# (unknown) 4 messages from 2016-04-11 to 2016-04-12. Participants: miwilliams@google.com, Jeff King, Matthieu Moy, Stefan Beller. Thread: https://gitlist.dev/t/41994 ## miwilliams@google.com, 2016-04-11 19:04 Subject: (unknown) Message-ID: <001a11492f107354a305303a369a@google.com> URL: https://gitlist.dev/e/001a11492f107354a305303a369a%40google.com ``` From 7201fe08ede76e502211a781250c9a0b702a78b2 Mon Sep 17 00:00:00 2001 From: Mike Williams Date: Mon, 11 Apr 2016 14:18:39 -0400 Subject: [PATCH 1/1] wt-status: Remove '!!' from wt_status_collect_changed_cb The wt_status_collect_changed_cb function uses an extraneous double negation (!!) when determining whether or not a submodule has new commits. Signed-off-by: Mike Williams --- wt-status.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/wt-status.c b/wt-status.c index ef74864..b955179 100644 --- a/wt-status.c +++ b/wt-status.c @@ -431,7 +431,7 @@ static void wt_status_collect_changed_cb(struct diff_queue_struct *q, d->worktree_status = p->status; d->dirty_submodule = p->two->dirty_submodule; if (S_ISGITLINK(p->two->mode)) - d->new_submodule_commits = !!hashcmp(p->one->sha1, p->two->sha1); + d->new_submodule_commits = hashcmp(p->one->sha1, p->two->sha1); } } -- 2.8.0 ``` ## Jeff King, 2016-04-11 19:13 Subject: Re: your mail Message-ID: <20160411191311.GA9057@sigill.intra.peff.net> URL: https://gitlist.dev/e/20160411191311.GA9057%40sigill.intra.peff.net In-Reply-To: <001a11492f107354a305303a369a@google.com> ``` On Mon, Apr 11, 2016 at 07:04:23PM +0000, miwilliams@google.com wrote: > From 7201fe08ede76e502211a781250c9a0b702a78b2 Mon Sep 17 00:00:00 2001 > From: Mike Williams > Date: Mon, 11 Apr 2016 14:18:39 -0400 > Subject: [PATCH 1/1] wt-status: Remove '!!' from > wt_status_collect_changed_cb These bits (minus the initial "From ..." line) should go into your actual email headers. As it is, your email has no subject line. > The wt_status_collect_changed_cb function uses an extraneous double > negation (!!) when determining whether or not a submodule has new > commits. > [...] > - d->new_submodule_commits = !!hashcmp(p->one->sha1, p->two->sha1); > + d->new_submodule_commits = hashcmp(p->one->sha1, p->two->sha1); It's not extraneous. hashcmp() returns 0 for equality, but an arbitrary positive or negative value depending on how the two arguments differ. The assigned "new_submodule_commits" is a bitfield of size 1. So the "!!" is normalizing the value into "0" or "1". -Peff ``` ## Matthieu Moy, 2016-04-11 19:18 Subject: Re: none Message-ID: URL: https://gitlist.dev/e/vpq37qsosyf.fsf%40anie.imag.fr In-Reply-To: <001a11492f107354a305303a369a@google.com> ``` miwilliams@google.com writes: > From 7201fe08ede76e502211a781250c9a0b702a78b2 Mon Sep 17 00:00:00 2001 > From: Mike Williams > Date: Mon, 11 Apr 2016 14:18:39 -0400 > Subject: [PATCH 1/1] wt-status: Remove '!!' from > wt_status_collect_changed_cb > > The wt_status_collect_changed_cb function uses an extraneous double > negation (!!) > when determining whether or not a submodule has new commits. It's not just a double negation, it's a way to ensure that the value is 0 or 1 (it's a relatively common idiom in C at least in Git's codebase). new_submodule_commits is a 1-bit bitfield, and you don't want to assign anything other than 1 or 0 (or you'll get modulo 2^n semantics, with n==1). So the old code is correct and your patch would introduce a bug. -- Matthieu Moy http://www-verimag.imag.fr/~moy/ ``` ## Stefan Beller, 2016-04-12 04:33 Subject: Re: Message-ID: URL: https://gitlist.dev/e/CAGZ79kYD7o3O_-zSGD24_DUy9hDc9%3Du6pPYXOOWp%2B-i-PW7vjQ%40mail.gmail.com In-Reply-To: <001a11492f107354a305303a369a@google.com> ``` On Mon, Apr 11, 2016 at 12:04 PM, wrote: > From 7201fe08ede76e502211a781250c9a0b702a78b2 Mon Sep 17 00:00:00 2001 > From: Mike Williams > Date: Mon, 11 Apr 2016 14:18:39 -0400 > Subject: [PATCH 1/1] wt-status: Remove '!!' from > wt_status_collect_changed_cb > > The wt_status_collect_changed_cb function uses an extraneous double negation > (!!) How is an !! errornous? It serves the purpose to map an integer value(-1,0,1,2,3,4) to a boolean (0,1, or a real bit in a bit field). > when determining whether or not a submodule has new commits. > > Signed-off-by: Mike Williams > --- > wt-status.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/wt-status.c b/wt-status.c > index ef74864..b955179 100644 > --- a/wt-status.c > +++ b/wt-status.c > @@ -431,7 +431,7 @@ static void wt_status_collect_changed_cb(struct > diff_queue_struct *q, > d->worktree_status = p->status; > d->dirty_submodule = p->two->dirty_submodule; > if (S_ISGITLINK(p->two->mode)) > - d->new_submodule_commits = !!hashcmp(p->one->sha1, > p->two->sha1); > + d->new_submodule_commits = hashcmp(p->one->sha1, > p->two->sha1); > } > } > > -- > 2.8.0 > > -- > To unsubscribe from this list: send the line "unsubscribe git" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ```