Create a merge commit when pulling/merging changes where all conflicts can be resolved automatically

[ralfebert]

Given: A local branch and remote branch, both with commits. When merging those, all conflicts can be resolved automatically, for example because different files were changed locally and remote.

When such a situation is merged via mergeBranchIntoCurrentBranch (for example as part of pullBranch) in this situation, a merge conflict error will be thrown:
https://github.com/libgit2/objective-git/blob/master/ObjectiveGit/GTRepository+Merging.m#L135

But then the conflicts are written to the index and this index might not have any conflicts because all conflicts were resolved automatically.

In this case, shouldn't the merge commit be created and the operation return without an error?

I tried to solve this, by instead of always returning with an error here: https://github.com/libgit2/objective-git/blob/master/ObjectiveGit/GTRepository+Merging.m#L148
I check if there are actually any remaining conflicts in the index that was written, and if not, I carry on creating the merge commit:

index = [self indexWithError:nil];
if (index.hasConflicts) {
	return NO;
} else {
	*error = nil;
}

This seems to work, not sure if it's the correct solution that covers all cases that can happen in this situation...

[pietbrauer]

Thanks for opening this. I think the best way to discuss this solution would be if you open a Pull Request so we can discuss it there.

[ralfebert]

Thanks for your feedback - I'll try to write a test case that shows the scenario and open a pull request for that in the next few days.
One thing that would help me with that: While merging, the index seems to be in a special state (the cmdline git prompt shows this as "MERGING", you can leave it via git merge --abort). I tried to find functions relating to this state (querying, finishing, aborting) in libgit2 as well but couldn't find anything. Any hints?

[jeffreybergier]

@ralfebert - (BOOL)cleanupStateWithError:(NSError * _Nullable __autoreleasing *)error; will clean up the mid-merge state.