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
