Re: What's cooking in git.git (Dec 2008, #04; Mon, 29)

[Christian Couder <chriscool@tuxfamily.org>]

Le mardi 30 décembre 2008, Junio C Hamano a écrit :
>
> * cc/bisect-replace (Mon Nov 24 22:20:30 2008 +0100) 9 commits
>  - bisect: add "--no-replace" option to bisect without using replace
>    refs
>  - rev-list: make it possible to disable replacing using "--no-
>    bisect-replace"
>  - bisect: use "--bisect-replace" options when checking merge bases
>  - merge-base: add "--bisect-replace" option to use fixed up revs
>  - commit: add "bisect_replace_all" prototype to "commit.h"
>  - rev-list: add "--bisect-replace" to list revisions with fixed up
>    history
>  - Documentation: add "git bisect replace" documentation
>  - bisect: add test cases for "git bisect replace"
>  - bisect: add "git bisect replace" subcommand
>
> I think a mechanism like this should be added to replace grafts, 

The problem with replacing grafts is that a graft can specify many parents 
for one commit while a ref associates only one object to a name.

One way to overcome this could be to use many refs for each graft, for 
example (in the packed ref format):

<1st parent sha1> refs/replace/grafts/<commit sha1>-<1st parent sha1>
<2nd parent sha1> refs/replace/grafts/<commit sha1>-<2nd parent sha1>
...

Another way would be to put all the parents in the ref name, for example:

<1st parent sha1> /refs/replace/grafts/<commit sha1>-<1st parent sha1>-<2nd 
parent sha1>-<3rd parent sha1>

There is the same kind of problem to mark many "good" (and "skip") commits 
when bisecting and we use something like the first solution above:

<1st good commit sha1> refs/bisect/good-<1st good commit sha1>
<2nd good commit sha1> refs/bisect/good-<2nd good commit sha1>
...

But I think the above solutions are not very clean and it might be better in 
the long run to make it possible to associate more than one object to a 
ref.

Am I missing something? Do you see another way?

Thanks and happy new year everybody,
Christian.