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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 09/10] builtin/diff-tree: learn --merge-base
Date: Fri, 18 Sep 2020 03:48:33 -0700	[thread overview]
Message-ID: <20200918104833.GB1874074@generichostname> (raw)
In-Reply-To: <xmqq363gs1mt.fsf@gitster.c.googlers.com>

On Thu, Sep 17, 2020 at 11:23:54AM -0700, Junio C Hamano wrote:
> Denton Liu <liu.denton@gmail.com> writes:
> 
> > +	if (read_stdin && merge_base)
> > +		die(_("--stdin and --merge-base are mutually exclusive"));
> > +
> > +	if (merge_base) {
> > +		struct object_id oid;
> > +
> > +		if (opt->pending.nr != 2)
> > +			die(_("--merge-base only works with two commits"));
> > +
> > +		diff_get_merge_base(opt, &oid);
> > +		opt->pending.objects[0].item = lookup_object(the_repository, &oid);
> > +	}
> > +
> 
> This looks quite straight-forward.
> 
> > -	/*
> > -	 * We saw two trees, ent0 and ent1.  If ent1 is uninteresting,
> > -	 * swap them.
> > -	 */
> > -	if (ent1->item->flags & UNINTERESTING)
> > -		swap = 1;
> > -	oid[swap] = &ent0->item->oid;
> > -	oid[1 - swap] = &ent1->item->oid;
> > +	if (merge_base) {
> > +		diff_get_merge_base(revs, &mb_oid);
> > +		oid[0] = &mb_oid;
> > +		oid[1] = &revs->pending.objects[1].item->oid;
> > +	} else {
> > +		int swap = 0;
> > +
> > +		/*
> > +		 * We saw two trees, ent0 and ent1.  If ent1 is uninteresting,
> > +		 * swap them.
> > +		 */
> > +		if (ent1->item->flags & UNINTERESTING)
> > +			swap = 1;
> > +		oid[swap] = &ent0->item->oid;
> > +		oid[1 - swap] = &ent1->item->oid;
> > +	}
> 
> It is not entirely clear why the original has to become an [else]
> clause here, unlike the change we saw earlier in cmd_diff_tree().
> It feels quite inconsistent.

Since we're only interested in the oids, I thought that it would be
possible to save a lookup_object() and just use the oids directly. If
it's clearer, this can be written as something like this but the lookup
feels unnecessary:

	/*
	 * We saw two trees, ent0 and ent1.  If ent1 is uninteresting,
	 * swap them.
	 */
	if (ent1->item->flags & UNINTERESTING)
		swap = 1;

	if (merge_base) {
		struct object_id mb_oid;
		if (swap)
			BUG("swap is unexpectedly set");
		if (diff_get_merge_base(revs, &mb_oid))
			exit(128);
		ent0->item = lookup_object(the_repository, &mb_oid);
	}


	oid[swap] = &ent0->item->oid;
	oid[1 - swap] = &ent1->item->oid;

Thanks,
Denton

  reply	other threads:[~2020-09-18 10:48 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-05 19:08 [PATCH 0/4] builtin/diff: " 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
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 [this message]
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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