Type hints like list[str] for required arguments cause error

[cod3licious]

🐛 Bug report

Type hints for lists for required arguments break --help functionality (and probably more).

To reproduce

Script test.py:

from jsonargparse import CLI

def main(required_arg: list[str]):
    """
    Args:
        required_arg: a str list
    """
    pass

if __name__ == '__main__':
    CLI()

-> Running: python test.py --help results in

Traceback (most recent call last):
  File "/Users/franzi/Desktop/test.py", line 13, in <module>
    CLI()
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/cli.py", line 66, in CLI
    _add_component_to_parser(component, parser, as_positional, config_help)
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/cli.py", line 115, in _add_component_to_parser
    parser.add_function_arguments(component, **kwargs)
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/signatures.py", line 175, in add_function_arguments
    return self._add_signature_arguments(
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/signatures.py", line 229, in _add_signature_arguments
    self._add_signature_parameter(
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/signatures.py", line 329, in _add_signature_parameter
    action = group.add_argument(*args, **kwargs)
  File "/Users/franzi/.local/share/virtualenvs/prism_minerva-QkUURSB3/lib/python3.10/site-packages/jsonargparse/core.py", line 107, in add_argument
    action = super().add_argument(*args, **kwargs)
  File "/Users/franzi/.pyenv/versions/3.10.2/lib/python3.10/argparse.py", line 1408, in add_argument
    kwargs = self._get_optional_kwargs(*args, **kwargs)
  File "/Users/franzi/.pyenv/versions/3.10.2/lib/python3.10/argparse.py", line 1543, in _get_optional_kwargs
    raise ValueError(msg % args)
ValueError: invalid option string 'required_arg': must start with a character '-'

While running the same code instead with def main(required_arg: list): or def main(required_arg: list[str] = None): results in the expected help output.

Expected behavior

Running the code with def main(required_arg: list[str]): should also print out the help message and not cause an error.

Environment

• jsonargparse version: 4.12.0
• Python version: 3.10
• How jsonargparse was installed: through pipenv with jsonargparse = {extras = ["argcomplete", "signatures"], version = ">=4.12.0"}
• OS: macOS 12.4

[mauvilsa]

Thank you reporting! I have just pushed a fix for it (commit aafbe17).