Re: skip_evaluation

[Ian Lance Taylor <iant at google dot com>]

Paolo Bonzini <paolo.bonzini@gmail.com> writes:

>> Presumably the early return is OK within a sizeof expression; it is OK
>> within an expression like (0 ? x : y)?
>
> From reading the code, I'd say yes.  The bug that Jason fixed is
> related to stuff that cannot appear within a constant expression
> except within sizeof -- for example
>
>    struct B {};
>    struct D : public B {
>        static const int i = sizeof((B*)(D*)0);
>    };
>
>    struct Z {};
>    struct A : Z {};
>    Z* implicitToZ (Z*);
>    struct B : A {
>        static const int i = sizeof(implicitToZ((B*)0));
>    };
>
>    struct B {};
>    struct D;
>    D* p;
>    struct D: public B {
>        static const int i = sizeof ((B*)p);
>    };
>
> (see PR27177).  All of these would still be forbidden within (0?x:y).

OK, but should they perhaps give an error which would perhaps not be
given if skip_evaluation is true?

Ian