python3-mypy 0.560-1 / usr / lib / python3 / dist-packages / mypy / main.py

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

import argparse
import configparser
import fnmatch
import os
import re
import sys
import time

from typing import Any, Dict, List, Mapping, Optional, Sequence, Set, Tuple

from mypy import build
from mypy import defaults
from mypy import experiments
from mypy import util
from mypy.build import BuildSource, BuildResult, PYTHON_EXTENSIONS
from mypy.errors import CompileError
from mypy.options import Options, BuildType
from mypy.report import reporter_classes

from mypy.version import __version__

PY_EXTENSIONS = tuple(PYTHON_EXTENSIONS)


class InvalidPackageName(Exception):
    """Exception indicating that a package name was invalid."""


orig_stat = os.stat


def stat_proxy(path: str) -> os.stat_result:
    try:
        st = orig_stat(path)
    except os.error as err:
        print("stat(%r) -> %s" % (path, 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(script_path: Optional[str], args: Optional[List[str]] = None) -> None:
    """Main entry point to the type checker.

    Args:
        script_path: Path to the 'mypy' script (used for finding data files).
        args: Custom command-line arguments.  If not given, sys.argv[1:] will
        be used.
    """
    t0 = time.time()
    # To log stat() calls: os.stat = stat_proxy
    if script_path:
        bin_dir = find_bin_directory(script_path)  # type: Optional[str]
    else:
        bin_dir = None
    sys.setrecursionlimit(2 ** 14)
    if args is None:
        args = sys.argv[1:]
    sources, options = process_options(args)
    serious = False
    try:
        res = type_check_only(sources, bin_dir, options)
        a = res.errors
    except CompileError as e:
        a = e.messages
        if not e.use_stdout:
            serious = True
    if options.warn_unused_configs and options.unused_configs:
        print("Warning: unused section(s) in %s: %s" %
              (options.config_file,
               ", ".join("[mypy-%s]" % glob for glob in options.unused_configs.values())),
              file=sys.stderr)
    if options.junit_xml:
        t1 = time.time()
        util.write_junit_xml(t1 - t0, serious, a, options.junit_xml)
    if a:
        f = sys.stderr if serious else sys.stdout
        try:
            for m in a:
                f.write(m + '\n')
        except BrokenPipeError:
            pass
        sys.exit(1)


def find_bin_directory(script_path: str) -> str:
    """Find the directory that contains this script.

    This is used by build to find stubs and other data files.
    """
    # Follow up to 5 symbolic links (cap to avoid cycles).
    for i in range(5):
        if os.path.islink(script_path):
            script_path = readlinkabs(script_path)
        else:
            break
    return os.path.dirname(script_path)


def readlinkabs(link: str) -> str:
    """Return an absolute path to symbolic link destination."""
    # Adapted from code by Greg Smith.
    assert os.path.islink(link)
    path = os.readlink(link)
    if os.path.isabs(path):
        return path
    return os.path.join(os.path.dirname(link), path)


def type_check_only(sources: List[BuildSource], bin_dir: Optional[str],
                    options: Options) -> BuildResult:
    # Type-check the program and dependencies.
    return build.build(sources=sources,
                       bin_dir=bin_dir,
                       options=options)


FOOTER = """environment variables:
MYPYPATH     additional module search path"""


class SplitNamespace(argparse.Namespace):
    def __init__(self, standard_namespace: object, alt_namespace: object, alt_prefix: str) -> None:
        self.__dict__['_standard_namespace'] = standard_namespace
        self.__dict__['_alt_namespace'] = alt_namespace
        self.__dict__['_alt_prefix'] = alt_prefix

    def _get(self) -> Tuple[Any, Any]:
        return (self._standard_namespace, self._alt_namespace)

    def __setattr__(self, name: str, value: Any) -> None:
        if name.startswith(self._alt_prefix):
            setattr(self._alt_namespace, name[len(self._alt_prefix):], value)
        else:
            setattr(self._standard_namespace, name, value)

    def __getattr__(self, name: str) -> Any:
        if name.startswith(self._alt_prefix):
            return getattr(self._alt_namespace, name[len(self._alt_prefix):])
        else:
            return getattr(self._standard_namespace, name)


def parse_version(v: str) -> Tuple[int, int]:
    m = re.match(r'\A(\d)\.(\d+)\Z', v)
    if not m:
        raise argparse.ArgumentTypeError(
            "Invalid python version '{}' (expected format: 'x.y')".format(v))
    major, minor = int(m.group(1)), int(m.group(2))
    if major == 2:
        if minor != 7:
            raise argparse.ArgumentTypeError(
                "Python 2.{} is not supported (must be 2.7)".format(minor))
    elif major == 3:
        if minor < defaults.PYTHON3_VERSION_MIN[1]:
            raise argparse.ArgumentTypeError(
                "Python 3.{0} is not supported (must be {1}.{2} or higher)".format(minor,
                                                                    *defaults.PYTHON3_VERSION_MIN))
    else:
        raise argparse.ArgumentTypeError(
            "Python major version '{}' out of range (must be 2 or 3)".format(major))
    return major, minor


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


# Define pairs of flag prefixes with inverse meaning.
flag_prefix_pairs = [
    ('allow', 'disallow'),
    ('show', 'hide'),
]
flag_prefix_map = {}  # type: 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 '--{}-{}'.format(flag_prefix_map[prefix], rest)
        elif prefix == 'no':
            return '--{}'.format(rest)

    return '--no-{}'.format(flag[2:])


def process_options(args: List[str],
                    require_targets: bool = True
                    ) -> Tuple[List[BuildSource], Options]:
    """Parse command line arguments."""

    parser = argparse.ArgumentParser(prog='mypy', epilog=FOOTER,
                                     fromfile_prefix_chars='@',
                                     formatter_class=AugmentedHelpFormatter)

    strict_flag_names = []  # type: List[str]
    strict_flag_assignments = []  # type: List[Tuple[str, bool]]

    def add_invertible_flag(flag: str,
                            *,
                            inverse: Optional[str] = None,
                            default: bool,
                            dest: Optional[str] = None,
                            help: str,
                            strict_flag: bool = False
                            ) -> None:
        if inverse is None:
            inverse = invert_flag_name(flag)

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

        arg = parser.add_argument(flag,  # type: ignore  # incorrect stub for add_argument
                                  action='store_false' if default else 'store_true',
                                  dest=dest,
                                  help=help)
        dest = arg.dest
        arg = parser.add_argument(inverse,  # type: ignore  # incorrect stub for add_argument
                                  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.
    parser.add_argument('-v', '--verbose', action='count', dest='verbosity',
                        help="more verbose messages")
    parser.add_argument('-V', '--version', action='version',
                        version='%(prog)s ' + __version__)
    parser.add_argument('--python-version', type=parse_version, metavar='x.y',
                        help='use Python x.y')
    parser.add_argument('--platform', action='store', metavar='PLATFORM',
                        help="typecheck special-cased code for the given OS platform "
                        "(defaults to sys.platform).")
    parser.add_argument('-2', '--py2', dest='python_version', action='store_const',
                        const=defaults.PYTHON2_VERSION, help="use Python 2 mode")
    parser.add_argument('--ignore-missing-imports', action='store_true',
                        help="silently ignore imports of missing modules")
    parser.add_argument('--follow-imports', choices=['normal', 'silent', 'skip', 'error'],
                        default='normal', help="how to treat imports (default normal)")
    parser.add_argument('--disallow-any-unimported', default=False, action='store_true',
                        help="disallow Any types resulting from unfollowed imports")
    parser.add_argument('--disallow-any-expr', default=False, action='store_true',
                        help='disallow all expressions that have type Any')
    parser.add_argument('--disallow-any-decorated', default=False, action='store_true',
                        help='disallow functions that have Any in their signature '
                             'after decorator transformation')
    parser.add_argument('--disallow-any-explicit', default=False, action='store_true',
                        help='disallow explicit Any in type positions')
    parser.add_argument('--disallow-any-generics', default=False, action='store_true',
                        help='disallow usage of generic types that do not specify explicit '
                             'type parameters')
    add_invertible_flag('--disallow-untyped-calls', default=False, strict_flag=True,
                        help="disallow calling functions without type annotations"
                        " from functions with type annotations")
    add_invertible_flag('--disallow-untyped-defs', default=False, strict_flag=True,
                        help="disallow defining functions without type annotations"
                        " or with incomplete type annotations")
    add_invertible_flag('--disallow-incomplete-defs', default=False, strict_flag=True,
                        help="disallow defining functions with incomplete type annotations")
    add_invertible_flag('--check-untyped-defs', default=False, strict_flag=True,
                        help="type check the interior of functions without type annotations")
    add_invertible_flag('--disallow-subclassing-any', default=False, strict_flag=True,
                        help="disallow subclassing values of type 'Any' when defining classes")
    add_invertible_flag('--warn-incomplete-stub', default=False,
                        help="warn if missing type annotation in typeshed, only relevant with"
                        " --check-untyped-defs enabled")
    add_invertible_flag('--disallow-untyped-decorators', default=False, strict_flag=True,
                        help="disallow decorating typed functions with untyped decorators")
    add_invertible_flag('--warn-redundant-casts', default=False, strict_flag=True,
                        help="warn about casting an expression to its inferred type")
    add_invertible_flag('--no-warn-no-return', dest='warn_no_return', default=True,
                        help="do not warn about functions that end without returning")
    add_invertible_flag('--warn-return-any', default=False, strict_flag=True,
                        help="warn about returning values of type Any"
                             " from non-Any typed functions")
    add_invertible_flag('--warn-unused-ignores', default=False, strict_flag=True,
                        help="warn about unneeded '# type: ignore' comments")
    add_invertible_flag('--warn-unused-configs', default=False, strict_flag=True,
                        help="warn about unnused '[mypy-<pattern>]' config sections")
    add_invertible_flag('--show-error-context', default=False,
                        dest='show_error_context',
                        help='Precede errors with "note:" messages explaining context')
    add_invertible_flag('--no-implicit-optional', default=False, strict_flag=True,
                        help="don't assume arguments with default values of None are Optional")
    parser.add_argument('-i', '--incremental', action='store_true',
                        help="enable module cache, (inverse: --no-incremental)")
    parser.add_argument('--no-incremental', action='store_false', dest='incremental',
                        help=argparse.SUPPRESS)
    parser.add_argument('--quick-and-dirty', action='store_true',
                        help="use cache even if dependencies out of date "
                        "(implies --incremental)")
    parser.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))
    parser.add_argument('--skip-version-check', action='store_true',
                        help="allow using cache written by older mypy version")
    add_invertible_flag('--strict-optional', default=False, strict_flag=True,
                        help="enable experimental strict Optional checks")
    parser.add_argument('--strict-optional-whitelist', metavar='GLOB', nargs='*',
                        help="suppress strict Optional errors in all but the provided files "
                        "(experimental -- read documentation before using!).  "
                        "Implies --strict-optional.  Has the undesirable side-effect of "
                        "suppressing other errors in non-whitelisted files.")
    parser.add_argument('--junit-xml', help="write junit.xml to the given file")
    parser.add_argument('--pdb', action='store_true', help="invoke pdb on fatal error")
    parser.add_argument('--show-traceback', '--tb', action='store_true',
                        help="show traceback on fatal error")
    parser.add_argument('--stats', action='store_true', dest='dump_type_stats', help="dump stats")
    parser.add_argument('--inferstats', action='store_true', dest='dump_inference_stats',
                        help="dump type inference stats")
    parser.add_argument('--custom-typing', metavar='MODULE', dest='custom_typing_module',
                        help="use a custom typing module")
    parser.add_argument('--custom-typeshed-dir', metavar='DIR',
                        help="use the custom typeshed in DIR")
    parser.add_argument('--scripts-are-modules', action='store_true',
                        help="Script x becomes module x instead of __main__")
    parser.add_argument('--config-file',
                        help="Configuration file, must have a [mypy] section "
                        "(defaults to {})".format(defaults.CONFIG_FILE))
    add_invertible_flag('--show-column-numbers', default=False,
                        help="Show column numbers in error messages")
    parser.add_argument('--find-occurrences', metavar='CLASS.MEMBER',
                        dest='special-opts:find_occurrences',
                        help="print out all usages of a class member (experimental)")
    strict_help = "Strict mode. Enables the following flags: {}".format(
        ", ".join(strict_flag_names))
    parser.add_argument('--strict', action='store_true', dest='special-opts:strict',
                        help=strict_help)
    parser.add_argument('--shadow-file', nargs=2, metavar=('SOURCE_FILE', 'SHADOW_FILE'),
                        dest='shadow_file',
                        help='Typecheck SHADOW_FILE in place of SOURCE_FILE.')
    # hidden options
    # --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)
    # deprecated options
    parser.add_argument('--disallow-any', dest='special-opts:disallow_any',
                        help=argparse.SUPPRESS)
    add_invertible_flag('--strict-boolean', default=False,
                        help=argparse.SUPPRESS)
    parser.add_argument('-f', '--dirty-stubs', action='store_true',
                        dest='special-opts:dirty_stubs',
                        help=argparse.SUPPRESS)
    parser.add_argument('--use-python-path', action='store_true',
                        dest='special-opts:use_python_path',
                        help=argparse.SUPPRESS)
    parser.add_argument('-s', '--silent-imports', action='store_true',
                        dest='special-opts:silent_imports',
                        help=argparse.SUPPRESS)
    parser.add_argument('--almost-silent', action='store_true',
                        dest='special-opts:almost_silent',
                        help=argparse.SUPPRESS)
    parser.add_argument('--fast-parser', action='store_true', dest='special-opts:fast_parser',
                        help=argparse.SUPPRESS)
    parser.add_argument('--no-fast-parser', action='store_true',
                        dest='special-opts:no_fast_parser',
                        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(reporter_classes):
        report_group.add_argument('--%s-report' % report_type.replace('_', '-'),
                                  metavar='DIR',
                                  dest='special-opts:%s_report' % report_type)

    code_group = parser.add_argument_group(title='How to specify the code to type check')
    code_group.add_argument('-m', '--module', action='append', metavar='MODULE',
                            dest='special-opts:modules',
                            help="type-check module; can repeat for more modules")
    # TODO: `mypy -p A -p B` currently silently ignores A
    # (last option wins).  Perhaps -c, -m and -p could just be
    # command-line flags that modify how we interpret self.files?
    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('-p', '--package', metavar='PACKAGE', dest='special-opts:package',
                            help="type-check all files in a directory")
    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
    if config_file is not None and not os.path.exists(config_file):
        parser.error("Cannot find config file '%s'" % config_file)

    # Parse config file first, so command line can override.
    options = Options()
    parse_config_file(options, config_file)

    # Set strict flags before parsing (if strict mode enabled), so other command
    # line options can override.
    if getattr(dummy, 'special-opts:strict'):
        for dest, value in strict_flag_assignments:
            setattr(options, dest, value)

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

    # --use-python-path is no longer supported; explain why.
    if special_opts.use_python_path:
        parser.error("Sorry, --use-python-path is no longer supported.\n"
                     "If you are trying this because your code depends on a library module,\n"
                     "you should really investigate how to obtain stubs for that module.\n"
                     "See https://github.com/python/mypy/issues/1411 for more discussion."
                     )

    # Process deprecated options
    if special_opts.disallow_any:
        print("--disallow-any option was split up into multiple flags. "
              "See http://mypy.readthedocs.io/en/latest/command_line.html#disallow-any-flags")
    if options.strict_boolean:
        print("Warning: --strict-boolean is deprecated; "
              "see https://github.com/python/mypy/issues/3195", file=sys.stderr)
    if special_opts.almost_silent:
        print("Warning: --almost-silent has been replaced by "
              "--follow-imports=errors", file=sys.stderr)
        if options.follow_imports == 'normal':
            options.follow_imports = 'errors'
    elif special_opts.silent_imports:
        print("Warning: --silent-imports has been replaced by "
              "--ignore-missing-imports --follow-imports=skip", file=sys.stderr)
        options.ignore_missing_imports = True
        if options.follow_imports == 'normal':
            options.follow_imports = 'skip'
    if special_opts.dirty_stubs:
        print("Warning: -f/--dirty-stubs is deprecated and no longer necessary. Mypy no longer "
              "checks the git status of stubs.",
              file=sys.stderr)
    if special_opts.fast_parser:
        print("Warning: --fast-parser is now the default (and only) parser.")
    if special_opts.no_fast_parser:
        print("Warning: --no-fast-parser no longer has any effect.  The fast parser "
              "is now mypy's default and only parser.")

    # Check for invalid argument combinations.
    if require_targets:
        code_methods = sum(bool(c) for c in [special_opts.modules,
                                             special_opts.command,
                                             special_opts.package,
                                             special_opts.files])
        if code_methods == 0:
            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.")

    # Set build flags.
    if options.strict_optional_whitelist is not None:
        # TODO: Deprecate, then kill this flag
        options.strict_optional = True
    if options.strict_optional:
        experiments.STRICT_OPTIONAL = True
    if special_opts.find_occurrences:
        experiments.find_occurrences = special_opts.find_occurrences.split('.')
        assert experiments.find_occurrences is not None
        if len(experiments.find_occurrences) < 2:
            parser.error("Can only find occurrences of class members.")
        if len(experiments.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

    # Let quick_and_dirty imply incremental.
    if options.quick_and_dirty:
        options.incremental = True

    # Set target.
    if special_opts.modules:
        options.build_type = BuildType.MODULE
        targets = [BuildSource(None, m, None) for m in special_opts.modules]
        return targets, options
    elif special_opts.package:
        if os.sep in special_opts.package or os.altsep and os.altsep in special_opts.package:
            fail("Package name '{}' cannot have a slash in it."
                 .format(special_opts.package))
        options.build_type = BuildType.MODULE
        lib_path = [os.getcwd()] + build.mypy_path()
        targets = build.find_modules_recursive(special_opts.package, lib_path)
        if not targets:
            fail("Can't find package '{}'".format(special_opts.package))
        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:
        targets = create_source_list(special_opts.files, options)
        return targets, options


def create_source_list(files: Sequence[str], options: Options) -> List[BuildSource]:
    targets = []
    for f in files:
        if f.endswith(PY_EXTENSIONS):
            try:
                targets.append(BuildSource(f, crawl_up(f)[1], None))
            except InvalidPackageName as e:
                fail(str(e))
        elif os.path.isdir(f):
            try:
                sub_targets = expand_dir(f)
            except InvalidPackageName as e:
                fail(str(e))
            if not sub_targets:
                fail("There are no .py[i] files in directory '{}'"
                     .format(f))
            targets.extend(sub_targets)
        else:
            mod = os.path.basename(f) if options.scripts_are_modules else None
            targets.append(BuildSource(f, mod, None))
    return targets


def keyfunc(name: str) -> Tuple[int, str]:
    """Determines sort order for directory listing.

    The desirable property is foo < foo.pyi < foo.py.
    """
    base, suffix = os.path.splitext(name)
    for i, ext in enumerate(PY_EXTENSIONS):
        if suffix == ext:
            return (i, base)
    return (-1, name)


def expand_dir(arg: str, mod_prefix: str = '') -> List[BuildSource]:
    """Convert a directory name to a list of sources to build."""
    f = get_init_file(arg)
    if mod_prefix and not f:
        return []
    seen = set()  # type: Set[str]
    sources = []
    if f and not mod_prefix:
        top_dir, top_mod = crawl_up(f)
        mod_prefix = top_mod + '.'
    if mod_prefix:
        sources.append(BuildSource(f, mod_prefix.rstrip('.'), None))
    names = os.listdir(arg)
    names.sort(key=keyfunc)
    for name in names:
        path = os.path.join(arg, name)
        if os.path.isdir(path):
            sub_sources = expand_dir(path, mod_prefix + name + '.')
            if sub_sources:
                seen.add(name)
                sources.extend(sub_sources)
        else:
            base, suffix = os.path.splitext(name)
            if base == '__init__':
                continue
            if base not in seen and '.' not in base and suffix in PY_EXTENSIONS:
                seen.add(base)
                src = BuildSource(path, mod_prefix + base, None)
                sources.append(src)
    return sources


def crawl_up(arg: str) -> Tuple[str, str]:
    """Given a .py[i] filename, return (root directory, module).

    We crawl up the path until we find a directory without
    __init__.py[i], or until we run out of path components.
    """
    dir, mod = os.path.split(arg)
    mod = strip_py(mod) or mod
    while dir and get_init_file(dir):
        dir, base = os.path.split(dir)
        if not base:
            break
        # Ensure that base is a valid python module name
        if not base.isidentifier():
            raise InvalidPackageName('{} is not a valid Python package name'.format(base))
        if mod == '__init__' or not mod:
            mod = base
        else:
            mod = base + '.' + mod

    return dir, mod


def strip_py(arg: str) -> Optional[str]:
    """Strip a trailing .py or .pyi suffix.

    Return None if no such suffix is found.
    """
    for ext in PY_EXTENSIONS:
        if arg.endswith(ext):
            return arg[:-len(ext)]
    return None


def get_init_file(dir: str) -> Optional[str]:
    """Check whether a directory contains a file named __init__.py[i].

    If so, return the file's name (with dir prefixed).  If not, return
    None.

    This prefers .pyi over .py (because of the ordering of PY_EXTENSIONS).
    """
    for ext in PY_EXTENSIONS:
        f = os.path.join(dir, '__init__' + ext)
        if os.path.isfile(f):
            return f
    return None


# For most options, the type of the default value set in options.py is
# sufficient, and we don't have to do anything here.  This table
# exists to specify types for values initialized to None or container
# types.
config_types = {
    'python_version': parse_version,
    'strict_optional_whitelist': lambda s: s.split(),
    'custom_typing_module': str,
    'custom_typeshed_dir': str,
    'mypy_path': lambda s: [p.strip() for p in re.split('[,:]', s)],
    'junit_xml': str,
    # These two are for backwards compatibility
    'silent_imports': bool,
    'almost_silent': bool,
    'plugins': lambda s: [p.strip() for p in s.split(',')],
}

SHARED_CONFIG_FILES = ('setup.cfg',)


def parse_config_file(options: Options, filename: Optional[str]) -> None:
    """Parse a config file into an Options object.

    Errors are written to stderr but are not fatal.

    If filename is None, fall back to default config file and then
    to setup.cfg.
    """
    if filename is not None:
        config_files = (filename,)  # type: Tuple[str, ...]
    else:
        config_files = (defaults.CONFIG_FILE,) + SHARED_CONFIG_FILES

    parser = configparser.RawConfigParser()

    for config_file in config_files:
        if not os.path.exists(config_file):
            continue
        try:
            parser.read(config_file)
        except configparser.Error as err:
            print("%s: %s" % (config_file, err), file=sys.stderr)
        else:
            file_read = config_file
            options.config_file = file_read
            break
    else:
        return

    if 'mypy' not in parser:
        if filename or file_read not in SHARED_CONFIG_FILES:
            print("%s: No [mypy] section in config file" % file_read, file=sys.stderr)
    else:
        section = parser['mypy']
        prefix = '%s: [%s]' % (file_read, 'mypy')
        updates, report_dirs = parse_section(prefix, options, section)
        for k, v in updates.items():
            setattr(options, k, v)
        options.report_dirs.update(report_dirs)

    for name, section in parser.items():
        if name.startswith('mypy-'):
            prefix = '%s: [%s]' % (file_read, name)
            updates, report_dirs = parse_section(prefix, options, section)
            if report_dirs:
                print("%s: Per-module sections should not specify reports (%s)" %
                      (prefix, ', '.join(s + '_report' for s in sorted(report_dirs))),
                      file=sys.stderr)
            if set(updates) - Options.PER_MODULE_OPTIONS:
                print("%s: Per-module sections should only specify per-module flags (%s)" %
                      (prefix, ', '.join(sorted(set(updates) - Options.PER_MODULE_OPTIONS))),
                      file=sys.stderr)
                updates = {k: v for k, v in updates.items() if k in Options.PER_MODULE_OPTIONS}
            globs = name[5:]
            for glob in globs.split(','):
                # For backwards compatibility, replace (back)slashes with dots.
                glob = glob.replace(os.sep, '.')
                if os.altsep:
                    glob = glob.replace(os.altsep, '.')
                pattern = re.compile(fnmatch.translate(glob))
                options.per_module_options[pattern] = updates
                options.unused_configs[pattern] = glob


def parse_section(prefix: str, template: Options,
                  section: Mapping[str, str]) -> Tuple[Dict[str, object], Dict[str, str]]:
    """Parse one section of a config file.

    Returns a dict of option values encountered, and a dict of report directories.
    """
    results = {}  # type: Dict[str, object]
    report_dirs = {}  # type: Dict[str, str]
    for key in section:
        orig_key = key
        key = key.replace('-', '_')
        if key in config_types:
            ct = config_types[key]
        else:
            dv = getattr(template, key, None)
            if dv is None:
                if key.endswith('_report'):
                    report_type = key[:-7].replace('_', '-')
                    if report_type in reporter_classes:
                        report_dirs[report_type] = section[orig_key]
                    else:
                        print("%s: Unrecognized report type: %s" % (prefix, orig_key),
                              file=sys.stderr)
                    continue
                print("%s: Unrecognized option: %s = %s" % (prefix, key, section[orig_key]),
                      file=sys.stderr)
                continue
            ct = type(dv)
        v = None  # type: Any
        try:
            if ct is bool:
                v = section.getboolean(key)  # type: ignore  # Until better stub
            elif callable(ct):
                try:
                    v = ct(section.get(key))
                except argparse.ArgumentTypeError as err:
                    print("%s: %s: %s" % (prefix, key, err), file=sys.stderr)
                    continue
            else:
                print("%s: Don't know what type %s should have" % (prefix, key), file=sys.stderr)
                continue
        except ValueError as err:
            print("%s: %s: %s" % (prefix, key, err), file=sys.stderr)
            continue
        if key == 'silent_imports':
            print("%s: silent_imports has been replaced by "
                  "ignore_missing_imports=True; follow_imports=skip" % prefix, file=sys.stderr)
            if v:
                if 'ignore_missing_imports' not in results:
                    results['ignore_missing_imports'] = True
                if 'follow_imports' not in results:
                    results['follow_imports'] = 'skip'
        if key == 'almost_silent':
            print("%s: almost_silent has been replaced by "
                  "follow_imports=error" % prefix, file=sys.stderr)
            if v:
                if 'follow_imports' not in results:
                    results['follow_imports'] = 'error'
        results[key] = v
    return results, report_dirs


def fail(msg: str) -> None:
    sys.stderr.write('%s\n' % msg)
    sys.exit(1)