@jerro: the same thing: I'm not trying to fix the problem that you mention. I'm trying to define a function which can safely accept rvalues and lvalues without having to make a copy.
My point was that saving an address of a const ref parameter is already unsafe if you call the function with a local variable as the parameter. If this behavior seems problematic to you when it concerns rvalues, it should seem equally problematic when it comes to local variables. It doesn't make sense to make passing rvalues as const ref parameters illegal because of this problem, when passing local variables causes the same problem and is legal. It would only make sense to introduce "in ref" whith an intent to solve this problem, if local variables would also have to be passed as "in ref" (or some kind of scope ref, not necessarily const). But that would break pretty much all code that uses ref.
The only case I can think of when passing a local variable as const ref is safe, but passing an rvalue wouldn't be, is when the called function returns the address of the const parameter (or assigns it to some other ref parameter).
