17 Templates [temp]

A template-argument for a template-parameter which is a type shall be a type-id.

[ Example:

template <class T> class X { };
template <class T> void f(T t) { }
struct { } unnamed_obj;

void f() {
  struct A { };
  enum { e1 };
  typedef struct { } B;
  B b;
  X<A> x1;          // OK
  X<A*> x2;         // OK
  X<B> x3;          // OK
  f(e1);            // OK
  f(unnamed_obj);   // OK
  f(b);             // OK
}

 — end example ] [ Note: A template type argument may be an incomplete type ([basic.types]).  — end note ]