Type can't `keyof`

🔎 Search Terms

• keyof

🕗 Version & Regression Information

• This is a crash

⏯ Playground Link

No response

💻 Code

export type IsEqual<A, B> =
  (<T>() => T extends A ? 1 : 2) extends
  (<T>() => T extends B ? 1 : 2) ? true : false

export type IsNotEqual<A, B> =
  (<T>() => T extends A ? 1 : 2) extends
  (<T>() => T extends B ? 1 : 2) ? false : true

export interface Entries<X> {
  100000: [true extends (
    & IsNotEqual<X, ArrayConstructor>
    // Simplifying the problem here allows for the removal of the next line.
    & ([X] extends [ObjectConstructor] ? true : false)
  ) ? true : false, {
    check: (
      & IsNotEqual<X, ArrayConstructor>
      & ([X] extends [ObjectConstructor] ? true : false)
    ),
    x: X
  }]
  [key: number & {}]: [boolean, any]
}
type Mapping<
  X,
  E extends Entries<X> = Entries<X>
> = {
  [ K in keyof E
      as true extends (
        IsEqual<E[K & number][0], true>
      ) ? K : never
  ]: E[K & number][1]
}
type A0 = keyof Mapping<ObjectConstructor>
//   ^? type A0 = 100000
type A1 = ObjectConstructor extends infer T ? Mapping<T> : never
//   ^? type A1 = { 10000: { check: true; x: ObjectConstructor } }
type A2 = ObjectConstructor extends infer T ? keyof Mapping<T> : never
//   ^? type A2 = never
type A3 = [ObjectConstructor] extends [infer T] ? keyof Mapping<T> : never
//   ^? type A3 = never
type A4 = keyof (ObjectConstructor extends infer T ? Mapping<T> : never)
//   ^? type A4 = 11000

export {};
//   ^?

{
  "compilerOptions": {
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "declaration": true,
    "target": "ES2017",
    "jsx": "react",
    "module": "ESNext",
    "moduleResolution": "node"
  }
}

Playground Link: Provided

🙁 Actual behavior

In the case of A2, the type obtained through the operation cannot be used with keyof to obtain the Keys of the corresponding type.

🙂 Expected behavior

type A2 = 11000

Additional information about the issue

No response

Comienza con la reproducción proporcionada de TypeScript Playground y compara A2 con A0–A4, centrándote en la evaluación de keyof para los tipos condicionales y mapeados mostrados. Se considera terminado cuando el fallo está resuelto y A2 se evalúa como 11000 sin cambiar el comportamiento esperado de los ejemplos adyacentes.