Re: Diftool problems

> Hi,
> 
> When git-difftool calls a diff tool, it uses file names given to it by
> git-diff. This is a problem because often one of the files to be
> compared is the same as the file to be merged into. What I mean is
> that, in the following fragment of the git-difftool--helper file, $1
> and $2 (I think) may end up being the same:
> 
> launch_merge_tool () {
> 	# Merged is the filename as it appears in the work tree
> 	# Local is the contents of a/filename
> 	# Remote is the contents of b/filename
> 	# Custom merge tool commands might use $BASE so we provide it
> 	MERGED="$1"
> 	LOCAL="$2"
> 	REMOTE="$3"
> 	BASE="$1"
> 
> Git-mergetool creates a temporary file for merging, but git-difftool
> does not. Since git-diff tools is not meant for merging anything, it
> may seem that there is no problem. However, some merge tools (such as
> ediff) do not like when the merge target is the same as one of the
> files to be compared. I use the following emacs snippet by Theodore
> Tso:
> 
> http://kerneltrap.org/mailarchive/git/2007/7/2/250505
> 
> With that emacs code, ediff refuses to do a diff with the way that
> difftool is done now. I do not have a patch, but it seems that a
> simple fix would be to copy the code that creates temporary files from
> mergetool.