From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: "René Scharfe" <l.s.r@web.de>,
"Vegard Nossum" <vegard.nossum@oracle.com>,
"Lars Schneider" <larsxschneider@gmail.com>,
allan.x.xavier@oracle.com,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Git List" <git@vger.kernel.org>
Subject: Re: [PATCH v1] Travis: also test on 32-bit Linux
Date: Fri, 10 Mar 2017 15:18:40 -0500 [thread overview]
Message-ID: <20170310201840.fubshjp2bjg4bjxq@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqfuikyjoo.fsf@gitster.mtv.corp.google.com>
On Fri, Mar 10, 2017 at 12:13:11PM -0800, Junio C Hamano wrote:
> René Scharfe <l.s.r@web.de> writes:
>
> >> I think this misses the other two cases: (*dst, src) and (*dst, *src).
> >
> > ... and that's why I left them out. You can't get dst vs. *dst wrong
> > with structs (at least not without the compiler complaining); only
> > safe transformations are included in this round.
>
> I haven't followed this discussion to the end, but the omission of 2
> out of obvious 4 did pique my curiosity when I saw it, too, and made
> me wonder if the omission was deliberate. If so, it would be nice
> to state why in the log message (or in copy.cocci file itself as a
> comment).
Yeah, it definitely would be worth mentioning. I'm still undecided on
whether we want to be endorsing struct assignment more fully.
> It also made me wonder if we would be helped with a further
> combinatorial explosion from "T **dstp, **srcp" and somesuch (in
> other words, I am wondering why a rule for 'T *src' that uses '*src'
> need to be spelled out separately when there already is a good rule
> for 'T src' that uses 'src'---is that an inherent restriction of the
> tool?).
I had that thought, too, but I think the 4-way rules are necessary,
because the transformations aren't the same in each case. E.g., for the
four cases, the resulting assignments are:
(dst, src): dst = src;
(dst, *src): dst = *src;
(*dst, src): *dst = src;
(*dst, *src): *dst = *src;
For pointer-to-pointer, I assumed the tool would handle that
automatically by matching "T" as "T*". Though if that is the case, I
think "(dst, src)" and "(*dst, *src)" would be equivalent (though of
course our rule matches are different, as you do not memcpy the raw
structs).
-Peff
next prev parent reply other threads:[~2017-03-10 20:18 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-28 19:17 [PATCH] Travis: also test on 32-bit Linux Johannes Schindelin
2017-02-28 20:34 ` Johannes Schindelin
2017-03-02 5:06 ` Junio C Hamano
2017-03-02 10:51 ` [PATCH v1] " Lars Schneider
2017-03-02 11:24 ` Johannes Schindelin
2017-03-02 11:38 ` Lars Schneider
2017-03-02 14:22 ` Johannes Schindelin
2017-03-02 15:53 ` Christian Couder
2017-03-02 18:03 ` Junio C Hamano
2017-03-03 2:17 ` Johannes Schindelin
2017-03-03 18:43 ` Junio C Hamano
2017-03-04 0:03 ` Junio C Hamano
2017-03-04 4:11 ` Junio C Hamano
2017-03-04 17:23 ` Lars Schneider
2017-03-04 18:08 ` Vegard Nossum
2017-03-04 19:49 ` Vegard Nossum
2017-03-04 20:08 ` Vegard Nossum
2017-03-05 11:36 ` Jeff King
2017-03-05 11:44 ` [PATCH] line-log: use COPY_ARRAY to fix mis-sized memcpy Jeff King
2017-03-05 12:20 ` Vegard Nossum
2017-03-05 11:46 ` [PATCH v1] Travis: also test on 32-bit Linux Jeff King
2017-03-10 0:14 ` René Scharfe
2017-03-10 8:18 ` Jeff King
2017-03-10 16:20 ` René Scharfe
2017-03-10 17:57 ` Jeff King
2017-03-10 18:31 ` René Scharfe
2017-03-10 20:13 ` Junio C Hamano
2017-03-10 20:18 ` Jeff King [this message]
2017-03-10 22:04 ` René Scharfe
2017-03-10 23:33 ` Junio C Hamano
2017-03-11 14:17 ` René Scharfe
2017-03-10 0:14 ` René Scharfe
2017-03-10 7:45 ` Jeff King
2017-03-02 15:17 ` Ramsay Jones
2017-03-05 17:38 ` Lars Schneider
2017-03-05 22:16 ` Ramsay Jones
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