Improve signature handling in autodoc (#13955)

Author: AA-Turner

doc/development/tutorials/examples/autodoc_intenum.py

@@ -30,8 +30,8 @@ def can_document_member(
         except TypeError:
             return False
 
-    def add_directive_header(self, sig: str) -> None:
-        super().add_directive_header(sig)
+    def add_directive_header(self) -> None:
+        super().add_directive_header()
         self.add_line('   :final:', self.get_sourcename())
 
     def add_content(

doc/usage/extensions/autodoc.rst

@@ -1411,7 +1411,7 @@ autodoc provides the following additional events:
       ``'(parameter_1, parameter_2)'``, or ``None`` if introspection didn't
       succeed and signature wasn't specified in the directive.
    :param return_annotation: function return annotation as a string of the form
-      ``' -> annotation'``, or ``None`` if there is no return annotation
+      ``'annotation'``, or ``''`` if there is no return annotation.
 
 The :mod:`sphinx.ext.autodoc` module provides factory functions for commonly
 needed docstring processing in event :event:`autodoc-process-docstring`:

sphinx/ext/autodoc/__init__.py

@@ -39,7 +39,6 @@
     PropertyDocumenter,
     TypeAliasDocumenter,
     autodoc_attrgetter,
-    py_ext_sig_re,
 )
 from sphinx.ext.autodoc._event_listeners import between, cut_lines
 from sphinx.ext.autodoc._member_finder import ObjectMember, special_member_re
@@ -50,6 +49,7 @@
 from sphinx.ext.autodoc._sentinels import (
     SLOTS_ATTR as SLOTSATTR,
 )
+from sphinx.ext.autodoc.importer import py_ext_sig_re
 
 if TYPE_CHECKING:
     from sphinx.application import Sphinx