diff --git a/setuptools/__init__.py b/setuptools/__init__.py
index 4f5c01708a..82c8d0179f 100644
--- a/setuptools/__init__.py
+++ b/setuptools/__init__.py
@@ -110,11 +110,12 @@ def _fetch_build_eggs(dist: Distribution):
         raise
 
 
-def setup(**attrs):
+def setup(**attrs) -> Distribution:
     logging.configure()
     # Make sure we have any requirements needed to interpret 'attrs'.
     _install_setup_requires(attrs)
-    return distutils.core.setup(**attrs)
+    # Override return type of distutils.core.Distribution with setuptools.dist.Distribution
+    return distutils.core.setup(**attrs)  # type: ignore[return-value]
 
 
 setup.__doc__ = distutils.core.setup.__doc__
@@ -216,14 +217,14 @@ def ensure_string_list(self, option: str) -> None:
     @overload
     def reinitialize_command(
         self, command: str, reinit_subcommands: bool = False, **kw
-    ) -> _Command: ...
+    ) -> Command: ...  # override distutils.cmd.Command with setuptools.Command
     @overload
     def reinitialize_command(
         self, command: _CommandT, reinit_subcommands: bool = False, **kw
     ) -> _CommandT: ...
     def reinitialize_command(
         self, command: str | _Command, reinit_subcommands: bool = False, **kw
-    ) -> _Command:
+    ) -> Command | _Command:
         cmd = _Command.reinitialize_command(self, command, reinit_subcommands)
         vars(cmd).update(kw)
         return cmd  # pyright: ignore[reportReturnType] # pypa/distutils#307
diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index 00fa5e1f70..3b209d6c2f 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -39,7 +39,7 @@
 import warnings
 from collections.abc import Iterable, Iterator, Mapping
 from pathlib import Path
-from typing import TYPE_CHECKING, Union
+from typing import TYPE_CHECKING, NoReturn, Union
 
 import setuptools
 
@@ -77,14 +77,14 @@ def __init__(self, specifiers) -> None:
 
 
 class Distribution(setuptools.dist.Distribution):
-    def fetch_build_eggs(self, specifiers):
+    def fetch_build_eggs(self, specifiers) -> NoReturn:
         specifier_list = list(parse_strings(specifiers))
 
         raise SetupRequirementsError(specifier_list)
 
     @classmethod
     @contextlib.contextmanager
-    def patch(cls):
+    def patch(cls) -> Iterator[None]:
         """
         Replace
         distutils.dist.Distribution with this class
@@ -307,7 +307,7 @@ def _get_build_requires(
 
         return requirements
 
-    def run_setup(self, setup_script: str = 'setup.py'):
+    def run_setup(self, setup_script: str = 'setup.py') -> None:
         # Note that we can reuse our build directory between calls
         # Correctness comes first, then optimization later
         __file__ = os.path.abspath(setup_script)
@@ -330,10 +330,14 @@ def run_setup(self, setup_script: str = 'setup.py'):
                 "setup-py-deprecated.html",
             )
 
-    def get_requires_for_build_wheel(self, config_settings: _ConfigSettings = None):
+    def get_requires_for_build_wheel(
+        self, config_settings: _ConfigSettings = None
+    ) -> list[str]:
         return self._get_build_requires(config_settings, requirements=[])
 
-    def get_requires_for_build_sdist(self, config_settings: _ConfigSettings = None):
+    def get_requires_for_build_sdist(
+        self, config_settings: _ConfigSettings = None
+    ) -> list[str]:
         return self._get_build_requires(config_settings, requirements=[])
 
     def _bubble_up_info_directory(
@@ -364,7 +368,7 @@ def _find_info_directory(self, metadata_directory: StrPath, suffix: str) -> Path
 
     def prepare_metadata_for_build_wheel(
         self, metadata_directory: StrPath, config_settings: _ConfigSettings = None
-    ):
+    ) -> str:
         sys.argv = [
             *sys.argv[:1],
             *self._global_args(config_settings),
@@ -420,7 +424,7 @@ def build_wheel(
         wheel_directory: StrPath,
         config_settings: _ConfigSettings = None,
         metadata_directory: StrPath | None = None,
-    ):
+    ) -> str:
         def _build(cmd: list[str]):
             with suppress_known_deprecation():
                 return self._build_with_temp_dir(
@@ -445,7 +449,7 @@ def _build(cmd: list[str]):
 
     def build_sdist(
         self, sdist_directory: StrPath, config_settings: _ConfigSettings = None
-    ):
+    ) -> str:
         return self._build_with_temp_dir(
             ['sdist', '--formats', 'gztar'], '.tar.gz', sdist_directory, config_settings
         )
@@ -467,7 +471,7 @@ def build_editable(
             wheel_directory: StrPath,
             config_settings: _ConfigSettings = None,
             metadata_directory: StrPath | None = None,
-        ):
+        ) -> str:
             # XXX can or should we hide our editable_wheel command normally?
             info_dir = self._get_dist_info_dir(metadata_directory)
             opts = ["--dist-info-dir", info_dir] if info_dir else []
@@ -479,12 +483,12 @@ def build_editable(
 
         def get_requires_for_build_editable(
             self, config_settings: _ConfigSettings = None
-        ):
+        ) -> list[str]:
             return self.get_requires_for_build_wheel(config_settings)
 
         def prepare_metadata_for_build_editable(
             self, metadata_directory: StrPath, config_settings: _ConfigSettings = None
-        ):
+        ) -> str:
             return self.prepare_metadata_for_build_wheel(
                 metadata_directory, config_settings
             )
@@ -502,7 +506,7 @@ class _BuildMetaLegacyBackend(_BuildMetaBackend):
     and will eventually be removed.
     """
 
-    def run_setup(self, setup_script: str = 'setup.py'):
+    def run_setup(self, setup_script: str = 'setup.py') -> None:
         # In order to maintain compatibility with scripts assuming that
         # the setup.py script is in a directory on the PYTHONPATH, inject
         # '' into sys.path. (pypa/setuptools#1642)
diff --git a/setuptools/command/bdist_egg.py b/setuptools/command/bdist_egg.py
index ac3e6ef1f9..e320205289 100644
--- a/setuptools/command/bdist_egg.py
+++ b/setuptools/command/bdist_egg.py
@@ -9,19 +9,21 @@
 import re
 import sys
 import textwrap
+from collections.abc import Iterator
 from sysconfig import get_path, get_python_version
 from types import CodeType
-from typing import TYPE_CHECKING, Literal
+from typing import TYPE_CHECKING, AnyStr, Literal
 
 from setuptools import Command
 from setuptools.extension import Library
 
-from .._path import StrPathT, ensure_directory
+from .._path import StrPath, StrPathT, ensure_directory
 
 from distutils import log
 from distutils.dir_util import mkpath, remove_tree
 
 if TYPE_CHECKING:
+    from _typeshed import GenericPath
     from typing_extensions import TypeAlias
 
 # Same as zipfile._ZipFileMode from typeshed
@@ -40,7 +42,9 @@ def strip_module(filename):
     return filename
 
 
-def sorted_walk(dir):
+def sorted_walk(
+    dir: GenericPath[AnyStr],
+) -> Iterator[tuple[AnyStr, list[AnyStr], list[AnyStr]]]:
     """Do os.walk in a reproducible way,
     independent of indeterministic filesystem readdir order
     """
@@ -163,7 +167,7 @@ def call_command(self, cmdname, **kw):
         self.run_command(cmdname)
         return cmd
 
-    def run(self):  # noqa: C901  # is too complex (14)  # FIXME
+    def run(self) -> None:  # noqa: C901  # is too complex (14)  # FIXME
         # Generate metadata first
         self.run_command("egg_info")
         # We run install_lib before install_data, because some data hacks
@@ -234,7 +238,7 @@ def run(self):  # noqa: C901  # is too complex (14)  # FIXME
             self.egg_output,
             archive_root,
             verbose=self.verbose,
-            dry_run=self.dry_run,
+            dry_run=self.dry_run,  # type: ignore[arg-type] # Is an actual boolean in vendored _distutils
             mode=self.gen_header(),
         )
         if not self.keep_temp:
@@ -247,7 +251,7 @@ def run(self):  # noqa: C901  # is too complex (14)  # FIXME
             self.egg_output,
         ))
 
-    def zap_pyfiles(self):
+    def zap_pyfiles(self) -> None:
         log.info("Removing .py files from temporary directory")
         for base, dirs, files in walk_egg(self.bdist_dir):
             for name in files:
@@ -262,6 +266,8 @@ def zap_pyfiles(self):
 
                     pattern = r'(?P<name>.+)\.(?P<magic>[^.]+)\.pyc'
                     m = re.match(pattern, name)
+                    # We shouldn't find any non-pyc files in __pycache__
+                    assert m is not None
                     path_new = os.path.join(base, os.pardir, m.group('name') + '.pyc')
                     log.info("Renaming file from [%s] to [%s]" % (path_old, path_new))
                     try:
@@ -325,7 +331,7 @@ def get_ext_outputs(self):
 NATIVE_EXTENSIONS: dict[str, None] = dict.fromkeys('.dll .so .dylib .pyd'.split())
 
 
-def walk_egg(egg_dir):
+def walk_egg(egg_dir: StrPath) -> Iterator[tuple[str, list[str], list[str]]]:
     """Walk an unpacked egg's contents, skipping the metadata directory"""
     walker = sorted_walk(egg_dir)
     base, dirs, files = next(walker)
@@ -411,7 +417,7 @@ def scan_module(egg_dir, base, name, stubs):
     return safe
 
 
-def iter_symbols(code):
+def iter_symbols(code: CodeType) -> Iterator[str]:
     """Yield names and strings used by `code` and its nested code objects"""
     yield from code.co_names
     for const in code.co_consts:
diff --git a/setuptools/command/build_ext.py b/setuptools/command/build_ext.py
index e5c6b76b38..39ae3594b1 100644
--- a/setuptools/command/build_ext.py
+++ b/setuptools/command/build_ext.py
@@ -93,7 +93,7 @@ class build_ext(_build_ext):
     editable_mode = False
     inplace = False
 
-    def run(self):
+    def run(self) -> None:
         """Build extensions in build directory, then copy if --inplace"""
         old_inplace, self.inplace = self.inplace, False
         _build_ext.run(self)
@@ -223,7 +223,7 @@ def finalize_options(self) -> None:
         if self.editable_mode:
             self.inplace = True
 
-    def setup_shlib_compiler(self):
+    def setup_shlib_compiler(self) -> None:
         compiler = self.shlib_compiler = new_compiler(
             compiler=self.compiler, dry_run=self.dry_run, force=self.force
         )
diff --git a/setuptools/command/build_py.py b/setuptools/command/build_py.py
index e7d60c6440..a09c222e48 100644
--- a/setuptools/command/build_py.py
+++ b/setuptools/command/build_py.py
@@ -41,7 +41,7 @@ class build_py(orig.build_py):
     editable_mode: bool = False
     existing_egg_info_dir: StrPath | None = None  #: Private API, internal use only.
 
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         orig.build_py.finalize_options(self)
         self.package_data = self.distribution.package_data
         self.exclude_package_data = self.distribution.exclude_package_data or {}
@@ -93,7 +93,7 @@ def _get_data_files(self):
         self.analyze_manifest()
         return list(map(self._get_pkg_data_files, self.packages or ()))
 
-    def get_data_files_without_manifest(self):
+    def get_data_files_without_manifest(self) -> list[tuple[str, str, str, list[str]]]:
         """
         Generate list of ``(package,src_dir,build_dir,filenames)`` tuples,
         but without triggering any attempt to analyze or build the manifest.
@@ -103,7 +103,7 @@ def get_data_files_without_manifest(self):
         self.__dict__.setdefault('manifest_files', {})
         return list(map(self._get_pkg_data_files, self.packages or ()))
 
-    def _get_pkg_data_files(self, package):
+    def _get_pkg_data_files(self, package: str) -> tuple[str, str, str, list[str]]:
         # Locate package source directory
         src_dir = self.get_package_dir(package)
 
@@ -272,7 +272,7 @@ def initialize_options(self):
         self.editable_mode = False
         self.existing_egg_info_dir = None
 
-    def get_package_dir(self, package):
+    def get_package_dir(self, package: str) -> str:
         res = orig.build_py.get_package_dir(self, package)
         if self.distribution.src_root is not None:
             return os.path.join(self.distribution.src_root, res)
diff --git a/setuptools/command/develop.py b/setuptools/command/develop.py
index 7eee29d491..777309e0a4 100644
--- a/setuptools/command/develop.py
+++ b/setuptools/command/develop.py
@@ -26,7 +26,7 @@ class develop(namespaces.DevelopInstaller, easy_install):
 
     command_consumes_arguments = False  # override base
 
-    def run(self):
+    def run(self) -> None:  # type: ignore[override] # Not including easy_install's show_deprecation argument
         if self.uninstall:
             self.multi_version = True
             self.uninstall_link()
diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
index 66fe68f7a9..bd393d3697 100644
--- a/setuptools/command/easy_install.py
+++ b/setuptools/command/easy_install.py
@@ -747,12 +747,15 @@ def install_item(
                     return dist
         return None
 
-    def select_scheme(self, name):
+    def select_scheme(self, name) -> None:
         try:
             install._select_scheme(self, name)
         except AttributeError:
             # stdlib distutils
-            install.install.select_scheme(self, name.replace('posix', 'unix'))
+            install.install.select_scheme(
+                self,  # type: ignore[arg-type] # Pretend it's the correct type for stdlib compatibility
+                name.replace('posix', 'unix'),
+            )
 
     # FIXME: 'easy_install.process_distribution' is too complex (12)
     def process_distribution(  # noqa: C901
diff --git a/setuptools/command/egg_info.py b/setuptools/command/egg_info.py
index a300356d33..48346394c0 100644
--- a/setuptools/command/egg_info.py
+++ b/setuptools/command/egg_info.py
@@ -2,6 +2,8 @@
 
 Create a distribution's .egg-info directory and contents"""
 
+from __future__ import annotations
+
 import functools
 import os
 import re
@@ -196,11 +198,11 @@ def initialize_options(self):
     # allow the 'tag_svn_revision' to be detected and
     # set, supporting sdists built on older Setuptools.
     @property
-    def tag_svn_revision(self) -> None:
+    def tag_svn_revision(self) -> int | None:
         pass
 
     @tag_svn_revision.setter
-    def tag_svn_revision(self, value):
+    def tag_svn_revision(self, value) -> None:
         pass
 
     ####################################
diff --git a/setuptools/command/sdist.py b/setuptools/command/sdist.py
index 64e866c96b..43e935f5bb 100644
--- a/setuptools/command/sdist.py
+++ b/setuptools/command/sdist.py
@@ -3,6 +3,7 @@
 import contextlib
 import os
 import re
+from collections.abc import Iterator
 from itertools import chain
 from typing import ClassVar
 
@@ -16,7 +17,7 @@
 _default_revctrl = list
 
 
-def walk_revctrl(dirname=''):
+def walk_revctrl(dirname='') -> Iterator:
     """Find all files under revision control"""
     for ep in metadata.entry_points(group='setuptools.file_finders'):
         yield from ep.load()(dirname)
@@ -195,7 +196,7 @@ def _manifest_is_not_generated(self):
             first_line = fp.readline()
         return first_line != b'# file GENERATED by distutils, do NOT edit\n'
 
-    def read_manifest(self):
+    def read_manifest(self) -> None:
         """Read the manifest file (named by 'self.manifest') and use it to
         fill in 'self.filelist', the list of files to include in the source
         distribution.
diff --git a/setuptools/command/setopt.py b/setuptools/command/setopt.py
index 200cdff0f7..62e670e431 100644
--- a/setuptools/command/setopt.py
+++ b/setuptools/command/setopt.py
@@ -27,7 +27,7 @@ def config_file(kind="local"):
     raise ValueError("config_file() type must be 'local', 'global', or 'user'", kind)
 
 
-def edit_config(filename, settings, dry_run=False):
+def edit_config(filename, settings, dry_run=False) -> None:
     """Edit a configuration file to include `settings`
 
     `settings` is a dictionary of dictionaries or ``None`` values, keyed by
@@ -88,7 +88,7 @@ def initialize_options(self):
         self.user_config = None
         self.filename = None
 
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         filenames = []
         if self.global_config:
             filenames.append(config_file('global'))
diff --git a/setuptools/command/test.py b/setuptools/command/test.py
index 341b11a20e..5d03c91102 100644
--- a/setuptools/command/test.py
+++ b/setuptools/command/test.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from typing import NoReturn
+
 from setuptools import Command
 from setuptools.warnings import SetuptoolsDeprecationWarning
 
@@ -35,11 +37,11 @@ class _test(Command):
         ('test-runner=', 'r', "Test runner to use"),
     ]
 
-    def initialize_options(self):
+    def initialize_options(self) -> None:
         pass
 
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         pass
 
-    def run(self):
+    def run(self) -> NoReturn:
         raise RuntimeError("Support for the test command was removed in Setuptools 72")
diff --git a/setuptools/config/expand.py b/setuptools/config/expand.py
index 54c68bed4f..1c48961fd5 100644
--- a/setuptools/config/expand.py
+++ b/setuptools/config/expand.py
@@ -387,7 +387,7 @@ def __init__(self, distribution: Distribution) -> None:
         self._dist = distribution
         self._called = False
 
-    def __call__(self):
+    def __call__(self) -> None:
         """Trigger the automatic package discovery, if it is still necessary."""
         if not self._called:
             self._called = True
@@ -401,7 +401,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_value: BaseException | None,
         traceback: TracebackType | None,
-    ):
+    ) -> None:
         if self._called:
             self._dist.set_defaults.analyse_name()  # Now we can set a default name
 
@@ -411,7 +411,7 @@ def _get_package_dir(self) -> Mapping[str, str]:
         return {} if pkg_dir is None else pkg_dir
 
     @property
-    def package_dir(self) -> Mapping[str, str]:
+    def package_dir(self) -> LazyMappingProxy[str, str]:
         """Proxy to ``package_dir`` that may trigger auto-discovery when used."""
         return LazyMappingProxy(self._get_package_dir)
 
diff --git a/setuptools/config/setupcfg.py b/setuptools/config/setupcfg.py
index b35d0b00cd..1a6830dda4 100644
--- a/setuptools/config/setupcfg.py
+++ b/setuptools/config/setupcfg.py
@@ -14,6 +14,7 @@
 import contextlib
 import functools
 import os
+from abc import abstractmethod
 from collections import defaultdict
 from collections.abc import Iterable, Iterator
 from functools import partial, wraps
@@ -269,7 +270,8 @@ def _section_options(
             yield name.lstrip('.'), value
 
     @property
-    def parsers(self):
+    @abstractmethod
+    def parsers(self) -> dict[str, Callable]:
         """Metadata item name to parser function mapping."""
         raise NotImplementedError(
             '%s must provide .parsers property' % self.__class__.__name__
@@ -546,7 +548,7 @@ def __init__(
         self.root_dir = root_dir
 
     @property
-    def parsers(self):
+    def parsers(self) -> dict[str, Callable]:
         """Metadata item name to parser function mapping."""
         parse_list = self._parse_list
         parse_file = partial(self._parse_file, root_dir=self.root_dir)
@@ -623,7 +625,7 @@ def _parse_requirements_list(self, label: str, value: str):
         return [line for line in parsed if not line.startswith("#")]
 
     @property
-    def parsers(self):
+    def parsers(self) -> dict[str, Callable]:
         """Metadata item name to parser function mapping."""
         parse_list = self._parse_list
         parse_bool = self._parse_bool
diff --git a/setuptools/dist.py b/setuptools/dist.py
index 5b3175fb5b..694fe4a56b 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -6,7 +6,7 @@
 import os
 import re
 import sys
-from collections.abc import Iterable, MutableMapping, Sequence
+from collections.abc import Iterable, Iterator, MutableMapping, Sequence
 from glob import iglob
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Union
@@ -696,7 +696,7 @@ def _finalize_setup_keywords(self):
             if value is not None:
                 ep.load()(self, ep.name, value)
 
-    def get_egg_cache_dir(self):
+    def get_egg_cache_dir(self) -> str:
         from . import windows_support
 
         egg_cache_dir = os.path.join(os.curdir, '.eggs')
@@ -943,7 +943,7 @@ def get_cmdline_options(self) -> dict[str, dict[str, str | None]]:
 
         return d
 
-    def iter_distribution_names(self):
+    def iter_distribution_names(self) -> Iterator[str]:
         """Yield all packages, modules, and extension names in distribution"""
 
         yield from self.packages or ()
diff --git a/setuptools/extension.py b/setuptools/extension.py
index 76e03d9d6b..98e819a4ae 100644
--- a/setuptools/extension.py
+++ b/setuptools/extension.py
@@ -13,7 +13,7 @@
 import distutils.extension
 
 
-def _have_cython():
+def _have_cython() -> bool:
     """
     Return True if Cython can be imported.
     """
diff --git a/setuptools/monkey.py b/setuptools/monkey.py
index d8e30dbb80..0e780b7fee 100644
--- a/setuptools/monkey.py
+++ b/setuptools/monkey.py
@@ -69,7 +69,7 @@ def get_unpatched_class(cls: type[_T]) -> type[_T]:
     return base
 
 
-def patch_all():
+def patch_all() -> None:
     import setuptools
 
     # we can't patch distutils.cmd, alas
@@ -105,7 +105,7 @@ def _patch_distribution_metadata():
         setattr(distutils.dist.DistributionMetadata, attr, new_val)
 
 
-def patch_func(replacement, target_mod, func_name):
+def patch_func(replacement, target_mod, func_name) -> None:
     """
     Patch func_name in target_mod with replacement
 
diff --git a/setuptools/msvc.py b/setuptools/msvc.py
index 8d6d2cf084..d2bf10cc75 100644
--- a/setuptools/msvc.py
+++ b/setuptools/msvc.py
@@ -13,7 +13,7 @@
 import os
 import os.path
 import platform
-from typing import TYPE_CHECKING, TypedDict
+from typing import TYPE_CHECKING, TypedDict, overload
 
 from more_itertools import unique_everseen
 
@@ -50,11 +50,11 @@ class PlatformInfo:
 
     current_cpu = environ.get('processor_architecture', '').lower()
 
-    def __init__(self, arch) -> None:
+    def __init__(self, arch: str) -> None:
         self.arch = arch.lower().replace('x64', 'amd64')
 
     @property
-    def target_cpu(self):
+    def target_cpu(self) -> str:
         """
         Return Target CPU architecture.
 
@@ -65,7 +65,7 @@ def target_cpu(self):
         """
         return self.arch[self.arch.find('_') + 1 :]
 
-    def target_is_x86(self):
+    def target_is_x86(self) -> bool:
         """
         Return True if target CPU is x86 32 bits..
 
@@ -76,7 +76,7 @@ def target_is_x86(self):
         """
         return self.target_cpu == 'x86'
 
-    def current_is_x86(self):
+    def current_is_x86(self) -> bool:
         """
         Return True if current CPU is x86 32 bits..
 
@@ -135,7 +135,7 @@ def target_dir(self, hidex86=False, x64=False) -> str:
             else r'\%s' % self.target_cpu
         )
 
-    def cross_dir(self, forcex86=False):
+    def cross_dir(self, forcex86=False) -> str:
         r"""
         Cross platform specific subfolder.
 
@@ -180,7 +180,7 @@ def __init__(self, platform_info) -> None:
         self.pi = platform_info
 
     @property
-    def visualstudio(self) -> str:
+    def visualstudio(self) -> LiteralString:
         """
         Microsoft Visual Studio root registry key.
 
@@ -192,7 +192,7 @@ def visualstudio(self) -> str:
         return 'VisualStudio'
 
     @property
-    def sxs(self):
+    def sxs(self) -> LiteralString:
         """
         Microsoft Visual Studio SxS registry key.
 
@@ -204,7 +204,7 @@ def sxs(self):
         return os.path.join(self.visualstudio, 'SxS')
 
     @property
-    def vc(self):
+    def vc(self) -> LiteralString:
         """
         Microsoft Visual C++ VC7 registry key.
 
@@ -216,7 +216,7 @@ def vc(self):
         return os.path.join(self.sxs, 'VC7')
 
     @property
-    def vs(self):
+    def vs(self) -> LiteralString:
         """
         Microsoft Visual Studio VS7 registry key.
 
@@ -228,7 +228,7 @@ def vs(self):
         return os.path.join(self.sxs, 'VS7')
 
     @property
-    def vc_for_python(self) -> str:
+    def vc_for_python(self) -> LiteralString:
         """
         Microsoft Visual C++ for Python registry key.
 
@@ -240,7 +240,7 @@ def vc_for_python(self) -> str:
         return r'DevDiv\VCForPython'
 
     @property
-    def microsoft_sdk(self) -> str:
+    def microsoft_sdk(self) -> LiteralString:
         """
         Microsoft SDK registry key.
 
@@ -252,7 +252,7 @@ def microsoft_sdk(self) -> str:
         return 'Microsoft SDKs'
 
     @property
-    def windows_sdk(self):
+    def windows_sdk(self) -> LiteralString:
         """
         Microsoft Windows/Platform SDK registry key.
 
@@ -264,7 +264,7 @@ def windows_sdk(self):
         return os.path.join(self.microsoft_sdk, 'Windows')
 
     @property
-    def netfx_sdk(self):
+    def netfx_sdk(self) -> LiteralString:
         """
         Microsoft .NET Framework SDK registry key.
 
@@ -276,7 +276,7 @@ def netfx_sdk(self):
         return os.path.join(self.microsoft_sdk, 'NETFXSDK')
 
     @property
-    def windows_kits_roots(self) -> str:
+    def windows_kits_roots(self) -> LiteralString:
         """
         Microsoft Windows Kits Roots registry key.
 
@@ -287,7 +287,11 @@ def windows_kits_roots(self) -> str:
         """
         return r'Windows Kits\Installed Roots'
 
-    def microsoft(self, key, x86=False):
+    @overload
+    def microsoft(self, key: LiteralString, x86: bool = False) -> LiteralString: ...
+    @overload
+    def microsoft(self, key: str, x86: bool = False) -> str: ...  # type: ignore[misc]
+    def microsoft(self, key: str, x86: bool = False) -> str:
         """
         Return key in Microsoft software registry.
 
@@ -306,7 +310,7 @@ def microsoft(self, key, x86=False):
         node64 = '' if self.pi.current_is_x86() or x86 else 'Wow6432Node'
         return os.path.join('Software', node64, 'Microsoft', key)
 
-    def lookup(self, key, name):
+    def lookup(self, key: str, name: str) -> str | None:
         """
         Look for values in registry in Microsoft software registry.
 
@@ -366,7 +370,9 @@ class SystemInfo:
     ProgramFiles = environ.get('ProgramFiles', '')
     ProgramFilesx86 = environ.get('ProgramFiles(x86)', ProgramFiles)
 
-    def __init__(self, registry_info, vc_ver=None) -> None:
+    def __init__(
+        self, registry_info: RegistryInfo, vc_ver: float | None = None
+    ) -> None:
         self.ri = registry_info
         self.pi = self.ri.pi
 
@@ -395,7 +401,7 @@ def _find_latest_available_vs_ver(self):
         vc_vers.update(self.known_vs_paths)
         return sorted(vc_vers)[-1]
 
-    def find_reg_vs_vers(self):
+    def find_reg_vs_vers(self) -> list[float]:
         """
         Find Microsoft Visual Studio versions available in registry.
 
@@ -486,7 +492,7 @@ def _as_float_version(version):
         return float('.'.join(version.split('.')[:2]))
 
     @property
-    def VSInstallDir(self):
+    def VSInstallDir(self) -> str:
         """
         Microsoft Visual Studio directory.
 
@@ -504,7 +510,7 @@ def VSInstallDir(self):
         return self.ri.lookup(self.ri.vs, '%0.1f' % self.vs_ver) or default
 
     @property
-    def VCInstallDir(self):
+    def VCInstallDir(self) -> str:
         """
         Microsoft Visual C++ directory.
 
@@ -595,7 +601,7 @@ def WindowsSdkVersion(self) -> tuple[LiteralString, ...]:
         return ()
 
     @property
-    def WindowsSdkLastVersion(self):
+    def WindowsSdkLastVersion(self) -> str:
         """
         Microsoft Windows SDK last version.
 
@@ -607,7 +613,7 @@ def WindowsSdkLastVersion(self):
         return self._use_last_dir_name(os.path.join(self.WindowsSdkDir, 'lib'))
 
     @property
-    def WindowsSdkDir(self) -> str | None:  # noqa: C901  # is too complex (12)  # FIXME
+    def WindowsSdkDir(self) -> str:  # noqa: C901  # is too complex (12)  # FIXME
         """
         Microsoft Windows SDK directory.
 
@@ -650,7 +656,7 @@ def WindowsSdkDir(self) -> str | None:  # noqa: C901  # is too complex (12)  # F
         return sdkdir
 
     @property
-    def WindowsSDKExecutablePath(self):
+    def WindowsSDKExecutablePath(self) -> str | None:
         """
         Microsoft Windows SDK executable directory.
 
@@ -687,7 +693,7 @@ def WindowsSDKExecutablePath(self):
         return None
 
     @property
-    def FSharpInstallDir(self):
+    def FSharpInstallDir(self) -> str:
         """
         Microsoft Visual F# directory.
 
@@ -700,7 +706,7 @@ def FSharpInstallDir(self):
         return self.ri.lookup(path, 'productdir') or ''
 
     @property
-    def UniversalCRTSdkDir(self):
+    def UniversalCRTSdkDir(self) -> str | None:
         """
         Microsoft Universal CRT SDK directory.
 
@@ -721,7 +727,7 @@ def UniversalCRTSdkDir(self):
         return None
 
     @property
-    def UniversalCRTSdkLastVersion(self):
+    def UniversalCRTSdkLastVersion(self) -> str:
         """
         Microsoft Universal C Runtime SDK last version.
 
@@ -733,7 +739,7 @@ def UniversalCRTSdkLastVersion(self):
         return self._use_last_dir_name(os.path.join(self.UniversalCRTSdkDir, 'lib'))
 
     @property
-    def NetFxSdkVersion(self):
+    def NetFxSdkVersion(self) -> tuple[LiteralString, ...]:
         """
         Microsoft .NET Framework SDK versions.
 
@@ -750,7 +756,7 @@ def NetFxSdkVersion(self):
         )
 
     @property
-    def NetFxSdkDir(self):
+    def NetFxSdkDir(self) -> str | None:
         """
         Microsoft .NET Framework SDK directory.
 
@@ -759,7 +765,6 @@ def NetFxSdkDir(self):
         str
             path
         """
-        sdkdir = ''
         for ver in self.NetFxSdkVersion:
             loc = os.path.join(self.ri.netfx_sdk, ver)
             sdkdir = self.ri.lookup(loc, 'kitsinstallationfolder')
@@ -768,7 +773,7 @@ def NetFxSdkDir(self):
         return sdkdir
 
     @property
-    def FrameworkDir32(self):
+    def FrameworkDir32(self) -> str:
         """
         Microsoft .NET Framework 32bit directory.
 
@@ -784,7 +789,7 @@ def FrameworkDir32(self):
         return self.ri.lookup(self.ri.vc, 'frameworkdir32') or guess_fw
 
     @property
-    def FrameworkDir64(self):
+    def FrameworkDir64(self) -> str:
         """
         Microsoft .NET Framework 64bit directory.
 
diff --git a/setuptools/package_index.py b/setuptools/package_index.py
index 97806e8ff8..3ae0f838ca 100644
--- a/setuptools/package_index.py
+++ b/setuptools/package_index.py
@@ -18,6 +18,7 @@
 import urllib.error
 import urllib.parse
 import urllib.request
+from collections.abc import Iterator
 from fnmatch import translate
 from functools import wraps
 from typing import NamedTuple
@@ -113,7 +114,7 @@ def egg_info_for_url(url):
     return base, fragment
 
 
-def distros_for_url(url, metadata=None):
+def distros_for_url(url, metadata=None) -> Iterator[Distribution]:
     """Yield egg or source distribution objects that might be found at a URL"""
     base, fragment = egg_info_for_url(url)
     yield from distros_for_location(url, base, metadata)
@@ -125,7 +126,9 @@ def distros_for_url(url, metadata=None):
             )
 
 
-def distros_for_location(location, basename, metadata=None):
+def distros_for_location(
+    location, basename, metadata=None
+) -> list[Distribution] | Iterator[Distribution]:
     """Yield egg or source distribution objects based on basename"""
     if basename.endswith('.egg.zip'):
         basename = basename[:-4]  # strip the .zip
@@ -169,7 +172,7 @@ def distros_for_filename(filename, metadata=None):
 
 def interpret_distro_name(
     location, basename, metadata, py_version=None, precedence=SOURCE_DIST, platform=None
-):
+) -> Iterator[Distribution]:
     """Generate the interpretation of a source distro name
 
     Note: if `location` is a filesystem filename, you should call
@@ -244,7 +247,7 @@ class ContentChecker:
     A null content checker that defines the interface for checking content
     """
 
-    def feed(self, block):
+    def feed(self, block) -> None:
         """
         Feed a block of data to the hash.
         """
@@ -256,7 +259,7 @@ def is_valid(self):
         """
         return True
 
-    def report(self, reporter, template):
+    def report(self, reporter, template) -> None:
         """
         Call reporter with information about the checker (hash name)
         substituted into the template.
@@ -286,7 +289,7 @@ def from_url(cls, url):
             return ContentChecker()
         return cls(**match.groupdict())
 
-    def feed(self, block):
+    def feed(self, block) -> None:
         self.hash.update(block)
 
     def is_valid(self):
@@ -1017,7 +1020,7 @@ def __str__(self) -> str:
 
 
 class PyPIConfig(configparser.RawConfigParser):
-    def __init__(self):
+    def __init__(self) -> None:
         """
         Load from ~/.pypirc
         """
diff --git a/setuptools/sandbox.py b/setuptools/sandbox.py
index 2d84242d66..88271cfc94 100644
--- a/setuptools/sandbox.py
+++ b/setuptools/sandbox.py
@@ -144,7 +144,7 @@ def __exit__(
         # suppress the exception
         return True
 
-    def resume(self):
+    def resume(self) -> None:
         "restore and re-raise any exception"
 
         if '_saved' not in vars(self):
@@ -300,7 +300,7 @@ def __exit__(
         exc_type: type[BaseException] | None,
         exc_value: BaseException | None,
         traceback: TracebackType | None,
-    ):
+    ) -> None:
         self._active = False
         builtins.open = _open
         self._copy(_os)
diff --git a/setuptools/wheel.py b/setuptools/wheel.py
index fb19f1a65a..9dac318da3 100644
--- a/setuptools/wheel.py
+++ b/setuptools/wheel.py
@@ -8,6 +8,7 @@
 import posixpath
 import re
 import zipfile
+from collections.abc import Iterator
 
 from packaging.tags import sys_tags
 from packaging.utils import canonicalize_name
@@ -62,7 +63,7 @@ def unpack(src_dir, dst_dir) -> None:
 
 
 @contextlib.contextmanager
-def disable_info_traces():
+def disable_info_traces() -> Iterator[None]:
     """
     Temporarily disable info traces.
     """