Drop support for running with Python 3.8 (#17492)

Similar to last year (#15566), start by dropping support for running
mypy with Python 3.8.
Users will still be able to type check 3.8 code with `--python-version
3.8` until typeshed drops the support for it.

It's a bit early as the EOL for Python 3.8 is in ~3 months. However,
since the branch for `1.11.0` has been cut already, we'd only drop the
support with `1.12.0` which isn't due for another 1-2 months.
Additionally dropping `3.8` now will make it easier to support `3.13`
with its C-API changes and also give us enough time to cleanup the
remaining 3.8 code blocks and documentation references.

---------

Co-authored-by: Ali Hamdan <ali.hamdan.dev@gmail.com>

Author: cdce8p

.github/workflows/test.yml

@@ -31,24 +31,18 @@ jobs:
         include:
         # Make sure to run mypyc compiled unit tests for both
         # the oldest and newest supported Python versions
-        - name: Test suite with py38-ubuntu, mypyc-compiled
-          python: '3.8'
+        - name: Test suite with py39-ubuntu, mypyc-compiled
+          python: '3.9'
           arch: x64
           os: ubuntu-latest
           toxenv: py
           tox_extra_args: "-n 4"
           test_mypyc: true
-        - name: Test suite with py38-windows-64
-          python: '3.8'
-          arch: x64
-          os: windows-latest
-          toxenv: py38
-          tox_extra_args: "-n 4"
-        - name: Test suite with py39-ubuntu
+        - name: Test suite with py39-windows-64
           python: '3.9'
           arch: x64
-          os: ubuntu-latest
-          toxenv: py
+          os: windows-latest
+          toxenv: py39
           tox_extra_args: "-n 4"
         - name: Test suite with py310-ubuntu
           python: '3.10'
@@ -88,7 +82,7 @@ jobs:
         #   test_mypyc: true
 
         - name: mypyc runtime tests with py39-macos
-          python: '3.9.18'
+          python: '3.9.21'
           arch: x64
           # TODO: macos-13 is the last one to support Python 3.9, change it to macos-latest when updating the Python version
           os: macos-13
@@ -98,20 +92,20 @@ jobs:
         # - https://github.com/python/mypy/issues/17819
         # - https://github.com/python/mypy/pull/17822
         # - name: mypyc runtime tests with py38-debug-build-ubuntu
-        #   python: '3.8.17'
+        #   python: '3.9.21'
         #   arch: x64
         #   os: ubuntu-latest
         #   toxenv: py
         #   tox_extra_args: "-n 4 mypyc/test/test_run.py mypyc/test/test_external.py"
         #   debug_build: true
 
-        - name: Type check our own code (py38-ubuntu)
-          python: '3.8'
+        - name: Type check our own code (py39-ubuntu)
+          python: '3.9'
           arch: x64
           os: ubuntu-latest
           toxenv: type
-        - name: Type check our own code (py38-windows-64)
-          python: '3.8'
+        - name: Type check our own code (py39-windows-64)
+          python: '3.9'
           arch: x64
           os: windows-latest
           toxenv: type

.github/workflows/test_stubgenc.yml

@@ -30,10 +30,10 @@ jobs:
 
     - uses: actions/checkout@v4
 
-    - name: Setup 🐍 3.8
+    - name: Setup 🐍 3.9
       uses: actions/setup-python@v5
       with:
-        python-version: 3.8
+        python-version: 3.9
 
     - name: Test stubgenc
       run: misc/test-stubgenc.sh

CONTRIBUTING.md

@@ -51,7 +51,7 @@ hash -r  # This resets shell PATH cache, not necessary on Windows
 ```
 
 > **Note**
-> You'll need Python 3.8 or higher to install all requirements listed in
+> You'll need Python 3.9 or higher to install all requirements listed in
 > test-requirements.txt
 
 ### Running tests

docs/source/getting_started.rst

@@ -16,7 +16,7 @@ may not make much sense otherwise.
 Installing and running mypy
 ***************************
 
-Mypy requires Python 3.8 or later to run.  You can install mypy using pip:
+Mypy requires Python 3.9 or later to run.  You can install mypy using pip:
 
 .. code-block:: shell
 

mypy/defaults.py

@@ -6,7 +6,7 @@
 # Earliest fully supported Python 3.x version. Used as the default Python
 # version in tests. Mypy wheels should be built starting with this version,
 # and CI tests should be run on this version (and later versions).
-PYTHON3_VERSION: Final = (3, 8)
+PYTHON3_VERSION: Final = (3, 9)
 
 # Earliest Python 3.x version supported via --python-version 3.x. To run
 # mypy, at least version PYTHON3_VERSION is needed.

mypy/test/meta/test_parse_data.py

@@ -50,13 +50,13 @@ def test_bad_ge_version_check(self) -> None:
             """
             [case abc]
             s: str
-            [out version>=3.8]
+            [out version>=3.9]
             abc
             """
         )
 
         # Assert
-        assert "version>=3.8 always true since minimum runtime version is (3, 8)" in actual.stdout
+        assert "version>=3.9 always true since minimum runtime version is (3, 9)" in actual.stdout
 
     def test_bad_eq_version_check(self) -> None:
         # Act
@@ -70,4 +70,4 @@ def test_bad_eq_version_check(self) -> None:
         )
 
         # Assert
-        assert "version==3.7 always false since minimum runtime version is (3, 8)" in actual.stdout
+        assert "version==3.7 always false since minimum runtime version is (3, 9)" in actual.stdout

mypy/util.py

@@ -490,10 +490,10 @@ def get_unique_redefinition_name(name: str, existing: Container[str]) -> str:
 def check_python_version(program: str) -> None:
     """Report issues with the Python used to run mypy, dmypy, or stubgen"""
     # Check for known bad Python versions.
-    if sys.version_info[:2] < (3, 8):  # noqa: UP036
+    if sys.version_info[:2] < (3, 9):
         sys.exit(
-            "Running {name} with Python 3.7 or lower is not supported; "
-            "please upgrade to 3.8 or newer".format(name=program)
+            "Running {name} with Python 3.8 or lower is not supported; "
+            "please upgrade to 3.9 or newer".format(name=program)
         )
 
 

mypy_self_check.ini

@@ -6,7 +6,7 @@ show_traceback = True
 pretty = True
 always_false = MYPYC
 plugins = mypy.plugins.proper_plugin
-python_version = 3.8
+python_version = 3.9
 exclude = mypy/typeshed/|mypyc/test-data/|mypyc/lib-rt/
 enable_error_code = ignore-without-code,redundant-expr
 enable_incomplete_feature = PreciseTupleTypes

mypyc/doc/getting_started.rst

@@ -38,7 +38,7 @@ Installation
 ------------
 
 Mypyc is shipped as part of the mypy distribution. Install mypy like
-this (you need Python 3.8 or later):
+this (you need Python 3.9 or later):
 
 .. code-block::
 

mypyc/test/test_run.py

@@ -320,6 +320,7 @@ def run_case_step(self, testcase: DataDrivenTestCase, incremental_step: int) ->
             # TODO: testDecorators1 hangs on 3.12, remove this once fixed
             proc.wait(timeout=30)
         output = proc.communicate()[0].decode("utf8")
+        output = output.replace(f'  File "{os.getcwd()}{os.sep}', '  File "')
         outlines = output.splitlines()
 
         if testcase.config.getoption("--mypyc-showc"):