Junio C Hamano (gitster@xxxxxxxxx) wrote on Aug 23, 2009:
> Thell Fowler <git@xxxxxxxxxxxxx> writes:
>
> > Because the flow is much more direct it also makes the test additions to
> > t4015 obsolete as they essentially tested for line end conditions instead
> > of whitespace (like they should have).
>
> Your patch 6/6 that added the tests were useful to find a bug I originally
> had, which is the one below that is commented out.
>
That's good to hear!
> >> + /*
> >> + * If we do not want -b to imply --ignore-space-at-eol
> >> + * then you would need to add this:
> >> + *
> >> + * if (!(flags & XDF_IGNORE_WHITESPACE_AT_EOL))
> >> + * return (s1 <= i1 && s2 <= i2);
> >> + *
> >> + */
> >> +
> >
> > While it would be nice to have -b and --ignore-space-at-eol be two
> > different options that could be merged together the documentation states
> > that -b ignores spaces at eol, and there are scripts that depend on this
> > behavior.
>
> Also that is how "diff -b" behaves, and that is why I said your tests
> found a _bug_ in my original. I'll drop the above large comment and
> replace it with just a "/* -b implies --ignore-space-at-eol */".
>
In that case the only other outstanding issue to being able to use
patch-id to validate a whitespace fixed patch is diff's -B option to catch
the situations where the original has multiple blank newlines at the end
of file.
> > Right now the xdl_recmatch() checks three distinct flags before having the
> > opportunity to do the default behavior of a straight diff. In
> > xdl_hash_record there is an initial check for whitespace flags.
> >
> > ...
> > if (flags & XDF_WHITESPACE_FLAGS)
> > return xdl_hash_record_with_whitespace(data, top, flags);
> > ...
> >
> > Perhaps a similar setup for xdl_rematch() and a
> > xdl_recmatch_with_whitespace() ?
>
> Or we can just move the final else clause up and start the function like
> this:
>
> int i1, i2;
>
> if (!(flags & XDF_WHITESPACE_FLAGS))
> return s1 == s2 && !memcmp(l1, l2, s1);
>
> i1 = i2 = 0;
> if (flags & XDF_IGNORE_WHITESPACE) {
> ...
>
> that would get rid of two unnecessary clearing of variables (i1 and i2,
> even though I suspect that the compiler _could_ optimize them out without
> such an change), and three flags-bit check in the most common case of not
> ignoring any whitespaces.
>
HA! That's a nifty way to do that with the variables.
> > Since your to counter-proposals give the same results, provide safer and
> > faster processing, eliminate the additional test, as well as being easier
> > to read and comprehend I propose a v3 with just those two patches. I'll
> > be glad to post it, with or without a xdl_recmatch_with_whitespace, if
> > need be. And should I, or do I need to, add something to the commit (ie:
> > ack, tested, ...) ?
>
> I can amend the counterproposal patches with tests from your 6/6 and add
> your "Tested-by:" and commit them myself.
>
Excellent.
> > Thank you again for taking the time to look at this change!
>
> Thank _you_ for bringing this issue up in the first place.
My pleasure! It has been quite the learning experience!
--
Thell
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