Re: using offsetof with g++

[Joe Buck <jbuck at synopsys dot com>]

I wrote:
> | It seems to me that there are four categories:
> | 
> | 1) Those cases where ISO C++ specifies what the answer is.
> | 
> | 2) Those cases where any reasonable implementation (and all
> |    implementations we know of) give the right answer, but ISO
> |    C++ says "undefined".
> | 
> | 3) Those cases where we know that g++ will give the right answer,
> |    but we can't be sure of other possible implementations.
> | 
> | 4) Those cases where use of offsetof() is nonsense, since the offset
> |    is not even constant.

On Thu, Nov 06, 2003 at 08:47:19PM +0100, Gabriel Dos Reis wrote:

> I don't know where you put my favorite example that involve
> references:
> 
>    int i;
> 
>    struct A {
>      int& r;
>      A() : r(i) { }
>    };
> 
>    int main()
>    {
>      cout << offsetof(A, r) << endl;
>    }

Case 4 (it will do the wrong thing).