Officially, what is typename for?

Question

On occasion I\'ve seen some really indecipherable error messages spit out by gcc when using templates... Specifically, I\'ve had problems where seemingly correc

Answer 1

Two uses:

1. As a template argument keyword (instead of class)
2. A typename keyword tells the compiler that an identifier is a type (rather than a static member variable)

template  class X  // [1]
{
    typename T::Y _member;  // [2] 
}