"Eric Niebler" <eric@boost-consulting.com> wrote
Arkadiy Vertleyb wrote:
Here is the minimal example:
// ---- #include "boost/mpl/vector.hpp" #include "boost/mpl/size_t.hpp"
template<class T> T make();
template<class T> struct et { typedef boost::mpl::vector1<int> type; };
template<class T> char(&sz(const T&))[ boost::mpl::size< typename et<T>::type >::value ];
template<class T, class U> struct add { typedef boost::mpl::vector1< boost::mpl::size_t<sizeof(sz(make<T>() + make<U>()))> //boost::mpl::size_t<sizeof(sz(T() + U()))> -- doesn't help here > type; };
int main() { return 0; } // ----
This example compiles fine with GCC, but both MS compilers choke on it.
I have experienced this problem before, and the fix is to calculate the return type of the sz() function as a separate step:
#include "boost/mpl/vector.hpp" #include "boost/mpl/size_t.hpp"
template<class T> T make();
template<class T> struct et { typedef boost::mpl::vector1<int> type; };
template<class T> struct sizer { typedef char(&type)[ boost::mpl::size< typename et<T>::type >::value ]; };
template<class T> typename sizer<T>::type sz(const T&);
template<class T, class U> struct add { typedef boost::mpl::vector1< boost::mpl::size_t<sizeof(sz(make<T>() + make<U>()))> > type; };
This compiles with VC7.1 and with gcc. I don't have VC8 beta installed.
Hi Eric, Your example does compile on VC8 beta -- thanks a lot. Now I'll try to aply it to typeof... As far as "Microsoft bug" is conserned, my testing wasn't accurate. After I #include "boost/mpl/size.hpp", which I use, VC7 is fine and VC8 is fine with T() + U(). It still can't handle make<T>() + make<U>(), though... Regards, Arkadiy