From: Christophe de Dinechin <dinechin@redhat.com>
To: Jonathan Wakely <jwakely.gcc@gmail.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: sign-compare warning for short and char
Date: Tue, 20 Feb 2018 15:43:00 -0000 [thread overview]
Message-ID: <1FE711F4-D99F-47DB-8434-DFB7C96D82E8@redhat.com> (raw)
In-Reply-To: <CAH6eHdQWbWdSehzcBRB8SLht7kUv0AAF5daO2n5ByVYVwmB1Eg@mail.gmail.com>
> On 20 Feb 2018, at 16:15, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>
> This question belongs on the gcc-help list really.
I posted here because I saw it as a possible diagnostic bug / limitation. Do such things go to gcc-help? Or is it that you thought I was asking for the correct option?
> On 20 February 2018 at 14:44, Christophe de Dinechin
> <dinechin@redhat.com> wrote:
>> I wonder why -Wsign-compare only warns when there is no int promotion?
>
> I suspect the correct-but-not-helpful answer is that after integer
> promotion the operands have the same type, and so there's no
> comparison between signed and unsigned types.
That’s an implementation explanation, not a rationale, right?
> But the compiler could make the warning apply *before* doing integer
> promotion, to diagnose this case.
That is what I am thinking, but I was wondering if there was not some rationale making this a bad idea.
next prev parent reply other threads:[~2018-02-20 15:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-20 14:44 Christophe de Dinechin
2018-02-20 15:15 ` Jonathan Wakely
2018-02-20 15:43 ` Christophe de Dinechin [this message]
2018-02-20 19:49 ` Jonathan Wakely
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