+  def test_typing_extensions_parameterized_protocol(self):
+    self.check("""
+      from typing import TypeVar
+
+      from typing_extensions import Protocol
+
+      T = TypeVar('T')
+
+      class Foo(Protocol[T]): ...
+    """, """
+      from typing import Generic, TypeVar
+      import typing_extensions
+
+      from typing_extensions import Protocol
+
+      T = TypeVar('T')
+
+      class Foo(typing_extensions.Protocol, Generic[T]): ...
+    """)
+
   def test_bad_typevar_in_mutation(self):
     self.check_error("""
       from typing import Generic, TypeVar