pythongh-114053: Fix another edge case involving get_type_hints, PEP 695 and PEP 563

Author: AlexWaygood

Lib/test/test_typing.py

@@ -4866,11 +4866,7 @@ def test_pep695_generic_with_future_annotations(self):
         self.assertIs(hints_for_A["z"].__args__[0], A_type_params[2])
 
         hints_for_B = get_type_hints(ann_module695.B)
-        self.assertEqual(hints_for_B.keys(), {"x", "y", "z"})
-        self.assertEqual(
-            set(hints_for_B.values()) ^ set(ann_module695.B.__type_params__),
-            set()
-        )
+        self.assertEqual(hints_for_B, {"x": int, "y": str, "z": bytes})
 
         hints_for_generic_function = get_type_hints(ann_module695.generic_function)
         func_t_params = ann_module695.generic_function.__type_params__

Lib/typing.py

@@ -1064,11 +1064,11 @@ def _evaluate(self, globalns, localns, type_params=_sentinel, *, recursive_guard
                 # "Inject" type parameters into the local namespace
                 # (unless they are shadowed by assignments *in* the local namespace),
                 # as a way of emulating annotation scopes when calling `eval()`
-                locals_to_pass = {param.__name__: param for param in type_params} | localns
+                globals_to_pass = {param.__name__: param for param in type_params} | globalns
             else:
-                locals_to_pass = localns
+                globals_to_pass = globalns
             type_ = _type_check(
-                eval(self.__forward_code__, globalns, locals_to_pass),
+                eval(self.__forward_code__, globals_to_pass, localns),
                 "Forward references must evaluate to types.",
                 is_argument=self.__forward_is_argument__,
                 allow_special_forms=self.__forward_is_class__,

Misc/NEWS.d/next/Library/2024-06-08-15-46-35.gh-issue-114053.Ub2XgJ.rst

@@ -0,0 +1,4 @@
+Fix edge-case bug where :func:`typing.get_type_hints` would produce
+incorrect results if type parameters in a class scope were overridden by
+assignments in a class scope and ``from __future__ import annotations``
+semantics were enabled. Patch by Alex Waygood.