`in` on function parameters: const, scope const, ref scope const ?

[tsbockman]

On Sunday, 5 April 2020 at 12:59:23 UTC, Petar Kirov [ZombineDev] 
wrote:
> `in` needs be its own parameter storage class, like `out` and 
> `ref` on the name-mangling / ABI level.

If we go with @kinke 's suggestion, then yes `in` definitely 
needs to be its own storage class, and we'll need good 
meta-programming tools for working with it.