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.

Beginne damit, das array-mismatch-Beispiel und das verknüpfte Promise-Beispiel im TypeScript playground zu reproduzieren. Das Issue nennt keine Compiler-Dateien oder Tests, also verfolge nach der Ermittlung der aktuellen Ausgabe den Pfad zur Diagnosegenerierung; abgeschlossen ist die Aufgabe, wenn die angeforderten container-spezifischen Diagnosen abgedeckt sind, ohne das Laufzeitverhalten zu ändern.