Drop Python 3.8 support (#4452)

.github/workflows/diff_shades.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Install diff-shades and support dependencies
         run: |
-          python -m pip install 'click==8.1.3' packaging urllib3
+          python -m pip install 'click>=8.1.7' packaging urllib3
           python -m pip install https://github.com/ichard26/diff-shades/archive/stable.zip
 
       - name: Calculate run configuration & metadata
@@ -64,7 +64,7 @@ jobs:
       - name: Install diff-shades and support dependencies
         run: |
           python -m pip install https://github.com/ichard26/diff-shades/archive/stable.zip
-          python -m pip install 'click==8.1.3' packaging urllib3
+          python -m pip install 'click>=8.1.7' packaging urllib3
           # After checking out old revisions, this might not exist so we'll use a copy.
           cat scripts/diff_shades_gha_helper.py > helper.py
           git config user.name "diff-shades-gha"

.github/workflows/fuzz.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12.4", "3.13"]
+        python-version: ["3.9", "3.10", "3.11", "3.12.4", "3.13"]
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/pypi_upload.yml

@@ -74,7 +74,7 @@ jobs:
             | pyp 'json.dumps({"only": x, "os": "ubuntu-latest"})'
           } | pyp 'json.dumps(list(map(json.loads, lines)))' > /tmp/matrix
         env:
-          CIBW_BUILD: "cp38-* cp312-*"
+          CIBW_BUILD: "cp39-* cp312-*"
           CIBW_ARCHS_LINUX: x86_64
       - id: set-matrix
         run: echo "include=$(cat /tmp/matrix)" | tee -a $GITHUB_OUTPUT

.github/workflows/test.yml

@@ -31,7 +31,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12.4", "3.13", "pypy-3.9"]
+        python-version: ["3.9", "3.10", "3.11", "3.12.4", "3.13", "pypy-3.9"]
         os: [ubuntu-latest, macOS-latest, windows-latest]
 
     steps:

CHANGES.md

@@ -13,6 +13,7 @@
 - Black will issue an error when used with Python 3.12.5, due to an upstream memory
   safety issue in Python 3.12.5 that can cause Black's AST safety checks to fail. Please
   use Python 3.12.6 or Python 3.12.4 instead. (#4447)
+- Black no longer supports running with Python 3.8 (#4452)
 
 ### Stable style
 

pyproject.toml

@@ -7,7 +7,7 @@
 
 [tool.black]
 line-length = 88
-target-version = ['py38']
+target-version = ['py39']
 include = '\.pyi?$'
 extend-exclude = '''
 /(
@@ -34,7 +34,7 @@ build-backend = "hatchling.build"
 name = "black"
 description = "The uncompromising code formatter."
 license = { text = "MIT" }
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 authors = [
   { name = "Łukasz Langa", email = "lukasz@langa.pl" },
 ]
@@ -55,7 +55,6 @@ classifiers = [
   "Operating System :: OS Independent",
   "Programming Language :: Python",
   "Programming Language :: Python :: 3 :: Only",
-  "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
@@ -152,7 +151,7 @@ options = { debug_level = "0" }
 build-verbosity = 1
 
 # So these are the environments we target:
-# - Python: CPython 3.8+ only
+# - Python: CPython 3.9+ only
 # - Architecture (64-bit only): amd64 / x86_64, universal2, and arm64
 # - OS: Linux (no musl), Windows, and macOS
 build = "cp3*"
@@ -232,7 +231,7 @@ branch = true
 # Specify the target platform details in config, so your developers are
 # free to run mypy on Windows, Linux, or macOS and get consistent
 # results.
-python_version = "3.8"
+python_version = "3.9"
 mypy_path = "src"
 strict = true
 # Unreachable blocks have been an issue when compiling mypyc, let's try to avoid 'em in the first place.

src/black/__init__.py

@@ -549,6 +549,7 @@ def main(  # noqa: C901
     """The uncompromising code formatter."""
     ctx.ensure_object(dict)
 
+    assert sys.version_info >= (3, 9), "Black requires Python 3.9+"
     if sys.version_info[:3] == (3, 12, 5):
         out(
             "Python 3.12.5 has a memory safety issue that can cause Black's "

src/black/cache.py

@@ -139,8 +139,7 @@ def write(self, sources: Iterable[Path]) -> None:
             with tempfile.NamedTemporaryFile(
                 dir=str(self.cache_file.parent), delete=False
             ) as f:
-                # We store raw tuples in the cache because pickling NamedTuples
+                # We store raw tuples in the cache because it's faster.
-                # doesn't work with mypyc on Python 3.8, and because it's faster.
                 data: Dict[str, Tuple[float, int, str]] = {
                     k: (*v,) for k, v in self.file_data.items()
                 }

src/black/files.py

@@ -272,8 +272,6 @@ def resolves_outside_root_or_cannot_stat(
     root directory. Also returns True if we failed to resolve the path.
     """
     try:
-        if sys.version_info < (3, 8, 6):
-            path = path.absolute()  # https://bugs.python.org/issue33660
         resolved_path = _cached_resolve(path)
     except OSError as e:
         if report:

src/black/schema.py

@@ -1,6 +1,5 @@
 import importlib.resources
 import json
-import sys
 from typing import Any
 
 
@@ -11,10 +10,6 @@ def get_schema(tool_name: str = "black") -> Any:
     pkg = "black.resources"
     fname = "black.schema.json"
 
-    if sys.version_info < (3, 9):
+    schema = importlib.resources.files(pkg).joinpath(fname)
-        with importlib.resources.open_text(pkg, fname, encoding="utf-8") as f:
-            return json.load(f)
-
-    schema = importlib.resources.files(pkg).joinpath(fname)  # type: ignore[unreachable]
     with schema.open(encoding="utf-8") as f:
         return json.load(f)

tests/test_black.py

@@ -2157,8 +2157,9 @@ def test_cache_single_file_already_cached(self) -> None:
     @event_loop()
     def test_cache_multiple_files(self) -> None:
         mode = DEFAULT_MODE
-        with cache_dir() as workspace, patch(
+        with (
-            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor
+            cache_dir() as workspace,
+            patch("concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor),
         ):
             one = (workspace / "one.py").resolve()
             one.write_text("print('hello')", encoding="utf-8")
@@ -2180,9 +2181,10 @@ def test_no_cache_when_writeback_diff(self, color: bool) -> None:
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")
-            with patch.object(black.Cache, "read") as read_cache, patch.object(
+            with (
-                black.Cache, "write"
+                patch.object(black.Cache, "read") as read_cache,
-            ) as write_cache:
+                patch.object(black.Cache, "write") as write_cache,
+            ):
                 cmd = [str(src), "--diff"]
                 if color:
                     cmd.append("--color")
@@ -2311,8 +2313,9 @@ def test_write_cache_creates_directory_if_needed(self) -> None:
     @event_loop()
     def test_failed_formatting_does_not_get_cached(self) -> None:
         mode = DEFAULT_MODE
-        with cache_dir() as workspace, patch(
+        with (
-            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor
+            cache_dir() as workspace,
+            patch("concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor),
         ):
             failing = (workspace / "failing.py").resolve()
             failing.write_text("not actually python", encoding="utf-8")