Not an answer as such, but just to demonstrate how hard parsing C++ correctly actually is. My favorite demo:
template<bool> struct a_t;
template<> struct a_t<true> {
template<int> struct b {};
};
template<> struct a_t<false> {
enum { b };
};
typedef a_t<sizeof(void*)==sizeof(int)> a;
enum { c, d };
int main() {
a::b<c>d; // declaration or expression?
}
This is perfectly valid, standard-compliant C++, but the exact meaning of commented line depends on your implementation. If sizeof(void*)==sizeof(int) (typical on 32-bit platforms), it is a declaration of local variable d of type a::b<c>. If the condition doesn't hold, then it is a no-op expression ((a::b < c) > d). Adding a constructor for a::b will actually let you expose the difference via presence/absence of side effects.
