[New-bugs-announce] [issue31768] argparse drops '|'s when the arguments are too long

[caveman]

New submission from caveman <toraboracaveman at gmail.com>:

if you execute the code below, mutually exclusive agrs are separated by '|' as expected. but if you uncomment the 1 line down there, then the args list will be too long, and as argparse tries to wrap the args around, it drops all '|'s which semantically destroys the intended syntax of the arguments.

import argparse

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()
group.add_argument("-v", "--verbose", action="store_true")
group.add_argument("-q", "--quiet", action="store_true")
group.add_argument("-x", metavar='X', type=str, help="the base", nargs='?')
group.add_argument("-y", metavar='Y', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')
#group.add_argument("z", metavar='Z', type=str, help="the exponent", nargs='?')

args = parser.parse_args()

----------
components: Library (Lib)
messages: 304184
nosy: caveman
priority: normal
severity: normal
status: open
title: argparse drops '|'s when the arguments are too long
type: behavior
versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue31768>
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