Drop support for --python-version 3.9

[hauntsaninja]

Resolves #20154

It's getting close to time. Typeshed will drop support in a few days.

Co-authored-by Codex

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

antidote (https://github.com/Finistere/antidote)
- pyproject.toml: [mypy]: python_version: Python 3.7 is not supported (must be 3.9 or higher)
+ pyproject.toml: [mypy]: python_version: Python 3.7 is not supported (must be 3.10 or higher)
- .../projects/_antidote_venv/lib/python3.14/site-packages/_pytest/terminal.py:1729: error: Pattern matching is only supported in Python 3.10 and greater  [syntax]
+ src/antidote/core/_wiring.py:15: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_wiring.py:15: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_wiring.py:15: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_wiring.py:15: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_injection.py:278: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_injection.py:278: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_injection.py:278: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_injection.py:278: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_inject.py:43: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:43: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_inject.py:43: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:43: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_inject.py:93: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:93: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_inject.py:93: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:93: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_inject.py:132: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:132: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_inject.py:141: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:141: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/_inject.py:147: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:147: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_inject.py:156: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/_inject.py:156: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/_inject.py:348: error: Expected iterable as variadic argument  [misc]
+ src/antidote/core/_inject.py:348: error: Argument after ** must be a mapping, not "dict[str, Any] | None"  [arg-type]
+ src/antidote/core/__init__.py:192: error: Overloaded function signatures 1 and 3 overlap with incompatible return types  [overload-overlap]
+ src/antidote/core/__init__.py:197: error: Overloaded function signatures 2 and 3 overlap with incompatible return types  [overload-overlap]
+ src/antidote/core/__init__.py:197: note: Flipping the order of overloads will fix this error
+ src/antidote/core/__init__.py:398: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/core/__init__.py:398: note: Flipping the order of overloads will fix this error
+ src/antidote/core/__init__.py:985: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:985: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/__init__.py:985: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:985: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/__init__.py:1033: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:1033: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/__init__.py:1042: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:1042: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/core/__init__.py:1048: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:1048: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/core/__init__.py:1057: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/core/__init__.py:1057: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/_lazy.py:104: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/_lazy.py:104: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/_lazy.py:110: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/_lazy.py:110: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:210: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:210: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:216: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:216: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:499: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:499: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:505: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:505: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:635: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/lazy_ext/__init__.py:635: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/_function.py:76: error: Unused "type: ignore" comment  [unused-ignore]
+ src/antidote/lib/interface_ext/_interface.py:78: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/_interface.py:78: note: Flipping the order of overloads will fix this error
+ src/antidote/lib/interface_ext/_interface.py:118: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/_interface.py:118: note: Flipping the order of overloads will fix this error
+ src/antidote/lib/interface_ext/_interface.py:257: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/_interface.py:257: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:357: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/__init__.py:357: note: Flipping the order of overloads will fix this error
+ src/antidote/lib/interface_ext/__init__.py:396: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/__init__.py:396: note: Flipping the order of overloads will fix this error
+ src/antidote/lib/interface_ext/__init__.py:576: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:576: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1014: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1017: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1026: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1029: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1035: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1068: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1207: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/__init__.py:1207: note: Flipping the order of overloads will fix this error
+ src/antidote/lib/interface_ext/__init__.py:1237: error: "classmethod" expects 3 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1237: error: Missing type arguments for generic type "classmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1241: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1241: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1263: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1263: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1266: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1266: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1278: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1278: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1281: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1281: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1289: error: Overloaded function signatures 1 and 5 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/__init__.py:1298: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1298: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1299: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1299: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1303: error: Overloaded function signature 4 will never be matched: signature 3's parameter type(s) are the same or broader  [overload-cannot-match]
+ src/antidote/lib/interface_ext/__init__.py:1303: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1303: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1321: error: Overloaded function signatures 1 and 5 overlap with incompatible return types  [overload-overlap]
+ src/antidote/lib/interface_ext/__init__.py:1330: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1330: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1331: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1331: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1335: error: Overloaded function signature 4 will never be matched: signature 3's parameter type(s) are the same or broader  [overload-cannot-match]
+ src/antidote/lib/interface_ext/__init__.py:1335: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1335: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1359: error: "staticmethod" expects 2 type arguments, but 1 given  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1359: error: Missing type arguments for generic type "staticmethod"  [type-arg]
+ src/antidote/lib/interface_ext/__init__.py:1369: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1369: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1372: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1372: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1384: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1384: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/__init__.py:1387: error: Missing return statement  [empty-body]
+ src/antidote/lib/interface_ext/__init__.py:1387: note: If the method is meant to be abstract, use @abc.abstractmethod
+ src/antidote/lib/interface_ext/_provider.py:312: error: Argument "weight" to "replace" of "CandidateImplementation[Weight]" has incompatible type "NewWeight"; expected "Weight"  [arg-type]
+ docs/conf.py:79: error: Function is missing a type annotation  [no-untyped-def]
+ docs/conf.py:177: error: Need type annotation for "latex_elements" (hint: "latex_elements: dict[<type>, <type>] = ...")  [var-annotated]
+ docs/conf.py:223: error: Function is missing a type annotation  [no-untyped-def]
+ tests/lib/lazy/test_lazy.py:286: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:293: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:301: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:308: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:316: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:324: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:658: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:662: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:668: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:672: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:677: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:682: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:845: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:849: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:855: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:859: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:864: error: Missing return statement  [empty-body]
+ tests/lib/lazy/test_lazy.py:869: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:33: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:142: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:161: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:184: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:205: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:253: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:435: error: Missing return statement  [empty-body]
+ tests/lib/interface/test_lazy.py:441: error: Missing return statement  [empty-body]

... (truncated 94 lines) ...

PyWinCtl (https://github.com/Kalmat/PyWinCtl)
- setup.cfg: [mypy]: python_version: Python 3.8 is not supported (must be 3.9 or higher)
+ setup.cfg: [mypy]: python_version: Python 3.8 is not supported (must be 3.10 or higher)

pywin32 (https://github.com/mhammond/pywin32)
+ mypy.ini: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher)

pybind11 (https://github.com/pybind/pybind11)
- pyproject.toml: [mypy]: python_version: Python 3.8 is not supported (must be 3.9 or higher)
+ pyproject.toml: [mypy]: python_version: Python 3.8 is not supported (must be 3.10 or higher)

build (https://github.com/pypa/build)
+ pyproject.toml: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher)

manticore (https://github.com/trailofbits/manticore)
- mypy.ini: [mypy]: python_version: Python 3.7 is not supported (must be 3.9 or higher)
+ mypy.ini: [mypy]: python_version: Python 3.7 is not supported (must be 3.10 or higher)

PyGithub (https://github.com/PyGithub/PyGithub)
+ pyproject.toml: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher)

mkosi (https://github.com/systemd/mkosi)
+ pyproject.toml: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher). You may need to put quotes around your Python version

com2ann (https://github.com/ilevkivskyi/com2ann)
+ usage: mypy [-h] [-v] [-V] [more options; see below]
+             [-m MODULE] [-p PACKAGE] [-c PROGRAM_TEXT] [files ...]
+ mypy: error: argument --python-version: Python 3.9 is not supported (must be 3.10 or higher)

packaging (https://github.com/pypa/packaging)
- pyproject.toml: [mypy]: python_version: Python 3.8 is not supported (must be 3.9 or higher)
+ pyproject.toml: [mypy]: python_version: Python 3.8 is not supported (must be 3.10 or higher)

git-revise (https://github.com/mystor/git-revise)
- mypy.ini: [mypy]: python_version: Python 3.8 is not supported (must be 3.9 or higher)
+ mypy.ini: [mypy]: python_version: Python 3.8 is not supported (must be 3.10 or higher)

scikit-build-core (https://github.com/scikit-build/scikit-build-core)
- .../projects/_scikit-build-core_venv/lib/python3.14/site-packages/_pytest/terminal.py:1729: error: Pattern matching is only supported in Python 3.10 and greater  [syntax]
+ pyproject.toml: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher)
+ tests/test_pyproject_pep517.py:374: error: "PackageMetadata" has no attribute "get"  [attr-defined]

dragonchain (https://github.com/dragonchain/dragonchain)
- mypy.ini: [mypy]: python_version: Python 3.8 is not supported (must be 3.9 or higher)
+ mypy.ini: [mypy]: python_version: Python 3.8 is not supported (must be 3.10 or higher)

nox (https://github.com/wntrblm/nox)
+ pyproject.toml: [mypy]: python_version: Python 3.9 is not supported (must be 3.10 or higher)
+ nox/_option_set.py:50: error: Only concrete class can be given where "type[PathLike[Any]]" is expected  [type-abstract]

[JukkaL]

Are the new errors in antidote expected?

[JelleZijlstra]

It seems we previously had a blocking error (because some dependency used pattern matching which is new in 3.10). Now that we only support 3.10+ mypy actually typechecks the package.

[JukkaL]

Ok, all is fine then!