Support error codes in ts-expect-error and ts-ignore comments

[jednano]

Search Terms

ts-expect-error ts-ignore comment specify support error code codes filter

Suggestion

Please consider supporting one or more error codes following a // @ts-expect-error or // @ts-ignore comment.

Use Cases

This makes testing TypeScript code extremely more accurate.

1. You want to ignore a specific error code or codes, but still fail on unexpected errors.
2. You expect a specific error code or codes, but you still don't want to compile unexpected errors.

Examples

// @ts-ignore(1, 2, ...)
// @ts-expect-error(1, 2, ...)

// ----------

// Type 'string' is not assignable to type 'number | boolean | null | undefined'.
// @ts-expect-error(2322)
fn<{ a: number }>({ a: 'b' });

// Type 'number' is not assignable to type 'boolean | null | undefined'.
// @ts-expect-error(2322)
fn<{ a: boolean }>({ a: 42 });

// This condition will always return 'false' since the types 'true' and 'false'
// have no overlap.
// @ts-expect-error(2367)
fn<{ a: boolean }>({ a: false }).a === false;

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.

[RyanCavanaugh]

Duplicate #19139