Is this std::ref behaviour logical?

Question

Consider this code:

#include 
#include 

int xx = 7;

template
void f1(T arg)
{
    arg += xx;
}

template

        

Answer 1

arg = xx;

Local arg now refers to (read as binds with) xx. (And no more refers to j)

arg += xx;

Implicit operator T& () is applied to match the argument of operator += and hence addition is performed on referred object i.e. j.

So the observed behaviour is correct.