New submission from Keith Smiley <keithbsmi...@gmail.com>:
With this code:
```
import argparse
parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument("--foo", default="1")
group.add_argument("--bar")
args = parser.parse_args()
print(args)
```
When you explicitly pass `--foo 1`, it is treated as if no argument was passed:
```
% python3 /tmp/bug.py --foo 1
usage: bug.py [-h] (--foo FOO | --bar BAR)
bug.py: error: one of the arguments --foo --bar is required
```
I can't tell if this behavior is intentional, but it was surprising to me. It
also seems to be somewhat based on the length of the default string. For
example on my macOS machine if I change the default to `longerstring` it does
not have this issue.
----------
components: Library (Lib)
messages: 386934
nosy: keith
priority: normal
severity: normal
status: open
title: Explicit default required arguments with add_mutually_exclusive_group
are rejected
versions: Python 3.10, Python 3.6, Python 3.7, Python 3.8, Python 3.9
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue43220>
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