[Boost-users] shared_ptr and polymorphism

Just a little problem that I can't fix. Suppose that I have these four classes class B {}; class D1: public B {}; class D2: public B {}; class E: public D1 {}; this test: void foo(D1 *) {} void foo(D2 *) {} int main() { E *e = new E; foo(e); return 0; } work just fine but this one void foo(shared_ptr<D1>) {} void foo(shared_ptr<D2>) {} int main() { shared_ptr<E> e(new E); foo(e); return 0; } the compiler say that the foo(boost::shared_ptr<E>&)' is ambiguous. Please, can someone help me to understand why and how can I fix this problem without changing the functions name. Thanks Boost 1.35 GCC 4.4.1 regards