Close #4422: autodoc: Support GenericAlias

CHANGES

@@ -49,6 +49,7 @@ Features added
 * #7143: autodoc: Support final classes and methods
 * #7384: autodoc: Support signatures defined by ``__new__()``, metaclasses and
   builtin base classes
+* #4422: autodoc: Support GenericAlias in Python 3.7 or above
 * #7466: autosummary: headings in generated documents are not translated
 * #7490: autosummary: Add ``:caption:`` option to autosummary directive to set a
   caption to the toctree

sphinx/ext/autodoc/__init__.py

@@ -1544,6 +1544,30 @@ class DataDeclarationDocumenter(DataDocumenter):
         super().add_content(more_content, no_docstring=True)
 
 
+class GenericAliasDocumenter(DataDocumenter):
+    """
+    Specialized Documenter subclass for GenericAliases.
+    """
+
+    objtype = 'genericalias'
+    directivetype = 'data'
+    priority = DataDocumenter.priority + 1
+
+    @classmethod
+    def can_document_member(cls, member: Any, membername: str, isattr: bool, parent: Any
+                            ) -> bool:
+        return inspect.isgenericalias(member)
+
+    def add_directive_header(self, sig: str) -> None:
+        self.options.annotation = SUPPRESS  # type: ignore
+        super().add_directive_header(sig)
+
+    def add_content(self, more_content: Any, no_docstring: bool = False) -> None:
+        name = stringify_typehint(self.object)
+        content = StringList([_('alias of %s') % name], source='')
+        super().add_content(content)
+
+
 class MethodDocumenter(DocstringSignatureMixin, ClassLevelDocumenter):  # type: ignore
     """
     Specialized Documenter subclass for methods (normal, static and class).
@@ -1902,6 +1926,7 @@ def setup(app: Sphinx) -> Dict[str, Any]:
     app.add_autodocumenter(ExceptionDocumenter)
     app.add_autodocumenter(DataDocumenter)
     app.add_autodocumenter(DataDeclarationDocumenter)
+    app.add_autodocumenter(GenericAliasDocumenter)
     app.add_autodocumenter(FunctionDocumenter)
     app.add_autodocumenter(DecoratorDocumenter)
     app.add_autodocumenter(MethodDocumenter)

sphinx/ext/autosummary/generate.py

@@ -91,14 +91,14 @@ def setup_documenters(app: Any) -> None:
         ModuleDocumenter, ClassDocumenter, ExceptionDocumenter, DataDocumenter,
         FunctionDocumenter, MethodDocumenter, AttributeDocumenter,
         InstanceAttributeDocumenter, DecoratorDocumenter, PropertyDocumenter,
-        SlotsAttributeDocumenter, DataDeclarationDocumenter,
+        SlotsAttributeDocumenter, DataDeclarationDocumenter, GenericAliasDocumenter,
         SingledispatchFunctionDocumenter,
     )
     documenters = [
         ModuleDocumenter, ClassDocumenter, ExceptionDocumenter, DataDocumenter,
         FunctionDocumenter, MethodDocumenter, AttributeDocumenter,
         InstanceAttributeDocumenter, DecoratorDocumenter, PropertyDocumenter,
-        SlotsAttributeDocumenter, DataDeclarationDocumenter,
+        SlotsAttributeDocumenter, DataDeclarationDocumenter, GenericAliasDocumenter,
         SingledispatchFunctionDocumenter,
     ]  # type: List[Type[Documenter]]
     for documenter in documenters:

tests/test_ext_autodoc.py

@@ -1587,6 +1587,37 @@ def test_autodoc_typed_instance_variables(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_autodoc_GenericAlias(app):
+    options = {"members": None,
+               "undoc-members": None}
+    actual = do_autodoc(app, 'module', 'target.genericalias', options)
+    if sys.version_info < (3, 7):
+        assert list(actual) == [
+            '',
+            '.. py:module:: target.genericalias',
+            '',
+            '',
+            '.. py:attribute:: T',
+            '   :module: target.genericalias',
+            '',
+            '   alias of :class:`typing.List`',
+        ]
+    else:
+        assert list(actual) == [
+            '',
+            '.. py:module:: target.genericalias',
+            '',
+            '',
+            '.. py:data:: T',
+            '   :module: target.genericalias',
+            '',
+            '   A list of int',
+            '',
+            '   alias of List[int]',
+        ]
+
+
 @pytest.mark.skipif(sys.version_info < (3, 9), reason='py39+ is required.')
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_autodoc_Annotated(app):