Re: Use a *real* built-in diff generator

Linus Torvalds [off-list ref] writes:

This uses a simplified libxdiff setup to generate unified diffs _without_ 
doing  fork/execve of GNU "diff".

Good stuff.

Now, in the interest of full disclosure, I should also point out a few 
downsides:

 - the libxdiff algorithm is different,...

 - GNU diff does some nice eye-candy, like trying to figure out what the 
   last function was, and adding that information to the "@@ .." line. 
   libxdiff doesn't do that. 

That's kind of sad --- Documentation/SubmittingPatches request
people to say "diff -u -p".

 - The libxdiff thing has some known deficiencies. In particular, it gets 
   the "\No newline at end of file" case wrong. So this is currently for 
   the experimental branch only. I hope Davide will help fix it.

Another thing I noticed is that while libxdiff always shows full
line counts "-n,m +l,k" GNU seems to omit them when it can (m,k
<=1).  I am not sure if apply.c is set up to grok what libxdiff
emits correctly.  Running t/t1200 shows some obvious examples.