Misleading debugging output for verbose regular expressions

[serhiy-storchaka]

BPO	26475
Nosy	@ezio-melotti, @serhiy-storchaka
Files	re_verbose_debug.patch

^{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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2016-03-06.07:18:28.449>
created_at = <Date 2016-03-03.08:19:16.569>
labels = ['expert-regex', 'type-bug']
title = 'Misleading debugging output for verbose regular expressions'
updated_at = <Date 2016-03-06.07:18:28.449>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2016-03-06.07:18:28.449>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-03-06.07:18:28.449>
closer = 'serhiy.storchaka'
components = ['Regular Expressions']
creation = <Date 2016-03-03.08:19:16.569>
creator = 'serhiy.storchaka'
dependencies = []
files = ['42066']
hgrepos = []
issue_num = 26475
keywords = ['patch']
message_count = 2.0
messages = ['261148', '261236']
nosy_count = 4.0
nosy_names = ['ezio.melotti', 'mrabarnett', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26475'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']

[serhiy-storchaka]

When the verbose mode is switched on by using the inline (?x) flag instead of re.VERBOSE argument, the debugging output is duplicated: once for non-verbose mode and then for verbose mode.

>>> import re
>>> re.compile(r' (?x)a', re.DEBUG)
LITERAL 32
LITERAL 97
LITERAL 97
re.compile(' (?x)a', re.VERBOSE|re.DEBUG)

Proposed patch makes the parser to produce only final output for verbose mode.

>>> re.compile(r' (?x)a', re.DEBUG)
LITERAL 97
re.compile(' (?x)a', re.VERBOSE|re.DEBUG)

[python-dev]

New changeset 910d0256601f by Serhiy Storchaka in branch '3.5':
Issue bpo-26475: Fixed debugging output for regular expressions with the (?x) flag.
https://hg.python.org/cpython/rev/910d0256601f

New changeset b8928725e8cc by Serhiy Storchaka in branch '2.7':
Issue bpo-26475: Fixed debugging output for regular expressions with the (?x) flag.
https://hg.python.org/cpython/rev/b8928725e8cc

New changeset 37cdbe0a16a4 by Serhiy Storchaka in branch 'default':
Issue bpo-26475: Fixed debugging output for regular expressions with the (?x) flag.
https://hg.python.org/cpython/rev/37cdbe0a16a4