Re: GNU diff and git diff - difference on myers algorithm?

From: Luis R. Rodriguez <mcgrof-3uybbjdb1yh774rrrx3eta@public.gmane.org>
Date: Jul 16, 2015, 19:07 UTC
Message-ID: <CAB=NE6UFMv0qu8fJ1P2-pJCF0tSGKoW+uKhfwt0jV5fj2wZGSQ@mail.gmail.com>
In-Reply-To: <CAB=NE6VGX332=CvhQM4sc27AM8ae5S1kdRnm5sMfoqkU=b=ebg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Fri, Jun 12, 2015 at 11:52 AM, Luis R. Rodriguez <mcgrof-3uybbJdB1yH774rrrx3eTA@public.gmane.org> wrote:

Show 19 quoted lines

> OK wells I'm curious about more research / effort when trying to
> evaluate a diff with two seprate but adjoining preprocessor directives
> and if anyone has implemented an optimizaiton option to let the diff
> generator join them.
>
> For example, to let it infer that:
>
> --- a/test.c
> +++ b/test.c
> @@ -10,8 +10,6 @@ int main(int argc, char *argv[])
>
>  #ifdef FOO
>         a = 4;
> -#endif /* FOO */
> -#ifdef FOO
>         a = 5;
>  #endif /* FOO */
>
> is possible.

Anyone familiar if any tool exists today that would optimize this? Is anyone working on it? Would git be a good place for such a thing? I'd consider it as an option to optimize a diff. This for example is extremely useful for us working with Coccinelle where we have a tool writing code for us, while such an optimization might be useful to Coccinelle it would seem like a rather generic feature, its just not clear to me where to give such a tool a proper home.

 Luis