Bug report
Bug description:
argparse.BooleanOptionalAction (doc) handles the creation of the boolean flags with positive and negative options by having user only needs to add the positive argument. However, it only works with those parsers whose prefix_chars contains '-', which is the default value, and otherwise failed to create the negative option silently.
>>> from argparse import BooleanOptionalAction, ArgumentParser >>> # normal usage >>> p = ArgumentParser() # prefix_chars defaults to '-' >>> p.add_argument("--foo", action=BooleanOptionalAction) BooleanOptionalAction(option_strings=['--foo', '--no-foo'], dest='foo', nargs=0, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None, deprecated=False) >>> p.parse_args(['--no-foo']) Namespace(foo=False) >>> >>> # parser with customized prefix_chars >>> p = ArgumentParser(prefix_chars='+') >>> p.add_argument("++foo", action=BooleanOptionalAction) BooleanOptionalAction(option_strings=['++foo'], dest='foo', nargs=0, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None, deprecated=False)
Raising warning/error is expected when argparse.BooleanOptionalAction is used with parsers whose prefix_chars has no '-'.
CPython versions tested on:
3.14
Operating systems tested on:
macOS