A second argument in Promise.all([...]) that returns a Record breaks the return signature

[dannycochran]

TypeScript Version:

3.7.2

Search Terms:

Promise.all, Record

Code

interface MoviesResponse {
    movies: [];
}

type CharactersResponse = Record<number, any>;

const getMovies = async (): Promise<MoviesResponse> => ({
    movies: [],
})

const getCharacters = async (): Promise<CharactersResponse> => ({
});

(async () => {
    const [{ movies }, characters] = await Promise.all([getMovies(), getCharacters()]);
    console.log(movies, characters);
})();

Expected behavior:

The first variable in the deconstructed array should be correctly typed as MoviesResponse, rather than CharactersResponse. This worked in 3.6.4.

Actual behavior:

Both variables in the deconstructed array are inferred to be CharactersResponse. So when I try to deconstruct the first argument doing { movies }, it's an invalid destructuring.

Interestingly, if we update CharactersResponse to not be a map type, the problem goes away, e.g:

interface CharactersResponse {
    characters: any[];
}
const getCharacters = async (): Promise<CharactersResponse> => ({
    characters: [],
});

Playground Link:

http://www.typescriptlang.org/play/?ssl=1&ssc=1&pln=17&pc=6#code/JYOwLgpgTgZghgYwgAgLIHsBuwIGcBKeADuiLigN4BQytyAtljrgFzIDaAugNxUC+VKmACeRFAGEAFnCiJIUAsVLlkAXmSEE6KABMAPCACu9AEbQANMjghhAPl5UtZMMgDmEMBmx41V3MJAEZAAKAEo2AAUodHpgcj0vZkJcEjIIWzUM4Oo6BiY8Ni5zflDBJ1wXdzApGTloXF84f0CQ8OQomLiIPRrZBHlFFOV0zJDqPlCHYKaAoLDRnLpyl3YKPO8GvksEaT6BzkaAdzhgFw7Y8gA6OAAbG+D2KsS8MMsq3rqFMM5JmiXldA3CCXG7oVzBRgbba7T64X4TMLcIA

Related Issues:

None found.

[nmain]

Both movies and characters are inferred to be CharactersResponse

But the playground you linked to types movies as any (with an error)?

[dannycochran]

Both movies and characters are inferred to be CharactersResponse

But the playground you linked to types movies as any (with an error)?

Sorry, you're right. It's that the first argument coming back from Promise.all is typed as CharactersResponse, so when I try to deconstruct it, it shows up as any. Will update my comment.

[nmain]

I see. Once the example is corrected, this appears to work as you'd like it to in 3.6.3, but not 3.7.2

[orta]

Maybe fixed by #33707

[AnyhowStep]

This will be fixed by #33707
I just tested

#33707 (comment)

[andrewbranch]

Actually, this is a specific reproduction of #34937. This one came first by some number of minutes or hours, but the other has more discussion, so I’m going to mark this one duplicate—nothing personal @dannycochran 😄

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.