Strict typing

.github/workflows/reusable-linters.yml

@@ -71,9 +71,7 @@ jobs:
       with:
         token: ${{ secrets.codecov-token }}
         files: >-
-          .tox/.tmp/.mypy/python-3.12/cobertura.xml,
-          .tox/.tmp/.mypy/python-3.10/cobertura.xml,
-          .tox/.tmp/.mypy/python-3.8/cobertura.xml
+          .tox/.tmp/.mypy/python-3.11/cobertura.xml
         flags: >-
           CI-GHA,
           MyPy

.mypy.ini

@@ -1,48 +1,33 @@
 [mypy]
-python_version = 3.8
-color_output = True
-error_summary = True
-files =
-  frozenlist/,
-  packaging/,
-  tests/
-
+files = frozenlist, packaging, tests
 check_untyped_defs = True
-
-disallow_untyped_defs = True
+follow_imports_for_stubs = True
+disallow_any_decorated = True
 disallow_any_generics = True
-
-enable_error_code =
-  ignore-without-code
-
-follow_imports = normal
-
-ignore_missing_imports = False
-
-pretty = true
-
-show_column_numbers = true
-show_error_codes = true
-strict_optional = True
-
-warn_no_return = True
+disallow_any_unimported = True
+disallow_incomplete_defs = True
+disallow_subclassing_any = True
+disallow_untyped_calls = True
+disallow_untyped_decorators = True
+disallow_untyped_defs = True
+# TODO(PY312): explicit-override
+enable_error_code = ignore-without-code, possibly-undefined, redundant-expr, redundant-self, truthy-bool, truthy-iterable, unused-awaitable
+extra_checks = True
+implicit_reexport = False
+no_implicit_optional = True
+pretty = True
+show_column_numbers = True
+show_error_codes = True
+show_error_code_links = True
+strict_equality = True
+warn_incomplete_stub = True
 warn_redundant_casts = True
+warn_return_any = True
+warn_unreachable = True
 warn_unused_ignores = True
 
 [mypy-Cython.*]
 ignore_missing_imports = true
 
-[mypy-distutils.*]
-ignore_missing_imports = true
-
-[mypy-expandvars]
-ignore_missing_imports = true
-
-[mypy-pep517_backend.*]
-check_untyped_defs = False
-disallow_any_generics = False
-disallow_untyped_defs = False
-warn_unused_ignores = False
-
-[mypy-tomllib]
+[mypy-expandvars.*]
 ignore_missing_imports = true

.pre-commit-config.yaml

@@ -168,8 +168,8 @@ repos:
   rev: v1.14.1
   hooks:
   - id: mypy
-    alias: mypy-py312
-    name: MyPy, for Python 3.12
+    alias: mypy-py311
+    name: MyPy, for Python 3.11
     additional_dependencies:
     - lxml  # dep of `--txt-report`, `--cobertura-xml-report` & `--html-report`
     - pytest
@@ -178,42 +178,10 @@ repos:
     args:
     - --install-types
     - --non-interactive
-    - --python-version=3.12
-    - --txt-report=.tox/.tmp/.mypy/python-3.12
-    - --cobertura-xml-report=.tox/.tmp/.mypy/python-3.12
-    - --html-report=.tox/.tmp/.mypy/python-3.12
-    pass_filenames: false
-  - id: mypy
-    alias: mypy-py310
-    name: MyPy, for Python 3.10
-    additional_dependencies:
-    - lxml  # dep of `--txt-report`, `--cobertura-xml-report` & `--html-report`
-    - pytest
-    - tomli  # requirement of packaging/pep517_backend/
-    - types-setuptools  # requirement of packaging/pep517_backend/
-    args:
-    - --install-types
-    - --non-interactive
-    - --python-version=3.10
-    - --txt-report=.tox/.tmp/.mypy/python-3.10
-    - --cobertura-xml-report=.tox/.tmp/.mypy/python-3.10
-    - --html-report=.tox/.tmp/.mypy/python-3.10
-    pass_filenames: false
-  - id: mypy
-    alias: mypy-py38
-    name: MyPy, for Python 3.8
-    additional_dependencies:
-    - lxml  # dep of `--txt-report`, `--cobertura-xml-report` & `--html-report`
-    - pytest
-    - tomli  # requirement of packaging/pep517_backend/
-    - types-setuptools  # requirement of packaging/pep517_backend/
-    args:
-    - --install-types
-    - --non-interactive
-    - --python-version=3.8
-    - --txt-report=.tox/.tmp/.mypy/python-3.8
-    - --cobertura-xml-report=.tox/.tmp/.mypy/python-3.8
-    - --html-report=.tox/.tmp/.mypy/python-3.8
+    - --python-version=3.11
+    - --txt-report=.tox/.tmp/.mypy/python-3.11
+    - --cobertura-xml-report=.tox/.tmp/.mypy/python-3.11
+    - --html-report=.tox/.tmp/.mypy/python-3.11
     pass_filenames: false
 
 - repo: https://github.com/rhysd/actionlint

packaging/pep517_backend/_backend.py

@@ -4,14 +4,14 @@
 from __future__ import annotations
 
 import os
-import typing as t
 from contextlib import contextmanager, nullcontext, suppress
 from functools import partial
 from pathlib import Path
 from shutil import copytree
 from sys import implementation as _system_implementation
 from sys import stderr as _standard_error_stream
 from tempfile import TemporaryDirectory
+from typing import Dict, Iterator, List, Union
 from warnings import warn as _warn_that
 
 from setuptools.build_meta import build_sdist as _setuptools_build_sdist
@@ -55,7 +55,7 @@
     'get_requires_for_build_wheel',
     'prepare_metadata_for_build_wheel',
     *(
-        () if _setuptools_build_editable is None
+        () if _setuptools_build_editable is None  # type: ignore[redundant-expr]
         else (
             'build_editable',
             'get_requires_for_build_editable',
@@ -64,7 +64,7 @@
     ),
 )
 
-_ConfigDict = t.Dict[str, t.Union[str, t.List[str], None]]
+_ConfigDict = Dict[str, Union[str, List[str], None]]
 
 
 CYTHON_TRACING_CONFIG_SETTING = 'with-cython-tracing'
@@ -86,7 +86,7 @@
 """A fallback for ``pure-python`` is not set."""
 
 
-def _is_truthy_setting_value(setting_value) -> bool:
+def _is_truthy_setting_value(setting_value: str) -> bool:
     truthy_values = {'', None, 'true', '1', 'on'}
     return setting_value.lower() in truthy_values
 
@@ -107,7 +107,7 @@ def _get_setting_value(
             continue
 
         with suppress(lookup_errors):  # type: ignore[arg-type]
-            return _is_truthy_setting_value(src_mapping[src_key])  # type: ignore[index]
+            return _is_truthy_setting_value(src_mapping[src_key])  # type: ignore[arg-type,index]
 
     return default
 
@@ -124,7 +124,7 @@ def _make_pure_python(config_settings: _ConfigDict | None = None) -> bool:
 def _include_cython_line_tracing(
         config_settings: _ConfigDict | None = None,
         *,
-        default=False,
+        default: bool = False,
 ) -> bool:
     return _get_setting_value(
         config_settings,
@@ -135,60 +135,61 @@ def _include_cython_line_tracing(
 
 
 @contextmanager
-def patched_distutils_cmd_install():
+def patched_distutils_cmd_install() -> Iterator[None]:
     """Make `install_lib` of `install` cmd always use `platlib`.
 
     :yields: None
     """
     # Without this, build_lib puts stuff under `*.data/purelib/` folder
     orig_finalize = _distutils_install_cmd.finalize_options
 
-    def new_finalize_options(self):  # noqa: WPS430
+    def new_finalize_options(self: _distutils_install_cmd) -> None:  # noqa: WPS430
         self.install_lib = self.install_platlib
         orig_finalize(self)
 
-    _distutils_install_cmd.finalize_options = new_finalize_options
+    _distutils_install_cmd.finalize_options = new_finalize_options  # type: ignore[method-assign]
     try:
         yield
     finally:
-        _distutils_install_cmd.finalize_options = orig_finalize
+        _distutils_install_cmd.finalize_options = orig_finalize  # type: ignore[method-assign]
 
 
 @contextmanager
-def patched_dist_has_ext_modules():
+def patched_dist_has_ext_modules() -> Iterator[None]:
     """Make `has_ext_modules` of `Distribution` always return `True`.
 
     :yields: None
     """
     # Without this, build_lib puts stuff under `*.data/platlib/` folder
     orig_func = _DistutilsDistribution.has_ext_modules
 
-    _DistutilsDistribution.has_ext_modules = lambda *args, **kwargs: True
+    _DistutilsDistribution.has_ext_modules = lambda *args, **kwargs: True  # type: ignore[method-assign]
     try:
         yield
     finally:
-        _DistutilsDistribution.has_ext_modules = orig_func
+        _DistutilsDistribution.has_ext_modules = orig_func  # type: ignore[method-assign]
 
 
 @contextmanager
-def patched_dist_get_long_description():
+def patched_dist_get_long_description() -> Iterator[None]:
     """Make `has_ext_modules` of `Distribution` always return `True`.
 
     :yields: None
     """
     # Without this, build_lib puts stuff under `*.data/platlib/` folder
     _orig_func = _DistutilsDistributionMetadata.get_long_description
 
-    def _get_sanitized_long_description(self):
+    def _get_sanitized_long_description(self: _DistutilsDistributionMetadata) -> str:
+        assert self.long_description is not None
         return sanitize_rst_roles(self.long_description)
 
-    _DistutilsDistributionMetadata.get_long_description = (
+    _DistutilsDistributionMetadata.get_long_description = (  # type: ignore[method-assign]
         _get_sanitized_long_description
     )
     try:
         yield
     finally:
-        _DistutilsDistributionMetadata.get_long_description = _orig_func
+        _DistutilsDistributionMetadata.get_long_description = _orig_func  # type: ignore[method-assign]
 
 
 def _exclude_dir_path(
@@ -215,7 +216,7 @@ def _exclude_dir_path(
 
 
 @contextmanager
-def _in_temporary_directory(src_dir: Path) -> t.Iterator[None]:
+def _in_temporary_directory(src_dir: Path) -> Iterator[None]:
     with TemporaryDirectory(prefix='.tmp-frozenlist-pep517-') as tmp_dir:
         tmp_dir_path = Path(tmp_dir)
         root_tmp_dir_path = tmp_dir_path.parent
@@ -238,7 +239,7 @@ def maybe_prebuild_c_extensions(
         line_trace_cython_when_unset: bool = False,
         build_inplace: bool = False,
         config_settings: _ConfigDict | None = None,
-) -> t.Generator[None, t.Any, t.Any]:
+) -> Iterator[None]:
     """Pre-build C-extensions in a temporary directory, when needed.
 
     This context manager also patches metadata, setuptools and distutils.

packaging/pep517_backend/_compat.py

@@ -1,16 +1,19 @@
 """Cross-python stdlib shims."""
 
 import os
-import typing as t
+import sys
 from contextlib import contextmanager
 from pathlib import Path
+from typing import Iterator
 
-try:
-    from contextlib import chdir as chdir_cm  # type: ignore[attr-defined]
-except ImportError:
+if sys.version_info >= (3, 11):
+    from contextlib import chdir as chdir_cm
+    from tomllib import loads as load_toml_from_string
+else:
+    from tomli import loads as load_toml_from_string
 
     @contextmanager  # type: ignore[no-redef]
-    def chdir_cm(path: os.PathLike) -> t.Iterator[None]:
+    def chdir_cm(path: "os.PathLike[str]") -> Iterator[None]:
         """Temporarily change the current directory, recovering on exit."""
         original_wd = Path.cwd()
         os.chdir(path)
@@ -20,10 +23,4 @@ def chdir_cm(path: os.PathLike) -> t.Iterator[None]:
             os.chdir(original_wd)
 
 
-try:
-    from tomllib import loads as load_toml_from_string
-except ImportError:
-    from tomli import loads as load_toml_from_string  # type: ignore[no-redef]
-
-
 __all__ = ("chdir_cm", "load_toml_from_string")  # noqa: WPS410

packaging/pep517_backend/_cython_configuration.py

@@ -6,14 +6,22 @@
 from contextlib import contextmanager
 from pathlib import Path
 from sys import version_info as _python_version_tuple
+from typing import Iterator, TypedDict
 
 from expandvars import expandvars
 
 from ._compat import load_toml_from_string
 from ._transformers import get_cli_kwargs_from_config, get_enabled_cli_flags_from_config
 
 
-def get_local_cython_config() -> dict:
+class Config(TypedDict):
+    env: dict[str, str]
+    flags: dict[str, bool]
+    kwargs: dict[str, str]
+    src: list[str]
+
+
+def get_local_cython_config() -> Config:
     """Grab optional build dependencies from pyproject.toml config.
 
     :returns: config section from ``pyproject.toml``
@@ -67,10 +75,10 @@ def get_local_cython_config() -> dict:
     """
     config_toml_txt = (Path.cwd().resolve() / 'pyproject.toml').read_text()
     config_mapping = load_toml_from_string(config_toml_txt)
-    return config_mapping['tool']['local']['cythonize']
+    return config_mapping['tool']['local']['cythonize']  # type: ignore[no-any-return]
 
 
-def make_cythonize_cli_args_from_config(config) -> list[str]:
+def make_cythonize_cli_args_from_config(config: Config) -> list[str]:
     py_ver_arg = f'-{_python_version_tuple.major!s}'
 
     cli_flags = get_enabled_cli_flags_from_config(config['flags'])
@@ -80,7 +88,7 @@ def make_cythonize_cli_args_from_config(config) -> list[str]:
 
 
 @contextmanager
-def patched_env(env: dict[str, str], cython_line_tracing_requested: bool):
+def patched_env(env: dict[str, str], cython_line_tracing_requested: bool) -> Iterator[None]:
     """Temporary set given env vars.
 
     :param env: tmp env vars to set