Update PEP 649/749 implementation (#596)

Author: JelleZijlstra

CHANGELOG.md

@@ -3,14 +3,17 @@
 - Drop support for Python 3.8 (including PyPy-3.8). Patch by [Victorien Plot](https://github.com/Viicos).
 - Do not attempt to re-export names that have been removed from `typing`,
   anticipating the removal of `typing.no_type_check_decorator` in Python 3.15.
+  Patch by Jelle Zijlstra.
+- Update `typing_extensions.Format` and `typing_extensions.evaluate_forward_ref` to align
+  with changes in Python 3.14. Patch by Jelle Zijlstra.
+- Fix tests for Python 3.14. Patch by Jelle Zijlstra.
 
 New features:
 
 - Add support for inline typed dictionaries ([PEP 764](https://peps.python.org/pep-0764/)).
   Patch by [Victorien Plot](https://github.com/Viicos).
 - Add `typing_extensions.Reader` and `typing_extensions.Writer`. Patch by
   Sebastian Rittau.
-- Fix tests for Python 3.14. Patch by Jelle Zijlstra.
 
 # Release 4.13.2 (April 10, 2025)
 

doc/index.rst

@@ -769,7 +769,7 @@ Functions
 
    .. versionadded:: 4.2.0
 
-.. function:: evaluate_forward_ref(forward_ref, *, owner=None, globals=None, locals=None, type_params=None, format=Format.VALUE)
+.. function:: evaluate_forward_ref(forward_ref, *, owner=None, globals=None, locals=None, type_params=None, format=None)
 
    Evaluate an :py:class:`typing.ForwardRef` as a :py:term:`type hint`.
 
@@ -796,7 +796,7 @@ Functions
    This parameter must be provided (though it may be an empty tuple) if *owner*
    is not given and the forward reference does not already have an owner set.
    *format* specifies the format of the annotation and is a member of
-   the :class:`Format` enum.
+   the :class:`Format` enum, defaulting to :attr:`Format.VALUE`.
 
    .. versionadded:: 4.13.0
 
@@ -952,9 +952,19 @@ Enums
       for the annotations. This format is identical to the return value for
       the function under earlier versions of Python.
 
+   .. attribute:: VALUE_WITH_FAKE_GLOBALS
+
+      Equal to 2. Special value used to signal that an annotate function is being
+      evaluated in a special environment with fake globals. When passed this
+      value, annotate functions should either return the same value as for
+      the :attr:`Format.VALUE` format, or raise :exc:`NotImplementedError`
+      to signal that they do not support execution in this environment.
+      This format is only used internally and should not be passed to
+      the functions in this module.
+
    .. attribute:: FORWARDREF
 
-      Equal to 2. When :pep:`649` is implemented, this format will attempt to return the
+      Equal to 3. When :pep:`649` is implemented, this format will attempt to return the
       conventional Python values for the annotations. However, if it encounters
       an undefined name, it dynamically creates a proxy object (a ForwardRef)
       that substitutes for that value in the expression.
@@ -964,7 +974,7 @@ Enums
 
    .. attribute:: STRING
 
-      Equal to 3. When :pep:`649` is implemented, this format will produce an annotation
+      Equal to 4. When :pep:`649` is implemented, this format will produce an annotation
       dictionary where the values have been replaced by strings containing
       an approximation of the original source code for the annotation expressions.
 

src/test_typing_extensions.py

@@ -29,7 +29,6 @@
 from _typed_dict_test_helper import Foo, FooGeneric, VeryAnnotated
 from typing_extensions import (
     _FORWARD_REF_HAS_CLASS,
-    _PEP_649_OR_749_IMPLEMENTED,
     Annotated,
     Any,
     AnyStr,
@@ -8533,7 +8532,7 @@ def test_stock_annotations_in_module(self):
             get_annotations(isa.MyClass, format=Format.STRING),
             {"a": "int", "b": "str"},
         )
-        mycls = "MyClass" if _PEP_649_OR_749_IMPLEMENTED else "inspect_stock_annotations.MyClass"
+        mycls = "MyClass" if sys.version_info >= (3, 14) else "inspect_stock_annotations.MyClass"
         self.assertEqual(
             get_annotations(isa.function, format=Format.STRING),
             {"a": "int", "b": "str", "return": mycls},
@@ -8581,7 +8580,7 @@ def test_stock_annotations_on_wrapper(self):
             get_annotations(wrapped, format=Format.FORWARDREF),
             {"a": int, "b": str, "return": isa.MyClass},
         )
-        mycls = "MyClass" if _PEP_649_OR_749_IMPLEMENTED else "inspect_stock_annotations.MyClass"
+        mycls = "MyClass" if sys.version_info >= (3, 14) else "inspect_stock_annotations.MyClass"
         self.assertEqual(
             get_annotations(wrapped, format=Format.STRING),
             {"a": "int", "b": "str", "return": mycls},

src/typing_extensions.py

@@ -3821,27 +3821,15 @@ def __eq__(self, other: object) -> bool:
     __all__.append("CapsuleType")
 
 
-# Using this convoluted approach so that this keeps working
-# whether we end up using PEP 649 as written, PEP 749, or
-# some other variation: in any case, inspect.get_annotations
-# will continue to exist and will gain a `format` parameter.
-_PEP_649_OR_749_IMPLEMENTED = (
-    hasattr(inspect, 'get_annotations')
-    and inspect.get_annotations.__kwdefaults__ is not None
-    and "format" in inspect.get_annotations.__kwdefaults__
-)
-
-
-class Format(enum.IntEnum):
-    VALUE = 1
-    VALUE_WITH_FAKE_GLOBALS = 2
-    FORWARDREF = 3
-    STRING = 4
-
-
-if _PEP_649_OR_749_IMPLEMENTED:
-    get_annotations = inspect.get_annotations
+if sys.version_info >= (3,14):
+    from annotationlib import Format, get_annotations
 else:
+    class Format(enum.IntEnum):
+        VALUE = 1
+        VALUE_WITH_FAKE_GLOBALS = 2
+        FORWARDREF = 3
+        STRING = 4
+
     def get_annotations(obj, *, globals=None, locals=None, eval_str=False,
                         format=Format.VALUE):
         """Compute the annotations dict for an object.
@@ -4122,7 +4110,7 @@ def evaluate_forward_ref(
         globals=None,
         locals=None,
         type_params=None,
-        format=Format.VALUE,
+        format=None,
         _recursive_guard=frozenset(),
     ):
         """Evaluate a forward reference as a type hint.