The code below compiles fine under Comeau and VC++7.1.

gcc 3.3.2 gives the following diagnostic:

t2x.cpp:14: error: parse error before `<' token
t2x.cpp:14: error: syntax error before `<' token
t2x.cpp:19: error: parse error before `}' token
t2x.cpp: In function `int main()':
t2x.cpp:33: error: conversion from `X' to non-scalar type `D<char, char>'
   requested
make: *** [t2x] Error 1

The "struct C" commented allows this to compile and function as expected which
indicates that there most likely is a parsing error (expecting a typename but
have a template instead).  Using the "typename" keyword does not correct the
problem.

struct X
{
//  struct C; //uncomment to make this work.

    template<typename T,  typename A, template<typename,typename> class C>
    C<T, A> Func()
    {
        return C<T, A>();
    }

    template<typename T,  typename A, template<typename,typename> class C >
    operator C<T, A> ()
    {
        return C<T, A>();
    }

};

template<typename dpt, typename dpa>
class D
{
};

int main()
{
    X   x;

    x.Func<char, char, D>();

    D<char,char>    d = x;
}


Credit for finding this problem goes to: Leor Zolman
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=58nt00110jirtteaml6p5o45j6l19le1cl%404ax.com&rnum=9