Re: [ANNOUNCE] Git v2.22.0-rc1

>
>
> On Tue, May 21 2019, Duy Nguyen wrote:
>
> > (dropping lkml and git-packagers)
> >
> > On Tue, May 21, 2019 at 3:31 PM Duy Nguyen <pclouds@gmail.com> wrote:
> >> > The bug there is that the old opt_arg() code would be torelant to empty
> >> > values. I noticed a similar change the other day with the --abbrev
> >> > option, but didn't think it was worth noting. Maybe it's a more general
> >> > problem, in both cases we had a blindspot in our tests.
> >>
> >> Hmm.. this one is different (at least it does not use opt_arg()). But
> >> I'll double check.
> >
> > What is wrong with --abbrev? The code is simple enough for me to just
> > compare line by line, and the only difference I can see is that if you
> > pass --abbrev=12a, then the old code accepts "12" while the new one
> > rejects.
> >
> > Granted, I said "no behavior change", but this may be pushing the
> > limits a bit. But maybe you're seeing something else?
> >
> > Note that "git diff --abbrev" still uses the old, but different,
> > parser in revision.c. parse_options() is only used for --abbrev with
> > --no-index.
>
> Before d877418390 ("diff-parseopt: convert --[no-]abbrev", 2019-03-24):
>
>     $ ~/g/git/git --exec-path=$PWD diff --raw --abbrev= --no-index {color,column}.c
>     :100644 100644 00000 00000 M    color.c
>
> after:
>
>     $ ~/g/git/git --exec-path=$PWD diff --raw --abbrev= --no-index {color,column}.c
>     :100644 100644 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 M      color.c
>
> This patch brings back the old behavior, but will break tests for
> describe/branch (we have no tests on this for the diff behavior, but I'm
> hoping to re-submit those after 2.22):
>
>     diff --git a/parse-options-cb.c b/parse-options-cb.c
>     index 6e2e8d6273..0a3c8bd565 100644
>     --- a/parse-options-cb.c
>     +++ b/parse-options-cb.c
>     @@ -23 +23 @@ int parse_opt_abbrev_cb(const struct option *opt, const char *arg, int unset)
>     -               if (v && v < MINIMUM_ABBREV)
>     +               if (v < MINIMUM_ABBREV)
>
> I discovered this the other day because I was rebasing my "relative
> abbrev" series and some of the tests I'd added here failed:
> https://public-inbox.org/git/20180608224136.20220-5-avarab@gmail.com/
>
> Now, in that case I think the change is fine, and is what we should do,
> and when I found this I couldn't imagine anyone relied on this
> empty-value '--abbrev=' behavior so I didn't bother to send an E-Mail
> about it. It also brought diff.c in line with what we did with
> empty-value '--abbrev=' elsewhere.

> I'm just noting it because it might be indicative of some logic errors
> in this conversion for other options, e.g. argument-less -U, and since
> we didn't test for (or --abbrev=) perhaps we have other blind spots.
> such a case.
>
> Unrelated to any potential bugs in yoeur changes, I just noticed that we
> should probably do this too:
>
>     diff --git a/parse-options-cb.c b/parse-options-cb.c
>     index 4b95d04a37..1216a71f4b 100644
>     --- a/parse-options-cb.c
>     +++ b/parse-options-cb.c
>     @@ -16,6 +16,9 @@ int parse_opt_abbrev_cb(const struct option *opt, const char *arg, int unset)
>             if (!arg) {
>                     v = unset ? 0 : DEFAULT_ABBREV;
>             } else {
>     +               if (!*arg)
>     +                       return error(_("option `%s' expects a value"),
>     +                                    opt->long_name);
>                     v = strtol(arg, (char **)&arg, 10);
>                     if (*arg)
>                             return error(_("option `%s' expects a numerical value"),
>
> I.e. we support and document --abbrev=0, but now we conflate it with
> --abbrev= for no good reason.