[SR-1283] RawRepresentable extension for Self:NSCoding breaks implicit RawRepresentable implementation for enums

描述

import Foundation

enum Status: Int {
    case Good
    case Bad
}

extension RawRepresentable where Self: NSCoding {
    init?(rawValue: NSData) {
        if let instance = NSKeyedUnarchiver.unarchiveObjectWithData(rawValue) as? Self {
            self = instance
        } else {
            return nil
        }
    }
    
    var rawValue: NSData {
        get {
            return NSKeyedArchiver.archivedDataWithRootObject(self)
        }
    }
}

贡献者指南

技术栈

swift

领域

tooling

议题类型

bug

难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。

3

预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。

1-2 days

活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。

stale

清晰度议题是否清楚说明期望改动、验收标准和下一步。

mostly clear

前置要求

Swift genericsRawRepresentableNSCoding

新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。

55

研究方向

The bug is due to an extension on RawRepresentable where Self: NSCoding providing a conflicting initializer and property. The fix likely requires modifying the Swift compiler's type checking to disallow such extensions when they conflict with enum's implicit RawRepresentable conformance. Look into the type checker's handling of conditional conformances and RawRepresentable conformance inference. Check the Swift compiler source, particularly the Sema module. The issue has a label 'StarterBug', which may indicate it has been triaged for beginners and there might be a suggested fix in related discussions.