Christoph Ludwig wrote:
On Thu, Jun 24, 2004 at 05:51:15PM +0200, Daniel Frey wrote:
Robert Ramey wrote:
BOOST_STATIC_ASSERT(false)
This *should* work. IMHO, if it doesn't, we should fix it, not work around it like Michiel suggested.
BOOST_STATIC_ASSERT(false) expands to a typedef that does not contain any dependent expression. I didn't check the detailed rules in my copy of the template book by Vandevoorde and Josuttis, but I think a compiler should check this typedef even if the function template is not instantiated.
The compiler is allowed but not required to reject a template that can never produce a legal instantiation. [...]
I don't know if my solution (sizeof(T) && false) has any (dis-)advantages compared to Michiel's solution ((T*) 0).
A compiler is allowed to reject both. I think that you need one additional level of indirection: template<class T> struct always_false { enum { value = 0 }; }; template<class T> struct always_assert { BOOST_STATIC_ASSERT( always_false<T>::value ); };