Re: show all merge conflicts

["Philip Oakley" <philipoakley@iee.org>]

From: "G. Sylvie Davies" <sylvie@bit-booster.com>
> On Fri, Jan 27, 2017 at 9:51 AM, Jeff King <peff@peff.net> 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

This feels as though there ought to be some sort of --left-right option to 
get an indication of which side various changes came from

>
>> 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
>