From: Denton Liu <liu.denton@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH v3 06/10] diff-lib: define diff_get_merge_base()
Date: Fri, 18 Sep 2020 03:34:00 -0700 [thread overview]
Message-ID: <20200918103400.GA1874074@generichostname> (raw)
In-Reply-To: <xmqqd02ks4qk.fsf@gitster.c.googlers.com>
Hi Junio,
On Thu, Sep 17, 2020 at 10:16:51AM -0700, Junio C Hamano wrote:
> Denton Liu <liu.denton@gmail.com> writes:
>
> > +void diff_get_merge_base(const struct rev_info *revs, struct object_id *mb)
> > +{
> > + int i;
> > + struct commit *mb_child[2] = {0};
> > + struct commit_list *merge_bases;
> > +
> > + for (i = 0; i < revs->pending.nr; i++) {
> > + struct object *obj = revs->pending.objects[i].item;
> > + if (obj->flags)
> > + die(_("--merge-base does not work with ranges"));
> > + if (obj->type != OBJ_COMMIT)
> > + die(_("--merge-base only works with commits"));
> > + }
>
> This is the first use of die() in this file, that is designed to
> keep a set of reusable library functions so that the caller(s) can
> do their own die(). They may want to become
Although this is the first instance of die(), run_diff_index() has an
exit(128), which is basically a die() in disguise.
> return error(_(...));
>
> The same comment applies to all die()s the patch adds.
I applied this change but then each callsite of diff_get_merge_base()
became something like
if (diff_get_merge_base(revs, &oid))
exit(128);
so I do agree with the spirit of the change but in reality, it just
creates more busywork for the callers.
> > + /*
> > + * This check must go after the for loop above because A...B
> > + * ranges produce three pending commits, resulting in a
> > + * misleading error message.
> > + */
>
> Should "git diff --merge-base A...B" be forbidden, or does it just
> ask the same thing twice and is not a die-worthy offence?
I think that it should be die-worthy because it's a logic error for a
user to do this. I can't think of any situation where it wouldn't be
more desirable error early to correct a user's thinking. Plus, we're
trying to move away from the `...` notation anyway ;)
> > + for (i = 0; i < revs->pending.nr; i++)
> > + mb_child[i] = lookup_commit_reference(the_repository, &revs->pending.objects[i].item->oid);
> > + if (revs->pending.nr < ARRAY_SIZE(mb_child)) {
> > + struct object_id oid;
> > +
> > + if (revs->pending.nr != 1)
> > + BUG("unexpected revs->pending.nr: %d", revs->pending.nr);
>
> This is an obviously impossible condition as we will not take more
> than 2.
We also want to ensure that revs->pending.nr isn't 0 here. That being
said, I can explicitly check earlier in the function that the number of
pending is 1 or 2 so that it's more clearly written.
Thanks,
Denton
next prev parent reply other threads:[~2020-09-18 10:34 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-05 19:08 [PATCH 0/4] builtin/diff: learn --merge-base Denton Liu
2020-09-05 19:08 ` [PATCH 1/4] t4068: remove unnecessary >tmp Denton Liu
2020-09-05 19:08 ` [PATCH 2/4] git-diff.txt: backtick quote command text Denton Liu
2020-09-05 19:08 ` [PATCH 3/4] builtin/diff: parse --no-index using parse_options() Denton Liu
2020-09-05 19:08 ` [PATCH 4/4] builtin/diff: learn --merge-base Denton Liu
2020-09-06 21:58 ` Junio C Hamano
2020-09-10 7:32 ` [PATCH v2 0/4] " Denton Liu
2020-09-10 7:32 ` [PATCH v2 1/4] t4068: remove unnecessary >tmp Denton Liu
2020-09-10 7:32 ` [PATCH v2 2/4] git-diff.txt: backtick quote command text Denton Liu
2020-09-10 7:32 ` [PATCH v2 3/4] builtin/diff: parse --no-index using parse_options() Denton Liu
2020-09-10 18:35 ` Junio C Hamano
2020-09-13 8:31 ` Denton Liu
2020-09-13 21:45 ` Junio C Hamano
2020-09-10 7:32 ` [PATCH v2 4/4] builtin/diff: learn --merge-base Denton Liu
2020-09-17 7:44 ` [PATCH v3 00/10] " Denton Liu
2020-09-17 7:44 ` [PATCH v3 01/10] t4068: remove unnecessary >tmp Denton Liu
2020-09-17 7:44 ` [PATCH v3 02/10] git-diff-index.txt: make --cached description a proper sentence Denton Liu
2020-09-17 7:44 ` [PATCH v3 03/10] git-diff.txt: backtick quote command text Denton Liu
2020-09-17 7:44 ` [PATCH v3 04/10] contrib/completion: extract common diff/difftool options Denton Liu
2020-09-17 7:44 ` [PATCH v3 05/10] diff-lib: accept option flags in run_diff_index() Denton Liu
2020-09-17 17:00 ` Junio C Hamano
2020-09-17 7:44 ` [PATCH v3 06/10] diff-lib: define diff_get_merge_base() Denton Liu
2020-09-17 17:16 ` Junio C Hamano
2020-09-18 10:34 ` Denton Liu [this message]
2020-09-19 0:33 ` Junio C Hamano
2020-09-17 7:44 ` [PATCH v3 07/10] t4068: add --merge-base tests Denton Liu
2020-09-17 7:44 ` [PATCH v3 08/10] builtin/diff-index: learn --merge-base Denton Liu
2020-09-17 17:28 ` Junio C Hamano
2020-09-17 18:13 ` Jeff King
2020-09-18 5:11 ` Junio C Hamano
2020-09-18 18:12 ` Jeff King
2020-09-17 7:44 ` [PATCH v3 09/10] builtin/diff-tree: " Denton Liu
2020-09-17 18:23 ` Junio C Hamano
2020-09-18 10:48 ` Denton Liu
2020-09-18 16:52 ` Junio C Hamano
2020-09-20 11:01 ` Denton Liu
2020-09-21 16:05 ` Junio C Hamano
2020-09-21 17:27 ` Denton Liu
2020-09-21 21:09 ` Junio C Hamano
2020-09-21 21:19 ` Junio C Hamano
2020-09-21 21:54 ` Denton Liu
2020-09-21 22:18 ` Junio C Hamano
2020-09-23 9:47 ` Denton Liu
2020-09-25 21:02 ` Junio C Hamano
2020-09-26 1:52 ` Denton Liu
2020-09-17 7:44 ` [PATCH v3 10/10] contrib/completion: complete `git diff --merge-base` Denton Liu
2020-09-20 11:22 ` [PATCH v4 00/10] builtin/diff: learn --merge-base Denton Liu
2020-09-20 11:22 ` [PATCH v4 01/10] t4068: remove unnecessary >tmp Denton Liu
2020-09-20 11:22 ` [PATCH v4 02/10] git-diff-index.txt: make --cached description a proper sentence Denton Liu
2020-09-20 11:22 ` [PATCH v4 03/10] git-diff.txt: backtick quote command text Denton Liu
2020-09-20 11:22 ` [PATCH v4 04/10] contrib/completion: extract common diff/difftool options Denton Liu
2020-09-20 11:22 ` [PATCH v4 05/10] diff-lib: accept option flags in run_diff_index() Denton Liu
2020-09-20 11:22 ` [PATCH v4 06/10] diff-lib: define diff_get_merge_base() Denton Liu
2020-09-20 11:22 ` [PATCH v4 07/10] t4068: add --merge-base tests Denton Liu
2020-09-20 11:22 ` [PATCH v4 08/10] builtin/diff-index: learn --merge-base Denton Liu
2020-09-29 19:53 ` Martin Ågren
2020-09-20 11:22 ` [PATCH v4 09/10] builtin/diff-tree: " Denton Liu
2020-09-20 11:22 ` [PATCH v4 10/10] contrib/completion: complete `git diff --merge-base` Denton Liu
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