Re: attribute data structure rewrite

["Giovanni Bajo" <giovannibajo@libero.it>]

Gabriel Dos Reis wrote:

> We used to accept it because we did not implement offsetof correctly.
> For example, the following variation should be rejected (in C89 an C++
> mode)
>
>    struct A { char foo[10]; };
>    void bar(void) {
>      int i;
>      for (int i = 0; i < 10; ++i)
>         {
>            char ary[offsetof(struct A, foo[i] + 1);
>         }
>    }

I don't understand your example because I don't think the +1 there is valid.
Unless you meant:

char ary[offsetof(struct A, foo[i])+1];

Anyway, what about this in C99? We don't need a constant expression in this
context, and even if offsetof is always a constant expression we could still
accept it as an extension. In other words, we could transform it to
offsetof(struct A, foo)+i*sizeof(foo[0]) in contexts that don't require a
constant expression.

Giovanni Bajo