Why this is causing C2102: '&' requires l-value

Question

I was wondering, why the following way of code (Already commented out) will cause
C2102: \'&\' requires l-value

Is there a better way to avoid u

Answer 1

Because a::get_dummy() returns a unnamed temporary object (int pointer).
Object returned by function sit ontop of the stack frame and it is meaningless to get its address since it might be invalid after expression ends.