Subject: Re: Test failures in t4034

From: Ramsay Jones <[email-masked]>
Date: Sun, 19 Aug 2012 15:50:49 +0100

Brian Gernhardt wrote:
> I've been getting a couple of test failures and finally had the time to track them down.
> 
> t4034-diff-words fails tests "22 diff driver 'bibtex'" and "26 diff driver 'html'".  Bisecting shows that the file started giving me errors in commit 8d96e72 "t4034: bulk verify builtin word regex sanity", which appears to introduce those tests.  I don't see anything obviously wrong with the tests and I'm not familiar with the diff-words code, so I'm not sure what's wrong.
> 
> I am running on OS X 10.8, with Xcode 4.4.1 (llvm-gcc 4.2.1).

I had the same problem (or at least it *looks* like the same problem) on Linux
last year (May 2011), which turned out to be a bug in the regex routines in an
old version of glibc. 

I don't know OS X at all, so this may not be relevent; does OS X use glibc?
(I didn't think so, but ...)

I sent some patches to the list which may be helpful. I can't get to gmane to
look up a reference, but you need to search for:

    [RFC/PATCH] userdiff.c: Avoid old glibc regex bug causing t4034-*.sh test failures

sent on 3rd May 2011.

Also, in the same thread, a reply to Jonathan Nieder on 7th May contains a
test which checks whether your regex routines suffer this bug.

These patches were not applied since I didn't think this would be a common
problem. I simply set NO_REGEX=1 in my config.mak, since the compat/ regex
routines don't suffer from this problem.

HTH

ATB,
Ramsay Jones