Re: using xdl_merge(), was Re: Resolving conflicts

[Junio C Hamano <junkio@cox.net>]

Linus Torvalds <torvalds@osdl.org> writes:

> On Tue, 5 Dec 2006, Ramsay Jones wrote:
>>
>> Have you had time to look at my test cases?
>> As I said, I found them very useful when debugging
>> my git-diff3 code, and (hopefully) you will find them
>> to be equally useful.
>
> It might be interesting to also do a simple test:
>
>  - take every single merge in git (or the kernel, if you want even more)
>
>  - ignore all the trivial ones that didn't have any file-level merging at 
>    all (ie done entirely in the index)
>
>  - for all the rest, just compare what the end result is when re-doing the 
>    merge with "xdl_merge" vs "external 3-way merge".
>
> [ Side note: DO NOT COMPARE AGAINST THE ACTUAL RESULT IN GIT OR IN THE 
>   KERNEL ARCHIVE! Those will obviously have been fixed up by humans in the 
>   event of a data conflict, and sometimes even in the _absense_ of a data 
>   conflict (ie "git commit --amend" to fix up something that got mismerged 
>   perfectly automatically or whatever).
>
>   So a script should literally re-do the merge two ways, and compare the 
>   end result ]
>
> Is that any "proof"? Of course not. And it will probably show differences 
> due to any conflict handling, but a lot of the time you'd expect to get 
> exactly the same end result, so the occasional differences are going to be 
> just all the more interesting ("it resolved differently, but it was 
> an equally good resolve" is interesting data on its own).
>
> Anybody want to write a small script to do this?
>
> 		Linus

I was planning to do this today anyway.  Thanks for the
reminder.