From: John Keeping <john@keeping.me.uk>
Date: Sat, 13 Aug 2016 10:36:39 GMT
Subject: Re: git difftool and git mergetool aren't returning errors when the tool has issues
Message-ID: <20160813103639.mxscvfyztee4hbvh@john.keeping.me.uk>
In-Reply-To: <57AD772501C207A400390148_0_15304@p057>

On Fri, Aug 12, 2016 at 07:13:41AM -0000, Tom Tanner (BLOOMBERG/ LONDON) wrote:
> For instance, if you set your diff/mergetool to meld and you don't have it installed:
> > git difftool
> 
> Viewing (1/1): 'blah'
> Launch 'meld' [Y/n]? y
> /home/ttanner/bin/meld[8]: /opt/swt/bin/meld: not found
> > echo $?
> 0
> 
> > /home/ttanner/bin/meld
> /home/ttanner/bin/meld[8]: /opt/swt/bin/meld: not found
> > echo $?
> 127

Have you looked at the --trust-exit-code option to git-difftool?

It would be nice if there was a way to differentiate between complete
failure and just the diff tool exiting with a non-zero return status
because the files differ, but I'm not sure whether we can do that
reliably.  POSIX uses 127 and 126 as errors that mean the command didn't
run [1] so it may be sensible to to treat those as special values.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_08_02