Re: How to selectively recreate merge state?

From: Michael J Gruber <git@drmicha.warpmail.net>
Date: Dec 11, 2009, 10:44 UTC
Message-ID: <4B222289.6000004@drmicha.warpmail.net>
In-Reply-To: <200912110233.18756.jnareb@gmail.com>

Jakub Narebski venit, vidit, dixit 11.12.2009 02:33:

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> Dnia piątek 11. grudnia 2009 02:11, Junio C Hamano napisał:
>> Jakub Narebski <jnareb@gmail.com> writes:
>>
>>>   --unresolve::
>>>         Restores the 'unmerged' or 'needs updating' state of a
>>>         file during a merge if it was cleared by accident.
>>>
>>> Unless "git add foo" not only adds current contents of foo at stage 0,
>>> but also removes higher stages from index...
>>
>> By definition, adding anything at stage #0 is to remove higher stages.
> 
> Hmmm... let's test it:
> 
>  $ git merge side-branch 
>  Auto-merging foo
>  CONFLICT (content): Merge conflict in foo
>  Automatic merge failed; fix conflicts and then commit the result.
>  $ git ls-files --stage
>  100644 257cc5642cb1a054f08cc83f2d943e56fd3ebe99 1       foo
>  100644 3bd1f0e29744a1f32b08d5650e62e2e62afb177c 2       foo
>  100644 469a41eda5c8b45503a3bfc32ad6b5decc658132 3       foo
>  $ <edit foo>
>  $ git add foo
>  $ git ls-files --stage
>  100644 a1b58d38ffa61e8e99b7cb95cdf540aedf2a96b3 0       foo
> 
> Now let's test '--unresolve' option of git-update-index:
> 
>  $ git update-index --unresolve foo
>  $ git ls-files --stage foo
>  100644 3bd1f0e29744a1f32b08d5650e62e2e62afb177c 2       foo
>  100644 469a41eda5c8b45503a3bfc32ad6b5decc658132 3       foo
> 
> WTF? What happened to stage 1 (ancestor)?

2 and 3 are easy (cheap) to recreate from HEAD and MERGE_HEAD, 1 is not. I guess that's why --unresolve doesn't even attempt to do anything with 1.

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> 
>  $ git checkout --conflict=merge foo
>  error: path 'foo' does not have all three versions
> 
> Let's recover it by hand:
> 
>  $ echo -e "100644 257cc5642cb1a054f08cc83f2d943e56fd3ebe99 1\tfoo" | 
>    git update-index --index-info
>  $ git ls-files --stage foo
>  100644 257cc5642cb1a054f08cc83f2d943e56fd3ebe99 1       foo
>  100644 3bd1f0e29744a1f32b08d5650e62e2e62afb177c 2       foo
>  100644 469a41eda5c8b45503a3bfc32ad6b5decc658132 3       foo
>  $ git checkout --conflict=merge foo

Yeah, if we knew that sha1...