calling convention optimisation & const/immutable ref

[John Colvin via Digitalmars-d]

On Monday, 7 November 2016 at 20:23:37 UTC, Jacob Carlborg wrote:
> Since D is a systems programming language, wouldn't the user 
> want to have control over this?

It's just another optimisation in a long list of optimisations 
that can be performed without changing semantics. What about this 
one is less "systems language" worthy than - for example - 
constant folding or dead code elimination?