gh-82129: Provide __annotate__ method for dataclasses from make_dataclass

Lib/dataclasses.py

@@ -244,6 +244,10 @@ def __repr__(self):
     property,
 })
 
+# Any marker is used in `make_dataclass` to mark unannotated fields as `Any`
+# without importing `typing` module.
+_ANY_MARKER = object()
+
 
 class InitVar:
     __slots__ = ('type', )
@@ -1530,7 +1534,7 @@ class C(Base):
     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 +1553,29 @@ class C(Base):
         seen.add(name)
         annotations[name] = tp
 
+    def annotate_method(format):
+        typing = sys.modules.get("typing")
+        if typing is None and format == annotationlib.Format.FORWARDREF:
+            typing_any = annotationlib.ForwardRef("Any", module="typing")
+            return {
+                ann: typing_any if t is _ANY_MARKER else t
+                for ann, t in annotations.items()
+            }
+
+        from typing import Any, _convert_to_source
+        ann_dict = {
+            ann: Any if t is _ANY_MARKER else t
+            for ann, t in annotations.items()
+        }
+        if format == annotationlib.Format.SOURCE:
+            return _convert_to_source(ann_dict)
+        return ann_dict
+
     # 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.

Lib/test/test_dataclasses/__init__.py

@@ -5,6 +5,7 @@
 from dataclasses import *
 
 import abc
+import annotationlib
 import io
 import pickle
 import inspect
@@ -23,6 +24,7 @@
 import dataclasses  # Needed for the string "dataclasses.InitVar[int]" to work as an annotation.
 
 from test import support
+from test.support import import_helper
 
 # Just any custom exception we can catch.
 class CustomError(Exception): pass
@@ -3667,7 +3669,6 @@ class A(WithDictSlot): ...
     @support.cpython_only
     def test_dataclass_slot_dict_ctype(self):
         # https://github.com/python/cpython/issues/123935
-        from test.support import import_helper
         # Skips test if `_testcapi` is not present:
         _testcapi = import_helper.import_module('_testcapi')
 
@@ -4159,16 +4160,50 @@ def test_no_types(self):
         C = make_dataclass('Point', ['x', 'y', 'z'])
         c = C(1, 2, 3)
         self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
-        self.assertEqual(C.__annotations__, {'x': 'typing.Any',
-                                             'y': 'typing.Any',
-                                             'z': 'typing.Any'})
+        self.assertEqual(C.__annotations__, {'x': typing.Any,
+                                             'y': typing.Any,
+                                             'z': typing.Any})
 
         C = make_dataclass('Point', ['x', ('y', int), 'z'])
         c = C(1, 2, 3)
         self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
-        self.assertEqual(C.__annotations__, {'x': 'typing.Any',
+        self.assertEqual(C.__annotations__, {'x': typing.Any,
                                              'y': int,
-                                             'z': 'typing.Any'})
+                                             'z': typing.Any})
+
+    def test_no_types_get_annotations(self):
+        C = make_dataclass('C', ['x', ('y', int), 'z'])
+
+        self.assertEqual(
+            annotationlib.get_annotations(C, format=annotationlib.Format.VALUE),
+            {'x': typing.Any, 'y': int, 'z': typing.Any},
+        )
+        self.assertEqual(
+            annotationlib.get_annotations(
+                C, format=annotationlib.Format.FORWARDREF),
+            {'x': typing.Any, 'y': int, 'z': typing.Any},
+        )
+        self.assertEqual(
+            annotationlib.get_annotations(
+                C, format=annotationlib.Format.SOURCE),
+            {'x': 'typing.Any', 'y': 'int', 'z': 'typing.Any'},
+        )
+
+    def test_no_types_no_typing_import(self):
+        import sys
+
+        C = make_dataclass('C', ['x', ('y', int)])
+
+        with import_helper.CleanImport('typing'):
+            self.assertEqual(
+                annotationlib.get_annotations(
+                    C, format=annotationlib.Format.FORWARDREF),
+                {
+                    'x': annotationlib.ForwardRef('Any', module='typing'),
+                    'y': int,
+                },
+            )
+            self.assertNotIn('typing', sys.modules)
 
     def test_module_attr(self):
         self.assertEqual(ByMakeDataClass.__module__, __name__)

Misc/NEWS.d/next/Library/2024-09-18-09-15-40.gh-issue-82129.GQwt3u.rst

@@ -0,0 +1,2 @@
+Fix :exc:`NameError` when calling :func:`typing.get_type_hints` on a :func:`dataclasses.dataclass` created by
+:func:`dataclasses.make_dataclass` with un-annotated fields.