[boost] Re: Re:Re: [static_assert] Regression with gcc 3.4.2?

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2004-09-19 00:15:44

"Robert Ramey" <ramey_at_[hidden]> wrote in message
news:20040919040443.D18A931132_at_acme.west.net...
> "David B. Held" <dheld_at_[hidden]> wrote in message
> news:cihmvu$3ik$1_at_sea.gmane.org...
> > #include <boost/static_assert.hpp>
> >
> > template <typename T>
> > struct foo
> > {
> >      void bar(void)
> >      {
> >          BOOST_STATIC_ASSERT(false);
> >      }
> > };
>
> I use
>
> ....
> BOOST_STATIC_ASSERT(sizeof(T) == 0);

The expression 'always_false<T>::value' can't be evaluated until the point of
instantiation, since always_false could be specialized for T. OTOH, the compiler
can tell immediately that 'sizeof(T) == 0' is false, so might it not replace
'sizeof(T) == 0' with 'false', and then issue the same error as in the quoted
case?

Jonathan