gh-119180: Add evaluate functions for type params and type aliases (#122212)

1 files changed, 16 insertions, 3 deletions

diff --git a/Lib/annotationlib.py b/Lib/annotationlib.py
index eea24232f9f..141e31bbf91 100644
--- a/Lib/annotationlib.py
+++ b/Lib/annotationlib.py
@@ -413,7 +413,16 @@ class _StringifierDict(dict):
         return fwdref
 
 
-def call_annotate_function(annotate, format, owner=None):
+def call_evaluate_function(evaluate, format, *, owner=None):
+    """Call an evaluate function. Evaluate functions are normally generated for
+    the value of type aliases and the bounds, constraints, and defaults of
+    type parameter objects.
+    """
+    return call_annotate_function(evaluate, format, owner=owner, _is_evaluate=True)
+
+
+def call_annotate_function(annotate, format, *, owner=None,
+                           _is_evaluate=False):
     """Call an __annotate__ function. __annotate__ functions are normally
     generated by the compiler to defer the evaluation of annotations. They
     can be called with any of the format arguments in the Format enum, but
@@ -459,8 +468,11 @@ def call_annotate_function(annotate, format, owner=None):
             closure = tuple(new_closure)
         else:
             closure = None
-        func = types.FunctionType(annotate.__code__, globals, closure=closure)
+        func = types.FunctionType(annotate.__code__, globals, closure=closure,
+                                  argdefs=annotate.__defaults__, kwdefaults=annotate.__kwdefaults__)
         annos = func(Format.VALUE)
+        if _is_evaluate:
+            return annos if isinstance(annos, str) else repr(annos)
         return {
             key: val if isinstance(val, str) else repr(val)
             for key, val in annos.items()
@@ -511,7 +523,8 @@ def call_annotate_function(annotate, format, owner=None):
             closure = tuple(new_closure)
         else:
             closure = None
-        func = types.FunctionType(annotate.__code__, globals, closure=closure)
+        func = types.FunctionType(annotate.__code__, globals, closure=closure,
+                                  argdefs=annotate.__defaults__, kwdefaults=annotate.__kwdefaults__)
         result = func(Format.VALUE)
         for obj in globals.stringifiers:
             obj.__class__ = ForwardRef