refCounted

// note that destructor is called from the parameter to refCounted, so we
// must trigger only counting destruction of non-init instances of the
// struct.
size_t dtorcalled = 0;
struct S
{
    int x;
    @safe ~this() {if(x) dtorcalled++;}
    @disable this(this);
}

{
    auto destroyme = S(1).refCounted;
    auto dm2 = destroyme;
    auto dm3 = destroyme;
}

assert(dtorcalled == 1);