Re: [PATCH] diff.c: increment buffer pointer in all code path

[Jeff King <peff@peff.net>]

On Thu, Oct 12, 2017 at 08:18:37PM -0400, Jeff King wrote:

> Fix this by entering the conditional only when we actually
> see whitespace. We can apply this also to the
> IGNORE_WHITESPACE change. That code path isn't buggy
> (because it falls through to returning the next
> non-whitespace byte), but it makes the logic more clear if
> we only bother to look at whitespace flags after seeing that
> the next byte is whitespace.

I think there actually _is_ a bug in that code path, but it's unrelated
to this one. If you have whitespace at the end of the buffer, then we'd
advance *cp until it matches *endp, and then return whatever is at *endp
(which is nonsense, or probably a NUL) rather than returning "-1".

I'm out of time for tonight and not familiar enough with the color-moved
code to come up with a reasonable test case quickly, but maybe you can
see if that can trigger bad behavior?

-Peff