Support bigint literals in const enums

Search Terms

• "const enum member initializers can only contain literal values"
• "bigint enum"
• "ts(2474)"

Suggestion

A bigint literal is a literal, but it does not seem usable in const enums.

const enum Foo {
  Bar = 123n
}

Currently produces, on 3.9.0-beta:

const enum member initializers can only contain literal values and other computed enum values. ts(2474)

Use Cases

Bigint compile-time constants 🙂

Examples

const enum Foo {
  Bar = 123n
}

console.log(Foo.Bar);

Should compile to

console.log(123n);

And log 123n when run.

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

この issue ではファイルもテストも指定されていません。まず、TypeScript コンパイラーにおける const enum の初期化子の検証と、それに関連する bigint リテラルの処理を特定してください。完了の条件は、示された const enum がコンパイルされ、console.log(123n) を出力し、123n をログに記録し、既存の enum 診断を後退させないことです。