Bug report

Bug description:

Combining argparse type and choices arguments results in cryptic usage messages.

import argparse

parser = argparse.ArgumentParser()

day_names = ["mo", "tu", "we", "th", "fr", "sa", "su"]
days = [1, 2, 3, 4, 5, 6, 7]

def name_day(value):
    return day_names.index(value) + 1

parser.add_argument(
    '--day',
    type=name_day,
    choices=days,
)
parser.parse_args()

This will result in the following usage message:

usage: example.py [-h] [--day {1,2,3,4,5,6,7}]

This is strange, because the user is expected to enter the day name as a string.

See https://discuss.python.org/t/argparse-unable-to-combine-type-and-choices/88687 for discussion.

CPython versions tested on:

3.10, 3.13

Operating systems tested on:

Linux

Linked PRs

• gh-132558: allow choices to be specified as strings in presence of a type argument  #132743
• gh-132558: add convert_choices parameter to add_argument #133826
• gh-132558: Improve argparse docs on combining type and choices #133827