Fix `black --help` output for `--python-cell-magics` option to be reproducible (...

[etc/vim.git] / src / black / __init__.py

diff --git a/src/black/__init__.py b/src/black/__init__.py
index b7bf822ed089456cc756d474374ea8f5449eec95..f24487fd398268f51d501b35cf3092b67cfb1cc7 100644 (file)
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -1,20 +1,16 @@
-import asyncio
-from json.decoder import JSONDecodeError
-import json
-from concurrent.futures import Executor, ThreadPoolExecutor, ProcessPoolExecutor
-from contextlib import contextmanager
-from datetime import datetime
-from enum import Enum

 import io
 import io

-from multiprocessing import Manager, freeze_support
-import os
-from pathlib import Path
-from pathspec.patterns.gitwildmatch import GitWildMatchPatternError
+import json
+import platform

 import re
 import re

-import signal

 import sys
 import tokenize
 import traceback
 import sys
 import tokenize
 import traceback

+from contextlib import contextmanager
+from dataclasses import replace
+from datetime import datetime
+from enum import Enum
+from json.decoder import JSONDecodeError
+from pathlib import Path

 from typing import (
     Any,
     Dict,
 from typing import (
     Any,
     Dict,


@@ -33,48 +29,62 @@ from typing import (
 
 import click
 from click.core import ParameterSource
 
 import click
 from click.core import ParameterSource

-from dataclasses import replace

 from mypy_extensions import mypyc_attr
 from mypy_extensions import mypyc_attr

+from pathspec import PathSpec
+from pathspec.patterns.gitwildmatch import GitWildMatchPatternError

 
 

-from black.const import DEFAULT_LINE_LENGTH, DEFAULT_INCLUDES, DEFAULT_EXCLUDES
-from black.const import STDIN_PLACEHOLDER
-from black.nodes import STARS, syms, is_simple_decorator_expression
-from black.nodes import is_string_token
-from black.lines import Line, EmptyLineTracker
-from black.linegen import transform_line, LineGenerator, LN
+from _black_version import version as __version__
+from black.cache import Cache, get_cache_info, read_cache, write_cache

 from black.comments import normalize_fmt_off
 from black.comments import normalize_fmt_off

-from black.mode import FUTURE_FLAG_TO_FEATURE, Mode, TargetVersion
-from black.mode import Feature, supports_feature, VERSION_TO_FEATURES
-from black.cache import read_cache, write_cache, get_cache_info, filter_cached, Cache
-from black.concurrency import cancel, shutdown, maybe_install_uvloop
-from black.output import dump_to_file, ipynb_diff, diff, color_diff, out, err
-from black.report import Report, Changed, NothingChanged
+from black.const import (
+    DEFAULT_EXCLUDES,
+    DEFAULT_INCLUDES,
+    DEFAULT_LINE_LENGTH,
+    STDIN_PLACEHOLDER,
+)

 from black.files import (
     find_project_root,
     find_pyproject_toml,
 from black.files import (
     find_project_root,
     find_pyproject_toml,

-    parse_pyproject_toml,

     find_user_pyproject_toml,
     find_user_pyproject_toml,

+    gen_python_files,
+    get_gitignore,
+    normalize_path_maybe_ignore,
+    parse_pyproject_toml,
+    wrap_stream_for_windows,

 )
 )

-from black.files import gen_python_files, get_gitignore, normalize_path_maybe_ignore
-from black.files import wrap_stream_for_windows
-from black.parsing import InvalidInput  # noqa F401
-from black.parsing import lib2to3_parse, parse_ast, stringify_ast

 from black.handle_ipynb_magics import (
 from black.handle_ipynb_magics import (

-    mask_cell,
-    unmask_cell,
-    remove_trailing_semicolon,
-    put_trailing_semicolon_back,
-    TRANSFORMED_MAGICS,

     PYTHON_CELL_MAGICS,
     PYTHON_CELL_MAGICS,

+    TRANSFORMED_MAGICS,

     jupyter_dependencies_are_installed,
     jupyter_dependencies_are_installed,

+    mask_cell,
+    put_trailing_semicolon_back,
+    remove_trailing_semicolon,
+    unmask_cell,

 )
 )

-
-
-# lib2to3 fork
-from blib2to3.pytree import Node, Leaf
+from black.linegen import LN, LineGenerator, transform_line
+from black.lines import EmptyLineTracker, LinesBlock
+from black.mode import (
+    FUTURE_FLAG_TO_FEATURE,
+    VERSION_TO_FEATURES,
+    Feature,
+    Mode,
+    TargetVersion,
+    supports_feature,
+)
+from black.nodes import (
+    STARS,
+    is_number_token,
+    is_simple_decorator_expression,
+    is_string_token,
+    syms,
+)
+from black.output import color_diff, diff, dump_to_file, err, ipynb_diff, out
+from black.parsing import InvalidInput  # noqa F401
+from black.parsing import lib2to3_parse, parse_ast, stringify_ast
+from black.report import Changed, NothingChanged, Report
+from black.trans import iter_fexpr_spans

 from blib2to3.pgen2 import token
 from blib2to3.pgen2 import token

-
-from _black_version import version as __version__
+from blib2to3.pytree import Leaf, Node

 
 COMPILED = Path(__file__).suffix in (".pyd", ".so")
 
 
 COMPILED = Path(__file__).suffix in (".pyd", ".so")
 


@@ -107,8 +117,6 @@ class WriteBack(Enum):
 # Legacy name, left for integrations.
 FileMode = Mode
 
 # Legacy name, left for integrations.
 FileMode = Mode
 

-DEFAULT_WORKERS = os.cpu_count()
-

 
 def read_pyproject_toml(
     ctx: click.Context, param: click.Parameter, value: Optional[str]
 
 def read_pyproject_toml(
     ctx: click.Context, param: click.Parameter, value: Optional[str]


@@ -236,11 +244,17 @@ def validate_regex(
     multiple=True,
     help=(
         "When processing Jupyter Notebooks, add the given magic to the list"
     multiple=True,
     help=(
         "When processing Jupyter Notebooks, add the given magic to the list"

-        f" of known python-magics ({', '.join(PYTHON_CELL_MAGICS)})."
+        f" of known python-magics ({', '.join(sorted(PYTHON_CELL_MAGICS))})."

         " Useful for formatting cells with custom python magics."
     ),
     default=[],
 )
         " Useful for formatting cells with custom python magics."
     ),
     default=[],
 )

+@click.option(
+    "-x",
+    "--skip-source-first-line",
+    is_flag=True,
+    help="Skip the first line of the source code.",
+)

 @click.option(
     "-S",
     "--skip-string-normalization",
 @click.option(
     "-S",
     "--skip-string-normalization",


@@ -357,9 +371,8 @@ def validate_regex(
     "-W",
     "--workers",
     type=click.IntRange(min=1),
     "-W",
     "--workers",
     type=click.IntRange(min=1),

-    default=DEFAULT_WORKERS,
-    show_default=True,
-    help="Number of parallel workers",
+    default=None,
+    help="Number of parallel workers [default: number of CPUs in the system]",

 )
 @click.option(
     "-q",
 )
 @click.option(
     "-q",


@@ -381,7 +394,10 @@ def validate_regex(
 )
 @click.version_option(
     version=__version__,
 )
 @click.version_option(
     version=__version__,

-    message=f"%(prog)s, %(version)s (compiled: {'yes' if COMPILED else 'no'})",
+    message=(
+        f"%(prog)s, %(version)s (compiled: {'yes' if COMPILED else 'no'})\n"
+        f"Python ({platform.python_implementation()}) {platform.python_version()}"
+    ),

 )
 @click.argument(
     "src",
 )
 @click.argument(
     "src",


@@ -419,6 +435,7 @@ def main(  # noqa: C901
     pyi: bool,
     ipynb: bool,
     python_cell_magics: Sequence[str],
     pyi: bool,
     ipynb: bool,
     python_cell_magics: Sequence[str],

+    skip_source_first_line: bool,

     skip_string_normalization: bool,
     skip_magic_trailing_comma: bool,
     experimental_string_processing: bool,
     skip_string_normalization: bool,
     skip_magic_trailing_comma: bool,
     experimental_string_processing: bool,


@@ -431,7 +448,7 @@ def main(  # noqa: C901
     extend_exclude: Optional[Pattern[str]],
     force_exclude: Optional[Pattern[str]],
     stdin_filename: Optional[str],
     extend_exclude: Optional[Pattern[str]],
     force_exclude: Optional[Pattern[str]],
     stdin_filename: Optional[str],

-    workers: int,
+    workers: Optional[int],

     src: Tuple[str, ...],
     config: Optional[str],
 ) -> None:
     src: Tuple[str, ...],
     config: Optional[str],
 ) -> None:


@@ -448,7 +465,9 @@ def main(  # noqa: C901
         out(main.get_usage(ctx) + "\n\nOne of 'SRC' or 'code' is required.")
         ctx.exit(1)
 
         out(main.get_usage(ctx) + "\n\nOne of 'SRC' or 'code' is required.")
         ctx.exit(1)
 

-    root, method = find_project_root(src) if code is None else (None, None)
+    root, method = (
+        find_project_root(src, stdin_filename) if code is None else (None, None)
+    )

     ctx.obj["root"] = root
 
     if verbose:
     ctx.obj["root"] = root
 
     if verbose:


@@ -459,14 +478,20 @@ def main(  # noqa: C901
             )
 
             normalized = [
             )
 
             normalized = [

-                (normalize_path_maybe_ignore(Path(source), root), source)
+                (
+                    (source, source)
+                    if source == "-"
+                    else (normalize_path_maybe_ignore(Path(source), root), source)
+                )

                 for source in src
             ]
             srcs_string = ", ".join(
                 [
                 for source in src
             ]
             srcs_string = ", ".join(
                 [

-                    f'"{_norm}"'
-                    if _norm
-                    else f'\033[31m"{source} (skipping - invalid)"\033[34m'
+                    (
+                        f'"{_norm}"'
+                        if _norm
+                        else f'\033[31m"{source} (skipping - invalid)"\033[34m'
+                    )

                     for _norm, source in normalized
                 ]
             )
                     for _norm, source in normalized
                 ]
             )


@@ -477,8 +502,10 @@ def main(  # noqa: C901
             user_level_config = str(find_user_pyproject_toml())
             if config == user_level_config:
                 out(
             user_level_config = str(find_user_pyproject_toml())
             if config == user_level_config:
                 out(

-                    f"Using configuration from user-level config at "
-                    f"'{user_level_config}'.",
+                    (
+                        "Using configuration from user-level config at "
+                        f"'{user_level_config}'."
+                    ),

                     fg="blue",
                 )
             elif config_source in (
                     fg="blue",
                 )
             elif config_source in (


@@ -488,6 +515,9 @@ def main(  # noqa: C901
                 out("Using configuration from project root.", fg="blue")
             else:
                 out(f"Using configuration in '{config}'.", fg="blue")
                 out("Using configuration from project root.", fg="blue")
             else:
                 out(f"Using configuration in '{config}'.", fg="blue")

+            if ctx.default_map:
+                for param, value in ctx.default_map.items():
+                    out(f"{param}: {value}")

 
     error_msg = "Oh no! 💥 💔 💥"
     if (
 
     error_msg = "Oh no! 💥 💔 💥"
     if (


@@ -515,6 +545,7 @@ def main(  # noqa: C901
         line_length=line_length,
         is_pyi=pyi,
         is_ipynb=ipynb,
         line_length=line_length,
         is_pyi=pyi,
         is_ipynb=ipynb,

+        skip_source_first_line=skip_source_first_line,

         string_normalization=not skip_string_normalization,
         magic_trailing_comma=not skip_magic_trailing_comma,
         experimental_string_processing=experimental_string_processing,
         string_normalization=not skip_string_normalization,
         magic_trailing_comma=not skip_magic_trailing_comma,
         experimental_string_processing=experimental_string_processing,


@@ -567,6 +598,8 @@ def main(  # noqa: C901
                 report=report,
             )
         else:
                 report=report,
             )
         else:

+            from black.concurrency import reformat_many
+

             reformat_many(
                 sources=sources,
                 fast=fast,
             reformat_many(
                 sources=sources,
                 fast=fast,


@@ -600,12 +633,12 @@ def get_sources(
 ) -> Set[Path]:
     """Compute the set of files to be formatted."""
     sources: Set[Path] = set()
 ) -> Set[Path]:
     """Compute the set of files to be formatted."""
     sources: Set[Path] = set()

+    root = ctx.obj["root"]

 
 

-    if exclude is None:
-        exclude = re_compile_maybe_verbose(DEFAULT_EXCLUDES)
-        gitignore = get_gitignore(ctx.obj["root"])
-    else:
-        gitignore = None
+    using_default_exclude = exclude is None
+    exclude = re_compile_maybe_verbose(DEFAULT_EXCLUDES) if exclude is None else exclude
+    gitignore: Optional[Dict[Path, PathSpec]] = None
+    root_gitignore = get_gitignore(root)

 
     for s in src:
         if s == "-" and stdin_filename:
 
     for s in src:
         if s == "-" and stdin_filename:


@@ -640,6 +673,12 @@ def get_sources(
 
             sources.add(p)
         elif p.is_dir():
 
             sources.add(p)
         elif p.is_dir():

+            p = root / normalize_path_maybe_ignore(p, ctx.obj["root"], report)
+            if using_default_exclude:
+                gitignore = {
+                    root: root_gitignore,
+                    p: get_gitignore(p),
+                }

             sources.update(
                 gen_python_files(
                     p.iterdir(),
             sources.update(
                 gen_python_files(
                     p.iterdir(),


@@ -697,6 +736,9 @@ def reformat_code(
         report.failed(path, str(exc))
 
 
         report.failed(path, str(exc))
 
 

+# diff-shades depends on being to monkeypatch this function to operate. I know it's
+# not ideal, but this shouldn't cause any issues ... hopefully. ~ichard26
+@mypyc_attr(patchable=True)

 def reformat_one(
     src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
 ) -> None:
 def reformat_one(
     src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
 ) -> None:


@@ -748,126 +790,6 @@ def reformat_one(
         report.failed(src, str(exc))
 
 
         report.failed(src, str(exc))
 
 

-# diff-shades depends on being to monkeypatch this function to operate. I know it's
-# not ideal, but this shouldn't cause any issues ... hopefully. ~ichard26
-@mypyc_attr(patchable=True)
-def reformat_many(
-    sources: Set[Path],
-    fast: bool,
-    write_back: WriteBack,
-    mode: Mode,
-    report: "Report",
-    workers: Optional[int],
-) -> None:
-    """Reformat multiple files using a ProcessPoolExecutor."""
-    executor: Executor
-    loop = asyncio.get_event_loop()
-    worker_count = workers if workers is not None else DEFAULT_WORKERS
-    if sys.platform == "win32":
-        # Work around https://bugs.python.org/issue26903
-        assert worker_count is not None
-        worker_count = min(worker_count, 60)
-    try:
-        executor = ProcessPoolExecutor(max_workers=worker_count)
-    except (ImportError, NotImplementedError, OSError):
-        # we arrive here if the underlying system does not support multi-processing
-        # like in AWS Lambda or Termux, in which case we gracefully fallback to
-        # a ThreadPoolExecutor with just a single worker (more workers would not do us
-        # any good due to the Global Interpreter Lock)
-        executor = ThreadPoolExecutor(max_workers=1)
-
-    try:
-        loop.run_until_complete(
-            schedule_formatting(
-                sources=sources,
-                fast=fast,
-                write_back=write_back,
-                mode=mode,
-                report=report,
-                loop=loop,
-                executor=executor,
-            )
-        )
-    finally:
-        shutdown(loop)
-        if executor is not None:
-            executor.shutdown()
-
-
-async def schedule_formatting(
-    sources: Set[Path],
-    fast: bool,
-    write_back: WriteBack,
-    mode: Mode,
-    report: "Report",
-    loop: asyncio.AbstractEventLoop,
-    executor: Executor,
-) -> None:
-    """Run formatting of `sources` in parallel using the provided `executor`.
-
-    (Use ProcessPoolExecutors for actual parallelism.)
-
-    `write_back`, `fast`, and `mode` options are passed to
-    :func:`format_file_in_place`.
-    """
-    cache: Cache = {}
-    if write_back not in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
-        cache = read_cache(mode)
-        sources, cached = filter_cached(cache, sources)
-        for src in sorted(cached):
-            report.done(src, Changed.CACHED)
-    if not sources:
-        return
-
-    cancelled = []
-    sources_to_cache = []
-    lock = None
-    if write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
-        # For diff output, we need locks to ensure we don't interleave output
-        # from different processes.
-        manager = Manager()
-        lock = manager.Lock()
-    tasks = {
-        asyncio.ensure_future(
-            loop.run_in_executor(
-                executor, format_file_in_place, src, fast, mode, write_back, lock
-            )
-        ): src
-        for src in sorted(sources)
-    }
-    pending = tasks.keys()
-    try:
-        loop.add_signal_handler(signal.SIGINT, cancel, pending)
-        loop.add_signal_handler(signal.SIGTERM, cancel, pending)
-    except NotImplementedError:
-        # There are no good alternatives for these on Windows.
-        pass
-    while pending:
-        done, _ = await asyncio.wait(pending, return_when=asyncio.FIRST_COMPLETED)
-        for task in done:
-            src = tasks.pop(task)
-            if task.cancelled():
-                cancelled.append(task)
-            elif task.exception():
-                report.failed(src, str(task.exception()))
-            else:
-                changed = Changed.YES if task.result() else Changed.NO
-                # If the file was written back or was successfully checked as
-                # well-formatted, store this information in the cache.
-                if write_back is WriteBack.YES or (
-                    write_back is WriteBack.CHECK and changed is Changed.NO
-                ):
-                    sources_to_cache.append(src)
-                report.done(src, changed)
-    if cancelled:
-        if sys.version_info >= (3, 7):
-            await asyncio.gather(*cancelled, return_exceptions=True)
-        else:
-            await asyncio.gather(*cancelled, loop=loop, return_exceptions=True)
-    if sources_to_cache:
-        write_cache(cache, sources_to_cache, mode)
-
-

 def format_file_in_place(
     src: Path,
     fast: bool,
 def format_file_in_place(
     src: Path,
     fast: bool,


@@ -887,7 +809,10 @@ def format_file_in_place(
         mode = replace(mode, is_ipynb=True)
 
     then = datetime.utcfromtimestamp(src.stat().st_mtime)
         mode = replace(mode, is_ipynb=True)
 
     then = datetime.utcfromtimestamp(src.stat().st_mtime)

+    header = b""

     with open(src, "rb") as buf:
     with open(src, "rb") as buf:

+        if mode.skip_source_first_line:
+            header = buf.readline()

         src_contents, encoding, newline = decode_bytes(buf.read())
     try:
         dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)
         src_contents, encoding, newline = decode_bytes(buf.read())
     try:
         dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)


@@ -897,6 +822,8 @@ def format_file_in_place(
         raise ValueError(
             f"File '{src}' cannot be parsed as valid Jupyter notebook."
         ) from None
         raise ValueError(
             f"File '{src}' cannot be parsed as valid Jupyter notebook."
         ) from None

+    src_contents = header.decode(encoding) + src_contents
+    dst_contents = header.decode(encoding) + dst_contents

 
     if write_back == WriteBack.YES:
         with open(src, "w", encoding=encoding, newline=newline) as f:
 
     if write_back == WriteBack.YES:
         with open(src, "w", encoding=encoding, newline=newline) as f:


@@ -998,7 +925,7 @@ def format_file_contents(src_contents: str, *, fast: bool, mode: Mode) -> FileCo
     valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
     `mode` is passed to :func:`format_str`.
     """
     valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
     `mode` is passed to :func:`format_str`.
     """

-    if not src_contents.strip():
+    if not mode.preview and not src_contents.strip():

         raise NothingChanged
 
     if mode.is_ipynb:
         raise NothingChanged
 
     if mode.is_ipynb:


@@ -1095,6 +1022,9 @@ def format_ipynb_string(src_contents: str, *, fast: bool, mode: Mode) -> FileCon
     Operate cell-by-cell, only on code cells, only for Python notebooks.
     If the ``.ipynb`` originally had a trailing newline, it'll be preserved.
     """
     Operate cell-by-cell, only on code cells, only for Python notebooks.
     If the ``.ipynb`` originally had a trailing newline, it'll be preserved.
     """

+    if mode.preview and not src_contents:
+        raise NothingChanged
+

     trailing_newline = src_contents[-1] == "\n"
     modified = False
     nb = json.loads(src_contents)
     trailing_newline = src_contents[-1] == "\n"
     modified = False
     nb = json.loads(src_contents)


@@ -1159,31 +1089,46 @@ def format_str(src_contents: str, *, mode: Mode) -> str:
 
 def _format_str_once(src_contents: str, *, mode: Mode) -> str:
     src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
 
 def _format_str_once(src_contents: str, *, mode: Mode) -> str:
     src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)

-    dst_contents = []
-    future_imports = get_future_imports(src_node)
+    dst_blocks: List[LinesBlock] = []

     if mode.target_versions:
         versions = mode.target_versions
     else:
     if mode.target_versions:
         versions = mode.target_versions
     else:

+        future_imports = get_future_imports(src_node)

         versions = detect_target_versions(src_node, future_imports=future_imports)
 
         versions = detect_target_versions(src_node, future_imports=future_imports)
 

-    normalize_fmt_off(src_node)
-    lines = LineGenerator(mode=mode)
-    elt = EmptyLineTracker(is_pyi=mode.is_pyi)
-    empty_line = Line(mode=mode)
-    after = 0
+    context_manager_features = {
+        feature
+        for feature in {Feature.PARENTHESIZED_CONTEXT_MANAGERS}
+        if supports_feature(versions, feature)
+    }
+    normalize_fmt_off(src_node, preview=mode.preview)
+    lines = LineGenerator(mode=mode, features=context_manager_features)
+    elt = EmptyLineTracker(mode=mode)

     split_line_features = {
         feature
         for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
         if supports_feature(versions, feature)
     }
     split_line_features = {
         feature
         for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
         if supports_feature(versions, feature)
     }

+    block: Optional[LinesBlock] = None

     for current_line in lines.visit(src_node):
     for current_line in lines.visit(src_node):

-        dst_contents.append(str(empty_line) * after)
-        before, after = elt.maybe_empty_lines(current_line)
-        dst_contents.append(str(empty_line) * before)
+        block = elt.maybe_empty_lines(current_line)
+        dst_blocks.append(block)

         for line in transform_line(
             current_line, mode=mode, features=split_line_features
         ):
         for line in transform_line(
             current_line, mode=mode, features=split_line_features
         ):

-            dst_contents.append(str(line))
+            block.content_lines.append(str(line))
+    if dst_blocks:
+        dst_blocks[-1].after = 0
+    dst_contents = []
+    for block in dst_blocks:
+        dst_contents.extend(block.all_lines())
+    if mode.preview and not dst_contents:
+        # Use decode_bytes to retrieve the correct source newline (CRLF or LF),
+        # and check if normalized_content has more than one line
+        normalized_content, _, newline = decode_bytes(src_contents.encode("utf-8"))
+        if "\n" in normalized_content:
+            return newline
+        return ""

     return "".join(dst_contents)
 
 
     return "".join(dst_contents)
 
 


@@ -1211,6 +1156,7 @@ def get_features_used(  # noqa: C901
 
     Currently looking for:
     - f-strings;
 
     Currently looking for:
     - f-strings;

+    - self-documenting expressions in f-strings (f"{x=}");

     - underscores in numeric literals;
     - trailing commas after * or ** in function signatures and calls;
     - positional only arguments in function signatures and lambdas;
     - underscores in numeric literals;
     - trailing commas after * or ** in function signatures and calls;
     - positional only arguments in function signatures and lambdas;


@@ -1218,6 +1164,10 @@ def get_features_used(  # noqa: C901
     - relaxed decorator syntax;
     - usage of __future__ flags (annotations);
     - print / exec statements;
     - relaxed decorator syntax;
     - usage of __future__ flags (annotations);
     - print / exec statements;

+    - parenthesized context managers;
+    - match statements;
+    - except* clause;
+    - variadic generics;

     """
     features: Set[Feature] = set()
     if future_imports:
     """
     features: Set[Feature] = set()
     if future_imports:


@@ -1232,9 +1182,13 @@ def get_features_used(  # noqa: C901
             value_head = n.value[:2]
             if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
                 features.add(Feature.F_STRINGS)
             value_head = n.value[:2]
             if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
                 features.add(Feature.F_STRINGS)

+                if Feature.DEBUG_F_STRINGS not in features:
+                    for span_beg, span_end in iter_fexpr_spans(n.value):
+                        if n.value[span_beg : span_end - 1].rstrip().endswith("="):
+                            features.add(Feature.DEBUG_F_STRINGS)
+                            break

 
 

-        elif n.type == token.NUMBER:
-            assert isinstance(n, Leaf)
+        elif is_number_token(n):

             if "_" in n.value:
                 features.add(Feature.NUMERIC_UNDERSCORES)
 
             if "_" in n.value:
                 features.add(Feature.NUMERIC_UNDERSCORES)
 


@@ -1289,6 +1243,42 @@ def get_features_used(  # noqa: C901
         ):
             features.add(Feature.ANN_ASSIGN_EXTENDED_RHS)
 
         ):
             features.add(Feature.ANN_ASSIGN_EXTENDED_RHS)
 

+        elif (
+            n.type == syms.with_stmt
+            and len(n.children) > 2
+            and n.children[1].type == syms.atom
+        ):
+            atom_children = n.children[1].children
+            if (
+                len(atom_children) == 3
+                and atom_children[0].type == token.LPAR
+                and atom_children[1].type == syms.testlist_gexp
+                and atom_children[2].type == token.RPAR
+            ):
+                features.add(Feature.PARENTHESIZED_CONTEXT_MANAGERS)
+
+        elif n.type == syms.match_stmt:
+            features.add(Feature.PATTERN_MATCHING)
+
+        elif (
+            n.type == syms.except_clause
+            and len(n.children) >= 2
+            and n.children[1].type == token.STAR
+        ):
+            features.add(Feature.EXCEPT_STAR)
+
+        elif n.type in {syms.subscriptlist, syms.trailer} and any(
+            child.type == syms.star_expr for child in n.children
+        ):
+            features.add(Feature.VARIADIC_GENERICS)
+
+        elif (
+            n.type == syms.tname_star
+            and len(n.children) == 3
+            and n.children[2].type == syms.star_expr
+        ):
+            features.add(Feature.VARIADIC_GENERICS)
+

     return features
 
 
     return features
 
 


@@ -1358,10 +1348,10 @@ def assert_equivalent(src: str, dst: str) -> None:
         src_ast = parse_ast(src)
     except Exception as exc:
         raise AssertionError(
         src_ast = parse_ast(src)
     except Exception as exc:
         raise AssertionError(

-            f"cannot use --safe with this file; failed to parse source file AST: "
+            "cannot use --safe with this file; failed to parse source file AST: "

             f"{exc}\n"
             f"{exc}\n"

-            f"This could be caused by running Black with an older Python version "
-            f"that does not support new syntax used in your source file."
+            "This could be caused by running Black with an older Python version "
+            "that does not support new syntax used in your source file."

         ) from exc
 
     try:
         ) from exc
 
     try:


@@ -1380,7 +1370,7 @@ def assert_equivalent(src: str, dst: str) -> None:
         log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
         raise AssertionError(
             "INTERNAL ERROR: Black produced code that is not equivalent to the"
         log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
         raise AssertionError(
             "INTERNAL ERROR: Black produced code that is not equivalent to the"

-            f" source.  Please report a bug on "
+            " source.  Please report a bug on "

             f"https://github.com/psf/black/issues.  This diff might be helpful: {log}"
         ) from None
 
             f"https://github.com/psf/black/issues.  This diff might be helpful: {log}"
         ) from None
 


@@ -1424,22 +1414,37 @@ def patch_click() -> None:
     file paths is minimal since it's Python source code.  Moreover, this crash was
     spurious on Python 3.7 thanks to PEP 538 and PEP 540.
     """
     file paths is minimal since it's Python source code.  Moreover, this crash was
     spurious on Python 3.7 thanks to PEP 538 and PEP 540.
     """

+    modules: List[Any] = []

     try:
         from click import core
     try:
         from click import core

-        from click import _unicodefun
-    except ModuleNotFoundError:
-        return
+    except ImportError:
+        pass
+    else:
+        modules.append(core)
+    try:
+        # Removed in Click 8.1.0 and newer; we keep this around for users who have
+        # older versions installed.
+        from click import _unicodefun  # type: ignore
+    except ImportError:
+        pass
+    else:
+        modules.append(_unicodefun)

 
 

-    for module in (core, _unicodefun):
+    for module in modules:

         if hasattr(module, "_verify_python3_env"):
         if hasattr(module, "_verify_python3_env"):

-            module._verify_python3_env = lambda: None  # type: ignore
+            module._verify_python3_env = lambda: None

         if hasattr(module, "_verify_python_env"):
         if hasattr(module, "_verify_python_env"):

-            module._verify_python_env = lambda: None  # type: ignore
+            module._verify_python_env = lambda: None

 
 
 def patched_main() -> None:
 
 
 def patched_main() -> None:

-    maybe_install_uvloop()
-    freeze_support()
+    # PyInstaller patches multiprocessing to need freeze_support() even in non-Windows
+    # environments so just assume we always need to call it if frozen.
+    if getattr(sys, "frozen", False):
+        from multiprocessing import freeze_support
+
+        freeze_support()
+

     patch_click()
     main()
 
     patch_click()
     main()