From: AJ D <aatsnps@gmail.com>
To: David Brown <david.brown@hesbynett.no>
Cc: Andreas Schwab <schwab@linux-m68k.org>, gcc@gcc.gnu.org
Subject: Re: Comma Operator - Left to Right Associativity
Date: Thu, 4 Feb 2021 14:46:48 -0800 [thread overview]
Message-ID: <CAJMvVjaSU11mYHrcQDcprtneow0-zF-pUyxgGEh=9+vbjerLng@mail.gmail.com> (raw)
In-Reply-To: <c20c8c2e-429e-d2cb-909f-073ac2f39baf@hesbynett.no>
Nope, -std=c++17 didn’t help either.
On Thu, Feb 4, 2021 at 1:33 PM David Brown <david.brown@hesbynett.no> wrote:
>
>
> On 04/02/2021 22:21, Andreas Schwab wrote:
> > On Feb 04 2021, David Brown wrote:
> >
> >> For the built-in comma operator, you get guaranteed order of evaluation
> >> (or more precisely, guaranteed order of visible side-effects). But for
> >> a user-defined comma operator, you do not - until C++17, which has
> >> guaranteed evaluation ordering in some circumstances.
> >
> > But not the evaluation order of function arguments. See
> > <https://en.cppreference.com/w/cpp/language/eval_order> Sequenced-before
> > rules, rule 15.
>
> Correct.
>
> >
> >> Try your test again with "-std=c++17" or "-std=g++17" - if the order is
> >> still reversed, it's a gcc bug (AFAICS).
> >
> > I don't think so.
> >
>
> Unless I am missing something, in the OP's program it is a user-defined
> comma operator that is called. There is only one argument to the
> "test_comma_operator" function, the result of that user-defined comma
> operator. So rule 15 above does not apply - rule 16 applies.
>
> At least that is /my/ reading of the cppreference page and the OP's
> program.
>
> David
>
>
next prev parent reply other threads:[~2021-02-04 22:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 20:08 AJ D
2021-02-04 20:58 ` David Brown
2021-02-04 21:21 ` Andreas Schwab
2021-02-04 21:33 ` David Brown
2021-02-04 22:46 ` AJ D [this message]
2021-02-04 22:51 ` AJ D
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