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.

The issue names no files or tests. Start by locating the const enum initializer validation and the related bigint literal handling in the TypeScript compiler. Done means the shown const enum compiles, emits console.log(123n), and logs 123n without regressing existing enum diagnostics.