[Issue 21298] New: Missing error when overriding interface method without in contract with class method with contract

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21298

          Issue ID: 21298
           Summary: Missing error when overriding interface method without
                    in contract with class method with contract
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: minor
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: default_357-line at yahoo.de

Consider the following code:

```
interface I
{
  void foo(int i);
}

class C : I
{
  override void foo(int i) in (i > 0) { }
}
```
If `I` was a class, the compiler would rightly inform us that "function C.foo
cannot have an in contract when overridden function I.foo does not have an in
contract". However, since I is an interface, this error doesn't trigger. But it
should, of course, for the same reason.

--