Fix readthedocs build (#1321)

[etc/vim.git] / black.py

diff --git a/black.py b/black.py
index ddeaa88435da41ade7db04a9a61a17c73b9141c0..31859d1a499411d60d027e4b71feb208def8a7e9 100644 (file)
--- a/black.py
+++ b/black.py
@@ -37,6 +37,8 @@ from typing import (
     Union,
     cast,
 )
     Union,
     cast,
 )

+from typing_extensions import Final
+from mypy_extensions import mypyc_attr

 
 from appdirs import user_cache_dir
 from dataclasses import dataclass, field, replace
 
 from appdirs import user_cache_dir
 from dataclasses import dataclass, field, replace


@@ -184,7 +186,7 @@ VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
 
 
 @dataclass
 
 
 @dataclass

-class FileMode:
+class Mode:

     target_versions: Set[TargetVersion] = field(default_factory=set)
     line_length: int = DEFAULT_LINE_LENGTH
     string_normalization: bool = True
     target_versions: Set[TargetVersion] = field(default_factory=set)
     line_length: int = DEFAULT_LINE_LENGTH
     string_normalization: bool = True


@@ -207,10 +209,31 @@ class FileMode:
         return ".".join(parts)
 
 
         return ".".join(parts)
 
 

+# Legacy name, left for integrations.
+FileMode = Mode
+
+

 def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
     return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
 
 
 def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
     return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
 
 

+def find_pyproject_toml(path_search_start: str) -> Optional[str]:
+    """Find the absolute filepath to a pyproject.toml if it exists"""
+    path_project_root = find_project_root(path_search_start)
+    path_pyproject_toml = path_project_root / "pyproject.toml"
+    return str(path_pyproject_toml) if path_pyproject_toml.is_file() else None
+
+
+def parse_pyproject_toml(path_config: str) -> Dict[str, Any]:
+    """Parse a pyproject toml file, pulling out relevant parts for Black
+
+    If parsing fails, will raise a toml.TomlDecodeError
+    """
+    pyproject_toml = toml.load(path_config)
+    config = pyproject_toml.get("tool", {}).get("black", {})
+    return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+
+

 def read_pyproject_toml(
     ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None]
 ) -> Optional[str]:
 def read_pyproject_toml(
     ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None]
 ) -> Optional[str]:


@@ -221,16 +244,12 @@ def read_pyproject_toml(
     """
     assert not isinstance(value, (int, bool)), "Invalid parameter type passed"
     if not value:
     """
     assert not isinstance(value, (int, bool)), "Invalid parameter type passed"
     if not value:

-        root = find_project_root(ctx.params.get("src", ()))
-        path = root / "pyproject.toml"
-        if path.is_file():
-            value = str(path)
-        else:
+        value = find_pyproject_toml(ctx.params.get("src", ()))
+        if value is None:

             return None
 
     try:
             return None
 
     try:

-        pyproject_toml = toml.load(value)
-        config = pyproject_toml.get("tool", {}).get("black", {})
+        config = parse_pyproject_toml(value)

     except (toml.TomlDecodeError, OSError) as e:
         raise click.FileError(
             filename=value, hint=f"Error reading configuration file: {e}"
     except (toml.TomlDecodeError, OSError) as e:
         raise click.FileError(
             filename=value, hint=f"Error reading configuration file: {e}"


@@ -241,12 +260,21 @@ def read_pyproject_toml(
 
     if ctx.default_map is None:
         ctx.default_map = {}
 
     if ctx.default_map is None:
         ctx.default_map = {}

-    ctx.default_map.update(  # type: ignore  # bad types in .pyi
-        {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
-    )
+    ctx.default_map.update(config)  # type: ignore  # bad types in .pyi

     return value
 
 
     return value
 
 

+def target_version_option_callback(
+    c: click.Context, p: Union[click.Option, click.Parameter], v: Tuple[str, ...]
+) -> List[TargetVersion]:
+    """Compute the target versions from a --target-version flag.
+
+    This is its own function because mypy couldn't infer the type correctly
+    when it was a lambda, causing mypyc trouble.
+    """
+    return [TargetVersion[val.upper()] for val in v]
+
+

 @click.command(context_settings=dict(help_option_names=["-h", "--help"]))
 @click.option("-c", "--code", type=str, help="Format the code passed in as a string.")
 @click.option(
 @click.command(context_settings=dict(help_option_names=["-h", "--help"]))
 @click.option("-c", "--code", type=str, help="Format the code passed in as a string.")
 @click.option(


@@ -261,7 +289,7 @@ def read_pyproject_toml(
     "-t",
     "--target-version",
     type=click.Choice([v.name.lower() for v in TargetVersion]),
     "-t",
     "--target-version",
     type=click.Choice([v.name.lower() for v in TargetVersion]),

-    callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v],
+    callback=target_version_option_callback,

     multiple=True,
     help=(
         "Python versions that should be supported by Black's output. [default: "
     multiple=True,
     help=(
         "Python versions that should be supported by Black's output. [default: "


@@ -388,7 +416,7 @@ def main(
     verbose: bool,
     include: str,
     exclude: str,
     verbose: bool,
     include: str,
     exclude: str,

-    src: Tuple[str],
+    src: Tuple[str, ...],

     config: Optional[str],
 ) -> None:
     """The uncompromising code formatter."""
     config: Optional[str],
 ) -> None:
     """The uncompromising code formatter."""


@@ -408,7 +436,7 @@ def main(
     else:
         # We'll autodetect later.
         versions = set()
     else:
         # We'll autodetect later.
         versions = set()

-    mode = FileMode(
+    mode = Mode(

         target_versions=versions,
         line_length=line_length,
         is_pyi=pyi,
         target_versions=versions,
         line_length=line_length,
         is_pyi=pyi,


@@ -429,7 +457,7 @@ def main(
     except re.error:
         err(f"Invalid regular expression for exclude given: {exclude!r}")
         ctx.exit(2)
     except re.error:
         err(f"Invalid regular expression for exclude given: {exclude!r}")
         ctx.exit(2)

-    report = Report(check=check, quiet=quiet, verbose=verbose)
+    report = Report(check=check, diff=diff, quiet=quiet, verbose=verbose)

     root = find_project_root(src)
     sources: Set[Path] = set()
     path_empty(src, quiet, verbose, ctx)
     root = find_project_root(src)
     sources: Set[Path] = set()
     path_empty(src, quiet, verbose, ctx)


@@ -470,7 +498,9 @@ def main(
     ctx.exit(report.return_code)
 
 
     ctx.exit(report.return_code)
 
 

-def path_empty(src: Tuple[str], quiet: bool, verbose: bool, ctx: click.Context) -> None:
+def path_empty(
+    src: Tuple[str, ...], quiet: bool, verbose: bool, ctx: click.Context
+) -> None:

     """
     Exit if there is no `src` provided for formatting
     """
     """
     Exit if there is no `src` provided for formatting
     """


@@ -481,7 +511,7 @@ def path_empty(src: Tuple[str], quiet: bool, verbose: bool, ctx: click.Context)
 
 
 def reformat_one(
 
 
 def reformat_one(

-    src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report"
+    src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"

 ) -> None:
     """Reformat a single file under `src` without spawning child processes.
 
 ) -> None:
     """Reformat a single file under `src` without spawning child processes.
 


@@ -514,11 +544,7 @@ def reformat_one(
 
 
 def reformat_many(
 
 
 def reformat_many(

-    sources: Set[Path],
-    fast: bool,
-    write_back: WriteBack,
-    mode: FileMode,
-    report: "Report",
+    sources: Set[Path], fast: bool, write_back: WriteBack, mode: Mode, report: "Report"

 ) -> None:
     """Reformat multiple files using a ProcessPoolExecutor."""
     loop = asyncio.get_event_loop()
 ) -> None:
     """Reformat multiple files using a ProcessPoolExecutor."""
     loop = asyncio.get_event_loop()


@@ -548,7 +574,7 @@ async def schedule_formatting(
     sources: Set[Path],
     fast: bool,
     write_back: WriteBack,
     sources: Set[Path],
     fast: bool,
     write_back: WriteBack,

-    mode: FileMode,
+    mode: Mode,

     report: "Report",
     loop: asyncio.AbstractEventLoop,
     executor: Executor,
     report: "Report",
     loop: asyncio.AbstractEventLoop,
     executor: Executor,


@@ -585,7 +611,7 @@ async def schedule_formatting(
         ): src
         for src in sorted(sources)
     }
         ): src
         for src in sorted(sources)
     }

-    pending: Iterable[asyncio.Future] = tasks.keys()
+    pending: Iterable["asyncio.Future[bool]"] = tasks.keys()

     try:
         loop.add_signal_handler(signal.SIGINT, cancel, pending)
         loop.add_signal_handler(signal.SIGTERM, cancel, pending)
     try:
         loop.add_signal_handler(signal.SIGINT, cancel, pending)
         loop.add_signal_handler(signal.SIGTERM, cancel, pending)


@@ -618,7 +644,7 @@ async def schedule_formatting(
 def format_file_in_place(
     src: Path,
     fast: bool,
 def format_file_in_place(
     src: Path,
     fast: bool,

-    mode: FileMode,
+    mode: Mode,

     write_back: WriteBack = WriteBack.NO,
     lock: Any = None,  # multiprocessing.Manager().Lock() is some crazy proxy
 ) -> bool:
     write_back: WriteBack = WriteBack.NO,
     lock: Any = None,  # multiprocessing.Manager().Lock() is some crazy proxy
 ) -> bool:


@@ -639,10 +665,10 @@ def format_file_in_place(
     except NothingChanged:
         return False
 
     except NothingChanged:
         return False
 

-    if write_back == write_back.YES:
+    if write_back == WriteBack.YES:

         with open(src, "w", encoding=encoding, newline=newline) as f:
             f.write(dst_contents)
         with open(src, "w", encoding=encoding, newline=newline) as f:
             f.write(dst_contents)

-    elif write_back == write_back.DIFF:
+    elif write_back == WriteBack.DIFF:

         now = datetime.utcnow()
         src_name = f"{src}\t{then} +0000"
         dst_name = f"{src}\t{now} +0000"
         now = datetime.utcnow()
         src_name = f"{src}\t{then} +0000"
         dst_name = f"{src}\t{now} +0000"


@@ -662,7 +688,7 @@ def format_file_in_place(
 
 
 def format_stdin_to_stdout(
 
 
 def format_stdin_to_stdout(

-    fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: FileMode
+    fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: Mode

 ) -> bool:
     """Format file on stdin. Return True if changed.
 
 ) -> bool:
     """Format file on stdin. Return True if changed.
 


@@ -694,9 +720,7 @@ def format_stdin_to_stdout(
         f.detach()
 
 
         f.detach()
 
 

-def format_file_contents(
-    src_contents: str, *, fast: bool, mode: FileMode
-) -> FileContent:
+def format_file_contents(src_contents: str, *, fast: bool, mode: Mode) -> FileContent:

     """Reformat contents a file and return new contents.
 
     If `fast` is False, additionally confirm that the reformatted code is
     """Reformat contents a file and return new contents.
 
     If `fast` is False, additionally confirm that the reformatted code is


@@ -716,11 +740,34 @@ def format_file_contents(
     return dst_contents
 
 
     return dst_contents
 
 

-def format_str(src_contents: str, *, mode: FileMode) -> FileContent:
+def format_str(src_contents: str, *, mode: Mode) -> FileContent:

     """Reformat a string and return new contents.
 
     `mode` determines formatting options, such as how many characters per line are
     """Reformat a string and return new contents.
 
     `mode` determines formatting options, such as how many characters per line are

-    allowed.
+    allowed.  Example:
+
+    >>> import black
+    >>> print(black.format_str("def f(arg:str='')->None:...", mode=Mode()))
+    def f(arg: str = "") -> None:
+        ...
+
+    A more complex example:
+    >>> print(
+    ...   black.format_str(
+    ...     "def f(arg:str='')->None: hey",
+    ...     mode=black.Mode(
+    ...       target_versions={black.TargetVersion.PY36},
+    ...       line_length=10,
+    ...       string_normalization=False,
+    ...       is_pyi=False,
+    ...     ),
+    ...   ),
+    ... )
+    def f(
+        arg: str = '',
+    ) -> None:
+        hey
+

     """
     src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
     dst_contents = []
     """
     src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
     dst_contents = []


@@ -745,11 +792,9 @@ def format_str(src_contents: str, *, mode: FileMode) -> FileContent:
         if supports_feature(versions, feature)
     }
     for current_line in lines.visit(src_node):
         if supports_feature(versions, feature)
     }
     for current_line in lines.visit(src_node):

-        for _ in range(after):
-            dst_contents.append(str(empty_line))
+        dst_contents.append(str(empty_line) * after)

         before, after = elt.maybe_empty_lines(current_line)
         before, after = elt.maybe_empty_lines(current_line)

-        for _ in range(before):
-            dst_contents.append(str(empty_line))
+        dst_contents.append(str(empty_line) * before)

         for line in split_line(
             current_line, line_length=mode.line_length, features=split_line_features
         ):
         for line in split_line(
             current_line, line_length=mode.line_length, features=split_line_features
         ):


@@ -865,8 +910,16 @@ class Visitor(Generic[T]):
         if node.type < 256:
             name = token.tok_name[node.type]
         else:
         if node.type < 256:
             name = token.tok_name[node.type]
         else:

-            name = type_repr(node.type)
-        yield from getattr(self, f"visit_{name}", self.visit_default)(node)
+            name = str(type_repr(node.type))
+        # We explicitly branch on whether a visitor exists (instead of
+        # using self.visit_default as the default arg to getattr) in order
+        # to save needing to create a bound method object and so mypyc can
+        # generate a native call to visit_default.
+        visitf = getattr(self, f"visit_{name}", None)
+        if visitf:
+            yield from visitf(node)
+        else:
+            yield from self.visit_default(node)

 
     def visit_default(self, node: LN) -> Iterator[T]:
         """Default `visit_*()` implementation. Recurses to children of `node`."""
 
     def visit_default(self, node: LN) -> Iterator[T]:
         """Default `visit_*()` implementation. Recurses to children of `node`."""


@@ -911,8 +964,8 @@ class DebugVisitor(Visitor[T]):
         list(v.visit(code))
 
 
         list(v.visit(code))
 
 

-WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
-STATEMENT = {
+WHITESPACE: Final = {token.DEDENT, token.INDENT, token.NEWLINE}
+STATEMENT: Final = {

     syms.if_stmt,
     syms.while_stmt,
     syms.for_stmt,
     syms.if_stmt,
     syms.while_stmt,
     syms.for_stmt,


@@ -922,10 +975,10 @@ STATEMENT = {
     syms.funcdef,
     syms.classdef,
 }
     syms.funcdef,
     syms.classdef,
 }

-STANDALONE_COMMENT = 153
+STANDALONE_COMMENT: Final = 153

 token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
 token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"

-LOGIC_OPERATORS = {"and", "or"}
-COMPARATORS = {
+LOGIC_OPERATORS: Final = {"and", "or"}
+COMPARATORS: Final = {

     token.LESS,
     token.GREATER,
     token.EQEQUAL,
     token.LESS,
     token.GREATER,
     token.EQEQUAL,


@@ -933,7 +986,7 @@ COMPARATORS = {
     token.LESSEQUAL,
     token.GREATEREQUAL,
 }
     token.LESSEQUAL,
     token.GREATEREQUAL,
 }

-MATH_OPERATORS = {
+MATH_OPERATORS: Final = {

     token.VBAR,
     token.CIRCUMFLEX,
     token.AMPER,
     token.VBAR,
     token.CIRCUMFLEX,
     token.AMPER,


@@ -949,23 +1002,23 @@ MATH_OPERATORS = {
     token.TILDE,
     token.DOUBLESTAR,
 }
     token.TILDE,
     token.DOUBLESTAR,
 }

-STARS = {token.STAR, token.DOUBLESTAR}
-VARARGS_SPECIALS = STARS | {token.SLASH}
-VARARGS_PARENTS = {
+STARS: Final = {token.STAR, token.DOUBLESTAR}
+VARARGS_SPECIALS: Final = STARS | {token.SLASH}
+VARARGS_PARENTS: Final = {

     syms.arglist,
     syms.argument,  # double star in arglist
     syms.trailer,  # single argument to call
     syms.typedargslist,
     syms.varargslist,  # lambdas
 }
     syms.arglist,
     syms.argument,  # double star in arglist
     syms.trailer,  # single argument to call
     syms.typedargslist,
     syms.varargslist,  # lambdas
 }

-UNPACKING_PARENTS = {
+UNPACKING_PARENTS: Final = {

     syms.atom,  # single element of a list or set literal
     syms.dictsetmaker,
     syms.listmaker,
     syms.testlist_gexp,
     syms.testlist_star_expr,
 }
     syms.atom,  # single element of a list or set literal
     syms.dictsetmaker,
     syms.listmaker,
     syms.testlist_gexp,
     syms.testlist_star_expr,
 }

-TEST_DESCENDANTS = {
+TEST_DESCENDANTS: Final = {

     syms.test,
     syms.lambdef,
     syms.or_test,
     syms.test,
     syms.lambdef,
     syms.or_test,


@@ -982,7 +1035,7 @@ TEST_DESCENDANTS = {
     syms.term,
     syms.power,
 }
     syms.term,
     syms.power,
 }

-ASSIGNMENTS = {
+ASSIGNMENTS: Final = {

     "=",
     "+=",
     "-=",
     "=",
     "+=",
     "-=",


@@ -998,13 +1051,13 @@ ASSIGNMENTS = {
     "**=",
     "//=",
 }
     "**=",
     "//=",
 }

-COMPREHENSION_PRIORITY = 20
-COMMA_PRIORITY = 18
-TERNARY_PRIORITY = 16
-LOGIC_PRIORITY = 14
-STRING_PRIORITY = 12
-COMPARATOR_PRIORITY = 10
-MATH_PRIORITIES = {
+COMPREHENSION_PRIORITY: Final = 20
+COMMA_PRIORITY: Final = 18
+TERNARY_PRIORITY: Final = 16
+LOGIC_PRIORITY: Final = 14
+STRING_PRIORITY: Final = 12
+COMPARATOR_PRIORITY: Final = 10
+MATH_PRIORITIES: Final = {

     token.VBAR: 9,
     token.CIRCUMFLEX: 8,
     token.AMPER: 7,
     token.VBAR: 9,
     token.CIRCUMFLEX: 8,
     token.AMPER: 7,


@@ -1020,7 +1073,7 @@ MATH_PRIORITIES = {
     token.TILDE: 3,
     token.DOUBLESTAR: 2,
 }
     token.TILDE: 3,
     token.DOUBLESTAR: 2,
 }

-DOT_PRIORITY = 1
+DOT_PRIORITY: Final = 1

 
 
 @dataclass
 
 
 @dataclass


@@ -1384,7 +1437,10 @@ class Line:
         for leaf_id, comments in self.comments.items():
             for comment in comments:
                 if is_type_comment(comment):
         for leaf_id, comments in self.comments.items():
             for comment in comments:
                 if is_type_comment(comment):

-                    if leaf_id not in ignored_ids or comment_seen:
+                    if comment_seen or (
+                        not is_type_comment(comment, " ignore")
+                        and leaf_id not in ignored_ids
+                    ):

                         return True
 
                 comment_seen = True
                         return True
 
                 comment_seen = True


@@ -1423,11 +1479,7 @@ class Line:
         return False
 
     def contains_multiline_strings(self) -> bool:
         return False
 
     def contains_multiline_strings(self) -> bool:

-        for leaf in self.leaves:
-            if is_multiline_string(leaf):
-                return True
-
-        return False
+        return any(is_multiline_string(leaf) for leaf in self.leaves)

 
     def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
         """Remove trailing comma if there is one and it's safe."""
 
     def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
         """Remove trailing comma if there is one and it's safe."""


@@ -1729,13 +1781,13 @@ class LineGenerator(Visitor[Line]):
                 self.current_line.append(node)
         yield from super().visit_default(node)
 
                 self.current_line.append(node)
         yield from super().visit_default(node)
 

-    def visit_INDENT(self, node: Node) -> Iterator[Line]:
+    def visit_INDENT(self, node: Leaf) -> Iterator[Line]:

         """Increase indentation level, maybe yield a line."""
         # In blib2to3 INDENT never holds comments.
         yield from self.line(+1)
         yield from self.visit_default(node)
 
         """Increase indentation level, maybe yield a line."""
         # In blib2to3 INDENT never holds comments.
         yield from self.line(+1)
         yield from self.visit_default(node)
 

-    def visit_DEDENT(self, node: Node) -> Iterator[Line]:
+    def visit_DEDENT(self, node: Leaf) -> Iterator[Line]:

         """Decrease indentation level, maybe yield a line."""
         # The current line might still wait for trailing comments.  At DEDENT time
         # there won't be any (they would be prefixes on the preceding NEWLINE).
         """Decrease indentation level, maybe yield a line."""
         # The current line might still wait for trailing comments.  At DEDENT time
         # there won't be any (they would be prefixes on the preceding NEWLINE).


@@ -2463,7 +2515,7 @@ def left_hand_split(line: Line, features: Collection[Feature] = ()) -> Iterator[
     body_leaves: List[Leaf] = []
     head_leaves: List[Leaf] = []
     current_leaves = head_leaves
     body_leaves: List[Leaf] = []
     head_leaves: List[Leaf] = []
     current_leaves = head_leaves

-    matching_bracket = None
+    matching_bracket: Optional[Leaf] = None

     for leaf in line.leaves:
         if (
             current_leaves is body_leaves
     for leaf in line.leaves:
         if (
             current_leaves is body_leaves


@@ -2506,8 +2558,8 @@ def right_hand_split(
     body_leaves: List[Leaf] = []
     head_leaves: List[Leaf] = []
     current_leaves = tail_leaves
     body_leaves: List[Leaf] = []
     head_leaves: List[Leaf] = []
     current_leaves = tail_leaves

-    opening_bracket = None
-    closing_bracket = None
+    opening_bracket: Optional[Leaf] = None
+    closing_bracket: Optional[Leaf] = None

     for leaf in reversed(line.leaves):
         if current_leaves is body_leaves:
             if leaf is opening_bracket:
     for leaf in reversed(line.leaves):
         if current_leaves is body_leaves:
             if leaf is opening_bracket:


@@ -2811,7 +2863,7 @@ def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None:
     match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL)
     assert match is not None, f"failed to match string {leaf.value!r}"
     orig_prefix = match.group(1)
     match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL)
     assert match is not None, f"failed to match string {leaf.value!r}"
     orig_prefix = match.group(1)

-    new_prefix = orig_prefix.lower()
+    new_prefix = orig_prefix.replace("F", "f").replace("B", "b").replace("U", "u")

     if remove_u_prefix:
         new_prefix = new_prefix.replace("u", "")
     leaf.value = f"{new_prefix}{match.group(2)}"
     if remove_u_prefix:
         new_prefix = new_prefix.replace("u", "")
     leaf.value = f"{new_prefix}{match.group(2)}"


@@ -3028,7 +3080,7 @@ def convert_one_fmt_off_pair(node: Node) -> bool:
                     # That happens when one of the `ignored_nodes` ended with a NEWLINE
                     # leaf (possibly followed by a DEDENT).
                     hidden_value = hidden_value[:-1]
                     # That happens when one of the `ignored_nodes` ended with a NEWLINE
                     # leaf (possibly followed by a DEDENT).
                     hidden_value = hidden_value[:-1]

-                first_idx = None
+                first_idx: Optional[int] = None

                 for ignored in ignored_nodes:
                     index = ignored.remove()
                     if first_idx is None:
                 for ignored in ignored_nodes:
                     index = ignored.remove()
                     if first_idx is None:


@@ -3399,8 +3451,8 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
     yield omit
 
     length = 4 * line.depth
     yield omit
 
     length = 4 * line.depth

-    opening_bracket = None
-    closing_bracket = None
+    opening_bracket: Optional[Leaf] = None
+    closing_bracket: Optional[Leaf] = None

     inner_brackets: Set[LeafID] = set()
     for index, leaf, leaf_length in enumerate_with_length(line, reversed=True):
         length += leaf_length
     inner_brackets: Set[LeafID] = set()
     for index, leaf, leaf_length in enumerate_with_length(line, reversed=True):
         length += leaf_length


@@ -3571,7 +3623,7 @@ def find_project_root(srcs: Iterable[str]) -> Path:
         # Append a fake file so `parents` below returns `common_base_dir`, too.
         common_base /= "fake-file"
     for directory in common_base.parents:
         # Append a fake file so `parents` below returns `common_base_dir`, too.
         common_base /= "fake-file"
     for directory in common_base.parents:

-        if (directory / ".git").is_dir():
+        if (directory / ".git").exists():

             return directory
 
         if (directory / ".hg").is_dir():
             return directory
 
         if (directory / ".hg").is_dir():


@@ -3588,6 +3640,7 @@ class Report:
     """Provides a reformatting counter. Can be rendered with `str(report)`."""
 
     check: bool = False
     """Provides a reformatting counter. Can be rendered with `str(report)`."""
 
     check: bool = False

+    diff: bool = False

     quiet: bool = False
     verbose: bool = False
     change_count: int = 0
     quiet: bool = False
     verbose: bool = False
     change_count: int = 0


@@ -3597,7 +3650,7 @@ class Report:
     def done(self, src: Path, changed: Changed) -> None:
         """Increment the counter for successful reformatting. Write out a message."""
         if changed is Changed.YES:
     def done(self, src: Path, changed: Changed) -> None:
         """Increment the counter for successful reformatting. Write out a message."""
         if changed is Changed.YES:

-            reformatted = "would reformat" if self.check else "reformatted"
+            reformatted = "would reformat" if self.check or self.diff else "reformatted"

             if self.verbose or not self.quiet:
                 out(f"{reformatted} {src}")
             self.change_count += 1
             if self.verbose or not self.quiet:
                 out(f"{reformatted} {src}")
             self.change_count += 1


@@ -3643,7 +3696,7 @@ class Report:
 
         Use `click.unstyle` to remove colors.
         """
 
         Use `click.unstyle` to remove colors.
         """

-        if self.check:
+        if self.check or self.diff:

             reformatted = "would be reformatted"
             unchanged = "would be left unchanged"
             failed = "would fail to reformat"
             reformatted = "would be reformatted"
             unchanged = "would be left unchanged"
             failed = "would fail to reformat"


@@ -3781,7 +3834,7 @@ def assert_equivalent(src: str, dst: str) -> None:
         ) from None
 
 
         ) from None
 
 

-def assert_stable(src: str, dst: str, mode: FileMode) -> None:
+def assert_stable(src: str, dst: str, mode: Mode) -> None:

     """Raise AssertionError if `dst` reformats differently the second time."""
     newdst = format_str(dst, mode=mode)
     if dst != newdst:
     """Raise AssertionError if `dst` reformats differently the second time."""
     newdst = format_str(dst, mode=mode)
     if dst != newdst:


@@ -3797,6 +3850,7 @@ def assert_stable(src: str, dst: str, mode: FileMode) -> None:
         ) from None
 
 
         ) from None
 
 

+@mypyc_attr(patchable=True)

 def dump_to_file(*output: str) -> str:
     """Dump `output` to a temporary file. Return path to the file."""
     with tempfile.NamedTemporaryFile(
 def dump_to_file(*output: str) -> str:
     """Dump `output` to a temporary file. Return path to the file."""
     with tempfile.NamedTemporaryFile(


@@ -3829,7 +3883,7 @@ def diff(a: str, b: str, a_name: str, b_name: str) -> str:
     )
 
 
     )
 
 

-def cancel(tasks: Iterable[asyncio.Task]) -> None:
+def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:

     """asyncio signal handler that cancels all `tasks` and reports to stderr."""
     err("Aborted!")
     for task in tasks:
     """asyncio signal handler that cancels all `tasks` and reports to stderr."""
     err("Aborted!")
     for task in tasks:


@@ -4051,11 +4105,11 @@ def can_omit_invisible_parens(line: Line, line_length: int) -> bool:
     return False
 
 
     return False
 
 

-def get_cache_file(mode: FileMode) -> Path:
+def get_cache_file(mode: Mode) -> Path:

     return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
 
 
     return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
 
 

-def read_cache(mode: FileMode) -> Cache:
+def read_cache(mode: Mode) -> Cache:

     """Read the cache if it exists and is well formed.
 
     If it is not well formed, the call to write_cache later should resolve the issue.
     """Read the cache if it exists and is well formed.
 
     If it is not well formed, the call to write_cache later should resolve the issue.


@@ -4095,7 +4149,7 @@ def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set
     return todo, done
 
 
     return todo, done
 
 

-def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> None:
+def write_cache(cache: Cache, sources: Iterable[Path], mode: Mode) -> None:

     """Update the cache file."""
     cache_file = get_cache_file(mode)
     try:
     """Update the cache file."""
     cache_file = get_cache_file(mode)
     try: