fix(combineLatest): improve typings for combineLatest (#4470)

* fix(combineLatest): improve typings for combineLatest

Existing typings did a poor job of getting proper types from code that passed an array of observables or observable inputs to combineLatest. This issue was caught while trying master in google3. This resolves that issue.

* fixup! fix(combineLatest): improve typings for combineLatest

Author: benlesh

spec-dtslint/observables/combineLatest-spec.ts

@@ -77,3 +77,63 @@ it('should accept 6 params and a result selector', () => {
 it('should accept 7 or more params and a result selector', () => {
   const o = combineLatest(a, b, c, d, e, f, g, g, g, () => new A()); // $ExpectType Observable<A>
 });
+
+it('should accept 1 param', () => {
+  const o = combineLatest([a]); // $ExpectType Observable<[A]>
+});
+
+it('should accept 2 params', () => {
+  const o = combineLatest([a, b]); // $ExpectType Observable<[A, B]>
+});
+
+it('should accept 3 params', () => {
+  const o = combineLatest([a, b, c]); // $ExpectType Observable<[A, B, C]>
+});
+
+it('should accept 4 params', () => {
+  const o = combineLatest([a, b, c, d]); // $ExpectType Observable<[A, B, C, D]>
+});
+
+it('should accept 5 params', () => {
+  const o = combineLatest([a, b, c, d, e]); // $ExpectType Observable<[A, B, C, D, E]>
+});
+
+it('should accept 6 params', () => {
+  const o = combineLatest([a, b, c, d, e, f]); // $ExpectType Observable<[A, B, C, D, E, F]>
+});
+
+it('should have basic support for 7 or more params', () => {
+  const o = combineLatest([a, b, c, d, e, f, g]); // $ExpectType Observable<(A | B | C | D | E | F | G)[]>
+});
+
+it('should handle an array of Observables', () => {
+  const o = combineLatest([a, a, a, a, a, a, a, a, a, a, a]); // $ExpectType Observable<A[]>
+});
+
+it('should accept 1 param and a result selector', () => {
+  const o = combineLatest([a], (a: A) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 2 params and a result selector', () => {
+  const o = combineLatest([a, b], (a: A, b: B) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 3 params and a result selector', () => {
+  const o = combineLatest([a, b, c], (a: A, b: B, c: C) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 4 params and a result selector', () => {
+  const o = combineLatest([a, b, c, d], (a: A, b: B, c: C, d: D) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 5 params and a result selector', () => {
+  const o = combineLatest([a, b, c, d, e], (a: A, b: B, c: C, d: D, e: E) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 6 params and a result selector', () => {
+  const o = combineLatest([a, b, c, d, e, f], (a: A, b: B, c: C, d: D, e: E, f: F) => new A()); // $ExpectType Observable<A>
+});
+
+it('should accept 7 or more params and a result selector', () => {
+  const o = combineLatest([a, b, c, d, e, f, g, g, g], (a: any, b: any, c: any, d: any, e: any, f: any, g1: any, g2: any, g3: any) => new A()); // $ExpectType Observable<A>
+});

spec-dtslint/observables/from-spec.ts

@@ -41,5 +41,5 @@ it('should accept an array of Inputs', () => {
     yield 42;
   }());
 
-  const o = from([of(1), ['test'], iterable]); // $ExpectType Observable<Observable<number> | IterableIterator<number> | string[]>
+  const o = from([of(1), ['test'], iterable]); // $ExpectType Observable<IterableIterator<number> | Observable<number> | string[]>
 });

src/internal/observable/combineLatest.ts

@@ -12,6 +12,24 @@ import { fromArray } from './fromArray';
 const NONE = {};
 
 /* tslint:disable:max-line-length */
+
+// If called with a single array, it "auto-spreads" the array, with result selector
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, R>(sources: [O1], resultSelector: (v1: ObservedValueOf<O1>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, R>(sources: [O1, O2], resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, R>(sources: [O1, O2, O3], resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, R>(sources: [O1, O2, O3, O4], resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, R>(sources: [O1, O2, O3, O4, O5], resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>, v5: ObservedValueOf<O5>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>, R>(sources: [O1, O2, O3, O4, O5, O6], resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>, v5: ObservedValueOf<O5>, v6: ObservedValueOf<O6>) => R, scheduler?: SchedulerLike): Observable<R>;
+/** @deprecated resultSelector no longer supported, pipe to map instead */
+export function combineLatest<O extends ObservableInput<any>, R>(sources: O[], resultSelector: (...args: ObservedValueOf<O>[]) => R, scheduler?: SchedulerLike): Observable<R>;
+
+// standard call, but with a result selector
 /** @deprecated resultSelector no longer supported, pipe to map instead */
 export function combineLatest<O1 extends ObservableInput<any>, R>(v1: O1, resultSelector: (v1: ObservedValueOf<O1>) => R, scheduler?: SchedulerLike): Observable<R>;
 /** @deprecated resultSelector no longer supported, pipe to map instead */
@@ -25,19 +43,25 @@ export function combineLatest<O1 extends ObservableInput<any>, O2 extends Observ
 /** @deprecated resultSelector no longer supported, pipe to map instead */
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>, R>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, v6: O6, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>, v5: ObservedValueOf<O5>, v6: ObservedValueOf<O6>) => R, scheduler?: SchedulerLike): Observable<R>;
 
+// If called with a single array, it "auto-spreads" the array.
+export function combineLatest<O1 extends ObservableInput<any>>(sources: [O1], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>]>;
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>>(sources: [O1, O2], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>]>;
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>>(sources: [O1, O2, O3], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>]>;
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>>(sources: [O1, O2, O3, O4], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>]>;
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>>(sources: [O1, O2, O3, O4, O5], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>]>;
+export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>>(sources: [O1, O2, O3, O4, O5, O6], scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>, ObservedValueOf<O6>]>;
+export function combineLatest<O extends ObservableInput<any>>(sources: O[], scheduler?: SchedulerLike): Observable<ObservedValueOf<O>[]>;
+
+// Standard calls
 export function combineLatest<O1 extends ObservableInput<any>>(v1: O1, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>]>;
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>>(v1: O1, v2: O2, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>]>;
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>]>;
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>]>;
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>]>;
 export function combineLatest<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, v6: O6, scheduler?: SchedulerLike): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>, ObservedValueOf<O6>]>;
 
-export function combineLatest<O extends ObservableInput<any>>(array: O[], scheduler?: SchedulerLike): Observable<ObservedValueOf<O>[]>;
-export function combineLatest<R>(array: ObservableInput<any>[], scheduler?: SchedulerLike): Observable<R>;
 /** @deprecated resultSelector no longer supported, pipe to map instead */
 export function combineLatest<O extends ObservableInput<any>, R>(array: O[], resultSelector: (...values: ObservedValueOf<O>[]) => R, scheduler?: SchedulerLike): Observable<R>;
-/** @deprecated resultSelector no longer supported, pipe to map instead */
-export function combineLatest<R>(array: ObservableInput<any>[], resultSelector: (...values: Array<any>) => R, scheduler?: SchedulerLike): Observable<R>;
 export function combineLatest<O extends ObservableInput<any>>(...observables: Array<O | SchedulerLike>): Observable<any[]>;
 export function combineLatest<O extends ObservableInput<any>, R>(...observables: Array<O | ((...values: ObservedValueOf<O>[]) => R) | SchedulerLike>): Observable<R>;
 export function combineLatest<R>(...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R) | SchedulerLike>): Observable<R>;