drop end of life python versions (#5731)

Author: davidism

.github/workflows/tests.yaml

@@ -19,7 +19,6 @@ jobs:
           - {python: '3.12'}
           - {python: '3.11'}
           - {python: '3.10'}
-          - {python: '3.9'}
           - {name: PyPy, python: 'pypy-3.11', tox: pypy3.11}
           - {name: Minimum Versions, python: '3.13', tox: tests-min}
           - {name: Development Versions, python: '3.10', tox: tests-dev}

CHANGES.rst

@@ -3,6 +3,7 @@ Version 3.2.0
 
 Unreleased
 
+-   Drop support for Python 3.9. :pr:`5730`
 -   Remove previously deprecated code: ``__version__``. :pr:`5648`
 
 

docs/extensiondev.rst

@@ -294,11 +294,13 @@ ecosystem remain consistent and compatible.
     indicate minimum compatibility support. For example,
     ``sqlalchemy>=1.4``.
 9.  Indicate the versions of Python supported using ``python_requires=">=version"``.
-    Flask itself supports Python >=3.9 as of October 2024, and this will update
-    over time.
+    Flask and Pallets policy is to support all Python versions that are not
+    within six months of end of life (EOL). See Python's `EOL calendar`_ for
+    timing.
 
 .. _PyPI: https://pypi.org/search/?c=Framework+%3A%3A+Flask
 .. _Discord Chat: https://discord.gg/pallets
 .. _GitHub Discussions: https://github.com/pallets/flask/discussions
 .. _Official Pallets Themes: https://pypi.org/project/Pallets-Sphinx-Themes/
 .. _Pallets-Eco: https://github.com/pallets-eco
+.. _EOL calendar: https://devguide.python.org/versions/

docs/installation.rst

@@ -5,7 +5,7 @@ Installation
 Python Version
 --------------
 
-We recommend using the latest version of Python. Flask supports Python 3.9 and newer.
+We recommend using the latest version of Python. Flask supports Python 3.10 and newer.
 
 
 Dependencies

pyproject.toml

@@ -19,11 +19,10 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Application Frameworks",
     "Typing :: Typed",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 dependencies = [
     "blinker>=1.9.0",
     "click>=8.1.3",
-    "importlib-metadata>=3.6.0; python_version < '3.10'",
     "itsdangerous>=2.2.0",
     "jinja2>=3.1.2",
     "markupsafe>=2.1.1",
@@ -58,7 +57,7 @@ pre-commit = [
 ]
 tests = [
     "asgiref",
-    "greenlet ; python_version < '3.11'",
+    "greenlet",
     "pytest",
     "python-dotenv",
 ]
@@ -126,7 +125,7 @@ exclude_also = [
 ]
 
 [tool.mypy]
-python_version = "3.9"
+python_version = "3.10"
 files = ["src", "tests/type_check"]
 show_error_codes = true
 pretty = true
@@ -142,7 +141,7 @@ module = [
 ignore_missing_imports = true
 
 [tool.pyright]
-pythonVersion = "3.9"
+pythonVersion = "3.10"
 include = ["src", "tests/type_check"]
 typeCheckingMode = "basic"
 
@@ -161,6 +160,9 @@ select = [
     "UP",  # pyupgrade
     "W",  # pycodestyle warning
 ]
+ignore = [
+    "UP038",  # keep isinstance tuple
+]
 
 [tool.ruff.lint.isort]
 force-single-line = true
@@ -173,7 +175,7 @@ tag-only = [
 
 [tool.tox]
 env_list = [
-    "py3.13", "py3.12", "py3.11", "py3.10", "py3.9",
+    "py3.13", "py3.12", "py3.11", "py3.10",
     "pypy3.11",
     "tests-min", "tests-dev",
     "style",

src/flask/cli.py

@@ -601,15 +601,7 @@ def _load_plugin_commands(self) -> None:
         if self._loaded_plugin_commands:
             return
 
-        if sys.version_info >= (3, 10):
-            from importlib import metadata
-        else:
-            # Use a backport on Python < 3.10. We technically have
-            # importlib.metadata on 3.8+, but the API changed in 3.10,
-            # so use the backport for consistency.
-            import importlib_metadata as metadata  # pyright: ignore
-
-        for ep in metadata.entry_points(group="flask.commands"):
+        for ep in importlib.metadata.entry_points(group="flask.commands"):
             self.add_command(ep.load(), ep.name)
 
         self._loaded_plugin_commands = True

src/flask/json/provider.py

@@ -135,7 +135,7 @@ class DefaultJSONProvider(JSONProvider):
         method) will call the ``__html__`` method to get a string.
     """
 
-    default: t.Callable[[t.Any], t.Any] = staticmethod(_default)  # type: ignore[assignment]
+    default: t.Callable[[t.Any], t.Any] = staticmethod(_default)
     """Apply this function to any object that :meth:`json.dumps` does
     not know how to serialize. It should return a valid JSON type or
     raise a ``TypeError``.

src/flask/sansio/app.py

@@ -213,7 +213,7 @@ class App(Scaffold):
     #:
     #: This attribute can also be configured from the config with the
     #: :data:`SECRET_KEY` configuration key. Defaults to ``None``.
-    secret_key = ConfigAttribute[t.Union[str, bytes, None]]("SECRET_KEY")
+    secret_key = ConfigAttribute[str | bytes | None]("SECRET_KEY")
 
     #: A :class:`~datetime.timedelta` which is used to set the expiration
     #: date of a permanent session.  The default is 31 days which makes a

src/flask/typing.py

@@ -23,8 +23,7 @@
 ]
 
 # the possible types for an individual HTTP header
-# This should be a Union, but mypy doesn't pass unless it's a TypeVar.
-HeaderValue = t.Union[str, list[str], tuple[str, ...]]
+HeaderValue = str | list[str] | tuple[str, ...]
 
 # the possible types for HTTP headers
 HeadersValue = t.Union[
@@ -47,47 +46,42 @@
 # callback annotated with flask.Response fail type checking.
 ResponseClass = t.TypeVar("ResponseClass", bound="Response")
 
-AppOrBlueprintKey = t.Optional[str]  # The App key is None, whereas blueprints are named
-AfterRequestCallable = t.Union[
-    t.Callable[[ResponseClass], ResponseClass],
-    t.Callable[[ResponseClass], t.Awaitable[ResponseClass]],
-]
-BeforeFirstRequestCallable = t.Union[
-    t.Callable[[], None], t.Callable[[], t.Awaitable[None]]
-]
-BeforeRequestCallable = t.Union[
-    t.Callable[[], t.Optional[ResponseReturnValue]],
-    t.Callable[[], t.Awaitable[t.Optional[ResponseReturnValue]]],
-]
+AppOrBlueprintKey = str | None  # The App key is None, whereas blueprints are named
+AfterRequestCallable = (
+    t.Callable[[ResponseClass], ResponseClass]
+    | t.Callable[[ResponseClass], t.Awaitable[ResponseClass]]
+)
+BeforeFirstRequestCallable = t.Callable[[], None] | t.Callable[[], t.Awaitable[None]]
+BeforeRequestCallable = (
+    t.Callable[[], ResponseReturnValue | None]
+    | t.Callable[[], t.Awaitable[ResponseReturnValue | None]]
+)
 ShellContextProcessorCallable = t.Callable[[], dict[str, t.Any]]
-TeardownCallable = t.Union[
-    t.Callable[[t.Optional[BaseException]], None],
-    t.Callable[[t.Optional[BaseException]], t.Awaitable[None]],
-]
-TemplateContextProcessorCallable = t.Union[
-    t.Callable[[], dict[str, t.Any]],
-    t.Callable[[], t.Awaitable[dict[str, t.Any]]],
-]
+TeardownCallable = (
+    t.Callable[[BaseException | None], None]
+    | t.Callable[[BaseException | None], t.Awaitable[None]]
+)
+TemplateContextProcessorCallable = (
+    t.Callable[[], dict[str, t.Any]] | t.Callable[[], t.Awaitable[dict[str, t.Any]]]
+)
 TemplateFilterCallable = t.Callable[..., t.Any]
 TemplateGlobalCallable = t.Callable[..., t.Any]
 TemplateTestCallable = t.Callable[..., bool]
 URLDefaultCallable = t.Callable[[str, dict[str, t.Any]], None]
-URLValuePreprocessorCallable = t.Callable[
-    [t.Optional[str], t.Optional[dict[str, t.Any]]], None
-]
+URLValuePreprocessorCallable = t.Callable[[str | None, dict[str, t.Any] | None], None]
 
 # This should take Exception, but that either breaks typing the argument
 # with a specific exception, or decorating multiple times with different
 # exceptions (and using a union type on the argument).
 # https://github.com/pallets/flask/issues/4095
 # https://github.com/pallets/flask/issues/4295
 # https://github.com/pallets/flask/issues/4297
-ErrorHandlerCallable = t.Union[
-    t.Callable[[t.Any], ResponseReturnValue],
-    t.Callable[[t.Any], t.Awaitable[ResponseReturnValue]],
-]
+ErrorHandlerCallable = (
+    t.Callable[[t.Any], ResponseReturnValue]
+    | t.Callable[[t.Any], t.Awaitable[ResponseReturnValue]]
+)
 
-RouteCallable = t.Union[
-    t.Callable[..., ResponseReturnValue],
-    t.Callable[..., t.Awaitable[ResponseReturnValue]],
-]
+RouteCallable = (
+    t.Callable[..., ResponseReturnValue]
+    | t.Callable[..., t.Awaitable[ResponseReturnValue]]
+)

tests/test_cli.py

@@ -462,7 +462,7 @@ def invoke(self, app, runner):
 
     def expect_order(self, order, output):
         # skip the header and match the start of each row
-        for expect, line in zip(order, output.splitlines()[2:]):
+        for expect, line in zip(order, output.splitlines()[2:], strict=False):
             # do this instead of startswith for nicer pytest output
             assert line[: len(expect)] == expect