Re: [c++] fold offsetof by hand

[Mark Mitchell <mark at codesourcery dot com>]

Richard Henderson wrote:

> On Sun, Aug 29, 2004 at 12:24:43PM -0700, Mark Mitchell wrote:
>
> > You should be checking whether or not the expression is dependent, not 
> > whether or not we are in a template.  Otherwise, we'll get various 
> > subtle semantics wrong.
>
>
> Example?

This should be accepted:

struct S { int i; };

template <unsigned int I> struct A;
template <> struct A<0> { typedef int T; };

template <typename T>
void f() {
  A<offsetof (S, i)>::T x
}

It will not be accepted if the compiler cannot figure out what the 
offset is.  Since S is not dependent, the compiler is supposed to figure 
that out.

--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com