gh-82128: Provide __annotate__ method for dataclasses from `make_da…

…taclass`
python · JelleZijlstra · May 5, 2025 · Jul 25, 2024 · Sep 17, 2024 · Sep 18, 2024
commit c2d85b7b03e472126e0561466c38adf231d0b99b
@@ -1527,10 +1527,11 @@ class C(Base):
     seen = set()
     annotations = {}
     defaults = {}
+    any_marker = object()
     for item in fields:
         if isinstance(item, str):
             name = item
-            tp = 'typing.Any'
+            tp = any_marker
         elif len(item) == 2:
             name, tp, = item
         elif len(item) == 3:
@@ -1549,11 +1550,20 @@ class C(Base):
         seen.add(name)
         annotations[name] = tp
 
+    def annotate_method(format):
+        if format != 1:
+            raise NotImplementedError
+        from typing import Any
+        return {
+            ann: Any if t is any_marker else t
+            for ann, t in annotations.items()
+        }
+
     # Update 'ns' with the user-supplied namespace plus our calculated values.
     def exec_body_callback(ns):
+        ns['__annotate__'] = annotate_method
         ns.update(namespace)
         ns.update(defaults)
-        ns['__annotations__'] = annotations
 
     # We use `types.new_class()` instead of simply `type()` to allow dynamic creation
     # of generic dataclasses.