[Issue 17930] [Contract Programming] 23.3 In, Out and Inheritance

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17930

--- Comment #3 from Rob <resmith5 at outlook.com> ---
Forgot return types on functions. Also, the function in Derived2 should have
"override".

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