But using the latest Swift snapshot from swift.org in Xcode will build successfully.

Then If I add another initialize function to the AlterKeys, It will build successfully too, like:
{code:swift}
@propertyWrapper
final class alterKeys<T> {
    
    public var wrappedValue: T
    
    public init(wrappedValue: @escaping @autoclosure () -> T, _ codingKeys: String...) {
        self.wrappedValue = wrappedValue()
    }
    public init(wrappedValue: @escaping @autoclosure () -> T) {
        self.wrappedValue = wrappedValue()
    }
}
struct A {
    // build success in Xcode 12
    @alterKeys("abc")
    var key: Int = 0
}