[New-bugs-announce] [issue4898] {context, unified}_diff add spurious trailing whitespace if fromfiledate/tofiledate are emptyk

Adeodato Simó report at bugs.python.org
Fri Jan 9 16:38:12 CET 2009

New submission from Adeodato Simó <dato at net.com.org.es>:


I recently noticed that Bazaar's unified_diff() was emiting ---/+++ 
lines with a trailing whitespace if fromfiledate/tofiledate were the 
empty string. (Which was bad because a program to detect spurious 
trailing whitespace in diffs would flag them as errors.)

A patch [1] was committed recently in their tree. During the 
discussion, it was pointed out that the affected function was a copy 
of Python's own unified_diff() in difflib, which suffered the same 

  [1]: http://bazaar.launchpad.net/~bzr/bzr/trunk/revision/3923

I'm now attaching a patch to fix this issue in Python. It'd be great 
if you'd consider applying it. (It seems that the correct character to 
separate dates is a tab and not a space; if you feel changing this is 
breaking backwards compatibility, feel free to s/\t/ / in my patch.)


components: Library (Lib)
files: python_difflib_fix.diff
keywords: patch
messages: 79473
nosy: dato, jameinel
severity: normal
status: open
title: {context,unified}_diff add spurious trailing whitespace if fromfiledate/tofiledate are emptyk
type: behavior
Added file: http://bugs.python.org/file12668/python_difflib_fix.diff

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