How to port C++ std::is_reference<T> to D ?

[Paul Backus]

On Wednesday, 6 May 2020 at 09:40:47 UTC, wjoe wrote:
> yes, I did read the spec. I read the language spec on traits as 
> well as std.traits docs as well as searching the internet for a 
> solution since day before yesterday. But I couldn't bring it 
> together because
>
>   } else static if (__traits(isRef, T)) {
>
> compiles, but e.g.
>
>    assert (modifier!(ref int) == "[out] ");
>
> doesn't.
> Anyways, thanks for your reply.

D doesn't have reference *types*, it only has reference 
*parameters*. Here's an example:

void fun(ref int r, int v) {
     static assert(is(typeof(r) == int)); // note: not `ref int`
     static assert(is(typeof(r) == typeof(v))); // `ref` makes no 
difference to type

     static assert(__traits(isRef, r)); // note: not 
`__traits(isRef, typeof(r))`
     static assert(!__traits(isRef, v));
}