Re: show all merge conflicts

[Jeff King <peff@peff.net>]

On Fri, Jan 27, 2017 at 11:56:08AM -0500, Michael Spiegel wrote:

> I'm trying to determine whether a merge required a conflict to resolve
> after the merge has occurred. The git book has some advice
> (https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging) to use
> `git show` on the merge commit or use `git log --cc -p -1`. These
> strategies work when the merge conflict was resolved with a change
> that is different from either parent. When the conflict is resolved
> with a change that is the same as one of the parents, then these
> commands are indistinguishable from a merge that did not conflict. Is
> it possible to distinguish between a conflict-free merge and a merge
> conflict that is resolved by with the changes from one the parents?

No. You'd have to replay the merge to know if it would have had
conflicts.

There was a patch series a few years ago that added a new diff-mode to
do exactly that, and show the diff against what was resolved. It had a
few issues (I don't remember exactly what) and never got merged.

Certainly one complication is that you don't know exactly _how_ the
merge was done in the first place (e.g., which merge strategy, which
custom merge drivers were in effect, etc). But in general, replaying
with a standard merge-recursive would get you most of what you want to
know.

I've done this manually sometimes when digging into erroneous merges
(e.g., somebody accidentally runs "git reset -- <paths>" in the middle
of a merge and throws away some changes.

You should be able to do:

  git checkout $merge^1
  git merge $merge^2
  git diff -R $merge

to see what the original resolution did.

-Peff