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', )
@@ -1591,7 +1595,7 @@ 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:
@@ -1610,11 +1614,29 @@ 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
+ ann_dict ={
+ ann: Any if t is _ANY_MARKER else t
+ for ann, t in annotations.items()
+ }
+ if format == annotationlib.Format.STRING:
+ return annotationlib.annotations_to_string(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

@@ -5,13 +5,15 @@
 from dataclasses import *
 
 import abc
+import annotationlib
 import io
 import pickle
 import inspect
 import builtins
 import types
 import weakref
 import traceback
+import sys
 import textwrap
 import unittest
 from unittest.mock import Mock
@@ -25,6 +27,7 @@
 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
@@ -3754,7 +3757,6 @@ 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')
 
@@ -4246,16 +4248,50 @@ 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.STRING),
+{'x': 'typing.Any', 'y': 'int', 'z': 'typing.Any'},
+ )
+
+ def test_no_types_no_typing_import(self):
+ with import_helper.CleanImport('typing'):
+ self.assertNotIn('typing', sys.modules)
+ C = make_dataclass('C', ['x', ('y', int)])
+
+ self.assertNotIn('typing', sys.modules)
+ 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.