[Issue 22775] The __traits does not see the scope attribute

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22775

--- Comment #2 from cbleser <cr at tagion.org> ---
I have detected a problem when using interfaces and scope variables.
It seems that the compile does not check the scope attributes.

The flowing compiles

```
struct S {
    int x;
}

@safe
interface I {
    int func(ref scope S s) @nogc;
}

@safe
class C : I {
    int func(ref S s) {
        return 2*s.x;
    }
}
```

The problem is that the interface function has a (ref scope S) parameter but
the class implements a (ref S).
(The code should be compiled with dip25 and dip1000)
The biggest problem is that sometimes it results in a segmentation fault. Due
to that, the compiler seems to treats it as two different when it is called
from the interface.

Note. It seems that the @nogc is carried to the C.func. (Maybe it is just
auto-adapted)

See. The attached example.

Keep up the good work tanks.

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