On Fri, Jan 27, 2017 at 9:51 AM, Jeff King <peff@xxxxxxxx> wrote: > 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. > Aside from the usual "git log -cc", I think this should work (replace HEAD with whichever commit you are analyzing): git diff --name-only HEAD^2...HEAD^1 > m1 git diff --name-only HEAD^1...HEAD^2 > b1 git diff --name-only HEAD^1..HEAD > m2 git diff --name-only HEAD^2..HEAD > b2 If files listed between m1 and b2 differ, then the merge is dirty. Similarly for m2 and b1. More information here: http://stackoverflow.com/questions/27683077/how-do-you-detect-an-evil-merge-in-git/41356308#41356308 - Sylvie > 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