Querying parameter passing semantics for `auto ref const` variables

[Nordlöw via Digitalmars-d-learn]

On Sunday, 15 January 2017 at 17:41:36 UTC, Nordlöw wrote:
> This
>
>     struct S { int x, y; }
>     void f()(auto ref const S s)
>     {
>         pragma(msg, "type:", typeof(s), " isRef:", isRef!s);
>     }
>     f(S.init);
>     S s;
>     f(s);
>
> prints
>
>     type:const(S) isRef:false
>     type:const(S) isRef:true

given that

     enum isRef(alias fn) = __traits(isRef, fn);

:)