🔎 搜索词

exactOptionalPropertyTypes optional generic indexed access undefined missing contextual constraint eopt

🕗 版本与回归信息

• 在5.3.0-dev.20230914中发生了变化

⏯ Playground链接

https://www.typescriptlang.org/play?exactOptionalPropertyTypes=true&ts=5.4.0-dev.20240111#code/PTAEAEFMA8EMGMAuB5ADoglgewHawDYAKATlqpMYgJ4AqV5AzgFyiLECukAUFxjohQBmCSKAAaAZUSwBAYVyCMAc3bEZ2HKADeXUKwAWkALaQA-CwBEsdoiwXQAH1AWAJrGIBre04v5l+xAsAbl1QADcMSAB3eXx2IxxzZwAjSAYMF0hvZwRMMKyQgF8eTPh8d1FBdhwkDVAlSEQANQZ4LEz5HEUVNUxcAB4aAD4ACgZIWtwWBjY+JQBKFhpHUGrMxRxIFxCuGFQsSlAqmr7NBsRO7tV1AYA5WBNQGAEcFwZQD0gqLEFxKRlIJdlNdTqNQngTCx7iYADRcRZ-aRyBTA3oaADa0MgAF1tKE2jgZvVIJtiBh4ABBBjpJR4ZIYPzUGhpRAsSRIwEono3HCYh440AAXlWr0gGy2QVAICexFIxB4emIjVUZ0aLTaHS5II0IwhkHmkulFDlXGKXAJRIJ8CVAipNLpDIwTJZbP+yK6qJ56M+31+7IBQO5p1xwrWYr4EqlYCwHi4QA

💻 代码

// @exactOptionalPropertyTypes: true

interface XStateConfiguration {
  theme?: "auto" | "dark" | "light";
  viewColumn?: "beside" | "active";
}

declare function getVscodeConfiguration<T>(section: string): T | undefined;

export function getConfiguration<Name extends keyof XStateConfiguration>(
  name: Name,
): XStateConfiguration[Name] {
  const genericAssignabilityTest: XStateConfiguration[Name] = undefined; // error

  return getVscodeConfiguration(name); // error
}

const concreteAssignabilityTest: XStateConfiguration[keyof XStateConfiguration] = undefined; // ok

🙁 实际行为

undefined 不能像这样分配给表达式空间中的索引访问

🙂 预期行为

我希望这能通过类型检查 - 就像具体的示例一样

关于问题的附加信息

• 无响应*