Better typings for Promise executor, like microsoft#31117

src/lib/es2015.promise.d.ts

@@ -10,7 +10,7 @@ interface PromiseConstructor {
      * a resolve callback used to 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) => void, reject: (reason?: any) => void) => void): Promise<T extends PromiseLike<infer U> ? U : T>;
 
     /**
      * Creates a Promise that is resolved with an array of results when all of the provided Promises

tests/baselines/reference/asyncArrowFunction10_es5.errors.txt

@@ -1,8 +1,33 @@
+tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction10_es5.ts(1,21): error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+  Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+    Types of property 'then' are incompatible.
+      Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+        Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+          Types of parameters 'value' and 'value' are incompatible.
+            Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+              'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+                  'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                    Type 'unknown' is not assignable to type 'T'.
+                      'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction10_es5.ts(3,11): error TS2304: Cannot find name 'await'.
 
 
-==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction10_es5.ts (1 errors) ====
+==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction10_es5.ts (2 errors) ====
     var foo = async (): Promise<void> => {
+                        ~~~~~~~~~~~~~
+!!! error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+!!! error TS1055:   Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+!!! error TS1055:     Types of property 'then' are incompatible.
+!!! error TS1055:       Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:         Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+!!! error TS1055:           Types of parameters 'value' and 'value' are incompatible.
+!!! error TS1055:             Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+!!! error TS1055:               'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                 Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+!!! error TS1055:                   'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                     Type 'unknown' is not assignable to type 'T'.
+!!! error TS1055:                       'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
        // Legal to use 'await' in a type context.
        var v: await;
               ~~~~~

tests/baselines/reference/asyncArrowFunction6_es5.errors.txt

@@ -1,11 +1,36 @@
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction6_es5.ts(1,22): error TS2524: 'await' expressions cannot be used in a parameter initializer.
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction6_es5.ts(1,27): error TS1109: Expression expected.
+tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction6_es5.ts(1,30): error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+  Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+    Types of property 'then' are incompatible.
+      Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+        Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+          Types of parameters 'value' and 'value' are incompatible.
+            Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+              'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+                  'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                    Type 'unknown' is not assignable to type 'T'.
+                      'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
 
-==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction6_es5.ts (2 errors) ====
+==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction6_es5.ts (3 errors) ====
     var foo = async (a = await): Promise<void> => {
                          ~~~~~
 !!! error TS2524: 'await' expressions cannot be used in a parameter initializer.
                               ~
 !!! error TS1109: Expression expected.
+                                 ~~~~~~~~~~~~~
+!!! error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+!!! error TS1055:   Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+!!! error TS1055:     Types of property 'then' are incompatible.
+!!! error TS1055:       Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:         Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+!!! error TS1055:           Types of parameters 'value' and 'value' are incompatible.
+!!! error TS1055:             Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+!!! error TS1055:               'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                 Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+!!! error TS1055:                   'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                     Type 'unknown' is not assignable to type 'T'.
+!!! error TS1055:                       'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
     }

tests/baselines/reference/asyncArrowFunction7_es5.errors.txt

@@ -1,14 +1,42 @@
+tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts(1,21): error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+  Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+    Types of property 'then' are incompatible.
+      Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+        Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+          Types of parameters 'value' and 'value' are incompatible.
+            Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+              'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+                  'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                    Type 'unknown' is not assignable to type 'T'.
+                      'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts(3,24): error TS2524: 'await' expressions cannot be used in a parameter initializer.
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts(3,29): error TS1109: Expression expected.
+tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts(3,32): error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
 
 
-==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts (2 errors) ====
+==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction7_es5.ts (4 errors) ====
     var bar = async (): Promise<void> => {
+                        ~~~~~~~~~~~~~
+!!! error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+!!! error TS1055:   Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+!!! error TS1055:     Types of property 'then' are incompatible.
+!!! error TS1055:       Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:         Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+!!! error TS1055:           Types of parameters 'value' and 'value' are incompatible.
+!!! error TS1055:             Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+!!! error TS1055:               'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                 Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+!!! error TS1055:                   'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                     Type 'unknown' is not assignable to type 'T'.
+!!! error TS1055:                       'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
       // 'await' here is an identifier, and not an await expression.
       var foo = async (a = await): Promise<void> => {
                            ~~~~~
 !!! error TS2524: 'await' expressions cannot be used in a parameter initializer.
                                 ~
 !!! error TS1109: Expression expected.
+                                   ~~~~~~~~~~~~~
+!!! error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
       }
     }

tests/baselines/reference/asyncArrowFunction8_es5.errors.txt

@@ -1,8 +1,33 @@
+tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction8_es5.ts(1,21): error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+  Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+    Types of property 'then' are incompatible.
+      Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+        Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+          Types of parameters 'value' and 'value' are incompatible.
+            Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+              'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+                  'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+                    Type 'unknown' is not assignable to type 'T'.
+                      'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction8_es5.ts(2,19): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction8_es5.ts (1 errors) ====
+==== tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction8_es5.ts (2 errors) ====
     var foo = async (): Promise<void> => {
+                        ~~~~~~~~~~~~~
+!!! error TS1055: Type 'PromiseConstructor' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
+!!! error TS1055:   Type 'Promise<T | (T extends PromiseLike<infer U> ? U : T)>' is not assignable to type 'PromiseLike<T>'.
+!!! error TS1055:     Types of property 'then' are incompatible.
+!!! error TS1055:       Type '<TResult1 = T | (T extends PromiseLike<infer U> ? U : T), TResult2 = never>(onfulfilled?: (value: T | (T extends PromiseLike<infer U> ? U : T)) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:         Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
+!!! error TS1055:           Types of parameters 'value' and 'value' are incompatible.
+!!! error TS1055:             Type 'T | (T extends PromiseLike<infer U> ? U : T)' is not assignable to type 'T'.
+!!! error TS1055:               'T | (T extends PromiseLike<infer U> ? U : T)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                 Type 'T extends PromiseLike<infer U> ? U : T' is not assignable to type 'T'.
+!!! error TS1055:                   'T extends PromiseLike<infer U> ? U : T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS1055:                     Type 'unknown' is not assignable to type 'T'.
+!!! error TS1055:                       'unknown' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
       var v = { [await]: foo }
                       ~
 !!! error TS1109: Expression expected.