Fix sphinx extension compat with sphinx8 (#826)

* Add required generic type as well.

README.rst

@@ -87,6 +87,10 @@ in development
 * Replace the deprecated dependency appdirs with platformdirs.
 * Fix WinError caused by the failure of the symlink creation process.
   Pydoctor should now run on windows without the need to be administrator.
+* Adjust the sphinx extension to support Sphinx 8.1. The entries dynamically added to the intersphinx config
+  from the ``pydoctor_url_path`` config option now includes a project name which defaults to 'main' (instead of putting None), 
+  use mapping instead of a list define your own project name.
+
 
 pydoctor 24.3.3
 ^^^^^^^^^^^^^^^

pydoctor/epydoc/markup/restructuredtext.py

@@ -41,7 +41,10 @@
 from __future__ import annotations
 __docformat__ = 'epytext en'
 
-from typing import Any, Iterable, List, Optional, Sequence, Set, cast
+from typing import TYPE_CHECKING, Any, Iterable, List, Optional, Sequence, Set, cast
+if TYPE_CHECKING:
+    from typing import TypeAlias
+
 import re
 from docutils import nodes
 
@@ -190,7 +193,12 @@ def report(self, error: nodes.system_message) -> None:
 
         self._errors.append(ParseError(msg, linenum, is_fatal))
 
-class _DocumentPseudoWriter(Writer):
+if TYPE_CHECKING:
+    _StrWriter: TypeAlias = Writer[str]
+else:
+    _StrWriter = Writer
+
+class _DocumentPseudoWriter(_StrWriter):
     """
     A pseudo-writer for the docutils framework, that can be used to
     access the document itself.  The output of C{_DocumentPseudoWriter}

pydoctor/sphinx_ext/build_apidocs.py

@@ -113,7 +113,7 @@ def on_builder_inited(app: Sphinx) -> None:
             intersphinx_mapping = config.intersphinx_mapping
             url = url_path.format(**{'rtd_version': rtd_version})
             inv = (str(temp_path / 'objects.inv'),)
-            intersphinx_mapping[f'{key}-api-docs'] = (None, (url, inv))
+            intersphinx_mapping[f'{key}-api-docs'] = (key, (url, inv))
 
         # Build the API docs in temporary path.
         shutil.rmtree(temp_path, ignore_errors=True)