Subclass initializer parameters don’t inherit result builder attributes

[beccadax]

Describe the bug

If a class has an initializer with a parameter that has a result builder on it, subclasses which inherit that initializer won’t have the result builder attribute on the parameter.

Steps To Reproduce

import SwiftUI

class Super {
    init<V: View>(@ViewBuilder body: () -> V) {}
}

class Sub: Super {
    // Empty
}

func fn() {
    _ = Sub {    // error: type ‘()’ cannot conform to ‘View’
        Text("Hello")
        Text("World!")
    }
}

Expected behavior

Sub.init(body:) would have @ViewBuilder on its parameter, so ViewBuilder would be applied to the closure and the code would typecheck.

Environment (please fill out the following information)

Seen in:

• Xcode 13.4.1 (13F100)
• Swift Playgrounds 4.1 (1676.15)

Additional context

We originally saw this with a simple custom result builder using a variadic buildBlock, so it’s not specific to @ViewBuilder.

Thanks to @quephird for showing me this bug.