argparse indentation overshoots due to colors

[9001]

Bug report

Bug description:

As of 3.14, argparse --help accidentally includes the ansi-escapes when calculating the length of the invocations, resulting in excessive margins between options and their helptext. Effectively, the indentation will always be 24 (max_help_position).

import argparse
argparse.ArgumentParser().print_help()

in 3.14, this produces:

options:
 -h, --help show this help message and exit

in previous versions, it produces:

options:
 -h, --help show this help message and exit

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-139736: Fix argparse indentation overshoot #139738
• [3.14] gh-139736: Fix argparse indentation overshoot (GH-139738) #139793

[hugovk]

Thanks for the report and fix!