autodoc: Ensure type statements don't inherit docstrings (#14068)

Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>

Author: LecrisUT

sphinx/ext/autodoc/_docstrings.py

@@ -88,7 +88,7 @@ def _prepare_docstrings(
 ) -> list[list[str]] | None:
     """Add content from docstrings, attribute documentation and user."""
     # add content from attribute documentation
-    if props.obj_type not in {'data', 'attribute'} and props.parts:
+    if props.obj_type not in {'data', 'attribute', 'type'} and props.parts:
         key = ('.'.join(props.parent_names), props.name)
         try:
             # make a copy of docstring for attributes to avoid cache
@@ -298,6 +298,20 @@ def _get_docstring_lines(
             return []
         return [prepare_docstring(docstring, tab_width)]
 
+    if props.obj_type == 'type':
+        try:
+            analyzer = ModuleAnalyzer.for_module(props.module_name)
+            analyzer.analyze()
+        except PycodeError:
+            return None
+
+        key = ('', props.name)
+        if key in analyzer.attr_docs:
+            if comment := list(analyzer.attr_docs[key]):
+                return [comment]
+
+        return None
+
     docstring = getdoc(
         obj,
         allow_inherited=inherit_docstrings,

tests/roots/test-ext-autodoc/target/pep695.py

@@ -22,6 +22,8 @@ class Foo:
 type Pep695Alias = Foo
 """This is PEP695 type alias."""
 
+type Pep695AliasUndocumented = Foo
+
 TypeAliasTypeExplicit = TypeAliasType('TypeAliasTypeExplicit', Foo)  # NoQA: UP040
 """This is an explicitly constructed typing.TypeAlias."""
 

tests/test_ext_autodoc/test_ext_autodoc.py

@@ -2292,6 +2292,12 @@ def test_autodoc_pep695_type_alias() -> None:
         '   This is PEP695 type alias of PEP695 alias.',
         '',
         '',
+        # Undocumented alias should not inherit any documentation
+        '.. py:type:: Pep695AliasUndocumented',
+        '   :module: target.pep695',
+        '   :canonical: ~target.pep695.Foo',
+        '',
+        '',
         '.. py:type:: Pep695AliasUnion',
         '   :module: target.pep695',
         '   :canonical: str | int',