Compilation Error: "Setter for 'property' is unavailable" when trying to modify property of a class type wrapped in a property wrapper #74283
Description
Description
I'm encountering a compilation error when trying to modify the property of a class that's been wrapped using a custom property wrapper. The error states Setter for 'property' is unavailable, which is unexpected because the property foo is a mutable property of a class (FooValue). This seems to suggest an issue with how the setter is being synthesized (or not synthesized) for the wrapped property.
Reproduction
import Foundation
class FooValue {
var foo: String = ""
}
@propertyWrapper
public struct Wrapper<Value> {
private let value: Value
public init(wrappedValue: Value) {
value = wrappedValue
}
@available(*, unavailable, message: "@Published is only available on properties of classes")
public var wrappedValue: Value {
get { fatalError() }
set { fatalError() }
}
public static subscript<EnclosingSelf>(
_enclosingInstance object: EnclosingSelf,
wrapped wrappedKeyPath: Swift.ReferenceWritableKeyPath<EnclosingSelf, Value>,
storage storageKeyPath: Swift.ReferenceWritableKeyPath<EnclosingSelf, Wrapper<Value>>
) -> Value where EnclosingSelf : AnyObject {
get { object[keyPath: storageKeyPath].value }
@available(*, unavailable)
set { }
}
}
class MyClass {
@Wrapper
var property: FooValue = FooValue()
}
let outer = MyClass()
outer.property.foo = ""Expected behavior
The property foo of the FooValue class should be mutable, and modifications to it via an instance of MyClass should be allowed, considering FooValue is a class with a mutable foo property.
Environment
swift-driver version: 1.109.2 Apple Swift version 6.0 (swiftlang-6.0.0.3.300 clang-1600.0.20.10)
Target: arm64-apple-macosx14.0
Additional information
No response
rdar://132309786