On Wed, Jul 10, 2024 at 10:06:28AM -0700, Junio C Hamano wrote:

quoted

I don't think we'd ever generate this ourselves, but could somebody
manually edit a hunk into this shape? When I tried it in practice, it
looks like we fail to apply the result even before my patch, though. I'm
not sure why that is. If I put "some garbage" without the blank line, we
correctly realize it should be discarded. It's possible I'm just holding
it wrong.

I've given up on the "hunk edit" doing wrong things to a patch
already.  

The "edit" codepath used to be a lot less careless before Phillip
whipped it into a much better shape with the series that ended at
436d18f2 (Merge branch 'pw/add-p-recount', 2018-03-14), that
introduced recount_edited_hunk() that special cases "+/-/ ".  It
already knows that a completely empty line in a patch is an empty
and unmodified line (which was ported from f4d35a6b (add -p: fix
counting empty context lines in edited patches, 2018-06-11)), so
this patch does not have to do anything new there.

Yeah, I was being paranoid without actually thinking through the
implications. As Phillip noted, we do not even run the code I changed on
the edited hunk (which already does handle the empty line). So not only
could I not break it, but it is already doing the right thing thanks to
that earlier work.

But "recounting" will be fooled by garbage left in the edited
result, so I think we have done all we can do to resolve possible
ambiguities.  The patch under discussion is not adding anything new
and making it any worse, I would say.

Yep, agreed. So modulo a slight inaccuracy in the commit message, I
think my patch is OK. That said, I like what Phillip showed in his
reply. If he wants to wrap that up into a patch, I think it could
replace mine.

-Peff