swiftlang/swift

[SR-5528] Allow multiple typealiases in a declaration

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#48,100 创建于 2017年7月22日

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 (3 评论) (0 反应) (1 负责人)Swift (69,989 star) (10,719 fork)batch import
compilerfeaturegood first issueparserswift evolution proposal neededtype checkertypealias

描述
Previous ID SR-5528
Radar None
Original Reporter @jckarter
Type Bug
Votes 0
Component/s Compiler
Labels Bug, StarterProposal
Assignee None
Priority Medium

md5: 2a0e34842e00129c1149fdebbc72bce0

Issue Description:

https://twitter.com/charlesismcom/status/888488466970955776

It would be consistent with let/var if you could write a comma-separated list of typealiases in one declaration, e.g.:

typealias Tomayto = Tomahto, Potayto = Potahto

贡献者指南

技术栈
swift
领域
developer experience
议题类型
feature
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。
half day
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。
clear
前置要求
Swift programmingCompiler basics
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
Examine how 'let' and 'var' declarations support multiple comma separated bindings in the Swift compiler's parser. Look for the parsing logic in the AST and Sema phases for typealias declarations. Review any comments on the issue for existing discussion. Consider implementing a similar pattern for typealias in the parser (e.g., in 'Parser::parseDeclTypeAlias') and updating the type checker accordingly.