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.

Empieza reproduciendo el ejemplo de array-mismatch y el ejemplo enlazado de Promise en el TypeScript playground. El issue no indica archivos del compilador ni tests, así que, después de establecer la salida actual, sigue la ruta de generación de diagnósticos; la tarea estará terminada cuando estén cubiertos los diagnósticos específicos del contenedor solicitados sin cambiar el comportamiento en tiempo de ejecución.