gh-89687: fix get_type_hints with dataclasses __init__ generation

Author: Tishka17

Lib/dataclasses.py

@@ -536,10 +536,25 @@ def _field_assign(frozen, name, value, self_name):
     return f'  {self_name}.{name}={value}'
 
 
-def _field_init(f, frozen, globals, self_name, slots):
+def _field_init(f, frozen, globals, self_name, slots, module):
     # Return the text of the line in the body of __init__ that will
     # initialize this field.
 
+    if f.init and isinstance(f.type, str):
+        from typing import ForwardRef  # `typing` is a heavy import
+        # We need to resolve this string type into a real `ForwardRef` object,
+        # because otherwise we might end up with unsolvable annotations.
+        # For example:
+        #   def __init__(self, d: collections.OrderedDict) -> None:
+        # We won't be able to resolve `collections.OrderedDict`
+        # with wrong `module` param, when placed in a different module. #45524
+        try:
+            f.type = ForwardRef(f.type, module=module, is_class=True)
+        except SyntaxError:
+            # We don't want to fail class creation
+            # when `ForwardRef` cannot be constructed.
+            pass
+
     default_name = f'__dataclass_dflt_{f.name}__'
     if f.default_factory is not MISSING:
         if f.init:
@@ -616,7 +631,7 @@ def _init_param(f):
 
 
 def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init,
-             self_name, func_builder, slots):
+             self_name, func_builder, slots, module):
     # fields contains both real fields and InitVar pseudo-fields.
 
     # Make sure we don't have fields without defaults following fields
@@ -643,7 +658,7 @@ def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init,
 
     body_lines = []
     for f in fields:
-        line = _field_init(f, frozen, locals, self_name, slots)
+        line = _field_init(f, frozen, locals, self_name, slots, module)
         # line is None means that this field doesn't require
         # initialization (it's a pseudo-field).  Just skip it.
         if line:
@@ -1093,6 +1108,7 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
                  else 'self',
                  func_builder,
                  slots,
+                 cls.__module__,
                  )
 
     _set_new_attribute(cls, '__replace__', _replace)

Lib/test/test_dataclasses/__init__.py

@@ -4140,6 +4140,130 @@ def test_text_annotations(self):
             {'foo': dataclass_textanno.Foo,
              'return': type(None)})
 
+    def test_dataclass_from_another_module(self):
+        # see bpo-45524
+        from test.test_dataclasses import dataclass_textanno
+        from dataclasses import dataclass
+
+        @dataclass
+        class Default(dataclass_textanno.Bar):
+            pass
+
+        @dataclass(init=False)
+        class WithInitFalse(dataclass_textanno.Bar):
+            pass
+
+        @dataclass(init=False)
+        class CustomInit(dataclass_textanno.Bar):
+            def __init__(self, foo: dataclass_textanno.Foo) -> None:
+                pass
+
+        @dataclass
+        class FutureInitChild(dataclass_textanno.WithFutureInit):
+            pass
+
+        classes = [
+            Default,
+            WithInitFalse,
+            CustomInit,
+            dataclass_textanno.WithFutureInit,
+            FutureInitChild,
+        ]
+        for klass in classes:
+            with self.subTest(klass=klass):
+                self.assertEqual(
+                    get_type_hints(klass),
+                    {'foo': dataclass_textanno.Foo},
+                )
+                self.assertEqual(get_type_hints(klass.__new__), {})
+                self.assertEqual(
+                    get_type_hints(klass.__init__),
+                    {'foo': dataclass_textanno.Foo, 'return': type(None)},
+                )
+
+    def test_dataclass_from_proxy_module(self):
+        # see bpo-45524
+        from test.test_dataclasses import dataclass_textanno
+        from test.test_dataclasses import dataclass_textanno2
+        from dataclasses import dataclass
+
+        @dataclass
+        class Default(dataclass_textanno2.Child):
+            pass
+
+        @dataclass(init=False)
+        class WithInitFalse(dataclass_textanno2.Child):
+            pass
+
+        @dataclass(init=False)
+        class CustomInit(dataclass_textanno2.Child):
+            def __init__(
+                self,
+                foo: dataclass_textanno.Foo,
+                custom: dataclass_textanno2.Custom,
+            ) -> None:
+                pass
+
+        @dataclass
+        class FutureInitChild(dataclass_textanno2.WithFutureInit):
+            pass
+
+        classes = [
+            Default,
+            WithInitFalse,
+            CustomInit,
+            dataclass_textanno2.WithFutureInit,
+            FutureInitChild,
+        ]
+        for klass in classes:
+            with self.subTest(klass=klass):
+                self.assertEqual(
+                    get_type_hints(klass),
+                    {
+                        'foo': dataclass_textanno.Foo,
+                        'custom': dataclass_textanno2.Custom,
+                    },
+                )
+                self.assertEqual(get_type_hints(klass.__new__), {})
+                self.assertEqual(
+                    get_type_hints(klass.__init__),
+                    {
+                        'foo': dataclass_textanno.Foo,
+                        'custom': dataclass_textanno2.Custom,
+                        'return': type(None),
+                    },
+                )
+
+    def test_dataclass_proxy_modules_matching_name_override(self):
+        # see bpo-45524
+        from test.test_dataclasses import dataclass_textanno2
+        from dataclasses import dataclass
+
+        @dataclass
+        class Default(dataclass_textanno2.WithMatchingNameOverride):
+            pass
+
+        classes = [
+            Default,
+            dataclass_textanno2.WithMatchingNameOverride
+        ]
+        for klass in classes:
+            with self.subTest(klass=klass):
+                self.assertEqual(
+                    get_type_hints(klass),
+                    {
+                        'foo': dataclass_textanno2.Foo,
+                    },
+                )
+                self.assertEqual(get_type_hints(klass.__new__), {})
+                self.assertEqual(
+                    get_type_hints(klass.__init__),
+                    {
+                        'foo': dataclass_textanno2.Foo,
+                        'return': type(None),
+                    },
+                )
+
 
 ByMakeDataClass = make_dataclass('ByMakeDataClass', [('x', int)])
 ManualModuleMakeDataClass = make_dataclass('ManualModuleMakeDataClass',

Lib/test/test_dataclasses/dataclass_text_anno2.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import dataclasses
+
+# We need to be sure that `Foo` is not in scope
+from test.test_dataclasses import dataclass_textanno
+
+
+class Custom:
+    pass
+
+
+@dataclasses.dataclass
+class Child(dataclass_textanno.Bar):
+    custom: Custom
+
+
+class Foo:  # matching name with `dataclass_testanno.Foo`
+    pass
+
+
+@dataclasses.dataclass
+class WithMatchingNameOverride(dataclass_textanno.Bar):
+    foo: Foo  # Existing `foo` annotation should be overridden
+
+
+@dataclasses.dataclass(init=False)
+class WithFutureInit(Child):
+    def __init__(self, foo: dataclass_textanno.Foo, custom: Custom) -> None:
+        pass

Lib/test/test_dataclasses/dataclass_textanno.py

@@ -10,3 +10,9 @@ class Foo:
 @dataclasses.dataclass
 class Bar:
     foo: Foo
+
+
+@dataclasses.dataclass(init=False)
+class WithFutureInit(Bar):
+    def __init__(self, foo: Foo) -> None:
+        pass

Misc/NEWS.d/next/Library/2025-07-28-14-24-07.gh-issue-89687.7uW1c8.rst

@@ -0,0 +1 @@
+Fix ``typing.get_type_hints()`` failure on ``@dataclass`` hierarchies in different modules.