Fix #8219: autodoc: Parameters for generic base class are not shown

CHANGES

@@ -41,6 +41,9 @@ Features added
 Bugs fixed
 ----------
 
+* #8219: autodoc: Parameters for generic class are not shown when super class is
+  a generic class and show-inheritance option is given (in Python 3.7 or above)
+
 Testing
 --------
 

sphinx/ext/autodoc/__init__.py

@@ -37,7 +37,7 @@
 from sphinx.util.inspect import (
     evaluate_signature, getdoc, object_description, safe_getattr, stringify_signature
 )
-from sphinx.util.typing import stringify as stringify_typehint
+from sphinx.util.typing import restify, stringify as stringify_typehint
 
 if False:
     # For type annotation
@@ -1522,13 +1522,16 @@ def add_directive_header(self, sig: str) -> None:
         if not self.doc_as_attr and self.options.show_inheritance:
             sourcename = self.get_sourcename()
             self.add_line('', sourcename)
-            if hasattr(self.object, '__bases__') and len(self.object.__bases__):
-                bases = [':class:`%s`' % b.__name__
-                         if b.__module__ in ('__builtin__', 'builtins')
-                         else ':class:`%s.%s`' % (b.__module__, b.__qualname__)
-                         for b in self.object.__bases__]
-                self.add_line('   ' + _('Bases: %s') % ', '.join(bases),
-                              sourcename)
+
+            if hasattr(self.object, '__orig_bases__') and len(self.object.__orig_bases__):
+                # A subclass of generic types
+                # refs: PEP-560 <https://www.python.org/dev/peps/pep-0560/>
+                bases = [restify(cls) for cls in self.object.__orig_bases__]
+                self.add_line('   ' + _('Bases: %s') % ', '.join(bases), sourcename)
+            elif hasattr(self.object, '__bases__') and len(self.object.__bases__):
+                # A normal class
+                bases = [restify(cls) for cls in self.object.__bases__]
+                self.add_line('   ' + _('Bases: %s') % ', '.join(bases), sourcename)
 
     def get_doc(self, encoding: str = None, ignore: int = None) -> List[List[str]]:
         if encoding is not None:

sphinx/util/typing.py

@@ -30,6 +30,10 @@ def _evaluate(self, globalns: Dict, localns: Dict) -> Any:
             ref = _ForwardRef(self.arg)
             return ref._eval_type(globalns, localns)
 
+if False:
+    # For type annotation
+    from typing import Type  # NOQA # for python3.5.1
+
 
 # An entry of Directive.option_spec
 DirectiveOption = Callable[[str], Any]
@@ -234,3 +238,37 @@ def _stringify_py36(annotation: Any) -> str:
                                ', '.join(param_strings))
 
     return qualname
+
+
+def restify(cls: "Type") -> str:
+    """Convert python class to a reST reference."""
+    from sphinx.util import inspect  # lazy loading
+
+    if cls.__module__ in ('__builtin__', 'builtins'):
+        return ':class:`%s`' % cls.__name__
+    elif inspect.isgenericalias(cls):
+        if cls._name:
+            if cls.__module__ == 'typing':
+                text = ':class:`%s`' % cls._name
+            else:
+                text = ':class:`%s.%s`' % (cls.__module__, cls._name)
+        else:
+            text = restify(cls.__origin__)
+
+        if cls.__args__:
+            text += r"\ [%s]" % ", ".join(restify(a) for a in cls.__args__)
+        return text
+    elif hasattr(cls, '__qualname__'):
+        if cls.__module__ == 'typing':
+            return ':class:`%s`' % cls.__qualname__
+        else:
+            return ':class:`%s.%s`' % (cls.__module__, cls.__qualname__)
+    elif hasattr(cls, '_name'):
+        # SpecialForm (ex. Union)
+        if cls.__module__ == 'typing':
+            return ':obj:`%s`' % cls._name
+        else:
+            return ':obj:`%s.%s`' % (cls.__module__, cls._name)
+    else:
+        # not a class (ex. TypeVar)
+        return ':obj:`%s.%s`' % (cls.__module__, cls.__name__)

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

@@ -1,3 +1,6 @@
+from typing import List, Union
+
+
 class Foo:
     pass
 
@@ -10,3 +13,8 @@ def __init__(self, x, y):
 class Baz:
     def __new__(cls, x, y):
         pass
+
+
+class Qux(List[Union[int, float]]):
+    """A subclass of List[Union[int, float]]"""
+    pass

tests/test_ext_autodoc_autoclass.py

@@ -0,0 +1,33 @@
+"""
+    test_ext_autodoc_autoclass
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Test the autodoc extension.  This tests mainly the Documenters; the auto
+    directives are tested in a test source file translated by test_build.
+
+    :copyright: Copyright 2007-2020 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+import sys
+
+import pytest
+
+from test_ext_autodoc import do_autodoc
+
+
+@pytest.mark.skipif(sys.version_info < (3, 7), reason='python 3.7+ is required.')
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_show_inheritance_for_subclass_of_generic_type(app):
+    options = {'show-inheritance': True}
+    actual = do_autodoc(app, 'class', 'target.classes.Qux', options)
+    assert list(actual) == [
+        '',
+        '.. py:class:: Qux(iterable=(), /)',
+        '   :module: target.classes',
+        '',
+        '   Bases: :class:`List`\\ [:obj:`Union`\\ [:class:`int`, :class:`float`]]',
+        '',
+        '   A subclass of List[Union[int, float]]',
+        '',
+    ]