From: Joseph Myers <joseph@codesourcery.com>
To: Marek Polacek <polacek@redhat.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, Jason Merrill <jason@redhat.com>
Subject: Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Date: Thu, 04 Jun 2015 21:05:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.10.1506042103560.6208@digraph.polyomino.org.uk> (raw)
In-Reply-To: <20150603130531.GF2756@redhat.com>
On Wed, 3 Jun 2015, Marek Polacek wrote:
> > Well, ok then. This new version incorporates Richard S.'s suggestion,
> > and warns even for 1 << 31 in C99/C11 (also in C90 when -Wshift-overflow
> > is explicitely specified). For C++, it warns about 1 << 31 by default
> > only in C++11 mode, in C++14 never, otherwise only if -Wshift-overflow
> > is specified.
> >
> > But the fallout seems to be nonnegligible. So I think the default should
> > be -Wshift-overflow=1 that doesn't warn about 1 << 31, but still rejects
> > e.g. enum { A = 1 << 31 };. And -Wshift-overflow=2 would warn even about
> > 1 << 31. (Perhaps this is exactly what you had in mind, but I'm not sure.)
>
> Done in the following. I think this is the best approach. The documentation
> hopefully makes it clear what's the intended behavior.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
The C changes are OK.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2015-06-04 21:04 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-25 20:12 [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) Marek Polacek
2015-05-26 11:07 ` Marek Polacek
2015-05-29 21:25 ` Joseph Myers
2015-06-02 19:26 ` [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 2) Marek Polacek
2015-06-03 13:07 ` [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3) Marek Polacek
2015-06-04 21:05 ` Joseph Myers [this message]
2015-06-05 9:42 ` Marek Polacek
2015-06-12 9:08 ` Marek Polacek
2015-06-19 10:51 ` Marek Polacek
2015-06-26 8:36 ` Marek Polacek
2015-07-03 7:42 ` Marek Polacek
2015-07-10 13:23 ` Marek Polacek
2015-07-17 8:32 ` Marek Polacek
2015-07-17 23:01 ` Jeff Law
2015-07-20 14:19 ` Marek Polacek
2015-06-01 20:06 ` [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) Richard Sandiford
2015-06-02 8:16 ` Richard Biener
2015-06-02 9:01 ` Richard Sandiford
2015-06-02 15:05 ` Marek Polacek
2015-07-20 20:40 [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3) David Edelsohn
2015-07-21 10:11 ` Marek Polacek
2015-07-22 12:48 ` David Edelsohn
2015-07-22 12:51 ` Marek Polacek
2015-07-22 12:52 ` Segher Boessenkool
2015-07-22 17:01 ` Marek Polacek
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