diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index e841bde57c..cbfd594433 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -34,6 +34,24 @@ env:
 
 
 jobs:
+  pyright:
+    strategy:
+      matrix:
+        python:
+        - "3.8"
+        - "3.11"
+        - "3.12"
+        platform:
+        - ubuntu-latest
+        - macos-latest
+        - windows-latest
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: jakebailey/pyright-action@v2
+        with:
+          python-version: ${{ matrix.python }}
+
   test:
     strategy:
       matrix:
diff --git a/_distutils_hack/__init__.py b/_distutils_hack/__init__.py
index c9d1e24790..68441354fb 100644
--- a/_distutils_hack/__init__.py
+++ b/_distutils_hack/__init__.py
@@ -54,6 +54,7 @@ def ensure_local_distutils():
 
     # check that submodules load as expected
     core = importlib.import_module('distutils.core')
+    assert core.__file__ is not None, core.__file__
     assert '_distutils' in core.__file__, core.__file__
     assert 'setuptools._distutils.log' not in sys.modules
 
diff --git a/docs/conf.py b/docs/conf.py
index 0a82ff2fe2..26e6375dbe 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,3 +1,6 @@
+from typing import Dict, Tuple
+
+
 extensions = [
     'sphinx.ext.autodoc',
     'jaraco.packaging.sphinx',
@@ -93,7 +96,7 @@
 # Include Python intersphinx mapping to prevent failures
 # jaraco/skeleton#51
 extensions += ['sphinx.ext.intersphinx']
-intersphinx_mapping = {
+intersphinx_mapping: Dict[str, Tuple[str, None]] = {
     'python': ('https://docs.python.org/3', None),
 }
 
diff --git a/mypy.ini b/mypy.ini
index b6f972769e..b007c27bf2 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,5 +1,21 @@
 [mypy]
+# CI should test for all versions, local development gets hints for oldest supported
+python_version = 3.8
+strict = False
+warn_unused_ignores = True
+# TODO: Not all dependencies are typed. setuptools itself should be typed too
+# TODO: Test environment is not yet properly configured to install all imported packages
 ignore_missing_imports = True
-# required to support namespace packages
-# https://github.com/python/mypy/issues/14057
+# required to support namespace packages: https://github.com/python/mypy/issues/14057
 explicit_package_bases = True
+exclude = (?x)(
+	^build/
+	| ^.tox/
+	| ^pkg_resources/tests/data/my-test-package-source/setup.py$ # Duplicate module name
+	| ^.+?/(_vendor|extern)/ # Vendored
+	| ^setuptools/_distutils/ # Vendored
+	)
+
+# https://github.com/pypa/setuptools/pull/3979#discussion_r1367968993
+[mypy-pkg_resources.extern.*,setuptools.extern.*]
+ignore_missing_imports = True
diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py
index d6847448eb..5ba791ab1c 100644
--- a/pkg_resources/__init__.py
+++ b/pkg_resources/__init__.py
@@ -27,7 +27,7 @@
 import time
 import re
 import types
-from typing import Protocol
+from typing import Any, Protocol, cast
 import zipfile
 import zipimport
 import warnings
@@ -71,8 +71,8 @@
     join_continuation,
 )
 
-from pkg_resources.extern import platformdirs
-from pkg_resources.extern import packaging
+from pkg_resources.extern import platformdirs  # type: ignore[attr-defined]
+from pkg_resources.extern import packaging  # type: ignore[attr-defined]
 
 __import__('pkg_resources.extern.packaging.version')
 __import__('pkg_resources.extern.packaging.specifiers')
@@ -80,25 +80,25 @@
 __import__('pkg_resources.extern.packaging.markers')
 __import__('pkg_resources.extern.packaging.utils')
 
-# declare some globals that will be defined later to
-# satisfy the linters.
-require = None
-working_set = None
-add_activation_listener = None
-resources_stream = None
-cleanup_resources = None
-resource_dir = None
-resource_stream = None
-set_extraction_path = None
-resource_isdir = None
-resource_string = None
-iter_entry_points = None
-resource_listdir = None
-resource_filename = None
-resource_exists = None
-_distribution_finders = None
-_namespace_handlers = None
-_namespace_packages = None
+def _dummy(*args: object, **kwargs: object) -> Any:
+    pass
+
+# declare some globals that will be defined later to satisfy linters.
+require = _dummy
+working_set = cast("WorkingSet", None)
+add_activation_listener = _dummy
+cleanup_resources = _dummy
+resource_stream = _dummy
+set_extraction_path = _dummy
+resource_isdir = _dummy
+resource_string = _dummy
+iter_entry_points = _dummy
+resource_listdir = _dummy
+resource_filename = _dummy
+resource_exists = _dummy
+_distribution_finders: dict = {}
+_namespace_handlers: dict = {}
+_namespace_packages: dict = {}
 
 
 warnings.warn(
@@ -3210,6 +3210,7 @@ def _find_adapter(registry, ob):
     for t in types:
         if t in registry:
             return registry[t]
+    raise ValueError("Adapter not found")
 
 
 def ensure_directory(path):
diff --git a/pkg_resources/tests/test_pkg_resources.py b/pkg_resources/tests/test_pkg_resources.py
index 0883642080..bfbf619c85 100644
--- a/pkg_resources/tests/test_pkg_resources.py
+++ b/pkg_resources/tests/test_pkg_resources.py
@@ -9,6 +9,7 @@
 import stat
 import distutils.dist
 import distutils.command.install_egg_info
+from typing import List
 
 from unittest import mock
 
@@ -32,7 +33,7 @@ def __call__(self):
 
 
 class TestZipProvider:
-    finalizers = []
+    finalizers: List[EggRemover] = []
 
     ref_time = datetime.datetime(2013, 5, 12, 13, 25, 0)
     "A reference time for a file modification"
diff --git a/pkg_resources/tests/test_resources.py b/pkg_resources/tests/test_resources.py
index 5b2308aea7..ea296a56b4 100644
--- a/pkg_resources/tests/test_resources.py
+++ b/pkg_resources/tests/test_resources.py
@@ -5,7 +5,7 @@
 import itertools
 
 import pytest
-from pkg_resources.extern import packaging
+from pkg_resources.extern import packaging  # type: ignore[attr-defined]
 
 import pkg_resources
 from pkg_resources import (
diff --git a/pyrightconfig.json b/pyrightconfig.json
new file mode 100644
index 0000000000..ea08e3f487
--- /dev/null
+++ b/pyrightconfig.json
@@ -0,0 +1,27 @@
+{
+	"$schema": "https://raw.githubusercontent.com/microsoft/pyright/main/packages/vscode-pyright/schemas/pyrightconfig.schema.json",
+	"exclude": [
+		"build",
+		".tox",
+		"**/extern", // Vendored
+		"**/_vendor", // Vendored
+		"setuptools/_distutils", // Vendored
+	],
+	// CI should test for all versions, local development gets hints for oldest supported
+	"pythonVersion": "3.8",
+	// For now we don't mind if mypy's `type: ignore` comments accidentally suppresses pyright issues
+	"enableTypeIgnoreComments": true,
+	"typeCheckingMode": "basic",
+	// TODO: Test environment is not yet properly configured to install all imported packages
+	"reportMissingImports": "none",
+	// Too many issues caused by vendoring and dynamic patching, still worth fixing when we can
+	"reportAttributeAccessIssue": "warning",
+	// Defered initialization (initialize_options/finalize_options) causes many "potentially None" issues
+	// TODO: Fix with type-guards or by changing how it's initialized
+	"reportCallIssue": "warning",
+	"reportArgumentType": "warning",
+	"reportOptionalIterable": "warning",
+	"reportOptionalMemberAccess": "warning",
+	"reportGeneralTypeIssues": "warning",
+	"reportOptionalOperand": "warning",
+}
diff --git a/setup.py b/setup.py
index 075d7c405f..1a6074766a 100755
--- a/setup.py
+++ b/setup.py
@@ -88,5 +88,6 @@ def _restore_install_lib(self):
 
 if __name__ == '__main__':
     # allow setup.py to run from another directory
-    here and os.chdir(here)
+    # TODO: Use a proper conditonal statement here
+    here and os.chdir(here)  # type: ignore[func-returns-value]
     dist = setuptools.setup(**setup_params)
diff --git a/setuptools/__init__.py b/setuptools/__init__.py
index 563ca1c4ba..6f3a95bc20 100644
--- a/setuptools/__init__.py
+++ b/setuptools/__init__.py
@@ -1,8 +1,10 @@
 """Extensions to the 'distutils' for large or complex distributions"""
 
+from collections.abc import Mapping
 import functools
 import os
 import re
+from typing import Any
 
 import _distutils_hack.override  # noqa: F401
 import distutils.core
@@ -46,7 +48,7 @@ class MinimalDistribution(distutils.core.Distribution):
         fetch_build_eggs interface.
         """
 
-        def __init__(self, attrs):
+        def __init__(self, attrs: Mapping[str, Any]):
             _incl = 'dependency_links', 'setup_requires'
             filtered = {k: attrs[k] for k in set(_incl) & set(attrs)}
             super().__init__(filtered)
@@ -109,7 +111,7 @@ def setup(**attrs):
 _Command = monkey.get_unpatched(distutils.core.Command)
 
 
-class Command(_Command):
+class Command(_Command):  # type: ignore[valid-type, misc]  # https://github.com/python/mypy/issues/14458
     """
     Setuptools internal actions are organized using a *command design pattern*.
     This means that each action (or group of closely related actions) executed during
diff --git a/setuptools/_core_metadata.py b/setuptools/_core_metadata.py
index 4bf3c7c947..9ca127d425 100644
--- a/setuptools/_core_metadata.py
+++ b/setuptools/_core_metadata.py
@@ -62,7 +62,8 @@ def _read_list_from_msg(msg: Message, field: str) -> Optional[List[str]]:
 
 
 def _read_payload_from_msg(msg: Message) -> Optional[str]:
-    value = msg.get_payload().strip()
+    payload = msg.get_payload()
+    value = payload.strip() if isinstance(payload, str) else ""
     if value == 'UNKNOWN' or not value:
         return None
     return value
diff --git a/setuptools/_entry_points.py b/setuptools/_entry_points.py
index 747a69067e..103700d9b3 100644
--- a/setuptools/_entry_points.py
+++ b/setuptools/_entry_points.py
@@ -8,6 +8,7 @@
 from ._importlib import metadata
 from ._itertools import ensure_unique
 from .extern.more_itertools import consume
+metadata_EntryPoints = metadata.EntryPoints
 
 
 def ensure_valid(ep):
@@ -33,14 +34,14 @@ def load_group(value, group):
     # normalize to a single sequence of lines
     lines = yield_lines(value)
     text = f'[{group}]\n' + '\n'.join(lines)
-    return metadata.EntryPoints._from_text(text)
+    return metadata_EntryPoints._from_text(text)
 
 
 def by_group_and_name(ep):
     return ep.group, ep.name
 
 
-def validate(eps: metadata.EntryPoints):
+def validate(eps: metadata_EntryPoints):
     """
     Ensure entry points are unique by group and name and validate each.
     """
@@ -56,7 +57,7 @@ def load(eps):
     groups = itertools.chain.from_iterable(
         load_group(value, group) for group, value in eps.items()
     )
-    return validate(metadata.EntryPoints(groups))
+    return validate(metadata_EntryPoints(groups))
 
 
 @load.register(str)
@@ -70,14 +71,14 @@ def _(eps):
     >>> ep.value
     'bar'
     """
-    return validate(metadata.EntryPoints(metadata.EntryPoints._from_text(eps)))
+    return validate(metadata_EntryPoints(metadata_EntryPoints._from_text(eps)))
 
 
 load.register(type(None), lambda x: x)
 
 
 @pass_none
-def render(eps: metadata.EntryPoints):
+def render(eps: metadata_EntryPoints):
     by_group = operator.attrgetter('group')
     groups = itertools.groupby(sorted(eps, key=by_group), by_group)
 
diff --git a/setuptools/_importlib.py b/setuptools/_importlib.py
index bd2b01e2b5..73ec89453b 100644
--- a/setuptools/_importlib.py
+++ b/setuptools/_importlib.py
@@ -38,14 +38,14 @@ def disable_importlib_metadata_finder(metadata):
 
 
 if sys.version_info < (3, 10):
-    from setuptools.extern import importlib_metadata as metadata
+    from setuptools.extern import importlib_metadata as metadata  # type: ignore[attr-defined]
 
     disable_importlib_metadata_finder(metadata)
 else:
     import importlib.metadata as metadata  # noqa: F401
-
+metadata=metadata
 
 if sys.version_info < (3, 9):
-    from setuptools.extern import importlib_resources as resources
+    from setuptools.extern import importlib_resources as resources  # type: ignore[attr-defined]
 else:
     import importlib.resources as resources  # noqa: F401
diff --git a/setuptools/_normalization.py b/setuptools/_normalization.py
index 8d4731eb60..5435562bd1 100644
--- a/setuptools/_normalization.py
+++ b/setuptools/_normalization.py
@@ -4,12 +4,9 @@
 """
 
 import re
-from pathlib import Path
-from typing import Union
 
-from .extern import packaging
+from .extern import packaging  # type: ignore[attr-defined]
 
-_Path = Union[str, Path]
 
 # https://packaging.python.org/en/latest/specifications/core-metadata/#name
 _VALID_NAME = re.compile(r"^([A-Z0-9]|[A-Z0-9][A-Z0-9._-]*[A-Z0-9])$", re.I)
diff --git a/setuptools/_reqs.py b/setuptools/_reqs.py
index 9f83437033..41b10a5fc8 100644
--- a/setuptools/_reqs.py
+++ b/setuptools/_reqs.py
@@ -24,13 +24,9 @@ def parse_strings(strs: _StrOrIter) -> Iterator[str]:
 
 
 @overload
-def parse(strs: _StrOrIter) -> Iterator[Requirement]: ...
-
-
+def parse(strs: _StrOrIter) -> "map[Requirement]": ...
 @overload
-def parse(strs: _StrOrIter, parser: Callable[[str], _T]) -> Iterator[_T]: ...
-
-
+def parse(strs: _StrOrIter, parser: Callable[[str], _T]) -> "map[_T]": ...
 def parse(strs, parser=parse_req):
     """
     Replacement for ``pkg_resources.parse_requirements`` that uses ``packaging``.
diff --git a/setuptools/command/__init__.py b/setuptools/command/__init__.py
index 5acd7687d6..4688b34aac 100644
--- a/setuptools/command/__init__.py
+++ b/setuptools/command/__init__.py
@@ -3,7 +3,7 @@
 
 if 'egg' not in bdist.format_commands:
     try:
-        bdist.format_commands['egg'] = ('bdist_egg', "Python .egg file")
+        bdist.format_commands['egg'] = ('bdist_egg', "Python .egg file") # pyright: ignore[reportCallIssue, reportArgumentType] # for backwards compatibility
     except TypeError:
         # For backward compatibility with older distutils (stdlib)
         bdist.format_command['egg'] = ('bdist_egg', "Python .egg file")
diff --git a/setuptools/command/_requirestxt.py b/setuptools/command/_requirestxt.py
index 7b732b11ab..b0c2d7059a 100644
--- a/setuptools/command/_requirestxt.py
+++ b/setuptools/command/_requirestxt.py
@@ -35,7 +35,7 @@ def _prepare(
 
 
 def _convert_extras_requirements(
-    extras_require: _StrOrIter,
+    extras_require: Mapping[str, _StrOrIter],
 ) -> Mapping[str, _Ordered[Requirement]]:
     """
     Convert requirements in `extras_require` of the form
diff --git a/setuptools/command/build.py b/setuptools/command/build.py
index afda7e3be9..197e84956f 100644
--- a/setuptools/command/build.py
+++ b/setuptools/command/build.py
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from typing import Dict, List, Protocol
 from distutils.command.build import build as _build
 
@@ -98,13 +99,17 @@ def finalize_options(self):
 
     def initialize_options(self):
         """(Required by the original :class:`setuptools.Command` interface)"""
+        ...
 
     def finalize_options(self):
         """(Required by the original :class:`setuptools.Command` interface)"""
+        ...
 
     def run(self):
         """(Required by the original :class:`setuptools.Command` interface)"""
+        ...
 
+    @abstractmethod
     def get_source_files(self) -> List[str]:
         """
         Return a list of all files that are used by the command to create the expected
@@ -115,7 +120,9 @@ def get_source_files(self) -> List[str]:
         with all the files necessary to build the distribution.
         All files should be strings relative to the project root directory.
         """
+        ...
 
+    @abstractmethod
     def get_outputs(self) -> List[str]:
         """
         Return a list of files intended for distribution as they would have been
@@ -128,7 +135,9 @@ def get_outputs(self) -> List[str]:
            in ``get_output_mapping()`` plus files that are generated during the build
            and don't correspond to any source file already present in the project.
         """
+        ...
 
+    @abstractmethod
     def get_output_mapping(self) -> Dict[str, str]:
         """
         Return a mapping between destination files as they would be produced by the
@@ -138,3 +147,4 @@ def get_output_mapping(self) -> Dict[str, str]:
         Destination files should be strings in the form of
         ``"{build_lib}/destination/file/path"``.
         """
+        ...
diff --git a/setuptools/command/build_ext.py b/setuptools/command/build_ext.py
index ef2a4da84d..51bc38e60a 100644
--- a/setuptools/command/build_ext.py
+++ b/setuptools/command/build_ext.py
@@ -3,10 +3,9 @@
 import itertools
 from importlib.machinery import EXTENSION_SUFFIXES
 from importlib.util import cache_from_source as _compiled_file_name
-from typing import Dict, Iterator, List, Tuple
+from typing import TYPE_CHECKING, Dict, Iterator, List, Tuple
 from pathlib import Path
 
-from distutils.command.build_ext import build_ext as _du_build_ext
 from distutils.ccompiler import new_compiler
 from distutils.sysconfig import customize_compiler, get_config_var
 from distutils import log
@@ -14,19 +13,23 @@
 from setuptools.errors import BaseError
 from setuptools.extension import Extension, Library
 
-try:
-    # Attempt to use Cython for building extensions, if available
-    from Cython.Distutils.build_ext import build_ext as _build_ext
+if TYPE_CHECKING:
+    from setuptools.dist import Distribution
+    from distutils.command.build_ext import build_ext as _build_ext
+else:
+    try:
+        # Attempt to use Cython for building extensions, if available
+        from Cython.Distutils.build_ext import build_ext as _build_ext
 
-    # Additionally, assert that the compiler module will load
-    # also. Ref #1229.
-    __import__('Cython.Compiler.Main')
-except ImportError:
-    _build_ext = _du_build_ext
+        # Additionally, assert that the compiler module will load
+        # also. Ref #1229.
+        __import__('Cython.Compiler.Main')
+    except ImportError:
+        from distutils.command.build_ext import build_ext as _build_ext
 
 # make sure _config_vars is initialized
 get_config_var("LDSHARED")
-from distutils.sysconfig import _config_vars as _CONFIG_VARS  # noqa
+from distutils.sysconfig import _config_vars as _CONFIG_VARS  # type: ignore # noqa # Not publicly exposed in distutils stubs
 
 
 def _customize_compiler_for_shlib(compiler):
@@ -76,11 +79,13 @@ def get_abi3_suffix():
             return suffix
         elif suffix == '.pyd':  # Windows
             return suffix
+    raise ValueError("suffix not found")
 
 
 class build_ext(_build_ext):
     editable_mode: bool = False
     inplace: bool = False
+    distribution: "Distribution"
 
     def run(self):
         """Build extensions in build directory, then copy if --inplace"""
@@ -97,7 +102,8 @@ def _get_inplace_equivalent(self, build_py, ext: Extension) -> Tuple[str, str]:
         package = '.'.join(modpath[:-1])
         package_dir = build_py.get_package_dir(package)
         inplace_file = os.path.join(package_dir, os.path.basename(filename))
-        regular_file = os.path.join(self.build_lib, filename)
+        # FIXME: How is `self.build_lib` anything else than None?
+        regular_file = os.path.join(self.build_lib, filename) #  pyright: ignore[reportCallIssue, reportArgumentType]
         return (inplace_file, regular_file)
 
     def copy_extensions_to_source(self):
@@ -127,7 +133,7 @@ def _get_output_mapping(self) -> Iterator[Tuple[str, str]]:
             return
 
         build_py = self.get_finalized_command('build_py')
-        opt = self.get_finalized_command('install_lib').optimize or ""
+        opt = self.get_finalized_command('install_lib').optimize or ""  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
 
         for ext in self.extensions:
             inplace_file, regular_file = self._get_inplace_equivalent(build_py, ext)
@@ -147,7 +153,7 @@ def _get_output_mapping(self) -> Iterator[Tuple[str, str]]:
                 output_cache = _compiled_file_name(regular_stub, optimization=opt)
                 yield (output_cache, inplace_cache)
 
-    def get_ext_filename(self, fullname):
+    def get_ext_filename(self, fullname: str):
         so_ext = os.getenv('SETUPTOOLS_EXT_SUFFIX')
         if so_ext:
             filename = os.path.join(*fullname.split('.')) + so_ext
@@ -338,7 +344,7 @@ def _write_stub_file(self, stub_file: str, ext: Extension, compile=False):
         log.info("writing stub loader for %s to %s", ext._full_name, stub_file)
         if compile and os.path.exists(stub_file):
             raise BaseError(stub_file + " already exists! Please delete.")
-        if not self.dry_run:
+        if not self.dry_run:  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
             f = open(stub_file, 'w')
             f.write(
                 '\n'.join([
@@ -373,13 +379,13 @@ def _write_stub_file(self, stub_file: str, ext: Extension, compile=False):
     def _compile_and_remove_stub(self, stub_file: str):
         from distutils.util import byte_compile
 
-        byte_compile([stub_file], optimize=0, force=True, dry_run=self.dry_run)
-        optimize = self.get_finalized_command('install_lib').optimize
+        byte_compile([stub_file], optimize=0, force=True, dry_run=self.dry_run)  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
+        optimize = self.get_finalized_command('install_lib').optimize  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
         if optimize > 0:
             byte_compile(
-                [stub_file], optimize=optimize, force=True, dry_run=self.dry_run
+                [stub_file], optimize=optimize, force=True, dry_run=self.dry_run  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
             )
-        if os.path.exists(stub_file) and not self.dry_run:
+        if os.path.exists(stub_file) and not self.dry_run:  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
             os.unlink(stub_file)
 
 
diff --git a/setuptools/command/build_py.py b/setuptools/command/build_py.py
index 3f40b060b3..4861a9a366 100644
--- a/setuptools/command/build_py.py
+++ b/setuptools/command/build_py.py
@@ -218,7 +218,7 @@ def _filter_build_files(self, files: Iterable[str], egg_info: str) -> Iterator[s
         This function should filter this case of invalid files out.
         """
         build = self.get_finalized_command("build")
-        build_dirs = (egg_info, self.build_lib, build.build_temp, build.build_base)
+        build_dirs = (egg_info, self.build_lib, build.build_temp, build.build_base)  # type: ignore[attr-defined] # TODO: Fix in distutils stubs
         norm_dirs = [os.path.normpath(p) for p in build_dirs if p]
 
         for file in files:
diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
index f73d857f08..1127548490 100644
--- a/setuptools/command/easy_install.py
+++ b/setuptools/command/easy_install.py
@@ -11,6 +11,7 @@
 """
 
 from glob import glob
+from typing import TYPE_CHECKING, Optional, Union
 from distutils.util import get_platform
 from distutils.util import convert_path, subst_vars
 from distutils.errors import (
@@ -25,6 +26,7 @@
 from distutils.command import install
 import sys
 import os
+from typing import TYPE_CHECKING, Dict, List, Optional, Union
 import zipimport
 import shutil
 import tempfile
@@ -78,6 +80,8 @@
 from .._path import ensure_directory
 from ..extern.jaraco.text import yield_lines
 
+if TYPE_CHECKING:
+    _FileDescriptorOrPath = Union[int, str, bytes, os.PathLike[str], os.PathLike[bytes]]
 
 # Turn on PEP440Warnings
 warnings.filterwarnings("default", category=pkg_resources.PEP440Warning)
@@ -1645,7 +1649,7 @@ def _load_raw(self):
         while paths and not paths[-1].strip():
             paths.pop()
             dirty = True
-        return paths, dirty or (paths and saw_import)
+        return paths, dirty or bool(paths and saw_import)
 
     def _load(self):
         if os.path.isfile(self.filename):
@@ -1766,7 +1770,7 @@ def _wrap_lines(cls, lines):
 
 
 if os.environ.get('SETUPTOOLS_SYS_PATH_TECHNIQUE', 'raw') == 'rewrite':
-    PthDistributions = RewritePthDistributions
+    PthDistributions = RewritePthDistributions  # type: ignore[misc]  # Overwriting type
 
 
 def _first_line_re():
@@ -1787,7 +1791,7 @@ def auto_chmod(func, arg, exc):
         return func(arg)
     et, ev, _ = sys.exc_info()
     # TODO: This code doesn't make sense. What is it trying to do?
-    raise (ev[0], ev[1] + (" %s %s" % (func, arg)))
+    raise (ev[0], ev[1] + (" %s %s" % (func, arg)))  # pyright: ignore[reportGeneralTypeIssues, reportIndexIssue, reportOptionalSubscript]
 
 
 def update_dist_caches(dist_path, fix_zipimporter_caches):
@@ -2016,7 +2020,13 @@ def is_python_script(script_text, filename):
     from os import chmod as _chmod
 except ImportError:
     # Jython compatibility
-    def _chmod(*args):
+    def _chmod(
+        path: "_FileDescriptorOrPath",
+        mode: int,
+        *,
+        dir_fd: Optional[int] = None,
+        follow_symlinks: bool = True,
+    ) -> None:
         pass
 
 
@@ -2034,8 +2044,8 @@ class CommandSpec(list):
     those passed to Popen.
     """
 
-    options = []
-    split_args = dict()
+    options: List[str] = []
+    split_args: Dict[str, bool] = dict()
 
     @classmethod
     def best(cls):
diff --git a/setuptools/command/editable_wheel.py b/setuptools/command/editable_wheel.py
index 8a4ae7928f..8b2582f23b 100644
--- a/setuptools/command/editable_wheel.py
+++ b/setuptools/command/editable_wheel.py
@@ -1,3 +1,5 @@
+# pyright: reportOptionalMemberAccess=false
+# TODO: Fix get_command_obj in distutils stubs (which should create by default)
 """
 Create a wheel that, when installed, will make the source package 'editable'
 (add it to the interpreter's path, including metadata) per PEP 660. Replaces
@@ -266,7 +268,7 @@ def _run_build_commands(
         self._run_install("data")
         return files, mapping
 
-    def _run_build_subcommands(self):
+    def _run_build_subcommands(self) -> None:
         """
         Issue #3501 indicates that some plugins/customizations might rely on:
 
@@ -280,7 +282,7 @@ def _run_build_subcommands(self):
         # TODO: Once plugins/customisations had the chance to catch up, replace
         #       `self._run_build_subcommands()` with `self.run_command("build")`.
         #       Also remove _safely_run, TestCustomBuildPy. Suggested date: Aug/2023.
-        build: Command = self.get_finalized_command("build")
+        build = self.get_finalized_command("build")
         for name in build.get_sub_commands():
             cmd = self.get_finalized_command(name)
             if name == "build_py" and type(cmd) != build_py_cls:
@@ -355,7 +357,7 @@ def _select_strategy(
         name: str,
         tag: str,
         build_lib: _Path,
-    ) -> "EditableStrategy":
+    ) -> "_LinkTree | _StaticPth | _TopLevelFinder":
         """Decides which strategy to use to implement an editable installation."""
         build_name = f"__editable__.{name}-{tag}"
         project_dir = Path(self.project_dir)
@@ -600,7 +602,7 @@ def _simple_layout(
     layout = {pkg: find_package_path(pkg, package_dir, project_dir) for pkg in packages}
     if not layout:
         return set(package_dir) in ({}, {""})
-    parent = os.path.commonpath(starmap(_parent_path, layout.items()))
+    parent = os.path.commonpath(starmap(_parent_path, layout.items()))  # type: ignore[call-overload] # FIXME upstream
     return all(
         _path.same_path(Path(parent, *key.split('.')), value)
         for key, value in layout.items()
diff --git a/setuptools/command/egg_info.py b/setuptools/command/egg_info.py
index 62d2feea9b..996950e158 100644
--- a/setuptools/command/egg_info.py
+++ b/setuptools/command/egg_info.py
@@ -27,7 +27,7 @@
 import setuptools.unicode_utils as unicode_utils
 from setuptools.glob import glob
 
-from setuptools.extern import packaging
+from setuptools.extern import packaging  # type: ignore[attr-defined]
 from ..warnings import SetuptoolsDeprecationWarning
 
 
@@ -559,7 +559,7 @@ def run(self):
 
     def _manifest_normalize(self, path):
         path = unicode_utils.filesys_decode(path)
-        return path.replace(os.sep, '/')
+        return path.replace(os.sep, '/') # pyright: ignore[reportOptionalMemberAccess] # Raise error on None
 
     def write_manifest(self):
         """
diff --git a/setuptools/command/install.py b/setuptools/command/install.py
index 606cce9d89..ff5a7b8c49 100644
--- a/setuptools/command/install.py
+++ b/setuptools/command/install.py
@@ -130,7 +130,9 @@ def do_egg_install(self):
         cmd.package_index.scan(glob.glob('*.egg'))
 
         self.run_command('bdist_egg')
-        args = [self.distribution.get_command_obj('bdist_egg').egg_output]
+        
+        # TODO: Fix get_command_obj in distutils stubs (which should create by default)
+        args = [self.distribution.get_command_obj('bdist_egg').egg_output]  # pyright: ignore[reportOptionalMemberAccess]
 
         if setuptools.bootstrap_install_from:
             # Bootstrap self-installation of setuptools
diff --git a/setuptools/command/rotate.py b/setuptools/command/rotate.py
index cfb78ce52d..6f73721c70 100644
--- a/setuptools/command/rotate.py
+++ b/setuptools/command/rotate.py
@@ -3,6 +3,7 @@
 from distutils.errors import DistutilsOptionError
 import os
 import shutil
+from typing import List
 
 from setuptools import Command
 
@@ -17,7 +18,7 @@ class rotate(Command):
         ('keep=', 'k', "number of matching distributions to keep"),
     ]
 
-    boolean_options = []
+    boolean_options: List[str] = []
 
     def initialize_options(self):
         self.match = None
diff --git a/setuptools/command/test.py b/setuptools/command/test.py
index 0a128f2a7a..4e609b779c 100644
--- a/setuptools/command/test.py
+++ b/setuptools/command/test.py
@@ -1,8 +1,11 @@
+from collections.abc import Callable
 import os
 import operator
 import sys
 import contextlib
 import itertools
+from typing import Generic, List, TypeVar, overload
+from typing_extensions import Self
 import unittest
 from distutils.errors import DistutilsError, DistutilsOptionError
 from distutils import log
@@ -61,12 +64,16 @@ def loadTestsFromModule(self, module, pattern=None):
         else:
             return tests[0]  # don't create a nested suite for only one return
 
-
+_T = TypeVar("_T")
 # adapted from jaraco.classes.properties:NonDataProperty
-class NonDataProperty:
-    def __init__(self, fget):
+class NonDataProperty(Generic[_T]):
+    def __init__(self, fget: Callable[..., _T]):
         self.fget = fget
 
+    @overload
+    def __get__(self, obj: None, objtype: object=None) -> Self: ...
+    @overload
+    def __get__(self, obj: object, objtype=None) -> _T: ...
     def __get__(self, obj, objtype=None):
         if obj is None:
             return self
@@ -113,7 +120,7 @@ def finalize_options(self):
             self.test_runner = getattr(self.distribution, 'test_runner', None)
 
     @NonDataProperty
-    def test_args(self):
+    def test_args(self) -> List[str]:
         return list(self._test_args())
 
     def _test_args(self):
@@ -168,8 +175,7 @@ def paths_on_pythonpath(paths):
 
         Do this in a context that restores the value on exit.
         """
-        nothing = object()
-        orig_pythonpath = os.environ.get('PYTHONPATH', nothing)
+        orig_pythonpath = os.environ.get('PYTHONPATH')
         current_pythonpath = os.environ.get('PYTHONPATH', '')
         try:
             prefix = os.pathsep.join(unique_everseen(paths))
@@ -179,7 +185,7 @@ def paths_on_pythonpath(paths):
                 os.environ['PYTHONPATH'] = new_path
             yield
         finally:
-            if orig_pythonpath is nothing:
+            if orig_pythonpath is None:
                 os.environ.pop('PYTHONPATH', None)
             else:
                 os.environ['PYTHONPATH'] = orig_pythonpath
diff --git a/setuptools/command/upload_docs.py b/setuptools/command/upload_docs.py
index 32c9abd796..6da37692d2 100644
--- a/setuptools/command/upload_docs.py
+++ b/setuptools/command/upload_docs.py
@@ -50,7 +50,7 @@ def has_sphinx(self):
             and metadata.entry_points(group='distutils.commands', name='build_sphinx')
         )
 
-    sub_commands = [('build_sphinx', has_sphinx)]
+    sub_commands = [('build_sphinx', has_sphinx)]  # type: ignore[list-item] # distutils stubs issue w/ Python 3.12
 
     def initialize_options(self):
         upload.initialize_options(self)
@@ -76,6 +76,8 @@ def finalize_options(self):
         self.announce('Using upload directory %s' % self.target_dir)
 
     def create_zipfile(self, filename):
+        if self.target_dir is None:
+            raise ValueError("self.target_dir cannot be None")
         zip_file = zipfile.ZipFile(filename, "w")
         try:
             self.mkpath(self.target_dir)  # just in case
diff --git a/setuptools/config/__init__.py b/setuptools/config/__init__.py
index fcc7d008d6..7d7719df2d 100644
--- a/setuptools/config/__init__.py
+++ b/setuptools/config/__init__.py
@@ -3,19 +3,22 @@
 """
 
 from functools import wraps
-from typing import Callable, TypeVar, cast
+from typing import Callable, TypeVar
+
+from typing_extensions import ParamSpec
 
 from ..warnings import SetuptoolsDeprecationWarning
 from . import setupcfg
 
-Fn = TypeVar("Fn", bound=Callable)
+_R = TypeVar("_R")
+_P = ParamSpec("_P")
 
-__all__ = ('parse_configuration', 'read_configuration')
+__all__ = ("parse_configuration", "read_configuration")
 
 
-def _deprecation_notice(fn: Fn) -> Fn:
+def _deprecation_notice(fn: Callable[_P, _R]) -> Callable[_P, _R]:
     @wraps(fn)
-    def _wrapper(*args, **kwargs):
+    def _wrapper(*args: _P.args, **kwargs: _P.kwargs):
         SetuptoolsDeprecationWarning.emit(
             "Deprecated API usage.",
             f"""
@@ -36,7 +39,7 @@ def _wrapper(*args, **kwargs):
         )
         return fn(*args, **kwargs)
 
-    return cast(Fn, _wrapper)
+    return _wrapper
 
 
 read_configuration = _deprecation_notice(setupcfg.read_configuration)
diff --git a/setuptools/config/_apply_pyprojecttoml.py b/setuptools/config/_apply_pyprojecttoml.py
index 4261f3e218..b412b9c25c 100644
--- a/setuptools/config/_apply_pyprojecttoml.py
+++ b/setuptools/config/_apply_pyprojecttoml.py
@@ -27,7 +27,6 @@
     Tuple,
     Type,
     Union,
-    cast,
 )
 
 from ..errors import RemovedConfigError
@@ -36,10 +35,11 @@
 if TYPE_CHECKING:
     from setuptools._importlib import metadata  # noqa
     from setuptools.dist import Distribution  # noqa
+    metadata_EntryPoint = metadata.EntryPoint
 
 EMPTY: Mapping = MappingProxyType({})  # Immutable dict-like
 _Path = Union[os.PathLike, str]
-_DictOrStr = Union[dict, str]
+_DictOrStr = Union[Dict[str, str], str]
 _CorrespFn = Callable[["Distribution", Any, _Path], None]
 _Correspondence = Union[str, _CorrespFn]
 
@@ -157,11 +157,11 @@ def _long_description(dist: "Distribution", val: _DictOrStr, root_dir: _Path):
     from setuptools.config import expand
 
     if isinstance(val, str):
-        file: Union[str, list] = val
+        file = val
         text = expand.read_files(file, root_dir)
         ctype = _guess_content_type(val)
     else:
-        file = val.get("file") or []
+        file = val.get("file") or ()
         text = val.get("text") or expand.read_files(file, root_dir)
         ctype = val["content-type"]
 
@@ -171,7 +171,7 @@ def _long_description(dist: "Distribution", val: _DictOrStr, root_dir: _Path):
         _set_config(dist, "long_description_content_type", ctype)
 
     if file:
-        dist._referenced_files.add(cast(str, file))
+        dist._referenced_files.add(file)
 
 
 def _license(dist: "Distribution", val: dict, root_dir: _Path):
@@ -280,7 +280,7 @@ def _valid_command_options(cmdclass: Mapping = EMPTY) -> Dict[str, Set[str]]:
     return valid_options
 
 
-def _load_ep(ep: "metadata.EntryPoint") -> Optional[Tuple[str, Type]]:
+def _load_ep(ep: "metadata_EntryPoint") -> Optional[Tuple[str, Type]]:
     # Ignore all the errors
     try:
         return (ep.name, ep.load())
diff --git a/setuptools/config/_validate_pyproject/__init__.py b/setuptools/config/_validate_pyproject/__init__.py
index dbe6cb4ca4..cddc1599ac 100644
--- a/setuptools/config/_validate_pyproject/__init__.py
+++ b/setuptools/config/_validate_pyproject/__init__.py
@@ -5,7 +5,7 @@
 from .error_reporting import detailed_errors, ValidationError
 from .extra_validations import EXTRA_VALIDATIONS
 from .fastjsonschema_exceptions import JsonSchemaException, JsonSchemaValueException
-from .fastjsonschema_validations import validate as _validate
+from .fastjsonschema_validations import validate as _validate  # type: ignore[attr-defined] # mypy false-positive. Pyright is fine here
 
 __all__ = [
     "validate",
diff --git a/setuptools/config/_validate_pyproject/error_reporting.py b/setuptools/config/_validate_pyproject/error_reporting.py
index d44e290e36..be8971bc34 100644
--- a/setuptools/config/_validate_pyproject/error_reporting.py
+++ b/setuptools/config/_validate_pyproject/error_reporting.py
@@ -5,7 +5,7 @@
 import re
 from contextlib import contextmanager
 from textwrap import indent, wrap
-from typing import Any, Dict, Iterator, List, Optional, Sequence, Union, cast
+from typing import Any, Dict, Iterator, List, Optional, Sequence, Union
 
 from .fastjsonschema_exceptions import JsonSchemaValueException
 
@@ -297,7 +297,7 @@ def _value(self, value: Any, path: Sequence[str]) -> str:
         if path[-1] == "type" and not self._is_property(path):
             type_ = self._jargon(value)
             return (
-                f"[{', '.join(type_)}]" if isinstance(value, list) else cast(str, type_)
+                f"[{', '.join(type_)}]" if isinstance(type_, list) else type_
             )
         return repr(value)
 
diff --git a/setuptools/config/_validate_pyproject/fastjsonschema_exceptions.py b/setuptools/config/_validate_pyproject/fastjsonschema_exceptions.py
index d2dddd6a10..bb9eee24ff 100644
--- a/setuptools/config/_validate_pyproject/fastjsonschema_exceptions.py
+++ b/setuptools/config/_validate_pyproject/fastjsonschema_exceptions.py
@@ -26,7 +26,7 @@ class JsonSchemaValueException(JsonSchemaException):
         Added all extra properties.
     """
 
-    def __init__(self, message, value=None, name=None, definition=None, rule=None):
+    def __init__(self, message, value=None, name="", definition={}, rule=None):
         super().__init__(message)
         self.message = message
         self.value = value
diff --git a/setuptools/config/expand.py b/setuptools/config/expand.py
index b48fc1187e..8d8be2eae5 100644
--- a/setuptools/config/expand.py
+++ b/setuptools/config/expand.py
@@ -19,7 +19,7 @@
 """
 
 import ast
-import importlib
+import importlib.util
 import os
 import pathlib
 import sys
@@ -39,7 +39,6 @@
     Tuple,
     TypeVar,
     Union,
-    cast,
 )
 from pathlib import Path
 from types import ModuleType
@@ -64,7 +63,7 @@ class StaticModule:
     """Proxy to a module object that avoids executing arbitrary code."""
 
     def __init__(self, name: str, spec: ModuleSpec):
-        module = ast.parse(pathlib.Path(spec.origin).read_bytes())
+        module = ast.parse(pathlib.Path(spec.origin).read_bytes())  # type: ignore[arg-type] # Let it raise an error on None
         vars(self).update(locals())
         del self.self
 
@@ -341,17 +340,17 @@ def version(value: Union[Callable, Iterable[Union[str, int]], str]) -> str:
     it should be normalised to string.
     """
     if callable(value):
-        value = value()
-
-    value = cast(Iterable[Union[str, int]], value)
+        _value = value()
+    else:
+        _value = value
 
-    if not isinstance(value, str):
-        if hasattr(value, '__iter__'):
-            value = '.'.join(map(str, value))
+    if not isinstance(_value, str):
+        if hasattr(_value, '__iter__'):
+            _value = '.'.join(map(str, _value))
         else:
-            value = '%s' % value
+            _value = '%s' % _value
 
-    return value
+    return _value
 
 
 def canonic_package_data(package_data: dict) -> dict:
@@ -385,7 +384,7 @@ def entry_points(text: str, text_source="entry-points") -> Dict[str, dict]:
     (that correspond to the entry-point value).
     """
     parser = ConfigParser(default_section=None, delimiters=("=",))  # type: ignore
-    parser.optionxform = str  # case sensitive
+    parser.optionxform = lambda optionstr: str(optionstr)  # case sensitive, support kwarg
     parser.read_string(text, text_source)
     groups = {k: dict(v.items()) for k, v in parser.items()}
     groups.pop(parser.default_section, None)
diff --git a/setuptools/config/pyprojecttoml.py b/setuptools/config/pyprojecttoml.py
index 321e106e40..88e3931181 100644
--- a/setuptools/config/pyprojecttoml.py
+++ b/setuptools/config/pyprojecttoml.py
@@ -23,6 +23,7 @@
 
 if TYPE_CHECKING:
     from setuptools.dist import Distribution  # noqa
+    from typing_extensions import Self
 
 _Path = Union[str, os.PathLike]
 _logger = logging.getLogger(__name__)
@@ -271,7 +272,7 @@ def _ensure_previously_set(self, dist: "Distribution", field: str):
     def _expand_directive(
         self, specifier: str, directive, package_dir: Mapping[str, str]
     ):
-        from setuptools.extern.more_itertools import always_iterable  # type: ignore
+        from setuptools.extern.more_itertools import always_iterable
 
         with _ignore_errors(self.ignore_option_errors):
             root_dir = self.root_dir
@@ -296,19 +297,23 @@ def _obtain(self, dist: "Distribution", field: str, package_dir: Mapping[str, st
     def _obtain_version(self, dist: "Distribution", package_dir: Mapping[str, str]):
         # Since plugins can set version, let's silently skip if it cannot be obtained
         if "version" in self.dynamic and "version" in self.dynamic_cfg:
-            return _expand.version(self._obtain(dist, "version", package_dir))
+            return _expand.version(
+                # We already do an early check for the presence of "version"
+                self._obtain(dist, "version", package_dir)  # pyright: ignore[reportArgumentType]
+            )
         return None
 
-    def _obtain_readme(self, dist: "Distribution") -> Optional[Dict[str, str]]:
+    def _obtain_readme(self, dist: "Distribution") -> Optional[Dict[str, Optional[str]]]:
         if "readme" not in self.dynamic:
             return None
 
         dynamic_cfg = self.dynamic_cfg
         if "readme" in dynamic_cfg:
             return {
+                # We already do an early check for the presence of "readme"
                 "text": self._obtain(dist, "readme", {}),
                 "content-type": dynamic_cfg["readme"].get("content-type", "text/x-rst"),
-            }
+            }  # pyright: ignore[reportReturnType]
 
         self._ensure_previously_set(dist, "readme")
         return None
@@ -401,7 +406,7 @@ def __init__(
         self._project_cfg = project_cfg
         self._setuptools_cfg = setuptools_cfg
 
-    def __enter__(self):
+    def __enter__(self) -> "Self":
         """When entering the context, the values of ``packages``, ``py_modules`` and
         ``package_dir`` that are missing in ``dist`` are copied from ``setuptools_cfg``.
         """
diff --git a/setuptools/config/setupcfg.py b/setuptools/config/setupcfg.py
index a7f02714cb..20ce71308d 100644
--- a/setuptools/config/setupcfg.py
+++ b/setuptools/config/setupcfg.py
@@ -108,7 +108,7 @@ def _apply(
     filenames = [*other_files, filepath]
 
     try:
-        _Distribution.parse_config_files(dist, filenames=filenames)
+        _Distribution.parse_config_files(dist, filenames=filenames)  # type: ignore[arg-type] # TODO: fix in disutils stubs
         handlers = parse_configuration(
             dist, dist.command_options, ignore_option_errors=ignore_option_errors
         )
@@ -475,7 +475,7 @@ def parse_section(self, section_options):
                 # Keep silent for a new option may appear anytime.
                 self[name] = value
 
-    def parse(self):
+    def parse(self) -> None:
         """Parses configuration file items from one
         or more related sections.
 
diff --git a/setuptools/dist.py b/setuptools/dist.py
index 0d35583dbc..2d0328719f 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -10,7 +10,7 @@
 from contextlib import suppress
 from glob import iglob
 from pathlib import Path
-from typing import List, Optional, Set
+from typing import Dict, List, MutableMapping, Optional, Set, Tuple
 
 import distutils.cmd
 import distutils.command
@@ -205,7 +205,7 @@ def check_packages(dist, attr, value):
 _Distribution = get_unpatched(distutils.core.Distribution)
 
 
-class Distribution(_Distribution):
+class Distribution(_Distribution):  # type: ignore[valid-type, misc]  # https://github.com/python/mypy/issues/14458
     """Distribution with support for tests and package data
 
     This is an enhanced version of 'distutils.dist.Distribution' that
@@ -257,6 +257,10 @@ class Distribution(_Distribution):
     the distribution.
     """
 
+    packages: Optional[List]
+    py_modules: Optional[List]
+    ext_modules: Optional[List]
+
     _DISTUTILS_UNSUPPORTED_METADATA = {
         'long_description_content_type': lambda: None,
         'project_urls': dict,
@@ -283,24 +287,24 @@ def patch_missing_pkg_info(self, attrs):
                 dist._version = _normalization.safe_version(str(attrs['version']))
                 self._patched_dist = dist
 
-    def __init__(self, attrs=None):
+    def __init__(self, attrs: Optional[MutableMapping] = None) -> None:
         have_package_data = hasattr(self, "package_data")
         if not have_package_data:
-            self.package_data = {}
+            self.package_data: Dict[str, List[str]] = {}
         attrs = attrs or {}
-        self.dist_files = []
+        self.dist_files: List[Tuple[str, str, str]] = []
         # Filter-out setuptools' specific options.
         self.src_root = attrs.pop("src_root", None)
         self.patch_missing_pkg_info(attrs)
         self.dependency_links = attrs.pop('dependency_links', [])
         self.setup_requires = attrs.pop('setup_requires', [])
         for ep in metadata.entry_points(group='distutils.setup_keywords'):
-            vars(self).setdefault(ep.name, None)
+            vars(self).setdefault(ep.name, None)  # type: ignore[attr-defined]  # https://github.com/python/mypy/issues/14458
 
         metadata_only = set(self._DISTUTILS_UNSUPPORTED_METADATA)
         metadata_only -= {"install_requires", "extras_require"}
         dist_attrs = {k: v for k, v in attrs.items() if k not in metadata_only}
-        _Distribution.__init__(self, dist_attrs)
+        super().__init__(dist_attrs)
 
         # Private API (setuptools-use only, not restricted to Distribution)
         # Stores files that are referenced by the configuration and need to be in the
@@ -381,7 +385,7 @@ def _normalize_requires(self):
             k: list(map(str, _reqs.parse(v or []))) for k, v in extras_require.items()
         }
 
-    def _finalize_license_files(self):
+    def _finalize_license_files(self) -> None:
         """Compute names of all license files which should be included."""
         license_files: Optional[List[str]] = self.metadata.license_files
         patterns: List[str] = license_files if license_files else []
@@ -394,7 +398,7 @@ def _finalize_license_files(self):
             # Default patterns match the ones wheel uses
             # See https://wheel.readthedocs.io/en/stable/user_guide.html
             # -> 'Including license files in the generated wheel file'
-            patterns = ('LICEN[CS]E*', 'COPYING*', 'NOTICE*', 'AUTHORS*')
+            patterns = ['LICEN[CS]E*', 'COPYING*', 'NOTICE*', 'AUTHORS*']
 
         self.metadata.license_files = list(
             unique_everseen(self._expand_patterns(patterns))
@@ -812,7 +816,7 @@ def _include_misc(self, name, value):
             )
         else:
             new = [item for item in value if item not in old]
-            setattr(self, name, old + new)
+            setattr(self, name, list(old) + new)
 
     def exclude(self, **attrs):
         """Remove items from distribution that are named in keyword arguments
diff --git a/setuptools/extension.py b/setuptools/extension.py
index 58c023f6b4..9eea0d6930 100644
--- a/setuptools/extension.py
+++ b/setuptools/extension.py
@@ -27,7 +27,7 @@ def _have_cython():
 _Extension = get_unpatched(distutils.core.Extension)
 
 
-class Extension(_Extension):
+class Extension(_Extension):  # type: ignore[valid-type, misc]  # https://github.com/python/mypy/issues/14458
     """
     Describes a single extension module.
 
diff --git a/setuptools/monkey.py b/setuptools/monkey.py
index da0993506c..715fb92dfc 100644
--- a/setuptools/monkey.py
+++ b/setuptools/monkey.py
@@ -8,18 +8,21 @@
 import sys
 import types
 from importlib import import_module
+from typing import List, Optional, TypeVar, Union, overload
 
 import distutils.filelist
 
 
-__all__ = []
+_UnpatchedT = TypeVar("_UnpatchedT", type, types.FunctionType)
+
+__all__: List[str] = []
 """
 Everything is private. Contact the project team
 if you think you need this functionality.
 """
 
 
-def _get_mro(cls):
+def _get_mro(cls: type):
     """
     Returns the bases classes for cls sorted by the MRO.
 
@@ -32,8 +35,11 @@ def _get_mro(cls):
         return (cls,) + cls.__bases__
     return inspect.getmro(cls)
 
-
-def get_unpatched(item):
+@overload
+def get_unpatched(item: _UnpatchedT) -> _UnpatchedT:...
+@overload
+def get_unpatched(item: object) -> None:...
+def get_unpatched(item: Union[type, types.FunctionType, object]) -> Optional[Union[type, types.FunctionType]]:
     lookup = (
         get_unpatched_class
         if isinstance(item, type)
@@ -114,7 +120,7 @@ def patch_func(replacement, target_mod, func_name):
     setattr(target_mod, func_name, replacement)
 
 
-def get_unpatched_function(candidate):
+def get_unpatched_function(candidate) -> types.FunctionType:
     return candidate.unpatched
 
 
diff --git a/setuptools/msvc.py b/setuptools/msvc.py
index aa69db5810..2bc9b08fa7 100644
--- a/setuptools/msvc.py
+++ b/setuptools/msvc.py
@@ -19,10 +19,13 @@
 import platform
 import itertools
 import subprocess
+from typing import TYPE_CHECKING
 import distutils.errors
+from typing import Dict, TYPE_CHECKING
 from setuptools.extern.more_itertools import unique_everseen
 
-if platform.system() == 'Windows':
+# https://github.com/python/mypy/issues/8166
+if not TYPE_CHECKING and platform.system() == 'Windows':
     import winreg
     from os import environ
 else:
@@ -34,7 +37,7 @@ class winreg:
         HKEY_LOCAL_MACHINE = None
         HKEY_CLASSES_ROOT = None
 
-    environ = dict()
+    environ: Dict[str, str] = dict()
 
 
 def _msvc14_find_vc2015():
diff --git a/setuptools/py311compat.py b/setuptools/py311compat.py
index 9231cbb290..36a63da6e1 100644
--- a/setuptools/py311compat.py
+++ b/setuptools/py311compat.py
@@ -4,4 +4,5 @@
 if sys.version_info >= (3, 11):
     import tomllib
 else:  # pragma: no cover
-    from setuptools.extern import tomli as tomllib
+    from setuptools.extern import tomli as tomllib  # type: ignore[attr-defined]
+tomllib = tomllib
diff --git a/setuptools/py312compat.py b/setuptools/py312compat.py
index 28175b1f75..d7a3ef701e 100644
--- a/setuptools/py312compat.py
+++ b/setuptools/py312compat.py
@@ -1,8 +1,10 @@
 import sys
 import shutil
 
+def _do_nothing(*args: object) -> None:
+    pass
 
-def shutil_rmtree(path, ignore_errors=False, onexc=None):
+def shutil_rmtree(path, ignore_errors=False, onexc=_do_nothing):
     if sys.version_info >= (3, 12):
         return shutil.rmtree(path, ignore_errors, onexc=onexc)
 
diff --git a/setuptools/sandbox.py b/setuptools/sandbox.py
index 757074166a..39e49fdc9b 100644
--- a/setuptools/sandbox.py
+++ b/setuptools/sandbox.py
@@ -9,6 +9,7 @@
 import pickle
 import textwrap
 import builtins
+from typing import Union, List
 
 import pkg_resources
 from distutils.errors import DistutilsError
@@ -19,7 +20,7 @@
 else:
     _os = sys.modules[os.name]
 try:
-    _file = file
+    _file = file  # type: ignore[name-defined] # Check for global variable
 except NameError:
     _file = None
 _open = open
@@ -298,7 +299,7 @@ def run(self, func):
         with self:
             return func()
 
-    def _mk_dual_path_wrapper(name):
+    def _mk_dual_path_wrapper(name: str):  # type: ignore[misc] # TODO: Extract or make static
         original = getattr(_os, name)
 
         def wrap(self, src, dst, *args, **kw):
@@ -312,7 +313,7 @@ def wrap(self, src, dst, *args, **kw):
         if hasattr(_os, name):
             locals()[name] = _mk_dual_path_wrapper(name)
 
-    def _mk_single_path_wrapper(name, original=None):
+    def _mk_single_path_wrapper(name: str, original=None):  # type: ignore[misc] # TODO: Extract or make static
         original = original or getattr(_os, name)
 
         def wrap(self, path, *args, **kw):
@@ -349,7 +350,7 @@ def wrap(self, path, *args, **kw):
         if hasattr(_os, name):
             locals()[name] = _mk_single_path_wrapper(name)
 
-    def _mk_single_with_return(name):
+    def _mk_single_with_return(name: str):  # type: ignore[misc] # TODO: Extract or make static
         original = getattr(_os, name)
 
         def wrap(self, path, *args, **kw):
@@ -364,7 +365,7 @@ def wrap(self, path, *args, **kw):
         if hasattr(_os, name):
             locals()[name] = _mk_single_with_return(name)
 
-    def _mk_query(name):
+    def _mk_query(name: str):  # type: ignore[misc] # TODO: Extract or make static
         original = getattr(_os, name)
 
         def wrap(self, *args, **kw):
@@ -424,7 +425,7 @@ class DirectorySandbox(AbstractSandbox):
         "tempnam",
     ])
 
-    _exception_patterns = []
+    _exception_patterns: List[Union[str, re.Pattern]] = []
     "exempt writing to paths that match the pattern"
 
     def __init__(self, sandbox, exceptions=_EXCEPTIONS):
@@ -441,11 +442,10 @@ def _violation(self, operation, *args, **kw):
         raise SandboxViolation(operation, args, kw)
 
     if _file:
-
         def _file(self, path, mode='r', *args, **kw):
             if mode not in ('r', 'rt', 'rb', 'rU', 'U') and not self._ok(path):
                 self._violation("file", path, mode, *args, **kw)
-            return _file(path, mode, *args, **kw)
+            return _file(path, mode, *args, **kw)  # pyright: ignore[reportOptionalCall] # Unsafe, but we never re-assign _file
 
     def _open(self, path, mode='r', *args, **kw):
         if mode not in ('r', 'rt', 'rb', 'rU', 'U') and not self._ok(path):
diff --git a/setuptools/tests/_packaging_compat.py b/setuptools/tests/_packaging_compat.py
index 5bdcc554d5..a34b261d72 100644
--- a/setuptools/tests/_packaging_compat.py
+++ b/setuptools/tests/_packaging_compat.py
@@ -1,6 +1,8 @@
+from typing import TYPE_CHECKING
+
 from packaging import __version__ as packaging_version
 
-if tuple(packaging_version.split(".")) >= ("23", "2"):
+if TYPE_CHECKING or tuple(packaging_version.split(".")) >= ("23", "2"):
     from packaging.metadata import Metadata
 else:
     # Just pretend it exists while waiting for release...
diff --git a/setuptools/tests/config/test_apply_pyprojecttoml.py b/setuptools/tests/config/test_apply_pyprojecttoml.py
index 6935523987..17f8c96ed0 100644
--- a/setuptools/tests/config/test_apply_pyprojecttoml.py
+++ b/setuptools/tests/config/test_apply_pyprojecttoml.py
@@ -9,6 +9,7 @@
 import tarfile
 from inspect import cleandoc
 from pathlib import Path
+from typing import Tuple
 from unittest.mock import Mock
 from zipfile import ZipFile
 
@@ -451,7 +452,7 @@ def core_metadata(dist) -> str:
     # Make sure core metadata is valid
     Metadata.from_email(pkg_file_txt, validate=True)  # can raise exceptions
 
-    skip_prefixes = ()
+    skip_prefixes: Tuple[str, ...] = ()
     skip_lines = set()
     # ---- DIFF NORMALISATION ----
     # PEP 621 is very particular about author/maintainer metadata conversion, so skip
diff --git a/setuptools/tests/integration/test_pip_install_sdist.py b/setuptools/tests/integration/test_pip_install_sdist.py
index 3467a5ec07..f5db400609 100644
--- a/setuptools/tests/integration/test_pip_install_sdist.py
+++ b/setuptools/tests/integration/test_pip_install_sdist.py
@@ -1,3 +1,5 @@
+# https://github.com/python/mypy/issues/8009#issuecomment-558335186
+# mypy: disable-error-code="has-type"
 """Integration tests for setuptools that focus on building packages via pip.
 
 The idea behind these tests is not to exhaustively check all the possible
@@ -25,10 +27,10 @@
 
 from .helpers import Archive, run
 
-
 pytestmark = pytest.mark.integration
 
-(LATEST,) = Enum("v", "LATEST")
+
+(LATEST,) = Enum("v", "LATEST")  # type: ignore[misc] # https://github.com/python/mypy/issues/8009#issuecomment-558335186
 """Default version to be checked"""
 # There are positive and negative aspects of checking the latest version of the
 # packages.
diff --git a/setuptools/tests/test_config_discovery.py b/setuptools/tests/test_config_discovery.py
index 85cb09730c..d193c06416 100644
--- a/setuptools/tests/test_config_discovery.py
+++ b/setuptools/tests/test_config_discovery.py
@@ -381,6 +381,7 @@ def test_skip_discovery_with_setupcfg_metadata(self, tmp_path):
         assert dist.get_version() == "42"
         assert dist.py_modules is None
         assert dist.packages is None
+        assert dist.ext_modules is not None
         assert len(dist.ext_modules) == 1
         assert dist.ext_modules[0].name == "proj"
 
diff --git a/setuptools/tests/test_editable_install.py b/setuptools/tests/test_editable_install.py
index 987c2fd67c..ca0f007486 100644
--- a/setuptools/tests/test_editable_install.py
+++ b/setuptools/tests/test_editable_install.py
@@ -120,7 +120,7 @@ def editable_opts(request):
 @pytest.mark.parametrize(
     "files",
     [
-        {**EXAMPLE, "setup.py": SETUP_SCRIPT_STUB},  # type: ignore
+        {**EXAMPLE, "setup.py": SETUP_SCRIPT_STUB},
         EXAMPLE,  # No setup.py script
     ],
 )
diff --git a/setuptools/tests/test_egg_info.py b/setuptools/tests/test_egg_info.py
index af7d2f8295..ef8536bf4e 100644
--- a/setuptools/tests/test_egg_info.py
+++ b/setuptools/tests/test_egg_info.py
@@ -79,7 +79,8 @@ def run():
     @staticmethod
     def _extract_mv_version(pkg_info_lines: List[str]) -> Tuple[int, int]:
         version_str = pkg_info_lines[0].split(' ')[1]
-        return tuple(map(int, version_str.split('.')[:2]))
+        major, minor, *_ = map(int, version_str.split('.'))
+        return major, minor
 
     def test_egg_info_save_version_info_setup_empty(self, tmpdir_cwd, env):
         """
diff --git a/setuptools/tests/test_manifest.py b/setuptools/tests/test_manifest.py
index fbd21b1976..16fa2c2460 100644
--- a/setuptools/tests/test_manifest.py
+++ b/setuptools/tests/test_manifest.py
@@ -10,6 +10,7 @@
 import logging
 from distutils import log
 from distutils.errors import DistutilsTemplateError
+from typing import List, Tuple
 
 from setuptools.command.egg_info import FileList, egg_info, translate_pattern
 from setuptools.dist import Distribution
@@ -75,7 +76,7 @@ def touch(filename):
 )
 
 
-translate_specs = [
+translate_specs: List[Tuple[str, List[str], List[str]]] = [
     ('foo', ['foo'], ['bar', 'foobar']),
     ('foo/bar', ['foo/bar'], ['foo/bar/baz', './foo/bar', 'foo']),
     # Glob matching
diff --git a/setuptools/tests/test_packageindex.py b/setuptools/tests/test_packageindex.py
index f27a5c63e9..c3024a05b5 100644
--- a/setuptools/tests/test_packageindex.py
+++ b/setuptools/tests/test_packageindex.py
@@ -1,4 +1,3 @@
-import sys
 import distutils.errors
 import urllib.request
 import urllib.error
@@ -126,7 +125,7 @@ def test_local_index(self, tmpdir):
             f.write('<div>content</div>')
         url = 'file:' + urllib.request.pathname2url(str(tmpdir)) + '/'
         res = setuptools.package_index.local_open(url)
-        assert 'content' in res.read()
+        assert 'content' in res.read()  # pyright: ignore[reportOperatorIssue] # TODO: This may be an upstream issue? To validate
 
     def test_egg_fragment(self):
         """
diff --git a/setuptools/tests/test_setuptools.py b/setuptools/tests/test_setuptools.py
index 0dc4769b93..d318e4ea36 100644
--- a/setuptools/tests/test_setuptools.py
+++ b/setuptools/tests/test_setuptools.py
@@ -53,7 +53,7 @@ def testExtractConst(self):
         def f1():
             global x, y, z
             x = "test"
-            y = z
+            y = z  # pyright: ignore[reportUnboundVariable] # Testing unassigned variables
 
         fc = f1.__code__
 
diff --git a/setuptools/tests/test_wheel.py b/setuptools/tests/test_wheel.py
index 03fb05d2f4..c54cb5b1b8 100644
--- a/setuptools/tests/test_wheel.py
+++ b/setuptools/tests/test_wheel.py
@@ -12,6 +12,7 @@
 import shutil
 import subprocess
 import sys
+from typing_extensions import Required, TypedDict
 import zipfile
 
 import pytest
@@ -176,9 +177,17 @@ def __init__(self, id, **kwargs):
     def __repr__(self):
         return '%s(**%r)' % (self._id, self._fields)
 
+class WheelInstallTest(TypedDict, total=False):
+    id: Required[str]
+    file_defs: dict
+    setup_kwargs: dict
+    install_tree: set
+    install_requires: str
+    extras_require: dict
+    requires_txt: str
 
 WHEEL_INSTALL_TESTS = (
-    dict(
+    WheelInstallTest(
         id='basic',
         file_defs={'foo': {'__init__.py': ''}},
         setup_kwargs=dict(
@@ -191,13 +200,13 @@ def __repr__(self):
             }
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='utf-8',
         setup_kwargs=dict(
             description='Description accentuée',
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='data',
         file_defs={
             'data.txt': DALS(
@@ -216,7 +225,7 @@ def __repr__(self):
             }
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='extension',
         file_defs={
             'extension.c': DALS(
@@ -284,7 +293,7 @@ def __repr__(self):
             ]
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='header',
         file_defs={
             'header.h': DALS(
@@ -309,7 +318,7 @@ def __repr__(self):
             ]
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='script',
         file_defs={
             'script.py': DALS(
@@ -340,7 +349,7 @@ def __repr__(self):
             }
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='requires1',
         install_requires='foobar==2.0',
         install_tree=flatten_tree({
@@ -360,7 +369,7 @@ def __repr__(self):
             """
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='requires2',
         install_requires="""
         bar
@@ -374,14 +383,14 @@ def __repr__(self):
             """
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='requires3',
         install_requires="""
         bar; %r != sys_platform
         """
         % sys.platform,
     ),
-    dict(
+    WheelInstallTest(
         id='requires4',
         install_requires="""
         foo
@@ -398,7 +407,7 @@ def __repr__(self):
             """
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='requires5',
         extras_require={
             'extra': 'foobar; %r != sys_platform' % sys.platform,
@@ -409,7 +418,7 @@ def __repr__(self):
             """
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='requires_ensure_order',
         install_requires="""
         foo
@@ -440,7 +449,7 @@ def __repr__(self):
             """
         ),
     ),
-    dict(
+    WheelInstallTest(
         id='namespace_package',
         file_defs={
             'foo': {
@@ -472,7 +481,7 @@ def __repr__(self):
             ]
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='empty_namespace_package',
         file_defs={
             'foobar': {
@@ -505,7 +514,7 @@ def __repr__(self):
             ]
         }),
     ),
-    dict(
+    WheelInstallTest(
         id='data_in_package',
         file_defs={
             'foo': {
diff --git a/tools/finalize.py b/tools/finalize.py
index f79f5b3b45..38a01bf8b2 100644
--- a/tools/finalize.py
+++ b/tools/finalize.py
@@ -24,7 +24,10 @@
 def get_version():
     cmd = bump_version_command + ['--dry-run', '--verbose']
     out = subprocess.check_output(cmd, text=True)
-    return re.search('^new_version=(.*)', out, re.MULTILINE).group(1)
+    match = re.search('^new_version=(.*)', out, re.MULTILINE)
+    if not match:
+        return None
+    return match.group(1)
 
 
 def update_changelog():