Issue Description:

If a static method of a nested type references an instance member of the outer type, that’s an error. But the error message is somewhat incorrect in that it states that the member “cannot be used on instance of nested type”, even though the use is not in an instance method, but a static method.

The first and second error messages here are correct, but the third one is incorrect:

struct Outer {
    var x: Int


    static func foo() {
        print(x) // Correct error: Instance member 'x' cannot be used on type 'Outer'
    }


    struct Inner {
        func bar() {
            print(x) // Correct error: Instance member 'x' of type 'Outer' cannot be used on instance of nested type 'Outer.Inner'
        }


        static func foo() {
            print(x) // Incorrect error: Instance member 'x' of type 'Outer' cannot be used on instance of nested type 'Outer.Inner'
        }
    }
}

Note: This is not the same issue as SR-5324, but I’m referencing it here because it probably touches the same places in the compiler.