Microsoft/TypeScript

Enum keys not accepted as computed properties if their name is not a valid identifier

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#25,083 创建于 2018年6月20日

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 (3 评论) (0 反应) (0 负责人)TypeScript (48,455 star) (6,726 fork)batch import
BugDomain: enumGood First Issue

描述

TypeScript Version: 2.9.2

Search Terms: computed property name

Code

enum Type {
  Foo = 'foo',
  '3x14' = '3x14'
}

type TypeMap = {
  [Type.Foo]: any
  [Type['3x14']]: any
}

Expected behavior: Type['3x14'] to be usable as a computed key in a type definition.

Actual behavior: A computed property name in a type literal must refer to an expression whose type is a literal type or a 'unique symbol' type.

This is the case even for Type.Foo if it's written as Type['Foo'] instead; so it seems there is some early bailout when the bracket operator is involved. For certain key names it may not be possible to write them without resorting to brackets, like a name that starts with a digit.

Playground Link: Link

贡献者指南

技术栈
typescript
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。
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
TypeScript type system basicsUnderstanding of computed properties
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。
20
研究方向
The issue involves the TypeScript checker's handling of computed property names in type literals. Look at the code path for checking computed property keys in checkComputedPropertyName or similar functions in src/compiler/checker.ts. The playground link shows the error. The fix likely requires allowing bracket access expressions like Type['3x14'] when they resolve to literal types. Consider the existing logic that allows Type.Foo but not Type['Foo'].