Copy constructors and IsExpression

[Stanislav Blinov]

On Monday, 1 June 2020 at 19:40:05 UTC, kinke wrote:
> On Monday, 1 June 2020 at 15:48:21 UTC, Stanislav Blinov wrote:
>> There are a few areas of the language and libraries, including 
>> druntime, that are ignoring copy constructors (for example, 
>> arrays). Is this also one of those?
>
> Very likely, as in not adapted after the addition of copy ctors.

Hm, having slept on it, I think, if `is(A:B)` did the check, this 
could blow up as a chicken-or-egg:

```
struct S {
     this(T)(ref scope T) if (!is(T : S)) { /* ... */ }
}
```