How to avoid inout type constructor with Optional type wrapper undoing string type

[aliak]

On Sunday, 29 July 2018 at 12:30:58 UTC, Steven Schveighoffer 
wrote:
> On 7/28/18 6:06 PM, aliak wrote:
>> [...]
>
> What I meant was that string is actually mutable (the data 
> isn't mutable, but the string can be re-assigned to another 
> one), so Optional!string is more useful than 
> immutable(Optional!(char[])). I shouldn't have said that 
> immutable(Optional!T) is useless, you are right, and it 
> wouldn't make sense for the defined flag to change there anyway.
>
> [...]

Ah right. So it seems inout is removing head qualifiers on by-val 
parameters?

Filed what I think I understood from this:

https://issues.dlang.org/show_bug.cgi?id=19125