Fix sphinx-doc#7510: py domain: keyword-only arguments are wrongly re…

…ndered

CHANGES

@@ -20,6 +20,8 @@ Bugs fixed
 ----------
 
 * #7461: py domain: fails with IndexError for empty tuple in type annotation
+* #7510: py domain: keyword-only arguments are documented as having a default of
+  None
 * #7418: std domain: :rst:role:`term` role could not match case-insensitively
 * #7461: autodoc: empty tuple in type annotation is not shown correctly
 * #7479: autodoc: Sphinx builds has been slower since 3.0.0 on mocking

sphinx/util/inspect.py

@@ -527,7 +527,7 @@ def signature_from_str(signature: str) -> inspect.Signature:
                                 annotation=annotation))
 
     for i, arg in enumerate(args.kwonlyargs):
-        default = ast_unparse(args.kw_defaults[i])
+        default = ast_unparse(args.kw_defaults[i]) or Parameter.empty
         annotation = ast_unparse(arg.annotation) or Parameter.empty
         params.append(Parameter(arg.arg, Parameter.KEYWORD_ONLY, default=default,
                                 annotation=annotation))

tests/test_util_inspect.py

@@ -317,6 +317,15 @@ def test_signature_from_str_complex_annotations():
     assert sig.return_annotation == 'Callable[[int, int], int]'
 
 
+def test_signature_from_str_kwonly_args():
+    sig = inspect.signature_from_str('(a, *, b)')
+    assert list(sig.parameters.keys()) == ['a', 'b']
+    assert sig.parameters['a'].kind == Parameter.POSITIONAL_OR_KEYWORD
+    assert sig.parameters['a'].default == Parameter.empty
+    assert sig.parameters['b'].kind == Parameter.KEYWORD_ONLY
+    assert sig.parameters['b'].default == Parameter.empty
+
+
 @pytest.mark.skipif(sys.version_info < (3, 8),
                     reason='python-3.8 or above is required')
 def test_signature_from_str_positionaly_only_args():