Symbols in const assertions should be considered unique

TypeScript Version: 3.8.0-dev.20191205

Search Terms:

• const assertion unique symbol
• "unique symbol" "as const"

Code

const prop = Symbol()
const dictionary = {
  prop: Symbol()
}
const sealedDictionary = {
  prop: Symbol()
} as const

class MyClass {
  // Works because "prop" is a unique symbol
  [prop]: 1

  // Does not work because "dictionary.prop" is not a unique symbol
  [dictionary.prop]: 2

  // Does not work because "sealedDictionary.prop" is not a unique symbol,
  // even though it probably should be?
  [sealedDictionary.prop]: 3
}

Expected behavior:

MyClass should probably accept sealedDictionary.prop as a computed property name since it should be considered a unique symbol.

Actual behavior:

TypeScript complains with TS1166:

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

Playground Link: Provided Updated (old link seems to be broken in new playground)

Related Issues: —

Commencez par la reproduction mise à jour dans TypeScript Playground et confirmez l’erreur TS1166 pour sealedDictionary.prop dans la propriété de classe calculée. Suivez le chemin de vérification des types pour const assertions et les noms de propriétés unique symbol, puis ajoutez une couverture montrant que le cas sealedDictionary est accepté sans modifier le cas dictionary rejeté.