On Thu, Apr 26, 2018 at 3:49 AM, Middelschulte, Leif <leif.middelschu...@klsmartin.com> wrote: > Hi, > > we're using git-flow as a basic development workflow. However, doing so > revealed unexpected merge-behavior by git. > > Assume the following setup: > > - Repository `S` is sourced by repository `p` as submodule `s` > - Repository `p` has two branches: `feature_x` and `develop` > - The revisions sourced via the submodule have a linear history > > > * 1c1d38f (feature_x) update submodule revision to b17e9d9 > | * 3290e69 (HEAD -> develop) update submodule revision to 0598394 > |/ > * cd5e1a5 initial submodule revision > > > Problem case: Merge either branch into the other > > Expected behavior: Merge conflict. > > Actual behavior: Auto merge without conflicts. > > Note 1: A merge conflict does occur, if the sourced revisions do *not* have a > linear history > > Did I get something wrong about how git resolves merges? Shouldn't git be > like: "hey, you're trying to merge two different contents for the same line" > (the submodule's revision)
Hard to say without saying what commit was referenced for the submodule in the merge-bases for the two repositories you have. In the basic case.. If branch A and branch B have different commits checked out in the submodule, say: A: deadbeef B: ba5eba11 then it's not clear whether there's a conflict or not. The merge-base (the common point of history) matters. So, for example if the original version (which I'll refer to as 'O") had: O: deadbeef then you would say, "Oh, branch A made no change to this submodule but B did. So let's go with what B has." Conversely, of O had ba5eba11, then you'd go the other way. But, there is some further smarts in that if either A or B point at commits that contain the other in their history and both contain the commit that O points at, then you can just do a fast-forward update to the newest. You didn't tell us how the merge-base (cd5e1a5 from the diagram you gave) differed in your example here between the two repositories. In fact, the non-linear case could have several merge-bases, in which case they all become potentially relevant (as does their merge-bases since at that point you'll trigger the recursive portion of merge-recursive). Giving us that info might help us point out what happened, though if either the fast-forward logic comes into play or the recursive logic gets in the mix, then we may need you to provide a testcase (or access to the repo in question) in order to explain it and/or determine if you've found a bug. Does that help? Elijah
