Re: How to debug a "git merge"?

>> On 14 Mar 2018, at 18:02, Derrick Stolee <stolee@gmail.com> wrote:
>>
>> On 3/14/2018 12:56 PM, Lars Schneider wrote:
>>> Hi,
>>>
>>> I am investigating a Git merge (a86dd40fe) in which an older version of
>>> a file won over the newer version. I try to understand why this is the
>>> case. I can reproduce the merge with the following commands:
>>> $ git checkout -b test a02fa3303
>>> $ GIT_MERGE_VERBOSITY=5 git merge --verbose c1b82995c
>>>
>>> The merge actually generates a merge conflict but not for my
>>> problematic file. The common ancestor of the two parents (merge base)
>>> is b91161554.
>>>
>>> The merge graph is not pretty (the committers don't have a clean
>>> branching scheme) but I cannot spot a problem between the merge commit
>>> and the common ancestor:
>>> $ git log --graph --oneline a86dd40fe
>> Have you tried `git log --graph --oneline --simplify-merges -- path` to see what changes and merges involved the file? I find that view to be very helpful (while the default history simplification can hide things). In particular, if there was a change that was reverted in one side and not another, we could find out.
> Thanks for this tip! Unfortunately, this only confirms my current view:
>
> ### First parent
> $ git log --graph --oneline --simplify-merges a02fa3303 -- path/to/problem
> * 4e47a10c7 <-- old version
> * 01f01f61c
>
> ### Second parent
> $ git log --graph --oneline --simplify-merges c1b82995c -- path/to/problem
> * 590e52ed1 <-- new version
> * 8e598828d
> * ad4e9034b
> * 4e47a10c7
> * 01f01f61c
>
> ### Merge
> $ git log --graph --oneline --simplify-merges a86dd40fe -- path/to/problem
> *   a86dd40fe <-- old version ?!?! That's the problem!
> |\
> | * 590e52ed1 <-- new version
> | * 8e598828d
> | * ad4e9034b
> |/
> * 4e47a10c7 <-- old version
> * 01f01f61c
>
>
>> You could also use the "A...B" to check your two commits for merging, and maybe add "--boundary".
> $ git diff --boundary a02fa3303...c1b82995c -- path/to/problem
>
> This looks like the correct diff. The "new version" is mark as +/add/green in the diff.
>
> Does this make any sense to you?
>
> Thank you,
> Lars