use git's word-diff for latex files

Question

I would like to have git diff outputs me regular diffs for all files, except *.tex. For *.tex files, I would like to see the output of git diff --word-diff.

I was playing around with .gitattributes and .gitconfig, but the furthest I got was to get a partial display for one .tex file, followed by a crash.

Is it possible to get this behaviour?

My .gitattributes:

*.tex diff=latex

.gitconfig:

[diff "latex"]
    wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
    command = ~/bin/word-diff.sh

and word-diff.sh:

#!/bin/sh 
git --no-pager diff --color-words "$2" "$5"

Facilitation

How did you come up with "$2" and "$5"? I can't find info about that anywhere. – Amadou

Found it, sorry. For others who were wondering, search for GIT_EXTERNAL_DIFF in the git man page. – Amadou

As a side remark, there is supposed to be a built-in diff pattern "tex" available which should give you reasonable hunk-headers. But that does not seem to work for me. – Dulcine

Answer 1

Can you post (or link to) a complete example? I've set up exactly what you've described and it seems to work fine. That is, the diff output highlights words rather than lines, and all of the changes I made were included (that is, it didn't crap out early or anything). The only anomaly was that diff would always exit with:

external diff died, stopping at foo.tex.

This happens because git diff, when run in the manner in which you're using it, behaves like the standalone diff tool: it exits with a nonzero exit code if the files differ. Git doesn't expect this behavior; it assumes that your custom command will always execute successfully and that error exit codes indicate an actual problem.

Git already knows that the files are difference and does not require the external command to make this determination. The external command is strictly a formatting tool.

If you modify your diff-words.sh script to always exit successfully, things should work out better:

#!/bin/sh
git --no-pager diff --color-words "$2" "$5"
exit 0

Juetta

That was the exact error message I got. Adding exit 0 did the trick, thanks! – Facilitation