Get better 'Source' annotations - break slots gc tests

Author: DavidCEllis

Lib/dataclasses.py

@@ -509,7 +509,7 @@ def add_fns_to_class(self, cls):
         for name, fn in zip(self.names, fns):
             fn.__qualname__ = f"{cls.__qualname__}.{fn.__name__}"
             if annotations := self.method_annotations.get(name):
-                fn.__annotate__ = _make_annotate_function(annotations)
+                fn.__annotate__ = _make_annotate_function(cls, annotations)
 
             if self.unconditional_adds.get(name, False):
                 setattr(cls, name, fn)
@@ -526,10 +526,13 @@ def add_fns_to_class(self, cls):
                     raise TypeError(error_msg)
 
 
-def _make_annotate_function(annotations):
+def _make_annotate_function(cls, annotations):
     # Create an __annotate__ function for a dataclass
     # Try to return annotations in the same format as they would be
     # from a regular __init__ function
+
+    # annotations should be in FORWARDREF format at this stage
+
     def __annotate__(format):
         match format:
             case annotationlib.Format.VALUE | annotationlib.Format.FORWARDREF:
@@ -538,19 +541,30 @@ def __annotate__(format):
                     if isinstance(v, annotationlib.ForwardRef) else v
                     for k, v in annotations.items()
                 }
+
             case annotationlib.Format.STRING:
+                cls_annotations = {}
+                for base in reversed(cls.__mro__):
+                    cls_annotations.update(
+                        annotationlib.get_annotations(base, format=format)
+                    )
+
                 string_annos = {}
                 for k, v in annotations.items():
-                    if isinstance(v, str):
-                        string_annos[k] = v
-                    elif isinstance(v, annotationlib.ForwardRef):
-                        string_annos[k] = v.evaluate(format=annotationlib.Format.STRING)
-                    else:
+                    try:
+                        string_annos[k] = cls_annotations[k]
+                    except KeyError:
+                        # This should be the return value
                         string_annos[k] = annotationlib.type_repr(v)
                 return string_annos
+
             case _:
                 raise NotImplementedError(format)
 
+    # This is a flag for _add_slots to know it needs to regenerate this method
+    # In order to remove references to the original class when it is replaced
+    __annotate__.__generated_by_dataclasses = True
+
     return __annotate__
 
 

Lib/test/test_dataclasses/__init__.py

@@ -2512,6 +2512,8 @@ class B:
         self.assertEqual(forwardref_annos, {'b': int, 'return': None})
         self.assertEqual(string_annos, {'b': 'undefined', 'return': 'None'})
 
+        del undefined  # Remove so we can use the name in later examples
+
         # Check `init=False` attributes don't get into the annotations of the __init__ function
         @dataclass
         class C:
@@ -2520,6 +2522,17 @@ class C:
         self.assertEqual(annotationlib.get_annotations(C.__init__), {'return': None})
 
 
+        # Check string annotations on objects containing a ForwardRef
+        @dataclass
+        class D:
+            d: list[undefined]
+
+        self.assertEqual(
+            annotationlib.get_annotations(D.__init__, format=annotationlib.Format.STRING),
+            {"d": "list[undefined]", "return": "None"}
+        )
+
+
 class TestRepr(unittest.TestCase):
     def test_repr(self):
         @dataclass