Compiler error message improvement: Special casing container objects

Search Terms

array promise container error message compare

Suggestion

Could it be worth having an extra special case message when the only difference is that you haven't included an array indicator instead of listing the property differences e.g.

3.7:

src/index.ts:356:5 - error TS2322: Type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; }[][]' is not assignable to type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; }[]'.
      Type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; }[]' is missing the following properties from type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; }': renderedMessage, id, category, code, start

    356     errors,
            ~~~~~~

      src/index.ts:235:3
        235   errors: {
              ~~~~~~
        The expected type comes from property 'errors' which is declared here on type 'TwoSlashReturn'

To:

src/index.ts:356:5 - error TS2322: Type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; length: number | undefined; }[][]' is not assignable to type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; length: number | undefined; }[]'.

Type '{ renderedMessage: string; id: string; category: 0 | 1 | 2 | 3; code: number; start: number | undefined; length: number | undefined; }[]' is in an array here:

    356     errors,
            ~~~~~~

      src/index.ts:235:3
        235   errors: {
              ~~~~~~
        But not here

and the reverse?

Use Cases

Any case of mismatched types where the difference is that the object on one side of the comparison is the same object but wrapped in an array. Perhaps this could also work for a Promise too?

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.

まず、TypeScript playground で array-mismatch の例と、リンクされた Promise の例を再現します。Issue ではコンパイラファイルやテストが指定されていないため、現在の出力を確認した後、診断生成パスを追跡します。要求されたコンテナ固有の診断が、ランタイム動作を変更せずに網羅されれば完了です。