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Date: Tue, 02 Jun 2015 15:05:00 -0000
From: Marek Polacek <polacek@redhat.com>
To: Richard Biener <richard.guenther@gmail.com>,        GCC Patches <gcc-patches@gcc.gnu.org>,        Jason Merrill <jason@redhat.com>,        Joseph Myers <joseph@codesourcery.com>, rdsandiford@googlemail.com
Subject: Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095)
Message-ID: <20150602145428.GC2756@redhat.com>
References: <20150525194816.GX27320@redhat.com> <877frnchxt.fsf@googlemail.com> <CAFiYyc2SO9ccW++-NhNwEn=eioeWBT9P4hSmhjHEzwLaT3vC-A@mail.gmail.com> <87wpzmbif9.fsf@googlemail.com>
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On Tue, Jun 02, 2015 at 09:53:14AM +0100, Richard Sandiford wrote:
>   unsigned int min_prec = (wi::min_precision (op0, SIGNED)
>   			   + TREE_INT_CST_LOW (op1));
>   bool overflowed = min_prec > TYPE_PRECISION (type0);
>   if (overflowed && c_inhibit_evaluation_warnings == 0)
>     warning_at (loc, OPT_Wshift_overflow,
>              "result of %qE requires %u bits to represent, "
>              "but %qT only has %u bits",
>              build2_loc (loc, LSHIFT_EXPR, type0, op0, op1),
>              min_prec, type0, TYPE_PRECISION (type0));
> 
> which seems simpler than anything involving wider precision.

Clearly your version is much better, so I'll use it - thanks!
I'm testing a new version of the patch, will post it soon.

	Marek