Transitive R-Value Inference and Move Construction a la Rust

[Nordlöw via Digitalmars-d]

On Monday, 26 September 2016 at 16:28:18 UTC, ag0aep6g wrote:
> Inside `top`, `a` is an lvalue. It wouldn't be correct to move 
> `a` just because it originated from an rvalue.

AFAICT, `top` can be moved in the call to `sub` if it's not used 
not returned below the call, right?