swiftlang/swift

[SR-4464] Assigning a property to itself fails in 3.1

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#47,041 创建于 2017年4月1日

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 (4 评论) (0 反应) (0 负责人)Swift (69,989 star) (10,719 fork)batch import
bugcompilerdiagnostics qualitygood first issue

描述
Previous ID SR-4464
Radar None
Original Reporter @iby
Type Bug
Status In Progress
Resolution

Attachment: Download
Votes 0
Component/s Compiler
Labels Bug, 3.1Regression, DiagnosticsQoI, StarterBug
Assignee None
Priority Medium

md5: 702671bd69d19bebf1a102eb3ec92355

Issue Description:

Prior 3.1 we could assign property to itself if needed with self.name = (self.name), now it fails. Also, see this for details – http://stackoverflow.com/a/31931318/458356.

Just discovered by luck, apparently the supported syntax now is (self.name = self.name), is this official?

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。
2
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。
1-3 hours
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 basicsCompiler toolchain setup
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。
60
研究方向
Review the linked Stack Overflow discussion and the Swift compiler's parser for self assignment syntax. Look at the AST for property access expressions and assignment nodes. The issue may be in how parentheses are handled around the assignment. Check the git history for changes around Swift 3.1 release.