On 4/6/2010 12:49 PM, Eric Niebler wrote:
The issue is whether the decltype keyword is too broken on VC10 to define BOOST_NO_DECLTYPE. I think it /may/ be, so we should define it just to be safe, at least for 1.43.
Actually, I may have been too hasty. I notice the same behavior on recent gcc builds. That is, the following program causes both vc10 and gcc in std=c++0x mode to run out of heap space. template<class T> struct S; template<class X, class Y> struct pair {}; template<class T> S<T> wrap(T) { return 0; } template<class T> struct S { S(int = 0) {} // The following use of decltype causes the compiler to blow up: decltype(wrap(pair<T,T>())) foo() { return wrap(pair<T,T>()); } // The following, which should be equivalent, compiles without // problem: //S<pair<T,T> > foo() { return wrap(pair<T,T>()); } }; int main() { S<int> s; } If these are both conforming implementations of decltype, that's bad news. It means that std::result_of has a significant and unfortunate change of behavior from tr1::result_of and boost::result_of, and also means that decltype cannot be safely used in all contexts. I think we need a decltype expert to weigh in on this. I may bring the issue up with the std committee. -- Eric Niebler BoostPro Computing http://www.boostpro.com