struct A
{
    A(int);
};

struct B
{
    B(A);
};

struct C
{
    C(B);
};

A(1);       // A <- int

B(1);       // B <- A <- int

C(A(1));    // C <- B <- A <- int
C(B(1));    // C <- B <- A <- int
C(B(A(1))); // C <- B <- A <- int

C(1);       // C <- B <- A <- int

error: no matching function for call to ‘C::C(int)’
no known conversion for argument 1 from ‘int’ to ‘B’