Re: git blame --reverse doesn't find line in HEAD

From: Nick Snyder <nick@sourcegraph.com>
Date: Dec 7, 2017, 17:02 UTC
Message-ID: <CA+SQVf3LuYj-N9NaDPxRcADjgWK5DFbF8LM=6VhY9N0GnbxyyA@mail.gmail.com>
In-Reply-To: <CA+SQVf14g4zBP14BHEZQkyeqUE5Oqif3bUVADEwBZQTSwE=bKA@mail.gmail.com>

I built from source and was unable to find a git version where this has ever worked correctly.

I wasn't able to compile and test versions older than 1.6.1.

Confirmed not working: 2.15.1 2.13.6 (Apple Git-96) 2.0.0 1.7.0 1.6.3 1.6.2 1.6.1

I updated the https://github.com/nicksnyder/git-blame-bug with a script to easily reproduce.

On Wed, Dec 6, 2017 at 10:00 AM, Nick Snyder <nick@sourcegraph.com> wrote:

Show 33 quoted lines

>> Can you bisect to see when the feature stopped working as you expect?
>
> I will see if I can do that but might take some time.
>
>> It finds up to which commit each line survived without getting touched since the oldest commit in the range.
>
> Right, this is where it is failing in my case.
>
> With a history like this:
> A <- B <- C <- HEAD
>
> I have a particular line in C (HEAD) that blames to commit A.
> If I run a git blame --reverse starting at commit A for that line, it
> doesn't give me back C, it gives me back B instead.
> The line is not added/deleted/moved between B and C.
>
>
>
> On Wed, Dec 6, 2017 at 9:22 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> Nick Snyder <nick@sourcegraph.com> writes:
>>
>>> This can be reproduced on Linux and Mac. This behavior seems to be a bug.
>>
>> Can you bisect to see when the feature stopped working as you expect?
>>
>> Unlike a forward blame, where the command tries to find a commit
>> that is responsible for a line being in the final result (i.e.
>> typically, HEAD), a reverse blame is not about finding a commit
>> that is responsible for a line (that used to be in the oldest
>> commit) not being in a more recent codebase.  It finds up to which
>> commit each line survived without getting touched since the oldest
>> commit in the range.
>>