Drop support for Python 3.7 (#3765)

.github/workflows/fuzz.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/test.yml

@@ -31,7 +31,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "pypy-3.7", "pypy-3.8"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "pypy-3.8"]
         os: [ubuntu-latest, macOS-latest, windows-latest]
 
     steps:

CHANGES.md

@@ -6,6 +6,9 @@
 
 <!-- Include any especially major or disruptive changes here -->
 
+- Runtime support for Python 3.7 has been removed. Formatting 3.7 code will still be
+  supported until further notice (#3765)
+
 ### Stable style
 
 <!-- Changes that affect Black's stable style -->

docs/integrations/editors.md

@@ -334,60 +334,6 @@ To run _Black_ on a key press (e.g. F9 below), add this:
 nnoremap <F9> :Black<CR>
 ```
 
-#### Troubleshooting
-
-**How to get Vim with Python 3.6?** On Ubuntu 17.10 Vim comes with Python 3.6 by
-default. On macOS with Homebrew run: `brew install vim`. When building Vim from source,
-use: `./configure --enable-python3interp=yes`. There's many guides online how to do
-this.
-
-**I get an import error when using _Black_ from a virtual environment**: If you get an
-error message like this:
-
-```text
-Traceback (most recent call last):
-  File "<string>", line 63, in <module>
-  File "/home/gui/.vim/black/lib/python3.7/site-packages/black.py", line 45, in <module>
-    from typed_ast import ast3, ast27
-  File "/home/gui/.vim/black/lib/python3.7/site-packages/typed_ast/ast3.py", line 40, in <module>
-    from typed_ast import _ast3
-ImportError: /home/gui/.vim/black/lib/python3.7/site-packages/typed_ast/_ast3.cpython-37m-x86_64-linux-gnu.so: undefined symbool: PyExc_KeyboardInterrupt
-```
-
-Then you need to install `typed_ast` directly from the source code. The error happens
-because `pip` will download [Python wheels](https://pythonwheels.com/) if they are
-available. Python wheels are a new standard of distributing Python packages and packages
-that have Cython and extensions written in C are already compiled, so the installation
-is much more faster. The problem here is that somehow the Python environment inside Vim
-does not match with those already compiled C extensions and these kind of errors are the
-result. Luckily there is an easy fix: installing the packages from the source code.
-
-The package that causes problems is:
-
-- [typed-ast](https://pypi.org/project/typed-ast/)
-
-Now remove those two packages:
-
-```console
-$ pip uninstall typed-ast -y
-```
-
-And now you can install them with:
-
-```console
-$ pip install --no-binary :all: typed-ast
-```
-
-The C extensions will be compiled and now Vim's Python environment will match. Note that
-you need to have the GCC compiler and the Python development files installed (on
-Ubuntu/Debian do `sudo apt-get install build-essential python3-dev`).
-
-If you later want to update _Black_, you should do it like this:
-
-```console
-$ pip install -U black --no-binary typed-ast
-```
-
 ### With ALE
 
 1. Install [`ale`](https://github.com/dense-analysis/ale)

mypy.ini

@@ -2,7 +2,7 @@
 # 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=3.7
+python_version=3.8
 
 mypy_path=src
 

pyproject.toml

@@ -33,7 +33,7 @@ build-backend = "hatchling.build"
 name = "black"
 description = "The uncompromising code formatter."
 license = { text = "MIT" }
-requires-python = ">=3.7"
+requires-python = ">=3.8"
 authors = [
   { name = "Łukasz Langa", email = "lukasz@langa.pl" },
 ]
@@ -69,7 +69,6 @@ dependencies = [
   "pathspec>=0.9.0",
   "platformdirs>=2",
   "tomli>=1.1.0; python_version < '3.11'",
-  "typed-ast>=1.4.2; python_version < '3.8' and implementation_name == 'cpython'",
   "typing_extensions>=3.10.0.0; python_version < '3.10'",
 ]
 dynamic = ["readme", "version"]
@@ -121,8 +120,6 @@ enable-by-default = false
 dependencies = [
   "hatch-mypyc>=0.16.0",
   "mypy==1.3",
-  # Required stubs to be removed when the packages support PEP 561 themselves
-  "types-typed-ast>=1.4.2",
 ]
 require-runtime-dependencies = true
 exclude = [
@@ -145,7 +142,7 @@ options = { debug_level = "0" }
 [tool.cibuildwheel]
 build-verbosity = 1
 # So these are the environments we target:
-# - Python: CPython 3.7+ only
+# - Python: CPython 3.8+ only
 # - Architecture (64-bit only): amd64 / x86_64, universal2, and arm64
 # - OS: Linux (no musl), Windows, and macOS
 build = "cp3*-*"
@@ -208,9 +205,6 @@ filterwarnings = [
     # this is mitigated by a try/catch in https://github.com/psf/black/pull/3198/
     # this ignore can be removed when support for aiohttp 3.x is dropped.
     '''ignore:Middleware decorator is deprecated since 4\.0 and its behaviour is default, you can simply remove this decorator:DeprecationWarning''',
-    # this is mitigated by https://github.com/python/cpython/issues/79071 in python 3.8+
-    # this ignore can be removed when support for 3.7 is dropped.
-    '''ignore:Bare functions are deprecated, use async ones:DeprecationWarning''',
     # aiohttp is using deprecated cgi modules - Safe to remove when fixed:
     # https://github.com/aio-libs/aiohttp/issues/6905
     '''ignore:'cgi' is deprecated and slated for removal in Python 3.13:DeprecationWarning''',

scripts/make_width_table.py

@@ -52,13 +52,7 @@ def main() -> None:
         f.write(f"""# Generated by {basename(__file__)}
 # wcwidth {wcwidth.__version__}
 # Unicode {wcwidth.list_versions()[-1]}
-import sys
+from typing import Final, List, Tuple
-from typing import List, Tuple
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 WIDTH_TABLE: Final[List[Tuple[int, int, int]]] = [
 """)

src/black/_width_table.py

@@ -1,13 +1,7 @@
 # Generated by make_width_table.py
 # wcwidth 0.2.6
 # Unicode 15.0.0
-import sys
+from typing import Final, List, Tuple
-from typing import List, Tuple
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 WIDTH_TABLE: Final[List[Tuple[int, int, int]]] = [
     (0, 0, 0),

src/black/brackets.py

@@ -1,13 +1,7 @@
 """Builds on top of nodes.py to track brackets."""
 
-import sys
 from dataclasses import dataclass, field
-from typing import Dict, Iterable, List, Optional, Sequence, Set, Tuple, Union
+from typing import Dict, Final, Iterable, List, Optional, Sequence, Set, Tuple, Union
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 from black.nodes import (
     BRACKET,

src/black/comments.py

@@ -1,13 +1,7 @@
 import re
-import sys
 from dataclasses import dataclass
 from functools import lru_cache
-from typing import Iterator, List, Optional, Union
+from typing import Final, Iterator, List, Optional, Union
-
-if sys.version_info >= (3, 8):
-    from typing import Final
-else:
-    from typing_extensions import Final
 
 from black.nodes import (
     CLOSING_BRACKETS,

src/black/mode.py

@@ -4,19 +4,13 @@
 chosen by the user.
 """
 
-import sys
 from dataclasses import dataclass, field
 from enum import Enum, auto
 from hashlib import sha256
 from operator import attrgetter
-from typing import Dict, Set
+from typing import Dict, Final, Set
 from warnings import warn
 
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
-
 from black.const import DEFAULT_LINE_LENGTH
 
 

src/black/nodes.py

@@ -3,12 +3,8 @@
 """
 
 import sys
-from typing import Generic, Iterator, List, Optional, Set, Tuple, TypeVar, Union
+from typing import Final, Generic, Iterator, List, Optional, Set, Tuple, TypeVar, Union
 
-if sys.version_info >= (3, 8):
-    from typing import Final
-else:
-    from typing_extensions import Final
 if sys.version_info >= (3, 10):
     from typing import TypeGuard
 else:

src/black/parsing.py

@@ -2,14 +2,8 @@
 Parse Python code and perform AST validation.
 """
 import ast
-import platform
 import sys
-from typing import Any, Iterable, Iterator, List, Set, Tuple, Type, Union
+from typing import Final, Iterable, Iterator, List, Set, Tuple
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 from black.mode import VERSION_TO_FEATURES, Feature, TargetVersion, supports_feature
 from black.nodes import syms
@@ -20,25 +14,6 @@
 from blib2to3.pgen2.tokenize import TokenError
 from blib2to3.pytree import Leaf, Node
 
-ast3: Any
-
-_IS_PYPY = platform.python_implementation() == "PyPy"
-
-try:
-    from typed_ast import ast3
-except ImportError:
-    if sys.version_info < (3, 8) and not _IS_PYPY:
-        print(
-            "The typed_ast package is required but not installed.\n"
-            "You can upgrade to Python 3.8+ or install typed_ast with\n"
-            "`python3 -m pip install typed-ast`.",
-            file=sys.stderr,
-        )
-        sys.exit(1)
-    else:
-        ast3 = ast
-
-
 PY2_HINT: Final = "Python 2 support was removed in version 22.0."
 
 
@@ -147,31 +122,14 @@ def lib2to3_unparse(node: Node) -> str:
 
 def parse_single_version(
     src: str, version: Tuple[int, int], *, type_comments: bool
-) -> Union[ast.AST, ast3.AST]:
+) -> ast.AST:
     filename = "<unknown>"
-    # typed-ast is needed because of feature version limitations in the builtin ast 3.8>
-    if sys.version_info >= (3, 8) and version >= (3,):
     return ast.parse(
         src, filename, feature_version=version, type_comments=type_comments
     )
 
-    if _IS_PYPY:
-        # PyPy 3.7 doesn't support type comment tracking which is not ideal, but there's
-        # not much we can do as typed-ast won't work either.
-        if sys.version_info >= (3, 8):
-            return ast3.parse(src, filename, type_comments=type_comments)
-        else:
-            return ast3.parse(src, filename)
-    else:
-        if type_comments:
-            # Typed-ast is guaranteed to be used here and automatically tracks type
-            # comments separately.
-            return ast3.parse(src, filename, feature_version=version[1])
-        else:
-            return ast.parse(src, filename)
 
-
+def parse_ast(src: str) -> ast.AST:
-def parse_ast(src: str) -> Union[ast.AST, ast3.AST]:
     # TODO: support Python 4+ ;)
     versions = [(3, minor) for minor in range(3, sys.version_info[1] + 1)]
 
@@ -193,9 +151,6 @@ def parse_ast(src: str) -> Union[ast.AST, ast3.AST]:
     raise SyntaxError(first_error)
 
 
-ast3_AST: Final[Type[ast3.AST]] = ast3.AST
-
-
 def _normalize(lineend: str, value: str) -> str:
     # To normalize, we strip any leading and trailing space from
     # each line...
@@ -206,22 +161,24 @@ def _normalize(lineend: str, value: str) -> str:
     return normalized.strip()
 
 
-def stringify_ast(node: Union[ast.AST, ast3.AST], depth: int = 0) -> Iterator[str]:
+def stringify_ast(node: ast.AST, depth: int = 0) -> Iterator[str]:
     """Simple visitor generating strings to compare ASTs by content."""
 
-    node = fixup_ast_constants(node)
+    if (
+        isinstance(node, ast.Constant)
+        and isinstance(node.value, str)
+        and node.kind == "u"
+    ):
+        # It's a quirk of history that we strip the u prefix over here. We used to
+        # rewrite the AST nodes for Python version compatibility and we never copied
+        # over the kind
+        node.kind = None
 
     yield f"{'  ' * depth}{node.__class__.__name__}("
 
-    type_ignore_classes: Tuple[Type[Any], ...]
     for field in sorted(node._fields):  # noqa: F402
-        # TypeIgnore will not be present using pypy < 3.8, so need for this
-        if not (_IS_PYPY and sys.version_info < (3, 8)):
         # TypeIgnore has only one field 'lineno' which breaks this comparison
-            type_ignore_classes = (ast3.TypeIgnore,)
+        if isinstance(node, ast.TypeIgnore):
-            if sys.version_info >= (3, 8):
-                type_ignore_classes += (ast.TypeIgnore,)
-            if isinstance(node, type_ignore_classes):
             break
 
         try:
@@ -237,22 +194,16 @@ def stringify_ast(node: Union[ast.AST, ast3.AST], depth: int = 0) -> Iterator[st
                 # parentheses and they change the AST.
                 if (
                     field == "targets"
-                    and isinstance(node, (ast.Delete, ast3.Delete))
+                    and isinstance(node, ast.Delete)
-                    and isinstance(item, (ast.Tuple, ast3.Tuple))
+                    and isinstance(item, ast.Tuple)
                 ):
                     for elt in item.elts:
                         yield from stringify_ast(elt, depth + 2)
 
-                elif isinstance(item, (ast.AST, ast3.AST)):
+                elif isinstance(item, ast.AST):
                     yield from stringify_ast(item, depth + 2)
 
-        # Note that we are referencing the typed-ast ASTs via global variables and not
+        elif isinstance(value, ast.AST):
-        # direct module attribute accesses because that breaks mypyc. It's probably
-        # something to do with the ast3 variables being marked as Any leading
-        # mypy to think this branch is always taken, leaving the rest of the code
-        # unanalyzed. Tighting up the types for the typed-ast AST types avoids the
-        # mypyc crash.
-        elif isinstance(value, (ast.AST, ast3_AST)):
             yield from stringify_ast(value, depth + 2)
 
         else:
@@ -271,17 +222,3 @@ def stringify_ast(node: Union[ast.AST, ast3.AST], depth: int = 0) -> Iterator[st
             yield f"{'  ' * (depth+2)}{normalized!r},  # {value.__class__.__name__}"
 
     yield f"{'  ' * depth})  # /{node.__class__.__name__}"
-
-
-def fixup_ast_constants(node: Union[ast.AST, ast3.AST]) -> Union[ast.AST, ast3.AST]:
-    """Map ast nodes deprecated in 3.8 to Constant."""
-    if isinstance(node, (ast.Str, ast3.Str, ast.Bytes, ast3.Bytes)):
-        return ast.Constant(value=node.s)
-
-    if isinstance(node, (ast.Num, ast3.Num)):
-        return ast.Constant(value=node.n)
-
-    if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
-        return ast.Constant(value=node.value)
-
-    return node

src/black/strings.py

@@ -5,16 +5,10 @@
 import re
 import sys
 from functools import lru_cache
-from typing import List, Match, Pattern
+from typing import Final, List, Match, Pattern
-
-from blib2to3.pytree import Leaf
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 from black._width_table import WIDTH_TABLE
+from blib2to3.pytree import Leaf
 
 STRING_PREFIX_CHARS: Final = "furbFURB"  # All possible string prefix characters.
 STRING_PREFIX_RE: Final = re.compile(

src/black/trans.py

@@ -2,7 +2,6 @@
 String transformers that can split and merge strings.
 """
 import re
-import sys
 from abc import ABC, abstractmethod
 from collections import defaultdict
 from dataclasses import dataclass
@@ -12,9 +11,11 @@
     ClassVar,
     Collection,
     Dict,
+    Final,
     Iterable,
     Iterator,
     List,
+    Literal,
     Optional,
     Sequence,
     Set,
@@ -23,11 +24,6 @@
     Union,
 )
 
-if sys.version_info < (3, 8):
-    from typing_extensions import Final, Literal
-else:
-    from typing import Literal, Final
-
 from mypy_extensions import trait
 
 from black.comments import contains_pragma_comment

src/blib2to3/pgen2/token.py

@@ -3,10 +3,7 @@
 import sys
 from typing import Dict
 
-if sys.version_info < (3, 8):
+from typing import Final
-    from typing_extensions import Final
-else:
-    from typing import Final
 
 #  Taken from Python (r53757) and modified to include some tokens
 #   originally monkeypatched in by pgen2.tokenize

src/blib2to3/pgen2/tokenize.py

@@ -42,10 +42,7 @@
     cast,
 )
 
-if sys.version_info >= (3, 8):
+from typing import Final
-    from typing import Final
-else:
-    from typing_extensions import Final
 
 from blib2to3.pgen2.token import *
 from blib2to3.pgen2.grammar import Grammar