In the page in the question,we want to deduce the T in int n2 = f(0) it says that before it conduct the deduction, it first adjust the equation(here is T&&=int)to solve, since 0 is a rvalue, we don't need to change the int to int&, then we conduct the deduction, in the deduction, the left hand side's reference is discarded, so we get T=int