main.py

"""Mypy type checker command line tool."""

from __future__ import annotations

import argparse
import os
import subprocess
import sys
import time
from gettext import gettext
from typing import IO, Any, NoReturn, Sequence, TextIO
from typing_extensions import Final

from mypy import build, defaults, state, util
from mypy.config_parser import get_config_module_names, parse_config_file, parse_version
from mypy.error_formatter import OUTPUT_CHOICES
from mypy.errorcodes import error_codes
from mypy.errors import CompileError
from mypy.find_sources import InvalidSourceList, create_source_list
from mypy.fscache import FileSystemCache
from mypy.modulefinder import BuildSource, FindModuleCache, SearchPaths, get_search_dirs, mypy_path
from mypy.options import INCOMPLETE_FEATURES, BuildType, Options
from mypy.split_namespace import SplitNamespace
from mypy.version import __version__

orig_stat: Final = os.stat
MEM_PROFILE: Final = False  # If True, dump memory profile


def stat_proxy(path: str) -> os.stat_result:
    try:
        st = orig_stat(path)
    except os.error as err:
        print(f"stat({path!r}) -> {err}")
        raise
    else:
        print(
            "stat(%r) -> (st_mode=%o, st_mtime=%d, st_size=%d)"
            % (path, st.st_mode, st.st_mtime, st.st_size)
        )
        return st


def main(
    *,
    args: list[str] | None = None,
    stdout: TextIO = sys.stdout,
    stderr: TextIO = sys.stderr,
    clean_exit: bool = False,
) -> None:
    """Main entry point to the type checker.

    Args:
        args: Custom command-line arguments.  If not given, sys.argv[1:] will
            be used.
        clean_exit: Don't hard kill the process on exit. This allows catching
            SystemExit.
    """
    util.check_python_version("mypy")
    t0 = time.time()
    # To log stat() calls: os.stat = stat_proxy
    sys.setrecursionlimit(2**14)
    if args is None:
        args = sys.argv[1:]

    fscache = FileSystemCache()
    sources, options = process_options(args, stdout=stdout, stderr=stderr, fscache=fscache)
    if clean_exit:
        options.fast_exit = False

    formatter = util.FancyFormatter(
        stdout, stderr, options.hide_error_codes, hide_success=bool(options.output)
    )

    if options.install_types and (stdout is not sys.stdout or stderr is not sys.stderr):
        # Since --install-types performs user input, we want regular stdout and stderr.
        fail("error: --install-types not supported in this mode of running mypy", stderr, options)

    if options.non_interactive and not options.install_types:
        fail("error: --non-interactive is only supported with --install-types", stderr, options)

    if options.install_types and not options.incremental:
        fail(
            "error: --install-types not supported with incremental mode disabled", stderr, options
        )

    if options.install_types and options.python_executable is None:
        fail(
            "error: --install-types not supported without python executable or site packages",
            stderr,
            options,
        )

    if options.install_types and not sources:
        install_types(formatter, options, non_interactive=options.non_interactive)
        return

    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)

    if options.non_interactive:
        missing_pkgs = read_types_packages_to_install(options.cache_dir, after_run=True)
        if missing_pkgs:
            # Install missing type packages and rerun build.
            install_types(formatter, options, after_run=True, non_interactive=True)
            fscache.flush()
            print()
            res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
        show_messages(messages, stderr, formatter, options)

    if MEM_PROFILE:
        from mypy.memprofile import print_memory_profile

        print_memory_profile()

    code = 0
    n_errors, n_notes, n_files = util.count_stats(messages)
    if messages and n_notes < len(messages):
        code = 2 if blockers else 1
    if options.error_summary:
        if n_errors:
            summary = formatter.format_error(
                n_errors, n_files, len(sources), blockers=blockers, use_color=options.color_output
            )
            stdout.write(summary + "\n")
        # Only notes should also output success
        elif not messages or n_notes == len(messages):
            stdout.write(formatter.format_success(len(sources), options.color_output) + "\n")
        stdout.flush()

    if options.install_types and not options.non_interactive:
        result = install_types(formatter, options, after_run=True, non_interactive=False)
        if result:
            print()
            print("note: Run mypy again for up-to-date results with installed types")
            code = 2

    if options.fast_exit:
        # Exit without freeing objects -- it's faster.
        #
        # NOTE: We don't flush all open files on exit (or run other destructors)!
        util.hard_exit(code)
    elif code:
        sys.exit(code)

    # HACK: keep res alive so that mypyc won't free it before the hard_exit
    list([res])


def run_build(
    sources: list[BuildSource],
    options: Options,
    fscache: FileSystemCache,
    t0: float,
    stdout: TextIO,
    stderr: TextIO,
) -> tuple[build.BuildResult | None, list[str], bool]:
    formatter = util.FancyFormatter(
        stdout, stderr, options.hide_error_codes, hide_success=bool(options.output)
    )

    messages = []

    def flush_errors(new_messages: list[str], serious: bool) -> None:
        if options.pretty:
            new_messages = formatter.fit_in_terminal(new_messages)
        messages.extend(new_messages)
        if options.non_interactive:
            # Collect messages and possibly show them later.
            return
        f = stderr if serious else stdout
        show_messages(new_messages, f, formatter, options)

    serious = False
    blockers = False
    res = None
    try:
        # Keep a dummy reference (res) for memory profiling afterwards, as otherwise
        # the result could be freed.
        res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
    except CompileError as e:
        blockers = True
        if not e.use_stdout:
            serious = True
    if (
        options.warn_unused_configs
        and options.unused_configs
        and not options.incremental
        and not options.non_interactive
    ):
        print(
            "Warning: unused section(s) in %s: %s"
            % (
                options.config_file,
                get_config_module_names(
                    options.config_file,
                    [
                        glob
                        for glob in options.per_module_options.keys()
                        if glob in options.unused_configs
                    ],
                ),
            ),
            file=stderr,
        )
    maybe_write_junit_xml(time.time() - t0, serious, messages, options)
    return res, messages, blockers


def show_messages(
    messages: list[str], f: TextIO, formatter: util.FancyFormatter, options: Options
) -> None:
    for msg in messages:
        if options.color_output:
            msg = formatter.colorize(msg)
        f.write(msg + "\n")
    f.flush()


# Make the help output a little less jarring.
class AugmentedHelpFormatter(argparse.RawDescriptionHelpFormatter):
    def __init__(self, prog: str) -> None:
        super().__init__(prog=prog, max_help_position=28)

    def _fill_text(self, text: str, width: int, indent: str) -> str:
        if "\n" in text:
            # Assume we want to manually format the text
            return super()._fill_text(text, width, indent)
        else:
            # Assume we want argparse to manage wrapping, indenting, and
            # formatting the text for us.
            return argparse.HelpFormatter._fill_text(self, text, width, indent)


# Define pairs of flag prefixes with inverse meaning.
flag_prefix_pairs: Final = [("allow", "disallow"), ("show", "hide")]
flag_prefix_map: Final[dict[str, str]] = {}
for a, b in flag_prefix_pairs:
    flag_prefix_map[a] = b
    flag_prefix_map[b] = a


def invert_flag_name(flag: str) -> str:
    split = flag[2:].split("-", 1)
    if len(split) == 2:
        prefix, rest = split
        if prefix in flag_prefix_map:
            return f"--{flag_prefix_map[prefix]}-{rest}"
        elif prefix == "no":
            return f"--{rest}"

    return f"--no-{flag[2:]}"


class PythonExecutableInferenceError(Exception):
    """Represents a failure to infer the version or executable while searching."""


def python_executable_prefix(v: str) -> list[str]:
    if sys.platform == "win32":
        # on Windows, all Python executables are named `python`. To handle this, there
        # is the `py` launcher, which can be passed a version e.g. `py -3.8`, and it will
        # execute an installed Python 3.8 interpreter. See also:
        # https://docs.python.org/3/using/windows.html#python-launcher-for-windows
        return ["py", f"-{v}"]
    else:
        return [f"python{v}"]


def _python_executable_from_version(python_version: tuple[int, int]) -> str:
    if sys.version_info[:2] == python_version:
        return sys.executable
    str_ver = ".".join(map(str, python_version))
    try:
        sys_exe = (
            subprocess.check_output(
                python_executable_prefix(str_ver) + ["-c", "import sys; print(sys.executable)"],
                stderr=subprocess.STDOUT,
            )
            .decode()
            .strip()
        )
        return sys_exe
    except (subprocess.CalledProcessError, FileNotFoundError) as e:
        raise PythonExecutableInferenceError(
            "failed to find a Python executable matching version {},"
            " perhaps try --python-executable, or --no-site-packages?".format(python_version)
        ) from e


def infer_python_executable(options: Options, special_opts: argparse.Namespace) -> None:
    """Infer the Python executable from the given version.

    This function mutates options based on special_opts to infer the correct Python executable
    to use.
    """
    # TODO: (ethanhs) Look at folding these checks and the site packages subprocess calls into
    # one subprocess call for speed.

    # Use the command line specified executable, or fall back to one set in the
    # config file. If an executable is not specified, infer it from the version
    # (unless no_executable is set)
    python_executable = special_opts.python_executable or options.python_executable

    if python_executable is None:
        if not special_opts.no_executable and not options.no_site_packages:
            python_executable = _python_executable_from_version(options.python_version)
    options.python_executable = python_executable


HEADER: Final = """%(prog)s [-h] [-v] [-V] [more options; see below]
            [-m MODULE] [-p PACKAGE] [-c PROGRAM_TEXT] [files ...]"""


DESCRIPTION: Final = """
Mypy is a program that will type check your Python code.

Pass in any files or folders you want to type check. Mypy will
recursively traverse any provided folders to find .py files:

    $ mypy my_program.py my_src_folder

For more information on getting started, see:

- https://mypy.readthedocs.io/en/stable/getting_started.html

For more details on both running mypy and using the flags below, see:

- https://mypy.readthedocs.io/en/stable/running_mypy.html
- https://mypy.readthedocs.io/en/stable/command_line.html

You can also use a config file to configure mypy instead of using
command line flags. For more details, see:

- https://mypy.readthedocs.io/en/stable/config_file.html
"""

FOOTER: Final = """Environment variables:
  Define MYPYPATH for additional module search path entries.
  Define MYPY_CACHE_DIR to override configuration cache_dir path."""


class CapturableArgumentParser(argparse.ArgumentParser):

    """Override ArgumentParser methods that use sys.stdout/sys.stderr directly.

    This is needed because hijacking sys.std* is not thread-safe,
    yet output must be captured to properly support mypy.api.run.
    """

    def __init__(self, *args: Any, **kwargs: Any):
        self.stdout = kwargs.pop("stdout", sys.stdout)
        self.stderr = kwargs.pop("stderr", sys.stderr)
        super().__init__(*args, **kwargs)

    # =====================
    # Help-printing methods
    # =====================
    def print_usage(self, file: IO[str] | None = None) -> None:
        if file is None:
            file = self.stdout
        self._print_message(self.format_usage(), file)

    def print_help(self, file: IO[str] | None = None) -> None:
        if file is None:
            file = self.stdout
        self._print_message(self.format_help(), file)

    def _print_message(self, message: str, file: IO[str] | None = None) -> None:
        if message:
            if file is None:
                file = self.stderr
            file.write(message)

    # ===============
    # Exiting methods
    # ===============
    def exit(self, status: int = 0, message: str | None = None) -> NoReturn:
        if message:
            self._print_message(message, self.stderr)
        sys.exit(status)

    def error(self, message: str) -> NoReturn:
        """error(message: string)

        Prints a usage message incorporating the message to stderr and
        exits.

        If you override this in a subclass, it should not return -- it
        should either exit or raise an exception.
        """
        self.print_usage(self.stderr)
        args = {"prog": self.prog, "message": message}
        self.exit(2, gettext("%(prog)s: error: %(message)s\n") % args)


class CapturableVersionAction(argparse.Action):

    """Supplement CapturableArgumentParser to handle --version.

    This is nearly identical to argparse._VersionAction except,
    like CapturableArgumentParser, it allows output to be captured.

    Another notable difference is that version is mandatory.
    This allows removing a line in __call__ that falls back to parser.version
    (which does not appear to exist).
    """

    def __init__(
        self,
        option_strings: Sequence[str],
        version: str,
        dest: str = argparse.SUPPRESS,
        default: str = argparse.SUPPRESS,
        help: str = "show program's version number and exit",
        stdout: IO[str] | None = None,
    ):
        super().__init__(
            option_strings=option_strings, dest=dest, default=default, nargs=0, help=help
        )
        self.version = version
        self.stdout = stdout or sys.stdout

    def __call__(
        self,
        parser: argparse.ArgumentParser,
        namespace: argparse.Namespace,
        values: str | Sequence[Any] | None,
        option_string: str | None = None,
    ) -> NoReturn:
        formatter = parser._get_formatter()
        formatter.add_text(self.version)
        parser._print_message(formatter.format_help(), self.stdout)
        parser.exit()


def process_options(
    args: list[str],
    stdout: TextIO | None = None,
    stderr: TextIO | None = None,
    require_targets: bool = True,
    server_options: bool = False,
    fscache: FileSystemCache | None = None,
    program: str = "mypy",
    header: str = HEADER,
) -> tuple[list[BuildSource], Options]:
    """Parse command line arguments.

    If a FileSystemCache is passed in, and package_root options are given,
    call fscache.set_package_root() to set the cache's package root.
    """
    stdout = stdout or sys.stdout
    stderr = stderr or sys.stderr

    parser = CapturableArgumentParser(
        prog=program,
        usage=header,
        description=DESCRIPTION,
        epilog=FOOTER,
        fromfile_prefix_chars="@",
        formatter_class=AugmentedHelpFormatter,
        add_help=False,
        stdout=stdout,
        stderr=stderr,
    )

    strict_flag_names: list[str] = []
    strict_flag_assignments: list[tuple[str, bool]] = []

    def add_invertible_flag(
        flag: str,
        *,
        inverse: str | None = None,
        default: bool,
        dest: str | None = None,
        help: str,
        strict_flag: bool = False,
        group: argparse._ActionsContainer | None = None,
    ) -> None:
        if inverse is None:
            inverse = invert_flag_name(flag)
        if group is None:
            group = parser

        if help is not argparse.SUPPRESS:
            help += f" (inverse: {inverse})"

        arg = group.add_argument(
            flag, action="store_false" if default else "store_true", dest=dest, help=help
        )
        dest = arg.dest
        group.add_argument(
            inverse,
            action="store_true" if default else "store_false",
            dest=dest,
            help=argparse.SUPPRESS,
        )
        if strict_flag:
            assert dest is not None
            strict_flag_names.append(flag)
            strict_flag_assignments.append((dest, not default))

    # Unless otherwise specified, arguments will be parsed directly onto an
    # Options object.  Options that require further processing should have
    # their `dest` prefixed with `special-opts:`, which will cause them to be
    # parsed into the separate special_opts namespace object.

    # Note: we have a style guide for formatting the mypy --help text. See
    # https://github.com/python/mypy/wiki/Documentation-Conventions

    general_group = parser.add_argument_group(title="Optional arguments")
    general_group.add_argument(
        "-h", "--help", action="help", help="Show this help message and exit"
    )
    general_group.add_argument(
        "-v", "--verbose", action="count", dest="verbosity", help="More verbose messages"
    )

    compilation_status = "no" if __file__.endswith(".py") else "yes"
    general_group.add_argument(
        "-V",
        "--version",
        action=CapturableVersionAction,
        version="%(prog)s " + __version__ + f" (compiled: {compilation_status})",
        help="Show program's version number and exit",
        stdout=stdout,
    )

    general_group.add_argument(
        "-O",
        "--output",
        metavar="FORMAT",
        help="Set a custom output format",
        choices=OUTPUT_CHOICES,
    )

    config_group = parser.add_argument_group(
        title="Config file",
        description="Use a config file instead of command line arguments. "
        "This is useful if you are using many flags or want "
        "to set different options per each module.",
    )
    config_group.add_argument(
        "--config-file",
        help="Configuration file, must have a [mypy] section "
        "(defaults to {})".format(", ".join(defaults.CONFIG_FILES)),
    )
    add_invertible_flag(
        "--warn-unused-configs",
        default=False,
        strict_flag=True,
        help="Warn about unused '[mypy-<pattern>]' or '[[tool.mypy.overrides]]' "
        "config sections",
        group=config_group,
    )

    imports_group = parser.add_argument_group(
        title="Import discovery", description="Configure how imports are discovered and followed."
    )
    add_invertible_flag(
        "--no-namespace-packages",
        dest="namespace_packages",
        default=True,
        help="Support namespace packages (PEP 420, __init__.py-less)",
        group=imports_group,
    )
    imports_group.add_argument(
        "--ignore-missing-imports",
        action="store_true",
        help="Silently ignore imports of missing modules",
    )
    imports_group.add_argument(
        "--follow-imports",
        choices=["normal", "silent", "skip", "error"],
        default="normal",
        help="How to treat imports (default normal)",
    )
    imports_group.add_argument(
        "--python-executable",
        action="store",
        metavar="EXECUTABLE",
        help="Python executable used for finding PEP 561 compliant installed"
        " packages and stubs",
        dest="special-opts:python_executable",
    )
    imports_group.add_argument(
        "--no-site-packages",
        action="store_true",
        dest="special-opts:no_executable",
        help="Do not search for installed PEP 561 compliant packages",
    )
    imports_group.add_argument(
        "--no-silence-site-packages",
        action="store_true",
        help="Do not silence errors in PEP 561 compliant installed packages",
    )

    platform_group = parser.add_argument_group(
        title="Platform configuration",
        description="Type check code assuming it will be run under certain "
        "runtime conditions. By default, mypy assumes your code "
        "will be run using the same operating system and Python "
        "version you are using to run mypy itself.",
    )
    platform_group.add_argument(
        "--python-version",
        type=parse_version,
        metavar="x.y",
        help="Type check code assuming it will be running on Python x.y",
        dest="special-opts:python_version",
    )
    platform_group.add_argument(
        "-2",
        "--py2",
        dest="special-opts:python_version",
        action="store_const",
        const=defaults.PYTHON2_VERSION,
        help="Use Python 2 mode (same as --python-version 2.7)",
    )
    platform_group.add_argument(
        "--platform",
        action="store",
        metavar="PLATFORM",
        help="Type check special-cased code for the given OS platform "
        "(defaults to sys.platform)",
    )
    platform_group.add_argument(
        "--always-true",
        metavar="NAME",
        action="append",
        default=[],
        help="Additional variable to be considered True (may be repeated)",
    )
    platform_group.add_argument(
        "--always-false",
        metavar="NAME",
        action="append",
        default=[],
        help="Additional variable to be considered False (may be repeated)",
    )

    disallow_any_group = parser.add_argument_group(
        title="Disallow dynamic typing",
        description="Disallow the use of the dynamic 'Any' type under certain conditions.",
    )
    disallow_any_group.add_argument(
        "--disallow-any-unimported",
        default=False,
        action="store_true",
        help="Disallow Any types resulting from unfollowed imports",
    )
    disallow_any_group.add_argument(
        "--disallow-any-expr",
        default=False,
        action="store_true",
        help="Disallow all expressions that have type Any",
    )
    disallow_any_group.add_argument(
        "--disallow-any-decorated",
        default=False,
        action="store_true",
        help="Disallow functions that have Any in their signature "
        "after decorator transformation",
    )
    disallow_any_group.add_argument(
        "--disallow-any-explicit",
        default=False,
        action="store_true",
        help="Disallow explicit Any in type positions",
    )
    add_invertible_flag(
        "--disallow-any-generics",
        default=False,
        strict_flag=True,
        help="Disallow usage of generic types that do not specify explicit type parameters",
        group=disallow_any_group,
    )
    add_invertible_flag(
        "--disallow-subclassing-any",
        default=False,
        strict_flag=True,
        help="Disallow subclassing values of type 'Any' when defining classes",
        group=disallow_any_group,
    )

    untyped_group = parser.add_argument_group(
        title="Untyped definitions and calls",
        description="Configure how untyped definitions and calls are handled. "
        "Note: by default, mypy ignores any untyped function definitions "
        "and assumes any calls to such functions have a return "
        "type of 'Any'.",
    )
    add_invertible_flag(
        "--disallow-untyped-calls",
        default=False,
        strict_flag=True,
        help="Disallow calling functions without type annotations"
        " from functions with type annotations",
        group=untyped_group,
    )
    add_invertible_flag(
        "--disallow-untyped-defs",
        default=False,
        strict_flag=True,
        help="Disallow defining functions without type annotations"
        " or with incomplete type annotations",
        group=untyped_group,
    )
    add_invertible_flag(
        "--disallow-incomplete-defs",
        default=False,
        strict_flag=True,
        help="Disallow defining functions with incomplete type annotations",
        group=untyped_group,
    )
    add_invertible_flag(
        "--check-untyped-defs",
        default=False,
        strict_flag=True,
        help="Type check the interior of functions without type annotations",
        group=untyped_group,
    )
    add_invertible_flag(
        "--disallow-untyped-decorators",
        default=False,
        strict_flag=True,
        help="Disallow decorating typed functions with untyped decorators",
        group=untyped_group,
    )

    none_group = parser.add_argument_group(
        title="None and Optional handling",
        description="Adjust how values of type 'None' are handled. For more context on "
        "how mypy handles values of type 'None', see: "
        "https://mypy.readthedocs.io/en/stable/kinds_of_types.html#no-strict-optional",
    )
    add_invertible_flag(
        "--implicit-optional",
        default=False,
        help="Assume arguments with default values of None are Optional",
        group=none_group,
    )
    none_group.add_argument("--strict-optional", action="store_true", help=argparse.SUPPRESS)
    none_group.add_argument(
        "--no-strict-optional",
        action="store_false",
        dest="strict_optional",
        help="Disable strict Optional checks (inverse: --strict-optional)",
    )

    add_invertible_flag(
        "--force-uppercase-builtins", default=False, help=argparse.SUPPRESS, group=none_group
    )

    add_invertible_flag(
        "--force-union-syntax", default=False, help=argparse.SUPPRESS, group=none_group
    )

    lint_group = parser.add_argument_group(
        title="Configuring warnings",
        description="Detect code that is sound but redundant or problematic.",
    )
    add_invertible_flag(
        "--warn-redundant-casts",
        default=False,
        strict_flag=True,
        help="Warn about casting an expression to its inferred type",
        group=lint_group,
    )
    add_invertible_flag(
        "--warn-unused-ignores",
        default=False,
        strict_flag=True,
        help="Warn about unneeded '# type: ignore' comments",
        group=lint_group,
    )
    add_invertible_flag(
        "--no-warn-no-return",
        dest="warn_no_return",
        default=True,
        help="Do not warn about functions that end without returning",
        group=lint_group,
    )
    add_invertible_flag(
        "--warn-return-any",
        default=False,
        strict_flag=True,
        help="Warn about returning values of type Any from non-Any typed functions",
        group=lint_group,
    )
    add_invertible_flag(
        "--warn-unreachable",
        default=False,
        strict_flag=False,
        help="Warn about statements or expressions inferred to be unreachable",
        group=lint_group,
    )

    # Note: this group is intentionally added here even though we don't add
    # --strict to this group near the end.
    #
    # That way, this group will appear after the various strictness groups
    # but before the remaining flags.
    # We add `--strict` near the end so we don't accidentally miss any strictness
    # flags that are added after this group.
    strictness_group = parser.add_argument_group(title="Miscellaneous strictness flags")

    add_invertible_flag(
        "--allow-untyped-globals",
        default=False,
        strict_flag=False,
        help="Suppress toplevel errors caused by missing annotations",
        group=strictness_group,
    )

    add_invertible_flag(
        "--allow-redefinition",
        default=False,
        strict_flag=False,
        help="Allow unconditional variable redefinition with a new type",
        group=strictness_group,
    )

    add_invertible_flag(
        "--no-implicit-reexport",
        default=True,
        strict_flag=True,
        dest="implicit_reexport",
        help="Treat imports as private unless aliased",
        group=strictness_group,
    )

    add_invertible_flag(
        "--strict-equality",
        default=False,
        strict_flag=True,
        help="Prohibit equality, identity, and container checks for non-overlapping types",
        group=strictness_group,
    )

    add_invertible_flag(
        "--strict-concatenate",
        default=False,
        strict_flag=True,
        help="Make arguments prepended via Concatenate be truly positional-only",
        group=strictness_group,
    )

    strict_help = "Strict mode; enables the following flags: {}".format(
        ", ".join(strict_flag_names)
    )
    strictness_group.add_argument(
        "--strict", action="store_true", dest="special-opts:strict", help=strict_help
    )

    strictness_group.add_argument(
        "--disable-error-code",
        metavar="NAME",
        action="append",
        default=[],
        help="Disable a specific error code",
    )
    strictness_group.add_argument(
        "--enable-error-code",
        metavar="NAME",
        action="append",
        default=[],
        help="Enable a specific error code",
    )

    error_group = parser.add_argument_group(
        title="Configuring error messages",
        description="Adjust the amount of detail shown in error messages.",
    )
    add_invertible_flag(
        "--show-error-context",
        default=False,
        dest="show_error_context",
        help='Precede errors with "note:" messages explaining context',
        group=error_group,
    )
    add_invertible_flag(
        "--show-column-numbers",
        default=False,
        help="Show column numbers in error messages",
        group=error_group,
    )
    add_invertible_flag(
        "--show-error-end",
        default=False,
        help="Show end line/end column numbers in error messages."
        " This implies --show-column-numbers",
        group=error_group,
    )
    add_invertible_flag(
        "--hide-error-codes",
        default=False,
        help="Hide error codes in error messages",
        group=error_group,
    )
    add_invertible_flag(
        "--pretty",
        default=False,
        help="Use visually nicer output in error messages:"
        " Use soft word wrap, show source code snippets,"
        " and show error location markers",
        group=error_group,
    )
    add_invertible_flag(
        "--no-color-output",
        dest="color_output",
        default=True,
        help="Do not colorize error messages",
        group=error_group,
    )
    add_invertible_flag(
        "--no-error-summary",
        dest="error_summary",
        default=True,
        help="Do not show error stats summary",
        group=error_group,
    )
    add_invertible_flag(
        "--show-absolute-path",
        default=False,
        help="Show absolute paths to files",
        group=error_group,
    )
    error_group.add_argument(
        "--soft-error-limit",
        default=defaults.MANY_ERRORS_THRESHOLD,
        type=int,
        dest="many_errors_threshold",
        help=argparse.SUPPRESS,
    )

    incremental_group = parser.add_argument_group(
        title="Incremental mode",
        description="Adjust how mypy incrementally type checks and caches modules. "
        "Mypy caches type information about modules into a cache to "
        "let you speed up future invocations of mypy. Also see "
        "mypy's daemon mode: "
        "mypy.readthedocs.io/en/stable/mypy_daemon.html#mypy-daemon",
    )
    incremental_group.add_argument(
        "-i", "--incremental", action="store_true", help=argparse.SUPPRESS
    )
    incremental_group.add_argument(
        "--no-incremental",
        action="store_false",
        dest="incremental",
        help="Disable module cache (inverse: --incremental)",
    )
    incremental_group.add_argument(
        "--cache-dir",
        action="store",
        metavar="DIR",
        help="Store module cache info in the given folder in incremental mode "
        "(defaults to '{}')".format(defaults.CACHE_DIR),
    )
    add_invertible_flag(
        "--sqlite-cache",
        default=False,
        help="Use a sqlite database to store the cache",
        group=incremental_group,
    )
    incremental_group.add_argument(
        "--cache-fine-grained",
        action="store_true",
        help="Include fine-grained dependency information in the cache for the mypy daemon",
    )
    incremental_group.add_argument(
        "--skip-version-check",
        action="store_true",
        help="Allow using cache written by older mypy version",
    )
    incremental_group.add_argument(
        "--skip-cache-mtime-checks",
        action="store_true",
        help="Skip cache internal consistency checks based on mtime",
    )

    internals_group = parser.add_argument_group(
        title="Advanced options", description="Debug and customize mypy internals."
    )
    internals_group.add_argument("--pdb", action="store_true", help="Invoke pdb on fatal error")
    internals_group.add_argument(
        "--show-traceback", "--tb", action="store_true", help="Show traceback on fatal error"
    )
    internals_group.add_argument(
        "--raise-exceptions", action="store_true", help="Raise exception on fatal error"
    )
    internals_group.add_argument(
        "--custom-typing-module",
        metavar="MODULE",
        dest="custom_typing_module",
        help="Use a custom typing module",
    )
    internals_group.add_argument(
        "--disable-recursive-aliases",
        action="store_true",
        help="Disable experimental support for recursive type aliases",
    )
    # Deprecated reverse variant of the above.
    internals_group.add_argument(
        "--enable-recursive-aliases", action="store_true", help=argparse.SUPPRESS
    )
    parser.add_argument(
        "--enable-incomplete-feature",
        action="append",
        metavar="FEATURE",
        help="Enable support of incomplete/experimental features for early preview",
    )
    internals_group.add_argument(
        "--custom-typeshed-dir", metavar="DIR", help="Use the custom typeshed in DIR"
    )
    add_invertible_flag(
        "--warn-incomplete-stub",
        default=False,
        help="Warn if missing type annotation in typeshed, only relevant with"
        " --disallow-untyped-defs or --disallow-incomplete-defs enabled",
        group=internals_group,
    )
    internals_group.add_argument(
        "--shadow-file",
        nargs=2,
        metavar=("SOURCE_FILE", "SHADOW_FILE"),
        dest="shadow_file",
        action="append",
        help="When encountering SOURCE_FILE, read and type check "
        "the contents of SHADOW_FILE instead.",
    )
    internals_group.add_argument("--fast-exit", action="store_true", help=argparse.SUPPRESS)
    internals_group.add_argument(
        "--no-fast-exit", action="store_false", dest="fast_exit", help=argparse.SUPPRESS
    )
    # This flag is useful for mypy tests, where function bodies may be omitted. Plugin developers
    # may want to use this as well in their tests.
    add_invertible_flag(
        "--allow-empty-bodies", default=False, help=argparse.SUPPRESS, group=internals_group
    )
    # This undocumented feature exports limited line-level dependency information.
    internals_group.add_argument("--export-ref-info", action="store_true", help=argparse.SUPPRESS)

    report_group = parser.add_argument_group(
        title="Report generation", description="Generate a report in the specified format."
    )
    for report_type in sorted(defaults.REPORTER_NAMES):
        if report_type not in {"memory-xml"}:
            report_group.add_argument(
                f"--{report_type.replace('_', '-')}-report",
                metavar="DIR",
                dest=f"special-opts:{report_type}_report",
            )

    other_group = parser.add_argument_group(title="Miscellaneous")
    other_group.add_argument("--quickstart-file", help=argparse.SUPPRESS)
    other_group.add_argument("--junit-xml", help="Write junit.xml to the given file")
    other_group.add_argument(
        "--find-occurrences",
        metavar="CLASS.MEMBER",
        dest="special-opts:find_occurrences",
        help="Print out all usages of a class member (experimental)",
    )
    other_group.add_argument(
        "--scripts-are-modules",
        action="store_true",
        help="Script x becomes module x instead of __main__",
    )

    add_invertible_flag(
        "--install-types",
        default=False,
        strict_flag=False,
        help="Install detected missing library stub packages using pip",
        group=other_group,
    )
    add_invertible_flag(
        "--non-interactive",
        default=False,
        strict_flag=False,
        help=(
            "Install stubs without asking for confirmation and hide "
            + "errors, with --install-types"
        ),
        group=other_group,
        inverse="--interactive",
    )

    if server_options:
        # TODO: This flag is superfluous; remove after a short transition (2018-03-16)
        other_group.add_argument(
            "--experimental",
            action="store_true",
            dest="fine_grained_incremental",
            help="Enable fine-grained incremental mode",
        )
        other_group.add_argument(
            "--use-fine-grained-cache",
            action="store_true",
            help="Use the cache in fine-grained incremental mode",
        )

    # hidden options
    parser.add_argument(
        "--stats", action="store_true", dest="dump_type_stats", help=argparse.SUPPRESS
    )
    parser.add_argument(
        "--inferstats", action="store_true", dest="dump_inference_stats", help=argparse.SUPPRESS
    )
    parser.add_argument("--dump-build-stats", action="store_true", help=argparse.SUPPRESS)
    # Dump timing stats for each processed file into the given output file
    parser.add_argument("--timing-stats", dest="timing_stats", help=argparse.SUPPRESS)
    # Dump per line type checking timing stats for each processed file into the given
    # output file. Only total time spent in each top level expression will be shown.
    # Times are show in microseconds.
    parser.add_argument(
        "--line-checking-stats", dest="line_checking_stats", help=argparse.SUPPRESS
    )
    # --debug-cache will disable any cache-related compressions/optimizations,
    # which will make the cache writing process output pretty-printed JSON (which
    # is easier to debug).
    parser.add_argument("--debug-cache", action="store_true", help=argparse.SUPPRESS)
    # --dump-deps will dump all fine-grained dependencies to stdout
    parser.add_argument("--dump-deps", action="store_true", help=argparse.SUPPRESS)
    # --dump-graph will dump the contents of the graph of SCCs and exit.
    parser.add_argument("--dump-graph", action="store_true", help=argparse.SUPPRESS)
    # --semantic-analysis-only does exactly that.
    parser.add_argument("--semantic-analysis-only", action="store_true", help=argparse.SUPPRESS)
    # --local-partial-types disallows partial types spanning module top level and a function
    # (implicitly defined in fine-grained incremental mode)
    parser.add_argument("--local-partial-types", action="store_true", help=argparse.SUPPRESS)
    # --logical-deps adds some more dependencies that are not semantically needed, but
    # may be helpful to determine relative importance of classes and functions for overall
    # type precision in a code base. It also _removes_ some deps, so this flag should be never
    # used except for generating code stats. This also automatically enables --cache-fine-grained.
    # NOTE: This is an experimental option that may be modified or removed at any time.
    parser.add_argument("--logical-deps", action="store_true", help=argparse.SUPPRESS)
    # --bazel changes some behaviors for use with Bazel (https://bazel.build).
    parser.add_argument("--bazel", action="store_true", help=argparse.SUPPRESS)
    # --package-root adds a directory below which directories are considered
    # packages even without __init__.py.  May be repeated.
    parser.add_argument(
        "--package-root", metavar="ROOT", action="append", default=[], help=argparse.SUPPRESS
    )
    # --cache-map FILE ... gives a mapping from source files to cache files.
    # Each triple of arguments is a source file, a cache meta file, and a cache data file.
    # Modules not mentioned in the file will go through cache_dir.
    # Must be followed by another flag or by '--' (and then only file args may follow).
    parser.add_argument(
        "--cache-map", nargs="+", dest="special-opts:cache_map", help=argparse.SUPPRESS
    )
    # --debug-serialize will run tree.serialize() even if cache generation is disabled.
    # Useful for mypy_primer to detect serialize errors earlier.
    parser.add_argument("--debug-serialize", action="store_true", help=argparse.SUPPRESS)
    # This one is deprecated, but we will keep it for few releases.
    parser.add_argument(
        "--enable-incomplete-features", action="store_true", help=argparse.SUPPRESS
    )
    parser.add_argument(
        "--disable-bytearray-promotion", action="store_true", help=argparse.SUPPRESS
    )
    parser.add_argument(
        "--disable-memoryview-promotion", action="store_true", help=argparse.SUPPRESS
    )

    # options specifying code to check
    code_group = parser.add_argument_group(
        title="Running code",
        description="Specify the code you want to type check. For more details, see "
        "mypy.readthedocs.io/en/stable/running_mypy.html#running-mypy",
    )
    add_invertible_flag(
        "--explicit-package-bases",
        default=False,
        help="Use current directory and MYPYPATH to determine module names of files passed",
        group=code_group,
    )
    add_invertible_flag(
        "--fast-module-lookup", default=False, help=argparse.SUPPRESS, group=code_group
    )
    code_group.add_argument(
        "--exclude",
        action="append",
        metavar="PATTERN",
        default=[],
        help=(
            "Regular expression to match file names, directory names or paths which mypy should "
            "ignore while recursively discovering files to check, e.g. --exclude '/setup\\.py$'. "
            "May be specified more than once, eg. --exclude a --exclude b"
        ),
    )
    code_group.add_argument(
        "-m",
        "--module",
        action="append",
        metavar="MODULE",
        default=[],
        dest="special-opts:modules",
        help="Type-check module; can repeat for more modules",
    )
    code_group.add_argument(
        "-p",
        "--package",
        action="append",
        metavar="PACKAGE",
        default=[],
        dest="special-opts:packages",
        help="Type-check package recursively; can be repeated",
    )
    code_group.add_argument(
        "-c",
        "--command",
        action="append",
        metavar="PROGRAM_TEXT",
        dest="special-opts:command",
        help="Type-check program passed in as string",
    )
    code_group.add_argument(
        metavar="files",
        nargs="*",
        dest="special-opts:files",
        help="Type-check given files or directories",
    )

    # Parse arguments once into a dummy namespace so we can get the
    # filename for the config file and know if the user requested all strict options.
    dummy = argparse.Namespace()
    parser.parse_args(args, dummy)
    config_file = dummy.config_file
    # Don't explicitly test if "config_file is not None" for this check.
    # This lets `--config-file=` (an empty string) be used to disable all config files.
    if config_file and not os.path.exists(config_file):
        parser.error(f"Cannot find config file '{config_file}'")

    options = Options()

    def set_strict_flags() -> None:
        for dest, value in strict_flag_assignments:
            setattr(options, dest, value)

    # Parse config file first, so command line can override.
    parse_config_file(options, set_strict_flags, config_file, stdout, stderr)

    # Set strict flags before parsing (if strict mode enabled), so other command
    # line options can override.
    if getattr(dummy, "special-opts:strict"):
        set_strict_flags()

    # Override cache_dir if provided in the environment
    environ_cache_dir = os.getenv("MYPY_CACHE_DIR", "")
    if environ_cache_dir.strip():
        options.cache_dir = environ_cache_dir
    options.cache_dir = os.path.expanduser(options.cache_dir)

    # Parse command line for real, using a split namespace.
    special_opts = argparse.Namespace()
    parser.parse_args(args, SplitNamespace(options, special_opts, "special-opts:"))

    # The python_version is either the default, which can be overridden via a config file,
    # or stored in special_opts and is passed via the command line.
    options.python_version = special_opts.python_version or options.python_version
    if options.python_version < (3,):
        parser.error(
            "Mypy no longer supports checking Python 2 code. "
            "Consider pinning to mypy<0.980 if you need to check Python 2 code."
        )
    try:
        infer_python_executable(options, special_opts)
    except PythonExecutableInferenceError as e:
        parser.error(str(e))

    if special_opts.no_executable or options.no_site_packages:
        options.python_executable = None

    # Paths listed in the config file will be ignored if any paths, modules or packages
    # are passed on the command line.
    if not (special_opts.files or special_opts.packages or special_opts.modules):
        if options.files:
            special_opts.files = options.files
        if options.packages:
            special_opts.packages = options.packages
        if options.modules:
            special_opts.modules = options.modules

    # Check for invalid argument combinations.
    if require_targets:
        code_methods = sum(
            bool(c)
            for c in [
                special_opts.modules + special_opts.packages,
                special_opts.command,
                special_opts.files,
            ]
        )
        if code_methods == 0 and not options.install_types:
            parser.error("Missing target module, package, files, or command.")
        elif code_methods > 1:
            parser.error("May only specify one of: module/package, files, or command.")
    if options.explicit_package_bases and not options.namespace_packages:
        parser.error(
            "Can only use --explicit-package-bases with --namespace-packages, since otherwise "
            "examining __init__.py's is sufficient to determine module names for files"
        )

    # Check for overlapping `--always-true` and `--always-false` flags.
    overlap = set(options.always_true) & set(options.always_false)
    if overlap:
        parser.error(
            "You can't make a variable always true and always false (%s)"
            % ", ".join(sorted(overlap))
        )

    # Process `--enable-error-code` and `--disable-error-code` flags
    disabled_codes = set(options.disable_error_code)
    enabled_codes = set(options.enable_error_code)

    valid_error_codes = set(error_codes.keys())

    invalid_codes = (enabled_codes | disabled_codes) - valid_error_codes
    if invalid_codes:
        parser.error(f"Invalid error code(s): {', '.join(sorted(invalid_codes))}")

    options.disabled_error_codes |= {error_codes[code] for code in disabled_codes}
    options.enabled_error_codes |= {error_codes[code] for code in enabled_codes}

    # Enabling an error code always overrides disabling
    options.disabled_error_codes -= options.enabled_error_codes

    # Validate incomplete features.
    for feature in options.enable_incomplete_feature:
        if feature not in INCOMPLETE_FEATURES:
            parser.error(f"Unknown incomplete feature: {feature}")
    if options.enable_incomplete_features:
        print(
            "Warning: --enable-incomplete-features is deprecated, use"
            " --enable-incomplete-feature=FEATURE instead"
        )
        options.enable_incomplete_feature = list(INCOMPLETE_FEATURES)

    # Compute absolute path for custom typeshed (if present).
    if options.custom_typeshed_dir is not None:
        options.abs_custom_typeshed_dir = os.path.abspath(options.custom_typeshed_dir)

    # Set build flags.
    if special_opts.find_occurrences:
        state.find_occurrences = special_opts.find_occurrences.split(".")
        assert state.find_occurrences is not None
        if len(state.find_occurrences) < 2:
            parser.error("Can only find occurrences of class members.")
        if len(state.find_occurrences) != 2:
            parser.error("Can only find occurrences of non-nested class members.")

    # Set reports.
    for flag, val in vars(special_opts).items():
        if flag.endswith("_report") and val is not None:
            report_type = flag[:-7].replace("_", "-")
            report_dir = val
            options.report_dirs[report_type] = report_dir

    # Process --package-root.
    if options.package_root:
        process_package_roots(fscache, parser, options)

    # Process --cache-map.
    if special_opts.cache_map:
        if options.sqlite_cache:
            parser.error("--cache-map is incompatible with --sqlite-cache")

        process_cache_map(parser, special_opts, options)

    # An explicitly specified cache_fine_grained implies local_partial_types
    # (because otherwise the cache is not compatible with dmypy)
    if options.cache_fine_grained:
        options.local_partial_types = True

    #  Implicitly show column numbers if error location end is shown
    if options.show_error_end:
        options.show_column_numbers = True

    # Let logical_deps imply cache_fine_grained (otherwise the former is useless).
    if options.logical_deps:
        options.cache_fine_grained = True

    if options.enable_recursive_aliases:
        print(
            "Warning: --enable-recursive-aliases is deprecated;"
            " recursive types are enabled by default"
        )

    # Set target.
    if special_opts.modules + special_opts.packages:
        options.build_type = BuildType.MODULE
        sys_path, _ = get_search_dirs(options.python_executable)
        search_paths = SearchPaths(
            (os.getcwd(),), tuple(mypy_path() + options.mypy_path), tuple(sys_path), ()
        )
        targets = []
        # TODO: use the same cache that the BuildManager will
        cache = FindModuleCache(search_paths, fscache, options)
        for p in special_opts.packages:
            if os.sep in p or os.altsep and os.altsep in p:
                fail(f"Package name '{p}' cannot have a slash in it.", stderr, options)
            p_targets = cache.find_modules_recursive(p)
            if not p_targets:
                fail(f"Can't find package '{p}'", stderr, options)
            targets.extend(p_targets)
        for m in special_opts.modules:
            targets.append(BuildSource(None, m, None))
        return targets, options
    elif special_opts.command:
        options.build_type = BuildType.PROGRAM_TEXT
        targets = [BuildSource(None, None, "\n".join(special_opts.command))]
        return targets, options
    else:
        try:
            targets = create_source_list(special_opts.files, options, fscache)
        # Variable named e2 instead of e to work around mypyc bug #620
        # which causes issues when using the same variable to catch
        # exceptions of different types.
        except InvalidSourceList as e2:
            fail(str(e2), stderr, options)
        return targets, options


def process_package_roots(
    fscache: FileSystemCache | None, parser: argparse.ArgumentParser, options: Options
) -> None:
    """Validate and normalize package_root."""
    if fscache is None:
        parser.error("--package-root does not work here (no fscache)")
    assert fscache is not None  # Since mypy doesn't know parser.error() raises.
    # Do some stuff with drive letters to make Windows happy (esp. tests).
    current_drive, _ = os.path.splitdrive(os.getcwd())
    dot = os.curdir
    dotslash = os.curdir + os.sep
    dotdotslash = os.pardir + os.sep
    trivial_paths = {dot, dotslash}
    package_root = []
    for root in options.package_root:
        if os.path.isabs(root):
            parser.error(f"Package root cannot be absolute: {root!r}")
        drive, root = os.path.splitdrive(root)
        if drive and drive != current_drive:
            parser.error(f"Package root must be on current drive: {drive + root!r}")
        # Empty package root is always okay.
        if root:
            root = os.path.relpath(root)  # Normalize the heck out of it.
            if not root.endswith(os.sep):
                root = root + os.sep
            if root.startswith(dotdotslash):
                parser.error(f"Package root cannot be above current directory: {root!r}")
            if root in trivial_paths:
                root = ""
        package_root.append(root)
    options.package_root = package_root
    # Pass the package root on the the filesystem cache.
    fscache.set_package_root(package_root)


def process_cache_map(
    parser: argparse.ArgumentParser, special_opts: argparse.Namespace, options: Options
) -> None:
    """Validate cache_map and copy into options.cache_map."""
    n = len(special_opts.cache_map)
    if n % 3 != 0:
        parser.error("--cache-map requires one or more triples (see source)")
    for i in range(0, n, 3):
        source, meta_file, data_file = special_opts.cache_map[i : i + 3]
        if source in options.cache_map:
            parser.error(f"Duplicate --cache-map source {source})")
        if not source.endswith(".py") and not source.endswith(".pyi"):
            parser.error(f"Invalid --cache-map source {source} (triple[0] must be *.py[i])")
        if not meta_file.endswith(".meta.json"):
            parser.error(
                "Invalid --cache-map meta_file %s (triple[1] must be *.meta.json)" % meta_file
            )
        if not data_file.endswith(".data.json"):
            parser.error(
                "Invalid --cache-map data_file %s (triple[2] must be *.data.json)" % data_file
            )
        options.cache_map[source] = (meta_file, data_file)


def maybe_write_junit_xml(td: float, serious: bool, messages: list[str], options: Options) -> None:
    if options.junit_xml:
        py_version = f"{options.python_version[0]}_{options.python_version[1]}"
        util.write_junit_xml(
            td, serious, messages, options.junit_xml, py_version, options.platform
        )


def fail(msg: str, stderr: TextIO, options: Options) -> NoReturn:
    """Fail with a serious error."""
    stderr.write(f"{msg}\n")
    maybe_write_junit_xml(0.0, serious=True, messages=[msg], options=options)
    sys.exit(2)


def read_types_packages_to_install(cache_dir: str, after_run: bool) -> list[str]:
    if not os.path.isdir(cache_dir):
        if not after_run:
            sys.stderr.write(
                "error: Can't determine which types to install with no files to check "
                + "(and no cache from previous mypy run)\n"
            )
        else:
            sys.stderr.write("error: --install-types failed (no mypy cache directory)\n")
        sys.exit(2)
    fnam = build.missing_stubs_file(cache_dir)
    if not os.path.isfile(fnam):
        # No missing stubs.
        return []
    with open(fnam) as f:
        return [line.strip() for line in f]


def install_types(
    formatter: util.FancyFormatter,
    options: Options,
    *,
    after_run: bool = False,
    non_interactive: bool = False,
) -> bool:
    """Install stub packages using pip if some missing stubs were detected."""
    packages = read_types_packages_to_install(options.cache_dir, after_run)
    if not packages:
        # If there are no missing stubs, generate no output.
        return False
    if after_run and not non_interactive:
        print()
    print("Installing missing stub packages:")
    assert options.python_executable, "Python executable required to install types"
    cmd = [options.python_executable, "-m", "pip", "install"] + packages
    print(formatter.style(" ".join(cmd), "none", bold=True))
    print()
    if not non_interactive:
        x = input("Install? [yN] ")
        if not x.strip() or not x.lower().startswith("y"):
            print(formatter.style("mypy: Skipping installation", "red", bold=True))
            sys.exit(2)
        print()
    subprocess.run(cmd)
    return True