rvalues -> ref (yup... again!)

[Johannes Pfau]

Am Sat, 24 Mar 2018 01:04:00 -0600 schrieb Jonathan M Davis:

> As it stands, because a function can't accept rvalues by ref, it's
> usually reasonable to assume that a function accepts its argument by ref
> because it's mutating that argument rather than simply because it's
> trying to avoid a copy. If ref suddenly starts accepting rvalues, then
> we lose that.

Any reason you can't simply use `ref` to imply 'modifies value' and 
`const ref` as 'passed by ref for performance reasons'?

-- 
Johannes