src/lib/es2020.promise.d.ts

interface PromiseFulfilledResult<T> {
    status: "fulfilled";
    value: T;
}

interface PromiseRejectedResult {
    status: "rejected";
    reason: any;
}

type PromiseSettledResult<T> = PromiseFulfilledResult<T> | PromiseRejectedResult;

interface PromiseConstructor {
    /**
     * Creates a Promise that is resolved with an array of results when all
     * of the provided Promises resolve or reject.
     * @param values An array of Promises.
     * @returns A new Promise.
     */
    allSettled<T extends readonly unknown[] | readonly [unknown]>(values: T):
        Promise<{ -readonly [P in keyof T]: PromiseSettledResult<T[P] extends PromiseLike<infer U> ? U : T[P]> }>;

    /**
     * Creates a Promise that is resolved with an array of results when all
     * of the provided Promises resolve or reject.
     * @param values An array of Promises.
     * @returns A new Promise.
     */
    allSettled<T>(values: Iterable<T>): Promise<PromiseSettledResult<T extends PromiseLike<infer U> ? U : T>[]>;
}