ref int foo(ref int x) { return x ; }

void main ()
{
    foo(3) ;
// Error: function rvalue_argument.foo (ref int x) is not callable using 
argument types (int)
// Comment: "argument ref int x of function rvalue_argument.foo cannot bind 
to an rvalue" would be clearer IMO

    int i ;
    ref ir = i ;
// Error: variable ref_type.main.ir only parameters or foreach declarations 
can be ref
// Comment: after the variable name add a colon, and add ", return values" 
after "parameters"
}