Drop 3.9

Author: A5rocks

.github/workflows/autodeps.yml

@@ -26,26 +26,27 @@ jobs:
       - name: Setup python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.9"
+          python-version: "3.10"
 
       - name: Bump dependencies
         run: |
           python -m pip install -U pip pre-commit
           python -m pip install -r test-requirements.txt
-          uv pip compile --universal --python-version=3.9 --upgrade test-requirements.in -o test-requirements.txt
+          uv pip compile --universal --python-version=3.10 --upgrade test-requirements.in -o test-requirements.txt
           uv pip compile --universal --python-version=3.11 --upgrade docs-requirements.in -o docs-requirements.txt
           pre-commit autoupdate --jobs 0
 
       - name: Install new requirements
         run: python -m pip install -r test-requirements.txt
 
       # apply newer versions' formatting
+      # TODO: are the following two required given they are in pre-commit?
       - name: Black
         run: black src/trio
 
       - name: uv
         run: |
-          uv pip compile --universal --python-version=3.9 test-requirements.in -o test-requirements.txt
+          uv pip compile --universal --python-version=3.10 test-requirements.in -o test-requirements.txt
           uv pip compile --universal --python-version=3.11 docs-requirements.in -o docs-requirements.txt
 
       - name: Commit changes and create automerge PR

.github/workflows/ci.yml

@@ -155,18 +155,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python: ['3.10', '3.11', '3.12', '3.13', '3.14']
         arch: ['x86', 'x64']
         lsp: ['']
         lsp_extract_file: ['']
         extra_name: ['']
         include:
-          - python: '3.9'
+          - python: '3.10'
             arch: 'x64'
             lsp: 'https://raw.githubusercontent.com/python-trio/trio-ci-assets/master/komodia-based-vpn-setup.zip'
             lsp_extract_file: 'komodia-based-vpn-setup.exe'
             extra_name: ', with Komodia LSP'
-          - python: '3.9'
+          - python: '3.10'
             arch: 'x64'
             lsp: 'https://www.proxifier.com/download/legacy/ProxifierSetup342.exe'
             lsp_extract_file: ''
@@ -176,7 +176,7 @@ jobs:
             lsp: ''
             lsp_extract_file: ''
             extra_name: ''
-          #- python: '3.9'
+          #- python: '3.10'
           #  arch: 'x64'
           #  lsp: 'http://download.pctools.com/mirror/updates/9.0.0.2308-SDavfree-lite_en.exe'
           #  lsp_extract_file: ''
@@ -228,7 +228,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['pypy-3.11', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python: ['pypy-3.11', '3.10', '3.10', '3.11', '3.12', '3.13', '3.14']
         check_formatting: ['0']
         no_test_requirements: ['0']
         extra_name: ['']
@@ -237,7 +237,7 @@ jobs:
             check_formatting: '1'
             extra_name: ', check formatting'
           # separate test run that doesn't install test-requirements.txt
-          - python: '3.9'
+          - python: '3.10'
             no_test_requirements: '1'
             extra_name: ', no test-requirements'
     continue-on-error: >-
@@ -301,7 +301,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['pypy-3.11', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python: ['pypy-3.11', '3.10', '3.11', '3.12', '3.13', '3.14']
     continue-on-error: >-
       ${{
         (
@@ -389,14 +389,17 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - python: '3.9'  # We support running on cython 2 and 3 for 3.9
-            cython: '<3'   # cython 2
-          - python: '3.9'
-            cython: '>=3'  # cython 3 (or greater)
-          - python: '3.11' # 3.11 is the last version Cy2 supports
-            cython: '<3'   # cython 2
-          - python: '3.13' # We support running cython3 on 3.13
-            cython: '>=3'  # cython 3 (or greater)
+          # Cython 2 supports 3.10 and 3.11 and Cython 3 supports all versions we do,
+          # so test both the lowest and higher version for both
+          - python: '3.10'
+            cython: '<3'
+          - python: '3.11'
+            cython: '<3'
+          # TODO: technically we should pin cython versions
+          - python: '3.10'
+            cython: '>=3'
+          - python: '3.14'
+            cython: '>=3'
     steps:
       - name: Retrieve the project source from an sdist inside the GHA artifact
         uses: re-actors/checkout-python-sdist@release/v2

.github/workflows/release.yml

@@ -16,7 +16,7 @@ jobs:
           persist-credentials: false
       - uses: actions/setup-python@v5
         with:
-          python-version: "3.9"
+          python-version: "3.10"
       - run: python -m pip install build
       - run: python -m build
 

.pre-commit-config.yaml

@@ -80,7 +80,7 @@ repos:
         name: uv pip-compile test-requirements.in
         args: [
           "--universal",
-          "--python-version=3.9",
+          "--python-version=3.10",
           "test-requirements.in",
           "-o",
           "test-requirements.txt"]

README.rst

@@ -92,7 +92,7 @@ demonstration of implementing the "Happy Eyeballs" algorithm in an
 older library versus Trio.
 
 **Cool, but will it work on my system?** Probably! As long as you have
-some kind of Python 3.9-or-better (CPython or `currently maintained versions of
+some kind of Python 3.10-or-better (CPython or `currently maintained versions of
 PyPy3 <https://doc.pypy.org/en/latest/faq.html#which-python-versions-does-pypy-implement>`__
 are both fine), and are using Linux, macOS, Windows, or FreeBSD, then Trio
 will work. Other environments might work too, but those

docs/source/index.rst

@@ -45,7 +45,7 @@ Vital statistics:
 
 * Supported environments: We test on
 
-  - Python: 3.9+ (CPython and PyPy)
+  - Python: 3.10+ (CPython and PyPy)
   - Windows, macOS, Linux (glibc and musl), FreeBSD
 
   Other environments might also work; give it a try and see.

docs/source/tutorial.rst

@@ -88,7 +88,7 @@ Okay, ready? Let's get started.
 Before you begin
 ----------------
 
-1. Make sure you're using Python 3.9 or newer.
+1. Make sure you're using Python 3.10 or newer.
 
 2. ``python3 -m pip install --upgrade trio`` (or on Windows, maybe
    ``py -3 -m pip install --upgrade trio`` – `details

pyproject.toml

@@ -26,15 +26,15 @@ classifiers = [
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Topic :: System :: Networking",
     "Typing :: Typed",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 dependencies = [
     # attrs 19.2.0 adds `eq` option to decorators
     # attrs 20.1.0 adds @frozen
@@ -215,7 +215,7 @@ disallow_untyped_defs = true
 check_untyped_defs = true
 
 [tool.pyright]
-pythonVersion = "3.9"
+pythonVersion = "3.10"
 reportUnnecessaryTypeIgnoreComment = true
 typeCheckingMode = "strict"
 

src/trio/_channel.py

@@ -22,7 +22,6 @@
     MultipleExceptionError,
     NoPublicConstructor,
     final,
-    generic_function,
     raise_single_exception_from_group,
 )
 
@@ -48,6 +47,20 @@
 def _open_memory_channel(
     max_buffer_size: int | float,  # noqa: PYI041
 ) -> tuple[MemorySendChannel[T], MemoryReceiveChannel[T]]:
+    if max_buffer_size != inf and not isinstance(max_buffer_size, int):
+        raise TypeError("max_buffer_size must be an integer or math.inf")
+    if max_buffer_size < 0:
+        raise ValueError("max_buffer_size must be >= 0")
+    state: MemoryChannelState[T] = MemoryChannelState(max_buffer_size)
+    return (
+        MemorySendChannel[T]._create(state),
+        MemoryReceiveChannel[T]._create(state),
+    )
+
+
+# written as a class so you can say open_memory_channel[int](5)
+@final
+class open_memory_channel(tuple["MemorySendChannel[T]", "MemoryReceiveChannel[T]"]):
     """Open a channel for passing objects between tasks within a process.
 
     Memory channels are lightweight, cheap to allocate, and entirely
@@ -99,36 +112,15 @@ def _open_memory_channel(
       this channel (summing over all clones).
 
     """
-    if max_buffer_size != inf and not isinstance(max_buffer_size, int):
-        raise TypeError("max_buffer_size must be an integer or math.inf")
-    if max_buffer_size < 0:
-        raise ValueError("max_buffer_size must be >= 0")
-    state: MemoryChannelState[T] = MemoryChannelState(max_buffer_size)
-    return (
-        MemorySendChannel[T]._create(state),
-        MemoryReceiveChannel[T]._create(state),
-    )
 
+    def __new__(  # type: ignore[misc]  # "must return a subtype"
+        cls,
+        max_buffer_size: int | float,  # noqa: PYI041
+    ) -> tuple[MemorySendChannel[T], MemoryReceiveChannel[T]]:
+        return _open_memory_channel(max_buffer_size)
 
-# This workaround requires python3.9+, once older python versions are not supported
-# or there's a better way of achieving type-checking on a generic factory function,
-# it could replace the normal function header
-if TYPE_CHECKING:
-    # written as a class so you can say open_memory_channel[int](5)
-    class open_memory_channel(tuple["MemorySendChannel[T]", "MemoryReceiveChannel[T]"]):
-        def __new__(  # type: ignore[misc]  # "must return a subtype"
-            cls,
-            max_buffer_size: int | float,  # noqa: PYI041
-        ) -> tuple[MemorySendChannel[T], MemoryReceiveChannel[T]]:
-            return _open_memory_channel(max_buffer_size)
-
-        def __init__(self, max_buffer_size: int | float) -> None:  # noqa: PYI041
-            ...
-
-else:
-    # apply the generic_function decorator to make open_memory_channel indexable
-    # so it's valid to say e.g. ``open_memory_channel[bytes](5)`` at runtime
-    open_memory_channel = generic_function(_open_memory_channel)
+    def __init__(self, max_buffer_size: int | float) -> None:  # noqa: PYI041
+        ...
 
 
 @attrs.frozen

src/trio/_core/_exceptions.py

@@ -9,8 +9,9 @@
 
 if TYPE_CHECKING:
     from collections.abc import Callable
+    from typing import TypeAlias
 
-    from typing_extensions import Self, TypeAlias
+    from typing_extensions import Self
 
 CancelReasonLiteral: TypeAlias = Literal[
     "KeyboardInterrupt",