python / python/cpython

difflib reports incorrect location of mismatch

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3.7 (EOL) 3.8 (EOL) stdlib type-bug
Dominant language
Python
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Description

BPO 35955
Nosy @tim-one, @jaraco, @cjerdonek, @tirkarthi

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 2019-02-10.14:11:58.219>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = 'difflib reports incorrect location of mismatch'
updated_at = <Date 2019-02-11.20:07:41.441>
user = 'https://github.com/jaraco'

bugs.python.org fields:

activity = <Date 2019-02-11.20:07:41.441>
actor = 'tim.peters'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-02-10.14:11:58.219>
creator = 'jaraco'
dependencies = []
files = []
hgrepos = []
issue_num = 35955
keywords = []
message_count = 13.0
messages = ['335154', '335155', '335156', '335158', '335231', '335235', '335246', '335247', '335248', '335252', '335257', '335268', '335269']
nosy_count = 4.0
nosy_names = ['tim.peters', 'jaraco', 'chris.jerdonek', 'xtreak']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35955'
versions = ['Python 2.7', 'Python 3.7', 'Python 3.8']

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue names Python's difflib library but provides no file, test, or reproduction. Start by locating the difflib implementation and reproducing the reported mismatch, then trace how the mismatch location is calculated. Done means the reported location is corrected and a regression test covers the case.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
38/100

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