sub function would not work without the flags but the search would work fine

[bayat]

BPO	41764
Nosy	@ezio-melotti

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-09-11.18:10:33.855>
created_at = <Date 2020-09-11.17:12:58.342>
labels = ['expert-regex', 'invalid', '3.8']
title = 'sub function would not work without the flags but the search would work fine'
updated_at = <Date 2020-09-11.18:10:33.854>
user = 'https://bugs.python.org/bayat'

bugs.python.org fields:

activity = <Date 2020-09-11.18:10:33.854>
actor = 'mrabarnett'
assignee = 'none'
closed = True
closed_date = <Date 2020-09-11.18:10:33.855>
closer = 'mrabarnett'
components = ['Regular Expressions']
creation = <Date 2020-09-11.17:12:58.342>
creator = 'bayat'
dependencies = []
files = []
hgrepos = []
issue_num = 41764
keywords = []
message_count = 2.0
messages = ['376734', '376736']
nosy_count = 3.0
nosy_names = ['ezio.melotti', 'mrabarnett', 'bayat']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue41764'
versions = ['Python 3.8']

[bayat]

it would work like this sub("pattern","replace", txt, flags= re.IGNORECASE | re.DOTALL)
but it wouldnt work like this sub("pattern","replace", txt, re.IGNORECASE | re.DOTALL)

[mrabarnett]

The arguments are: re.sub(pattern, repl, string, count=0, flags=0).

Therefore:

 re.sub("pattern","replace", txt, re.IGNORECASE | re.DOTALL)

is passing re.IGNORECASE | re.DOTALL as the count, not the flags.

It's in the documentation and the interactive help.