str.title() is overzealous by upcasing combining marks inappropriately

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
backend

Research direction

Start by reading the linked titletest.python and titletest.py demonstrations and reproduce their str.title() results. Then inspect the relevant string-titlecasing implementation and determine the intended treatment of combining marks. The issue is done when the demonstrated inappropriate upcasing is corrected and the behavior has regression coverage.

Written by the indexing model from the issue text.

Description

3.10 3.9 (EOL) stdlib type-bug
BPO 12737
Nosy @gvanrossum, @loewis, @terryjreedy, @ezio-melotti, @florentx, @iritkatriel
Files
  • titletest.python: demo showing python uses incorrect sense of \w for words in titlecasing
  • titletest.py: slightly improved demo
    		•

    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 = None
created_at = <Date 2011-08-11.22:37:33.658>
labels = ['type-bug', 'library', '3.9', '3.10']
title = 'str.title() is overzealous by upcasing combining marks\tinappropriately'
updated_at = <Date 2021-07-24.18:29:50.490>
user = 'https://bugs.python.org/tchrist'

    bugs.python.org fields:

    activity = <Date 2021-07-24.18:29:50.490>
actor = 'terry.reedy'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2011-08-11.22:37:33.658>
creator = 'tchrist'
dependencies = []
files = ['22884', '23271']
hgrepos = []
issue_num = 12737
keywords = []
message_count = 20.0
messages = ['141929', '141998', '142106', '142110', '143038', '143046', '144207', '144233', '144661', '144683', '144688', '144690', '144722', '144723', '144735', '379614', '379629', '379656', '398165', '398173']
nosy_count = 9.0
nosy_names = ['gvanrossum', 'loewis', 'terry.reedy', 'ezio.melotti', 'Arfrever', 'flox', 'tchrist', 'iritkatriel', 'vishvas.vasuki']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue12737'
versions = ['Python 3.9', 'Python 3.10']

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