diff --git a/sphinx/application.py b/sphinx/application.py
index 9878a3e71..741776fbb 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -526,8 +526,7 @@ class Sphinx:
            ``'env'``) to a string.  However, booleans are still accepted and
            converted internally.
         """
-        logger.debug('[app] adding config value: %r',
-                     (name, default, rebuild) + ((types,) if types else ()))
+        logger.debug('[app] adding config value: %r', (name, default, rebuild, types))
         if rebuild in (False, True):
             rebuild = 'env' if rebuild else ''
         self.config.add(name, default, rebuild, types)
diff --git a/sphinx/builders/_epub_base.py b/sphinx/builders/_epub_base.py
index 65fb1ff9a..103033478 100644
--- a/sphinx/builders/_epub_base.py
+++ b/sphinx/builders/_epub_base.py
@@ -270,7 +270,7 @@ class EpubBuilder(StandaloneHTMLBuilder):
         """
         def update_node_id(node: Element) -> None:
             """Update IDs of given *node*."""
-            new_ids = []
+            new_ids: List[str] = []
             for node_id in node['ids']:
                 new_id = self.fix_fragment('', node_id)
                 if new_id not in new_ids:
diff --git a/sphinx/ext/autosummary/generate.py b/sphinx/ext/autosummary/generate.py
index 2b17ccbb9..55cad705f 100644
--- a/sphinx/ext/autosummary/generate.py
+++ b/sphinx/ext/autosummary/generate.py
@@ -407,7 +407,7 @@ def generate_autosummary_docs(sources: List[str], output_dir: str = None,
                 logger.warning(__('[autosummary] failed to import %r: %s') % (entry.name, e))
                 continue
 
-        context = {}
+        context: Dict[str, Any] = {}
         if app:
             context.update(app.config.autosummary_context)
 
diff --git a/sphinx/registry.py b/sphinx/registry.py
index 67e2564ff..f10f1fac6 100644
--- a/sphinx/registry.py
+++ b/sphinx/registry.py
@@ -12,7 +12,8 @@ import traceback
 import warnings
 from importlib import import_module
 from types import MethodType
-from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Tuple, Type, Union
+from typing import (TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Optional, Tuple, Type,
+                    Union)
 
 from docutils import nodes
 from docutils.io import Input
@@ -286,7 +287,7 @@ class SphinxComponentRegistry:
             parser.set_application(app)
         return parser
 
-    def get_source_input(self, filetype: str) -> Type[Input]:
+    def get_source_input(self, filetype: str) -> Optional[Type[Input]]:
         warnings.warn('SphinxComponentRegistry.get_source_input() is deprecated.',
                       RemovedInSphinx60Warning)
 
diff --git a/sphinx/util/inspect.py b/sphinx/util/inspect.py
index 921dbc5e2..96f04a3d3 100644
--- a/sphinx/util/inspect.py
+++ b/sphinx/util/inspect.py
@@ -749,7 +749,7 @@ def getdoc(obj: Any, attrgetter: Callable = safe_getattr,
     elif doc is None and allow_inherited:
         doc = inspect.getdoc(obj)
 
-        if doc is None and cls:
+        if doc is None and cls and name:
             # inspect.getdoc() does not support some kind of inherited and decorated methods.
             # This tries to obtain the docstring from super classes.
             for basecls in getattr(cls, '__mro__', []):