declarationEmitPromise.ts

// @declaration: true
// @noImplicitThis: false
// @module: commonjs
// @target: es6

export class bluebird<T> {
    static all: Array<bluebird<any>>;
}

export async function runSampleWorks<A, B, C, D, E>(
    a: bluebird<A>, b?: bluebird<B>, c?: bluebird<C>, d?: bluebird<D>, e?: bluebird<E>) {
    let result = await (bluebird.all as any)([a, b, c, d, e].filter(el => !!el));
    let func = <T>(f: (a: A, b?: B, c?: C, d?: D, e?: E) => T): T =>
        f.apply(this, result);
    let rfunc: typeof func & {} = func as any; // <- This is the only difference
    return rfunc
}

export async function runSampleBreaks<A, B, C, D, E>(
    a: bluebird<A>, b?: bluebird<B>, c?: bluebird<C>, d?: bluebird<D>, e?: bluebird<E>) {
    let result = await (bluebird.all as any)([a, b, c, d, e].filter(el => !!el));
    let func = <T>(f: (a: A, b?: B, c?: C, d?: D, e?: E) => T): T =>
        f.apply(this, result);
    let rfunc: typeof func = func as any; // <- This is the only difference
    return rfunc
}