Validation error: Can only refer to own type parameters in nested class/enum

[lars-reimann]

Is your feature request related to a problem?

This code is currently legal:

class MyClass<T> {
    class Inner(p: T) {
        attr a: T

        fun f<S>(p: T, q: S)
    }

    enum InnerEnum {
        Variant(p: T)
    }
}

Desired solution

However, a class/enum variant should only be able to refer to its own type parameters. A function should be able to refer to its own type parameters and the type parameters of the containing class. Add validation for this.

Possible alternatives (optional)

No response

Screenshots (optional)

No response

Additional Context (optional)

No response