obtaining full file paths in git merge

Question

I'm working on a tool to analyse the output of merging many topic branches and produce a detailed conflict report. I've run into a slight problem in that sometimes Git will produce a truncated file name in the merge command's output, such as

Merge made by recursive.
 .../somepath/anotherpath/toolong/default.css     |    2 +-

When in other cases it gives the full path

Auto-merging thefullpath/to/myfile/default.jsp

I would like to always have the full path available in order to match files between merges.

Answer 1

I'm a little confused by your end goal, but I think I can provide an answer anyway.

If you want to get a good report of changes when a merge runs into conflicts, i.e. while everything is still uncommitted, you should use git status --porcelain. It gives a nice, machine-readable list of all files and their statuses (including merge conflict states) and is well-documented in the manpage. Depending on your use case, you might even use git merge --no-commit to ensure you have the chance to inspect the merge result before proceeding (committing). You could also use git diff HEAD --numstat to get a machine-readable report of the added/removed line counts by file.

If you want to examine merges after the fact, it's a very good use case for git diff-tree:

git diff-tree -c --numstat <commit>

The -c tells it to diff merge commits against both parents, and the --numstat gets you a nice machine-readable output as before.

Finally, if you wanted to generate extremely detailed conflict reports, you could pass -p instead of --numstat, giving you full patch output. This is the kind of patch you'll see in gitk, where there are two characters at the start of each line, indicating whether the line was added/removed relative to each parent. Changes coming from just one parent have just one symbol (e.g. '+ ', ' -', quotes added to make spaces visible), while lines changed manually as part of conflict resolution will have two (--, ++). You could parse it yourself if you really had to. (Unfortunately I don't think there's anything like --numstat on steroids for merge commits.)