Add Awaited<T> to core library

microsoft · Feb 4, 2018 · c4d7e48 · c4d7e48
1 parent 3ef1b56
commit c4d7e48
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diff --git a/src/lib/es2015.iterable.d.ts b/src/lib/es2015.iterable.d.ts
@@ -195,15 +195,15 @@ interface PromiseConstructor {
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<TAll>(values: Iterable<TAll | PromiseLike<TAll>>): Promise<TAll[]>;
+    all<T>(values: Iterable<T>): Promise<Awaited<T>[]>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T>(values: Iterable<T | PromiseLike<T>>): Promise<T>;
+    race<T>(values: Iterable<T>): Promise<Awaited<T>>;
 }
 
 declare namespace Reflect {

diff --git a/src/lib/es2015.promise.d.ts b/src/lib/es2015.promise.d.ts
@@ -10,188 +10,181 @@ interface PromiseConstructor {
      * a resolve callback used resolve the promise with a value or the result of another promise,
      * and a reject callback used to reject the promise with a provided reason or error.
      */
-    new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void): Promise<T>;
+    new <T>(executor: (resolve: (value?: T | Awaitable<T>) => void, reject: (reason?: any) => void) => void): Promise<T>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>, T9 | PromiseLike<T9>, T10 | PromiseLike<T10>]): Promise<[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]>;
+    all<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(values: [T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>, Awaited<T6>, Awaited<T7>, Awaited<T8>, Awaited<T9>, Awaited<T10>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5, T6, T7, T8, T9>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>, T9 | PromiseLike<T9>]): Promise<[T1, T2, T3, T4, T5, T6, T7, T8, T9]>;
+    all<T1, T2, T3, T4, T5, T6, T7, T8, T9>(values: [T1, T2, T3, T4, T5, T6, T7, T8, T9]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>, Awaited<T6>, Awaited<T7>, Awaited<T8>, Awaited<T9>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5, T6, T7, T8>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>]): Promise<[T1, T2, T3, T4, T5, T6, T7, T8]>;
+    all<T1, T2, T3, T4, T5, T6, T7, T8>(values: [T1, T2, T3, T4, T5, T6, T7, T8]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>, Awaited<T6>, Awaited<T7>, Awaited<T8>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5, T6, T7>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>]): Promise<[T1, T2, T3, T4, T5, T6, T7]>;
+    all<T1, T2, T3, T4, T5, T6, T7>(values: [T1, T2, T3, T4, T5, T6, T7]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>, Awaited<T6>, Awaited<T7>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5, T6>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>]): Promise<[T1, T2, T3, T4, T5, T6]>;
+    all<T1, T2, T3, T4, T5, T6>(values: [T1, T2, T3, T4, T5, T6]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>, Awaited<T6>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4, T5>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>, T5 | PromiseLike<T5>]): Promise<[T1, T2, T3, T4, T5]>;
+    all<T1, T2, T3, T4, T5>(values: [T1, T2, T3, T4, T5]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>, Awaited<T5>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3, T4>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike <T4>]): Promise<[T1, T2, T3, T4]>;
+    all<T1, T2, T3, T4>(values: [T1, T2, T3, T4]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>, Awaited<T4>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2, T3>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>]): Promise<[T1, T2, T3]>;
+    all<T1, T2, T3>(values: [T1, T2, T3]): Promise<[Awaited<T1>, Awaited<T2>, Awaited<T3>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T1, T2>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>]): Promise<[T1, T2]>;
+    all<T1, T2>(values: [T1, T2]): Promise<[Awaited<T1>, Awaited<T2>]>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises
      * resolve, or rejected when any Promise is rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    all<T>(values: (T | PromiseLike<T>)[]): Promise<T[]>;
+    all<T>(values: T[]): Promise<Awaited<T>[]>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>, T9 | PromiseLike<T9>, T10 | PromiseLike<T10>]): Promise<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>;
+    race<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(values: [T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]): Promise<Awaited<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5, T6, T7, T8, T9>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>, T9 | PromiseLike<T9>]): Promise<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9>;
+    race<T1, T2, T3, T4, T5, T6, T7, T8, T9>(values: [T1, T2, T3, T4, T5, T6, T7, T8, T9]): Promise<Awaited<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5, T6, T7, T8>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>, T8 | PromiseLike<T8>]): Promise<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8>;
+    race<T1, T2, T3, T4, T5, T6, T7, T8>(values: [T1, T2, T3, T4, T5, T6, T7, T8]): Promise<Awaited<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5, T6, T7>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>, T7 | PromiseLike<T7>]): Promise<T1 | T2 | T3 | T4 | T5 | T6 | T7>;
+    race<T1, T2, T3, T4, T5, T6, T7>(values: [T1, T2, T3, T4, T5, T6, T7]): Promise<Awaited<T1 | T2 | T3 | T4 | T5 | T6 | T7>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5, T6>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>, T6 | PromiseLike<T6>]): Promise<T1 | T2 | T3 | T4 | T5 | T6>;
+    race<T1, T2, T3, T4, T5, T6>(values: [T1, T2, T3, T4, T5, T6]): Promise<Awaited<T1 | T2 | T3 | T4 | T5 | T6>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4, T5>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>, T5 | PromiseLike<T5>]): Promise<T1 | T2 | T3 | T4 | T5>;
+    race<T1, T2, T3, T4, T5>(values: [T1, T2, T3, T4, T5]): Promise<Awaited<T1 | T2 | T3 | T4 | T5>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3, T4>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>, T4 | PromiseLike<T4>]): Promise<T1 | T2 | T3 | T4>;
+    race<T1, T2, T3, T4>(values: [T1, T2, T3, T4]): Promise<Awaited<T1 | T2 | T3 | T4>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2, T3>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>, T3 | PromiseLike<T3>]): Promise<T1 | T2 | T3>;
+    race<T1, T2, T3>(values: [T1, T2, T3]): Promise<Awaited<T1 | T2 | T3>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T1, T2>(values: [T1 | PromiseLike<T1>, T2 | PromiseLike<T2>]): Promise<T1 | T2>;
+    race<T1, T2>(values: [T1, T2]): Promise<Awaited<T1 | T2>>;
 
     /**
      * Creates a Promise that is resolved or rejected when any of the provided Promises are resolved
      * or rejected.
      * @param values An array of Promises.
      * @returns A new Promise.
      */
-    race<T>(values: (T | PromiseLike<T>)[]): Promise<T>;
+    race<T>(values: T[]): Promise<Awaited<T>>;
 
     /**
      * Creates a new rejected promise for the provided reason.
      * @param reason The reason the promise was rejected.
      * @returns A new rejected Promise.
      */
-    reject(reason: any): Promise<never>;
-
-    /**
-     * Creates a new rejected promise for the provided reason.
-     * @param reason The reason the promise was rejected.
-     * @returns A new rejected Promise.
-     */
-    reject<T>(reason: any): Promise<T>;
+    reject<T = never>(reason: any): Promise<Awaited<T>>;
 
     /**
      * Creates a new resolved promise for the provided value.
      * @param value A promise.
      * @returns A promise whose internal state matches the provided promise.
      */
-    resolve<T>(value: T | PromiseLike<T>): Promise<T>;
+    resolve<T>(value: T): Promise<Awaited<T>>;
 
     /**
      * Creates a new resolved promise .

diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
@@ -1273,7 +1273,20 @@ declare type PropertyDecorator = (target: Object, propertyKey: string | symbol)
 declare type MethodDecorator = <T>(target: Object, propertyKey: string | symbol, descriptor: TypedPropertyDescriptor<T>) => TypedPropertyDescriptor<T> | void;
 declare type ParameterDecorator = (target: Object, propertyKey: string | symbol, parameterIndex: number) => void;
 
-declare type PromiseConstructorLike = new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void) => PromiseLike<T>;
+/** An object type that can be definitely be awaited. Do not inherit from this type. */
+declare type Awaitable<T> = { then(onfulfilled: (value: T) => any): any; };
+
+/** An object type that may not be awaitable. Do not inherit from this type. */
+declare type NonAwaitable = { then(...args: any[]): any; };
+
+/** Gets the type resulting from awaiting `T`. This does **not** recursively unwrap nested promises. */
+declare type Awaited<T> =
+    T extends Awaitable<Awaitable<infer U>> ? U :
+    T extends Awaitable<infer U> ? U :
+    T extends NonAwaitable ? never :
+    T;
+
+declare type PromiseConstructorLike = new <T>(executor: (resolve: (value?: T | Awaitable<T>) => void, reject: (reason?: any) => void) => void) => PromiseLike<T>;
 
 interface PromiseLike<T> {
     /**
@@ -1282,7 +1295,7 @@ interface PromiseLike<T> {
      * @param onrejected The callback to execute when the Promise is rejected.
      * @returns A Promise for the completion of which ever callback is executed.
      */
-    then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: T) => TResult1 | PromiseLike<TResult1>) | undefined | null, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | undefined | null): PromiseLike<TResult1 | TResult2>;
+    then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: Awaited<T>) => TResult1) | null, onrejected?: ((reason: any) => TResult2) | null): PromiseLike<Awaited<TResult1 | TResult2>>;
 }
 
 /**
@@ -1295,14 +1308,14 @@ interface Promise<T> {
      * @param onrejected The callback to execute when the Promise is rejected.
      * @returns A Promise for the completion of which ever callback is executed.
      */
-    then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: T) => TResult1 | PromiseLike<TResult1>) | undefined | null, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | undefined | null): Promise<TResult1 | TResult2>;
+    then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: Awaited<T>) => TResult1) | null, onrejected?: ((reason: any) => TResult2) | null): Promise<Awaited<TResult1 | TResult2>>;
 
     /**
      * Attaches a callback for only the rejection of the Promise.
      * @param onrejected The callback to execute when the Promise is rejected.
      * @returns A Promise for the completion of the callback.
      */
-    catch<TResult = never>(onrejected?: ((reason: any) => TResult | PromiseLike<TResult>) | undefined | null): Promise<T | TResult>;
+    catch<TResult = never>(onrejected?: ((reason: any) => TResult) | null): Promise<Awaited<T | TResult>>;
 }
 
 interface ArrayLike<T> {

diff --git a/src/lib/esnext.promise.d.ts b/src/lib/esnext.promise.d.ts
@@ -8,5 +8,5 @@ interface Promise<T> {
      * @param onfinally The callback to execute when the Promise is settled (fulfilled or rejected).
      * @returns A Promise for the completion of the callback.
      */
-    finally(onfinally?: (() => void) | undefined | null): Promise<T>
+    finally(onfinally?: (() => void) | null): Promise<Awaited<T>>
 }
diff --git a/src/services/utilities.ts b/src/services/utilities.ts
@@ -3,8 +3,9 @@
 interface PromiseConstructor {
     new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void): Promise<T>;
     reject(reason: any): Promise<never>;
-    all<T>(values: (T | PromiseLike<T>)[]): Promise<T[]>;
+    all<T>(values: PromiseLike<T>[]): Promise<T[]>;
 }
+
 /* @internal */
 declare var Promise: PromiseConstructor;
 

diff --git a/tests/baselines/reference/asyncAwaitNestedClasses_es5.types b/tests/baselines/reference/asyncAwaitNestedClasses_es5.types
@@ -15,10 +15,10 @@ class A {
             return new Promise((resolve) => { resolve(null); });
 >new Promise((resolve) => { resolve(null); }) : Promise<void>
 >Promise : PromiseConstructor
->(resolve) => { resolve(null); } : (resolve: (value?: void | PromiseLike<void>) => void) => void
->resolve : (value?: void | PromiseLike<void>) => void
+>(resolve) => { resolve(null); } : (resolve: (value?: void | Awaitable<void>) => void) => void
+>resolve : (value?: void | Awaitable<void>) => void
 >resolve(null) : void
->resolve : (value?: void | PromiseLike<void>) => void
+>resolve : (value?: void | Awaitable<void>) => void
 >null : null
         }
         static C = class C {