For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; }
This code does not compile on my copy of MSVC10.
-->error C2899: typename cannot be used outside a template declaration
Thanks. Is anyone positive about what the C++11 standard says in this case? This code compiles on my GCC 4.5.3 with -std=c++0x... who's right MSVC or GCC?
C++03 section 14.2 paragraph 5 says: "[Note: just as is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the expression on the left of the -> or ., or the nested-name-specifier is not dependent on a template-parameter.]" C++11 amends this to: "[Note: As is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the nested-name-specifier or the expression on the left of the -> or . is not dependent on a template-parameter, or the use does not appear in the scope of a template.]" The addition of "or the use does not appear in the scope of a template" makes your example valid in C++11 (but it was invalid in C++03). It seems recent versions of GCC have adopted the C++11 behaviour, but MSVC has not (yet, as of version 10). Regards, Nate