Rename _InstallerTypeT and mark type aliases with TypeAlias (#4436)

* Rename _InstallerTypeT & Mark type aliases with TypeAlias to help static checkers

pkg_resources/__init__.py

@@ -106,7 +106,7 @@
 
 if TYPE_CHECKING:
     from _typeshed import BytesPath, StrPath, StrOrBytesPath
-    from typing_extensions import Self
+    from typing_extensions import Self, TypeAlias
 
 warnings.warn(
     "pkg_resources is deprecated as an API. "
@@ -118,20 +118,20 @@
 _T = TypeVar("_T")
 _DistributionT = TypeVar("_DistributionT", bound="Distribution")
 # Type aliases
-_NestedStr = Union[str, Iterable[Union[str, Iterable["_NestedStr"]]]]
-_InstallerTypeT = Callable[["Requirement"], "_DistributionT"]
-_InstallerType = Callable[["Requirement"], Union["Distribution", None]]
-_PkgReqType = Union[str, "Requirement"]
-_EPDistType = Union["Distribution", _PkgReqType]
-_MetadataType = Union["IResourceProvider", None]
-_ResolvedEntryPoint = Any  # Can be any attribute in the module
-_ResourceStream = Any  # TODO / Incomplete: A readable file-like object
+_NestedStr: TypeAlias = Union[str, Iterable[Union[str, Iterable["_NestedStr"]]]]
+_StrictInstallerType: TypeAlias = Callable[["Requirement"], "_DistributionT"]
+_InstallerType: TypeAlias = Callable[["Requirement"], Union["Distribution", None]]
+_PkgReqType: TypeAlias = Union[str, "Requirement"]
+_EPDistType: TypeAlias = Union["Distribution", _PkgReqType]
+_MetadataType: TypeAlias = Union["IResourceProvider", None]
+_ResolvedEntryPoint: TypeAlias = Any  # Can be any attribute in the module
+_ResourceStream: TypeAlias = Any  # TODO / Incomplete: A readable file-like object
 # Any object works, but let's indicate we expect something like a module (optionally has __loader__ or __file__)
-_ModuleLike = Union[object, types.ModuleType]
+_ModuleLike: TypeAlias = Union[object, types.ModuleType]
 # Any: Should be _ModuleLike but we end up with issues where _ModuleLike doesn't have _ZipLoaderModule's __loader__
-_ProviderFactoryType = Callable[[Any], "IResourceProvider"]
-_DistFinderType = Callable[[_T, str, bool], Iterable["Distribution"]]
-_NSHandlerType = Callable[[_T, str, str, types.ModuleType], Union[str, None]]
+_ProviderFactoryType: TypeAlias = Callable[[Any], "IResourceProvider"]
+_DistFinderType: TypeAlias = Callable[[_T, str, bool], Iterable["Distribution"]]
+_NSHandlerType: TypeAlias = Callable[[_T, str, str, types.ModuleType], Union[str, None]]
 _AdapterT = TypeVar(
     "_AdapterT", _DistFinderType[Any], _ProviderFactoryType, _NSHandlerType[Any]
 )
@@ -814,7 +814,7 @@ def resolve(
         self,
         requirements: Iterable[Requirement],
         env: Environment | None,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
         replace_conflicting: bool = False,
         extras: tuple[str, ...] | None = None,
     ) -> list[_DistributionT]: ...
@@ -824,7 +824,7 @@ def resolve(
         requirements: Iterable[Requirement],
         env: Environment | None = None,
         *,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
         replace_conflicting: bool = False,
         extras: tuple[str, ...] | None = None,
     ) -> list[_DistributionT]: ...
@@ -841,7 +841,7 @@ def resolve(
         self,
         requirements: Iterable[Requirement],
         env: Environment | None = None,
-        installer: _InstallerType | None | _InstallerTypeT[_DistributionT] = None,
+        installer: _InstallerType | None | _StrictInstallerType[_DistributionT] = None,
         replace_conflicting: bool = False,
         extras: tuple[str, ...] | None = None,
     ) -> list[Distribution] | list[_DistributionT]:
@@ -947,7 +947,7 @@ def find_plugins(
         self,
         plugin_env: Environment,
         full_env: Environment | None,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
         fallback: bool = True,
     ) -> tuple[list[_DistributionT], dict[Distribution, Exception]]: ...
     @overload
@@ -956,7 +956,7 @@ def find_plugins(
         plugin_env: Environment,
         full_env: Environment | None = None,
         *,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
         fallback: bool = True,
     ) -> tuple[list[_DistributionT], dict[Distribution, Exception]]: ...
     @overload
@@ -971,7 +971,7 @@ def find_plugins(
         self,
         plugin_env: Environment,
         full_env: Environment | None = None,
-        installer: _InstallerType | None | _InstallerTypeT[_DistributionT] = None,
+        installer: _InstallerType | None | _StrictInstallerType[_DistributionT] = None,
         fallback: bool = True,
     ) -> tuple[
         list[Distribution] | list[_DistributionT],
@@ -1217,7 +1217,7 @@ def best_match(
         self,
         req: Requirement,
         working_set: WorkingSet,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
         replace_conflicting: bool = False,
     ) -> _DistributionT: ...
     @overload
@@ -1232,7 +1232,7 @@ def best_match(
         self,
         req: Requirement,
         working_set: WorkingSet,
-        installer: _InstallerType | None | _InstallerTypeT[_DistributionT] = None,
+        installer: _InstallerType | None | _StrictInstallerType[_DistributionT] = None,
         replace_conflicting: bool = False,
     ) -> Distribution | None:
         """Find distribution best matching `req` and usable on `working_set`
@@ -1265,7 +1265,7 @@ def best_match(
     def obtain(
         self,
         requirement: Requirement,
-        installer: _InstallerTypeT[_DistributionT],
+        installer: _StrictInstallerType[_DistributionT],
     ) -> _DistributionT: ...
     @overload
     def obtain(
@@ -1285,7 +1285,7 @@ def obtain(
         installer: Callable[[Requirement], None]
         | _InstallerType
         | None
-        | _InstallerTypeT[_DistributionT] = None,
+        | _StrictInstallerType[_DistributionT] = None,
     ) -> Distribution | None:
         """Obtain a distribution matching `requirement` (e.g. via download)
 

setuptools/_path.py

@@ -1,15 +1,21 @@
+from __future__ import annotations
+
 import contextlib
 import os
 import sys
-from typing import Union
+from typing import Union, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+
 
 from more_itertools import unique_everseen
 
 
 if sys.version_info >= (3, 9):
-    StrPath = Union[str, os.PathLike[str]]  #  Same as _typeshed.StrPath
+    StrPath: TypeAlias = Union[str, os.PathLike[str]]  #  Same as _typeshed.StrPath
 else:
-    StrPath = Union[str, os.PathLike]
+    StrPath: TypeAlias = Union[str, os.PathLike]
 
 
 def ensure_directory(path):

setuptools/_reqs.py

@@ -1,11 +1,15 @@
-from functools import lru_cache
-from typing import Callable, Iterable, Iterator, TypeVar, Union, overload
+from __future__ import annotations
 
+from functools import lru_cache
+from typing import Callable, Iterable, Iterator, TypeVar, Union, overload, TYPE_CHECKING
 import jaraco.text as text
 from packaging.requirements import Requirement
 
+if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+
 _T = TypeVar("_T")
-_StrOrIter = Union[str, Iterable[str]]
+_StrOrIter: TypeAlias = Union[str, Iterable[str]]
 
 
 parse_req: Callable[[str], Requirement] = lru_cache()(Requirement)

setuptools/build_meta.py

@@ -38,7 +38,7 @@
 import tempfile
 import warnings
 from pathlib import Path
-from typing import Dict, Iterator, List, Optional, Union, Iterable
+from typing import TYPE_CHECKING, Dict, Iterator, List, Union, Iterable
 
 import setuptools
 import distutils
@@ -48,6 +48,9 @@
 from .warnings import SetuptoolsDeprecationWarning
 from distutils.util import strtobool
 
+if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+
 
 __all__ = [
     'get_requires_for_build_sdist',
@@ -142,7 +145,7 @@ def suppress_known_deprecation():
         yield
 
 
-_ConfigSettings = Optional[Dict[str, Union[str, List[str], None]]]
+_ConfigSettings: TypeAlias = Union[Dict[str, Union[str, List[str], None]], None]
 """
 Currently the user can run::
 

setuptools/compat/py311.py

@@ -6,9 +6,10 @@
 
 if TYPE_CHECKING:
     from _typeshed import StrOrBytesPath, ExcInfo
+    from typing_extensions import TypeAlias
 
 # Same as shutil._OnExcCallback from typeshed
-_OnExcCallback = Callable[[Callable[..., Any], str, BaseException], object]
+_OnExcCallback: TypeAlias = Callable[[Callable[..., Any], str, BaseException], object]
 
 
 def shutil_rmtree(

setuptools/config/_apply_pyprojecttoml.py

@@ -33,11 +33,12 @@
     from distutils.dist import _OptionsList
     from setuptools._importlib import metadata
     from setuptools.dist import Distribution
+    from typing_extensions import TypeAlias
 
 EMPTY: Mapping = MappingProxyType({})  # Immutable dict-like
-_ProjectReadmeValue = Union[str, Dict[str, str]]
-_CorrespFn = Callable[["Distribution", Any, StrPath], None]
-_Correspondence = Union[str, _CorrespFn]
+_ProjectReadmeValue: TypeAlias = Union[str, Dict[str, str]]
+_CorrespFn: TypeAlias = Callable[["Distribution", Any, StrPath], None]
+_Correspondence: TypeAlias = Union[str, _CorrespFn]
 
 _logger = logging.getLogger(__name__)