From f58e1a2b17ad5299e8ac9624e8a6d1619dc21ee4 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Wed, 14 Dec 2016 14:59:00 -0800
Subject: [PATCH 1/4] Map both declared properties and string index signatures

---
 src/compiler/checker.ts | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 26164a528f3..5246bbfc700 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4536,15 +4536,27 @@ namespace ts {
             const typeParameter = getTypeParameterFromMappedType(type);
             const constraintType = getConstraintTypeFromMappedType(type);
             const templateType = getTemplateTypeFromMappedType(type);
-            const modifiersType = getModifiersTypeFromMappedType(type);
+            const modifiersType = getApparentType(getModifiersTypeFromMappedType(type));
             const templateReadonly = !!type.declaration.readonlyToken;
             const templateOptional = !!type.declaration.questionToken;
-            // First, if the constraint type is a type parameter, obtain the base constraint. Then,
-            // if the key type is a 'keyof X', obtain 'keyof C' where C is the base constraint of X.
-            // Finally, iterate over the constituents of the resulting iteration type.
-            const keyType = constraintType.flags & TypeFlags.TypeVariable ? getApparentType(constraintType) : constraintType;
-            const iterationType = keyType.flags & TypeFlags.Index ? getIndexType(getApparentType((<IndexType>keyType).type)) : keyType;
-            forEachType(iterationType, t => {
+            if (type.declaration.typeParameter.constraint.kind === SyntaxKind.TypeOperator) {
+                // We have a { [P in keyof T]: X }
+                forEachType(getLiteralTypeFromPropertyNames(modifiersType), addMemberForKeyType);
+                if (getIndexInfoOfType(modifiersType, IndexKind.String)) {
+                    addMemberForKeyType(stringType);
+                }
+            }
+            else {
+                // First, if the constraint type is a type parameter, obtain the base constraint. Then,
+                // if the key type is a 'keyof X', obtain 'keyof C' where C is the base constraint of X.
+                // Finally, iterate over the constituents of the resulting iteration type.
+                const keyType = constraintType.flags & TypeFlags.TypeVariable ? getApparentType(constraintType) : constraintType;
+                const iterationType = keyType.flags & TypeFlags.Index ? getIndexType(getApparentType((<IndexType>keyType).type)) : keyType;
+                forEachType(iterationType, addMemberForKeyType);
+            }
+            setStructuredTypeMembers(type, members, emptyArray, emptyArray, stringIndexInfo, undefined);
+
+            function addMemberForKeyType(t: Type) {
                 // Create a mapper from T to the current iteration type constituent. Then, if the
                 // mapped type is itself an instantiated type, combine the iteration mapper with the
                 // instantiation mapper.
@@ -4565,8 +4577,7 @@ namespace ts {
                 else if (t.flags & TypeFlags.String) {
                     stringIndexInfo = createIndexInfo(propType, templateReadonly);
                 }
-            });
-            setStructuredTypeMembers(type, members, emptyArray, emptyArray, stringIndexInfo, undefined);
+            }
         }
 
         function getTypeParameterFromMappedType(type: MappedType) {

From 6cd7454a9b7e3db223295c18d51a668c4eaddc4f Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Wed, 14 Dec 2016 14:59:10 -0800
Subject: [PATCH 2/4] Add tests

---
 .../types/mapped/mappedTypeErrors.ts          |  6 +++++
 .../types/mapped/mappedTypeModifiers.ts       | 25 ++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/tests/cases/conformance/types/mapped/mappedTypeErrors.ts b/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
index 4be6b6b098d..458dbe9caa4 100644
--- a/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
+++ b/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
@@ -125,3 +125,9 @@ c.setState({ });
 c.setState(foo);
 c.setState({ a: undefined });  // Error
 c.setState({ c: true });  // Error
+
+type T2 = { a?: number, [key: string]: any };
+
+let x1: T2 = { a: 'no' };  // Error
+let x2: Partial<T2> = { a: 'no' }; // Error
+let x3: { [P in keyof T2]: T2[P]} = { a: 'no' };  // Error
\ No newline at end of file
diff --git a/tests/cases/conformance/types/mapped/mappedTypeModifiers.ts b/tests/cases/conformance/types/mapped/mappedTypeModifiers.ts
index 1fe6872965c..a111d186d16 100644
--- a/tests/cases/conformance/types/mapped/mappedTypeModifiers.ts
+++ b/tests/cases/conformance/types/mapped/mappedTypeModifiers.ts
@@ -1,4 +1,5 @@
 // @strictNullChecks: true
+// @noimplicitany: true
 
 type T = { a: number, b: string };
 type TP = { a?: number, b?: string };
@@ -74,4 +75,26 @@ var b04: Readonly<BP>;
 var b04: Partial<Readonly<B>>;
 var b04: Readonly<Partial<B>>;
 var b04: { [P in keyof BPR]: BPR[P] }
-var b04: Pick<BPR, keyof BPR>;
\ No newline at end of file
+var b04: Pick<BPR, keyof BPR>;
+
+type Foo = { prop: number, [x: string]: number };
+
+function f1(x: Partial<Foo>) {
+    x.prop; // ok
+    (x["other"] || 0).toFixed();
+}
+
+function f2(x: Readonly<Foo>) {
+    x.prop; // ok
+    x["other"].toFixed();
+}
+
+function f3(x: Boxified<Foo>) {
+    x.prop; // ok
+    x["other"].x.toFixed();
+}
+
+function f4(x: { [P in keyof Foo]: Foo[P] }) {
+    x.prop; // ok
+    x["other"].toFixed();
+}

From a597d3c2666b73596b123358f2e5bedad6f29d2e Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Wed, 14 Dec 2016 15:03:13 -0800
Subject: [PATCH 3/4] Accept new baselines

---
 .../reference/mappedTypeErrors.errors.txt     | 30 +++++-
 tests/baselines/reference/mappedTypeErrors.js | 19 +++-
 .../reference/mappedTypeModifiers.js          | 41 ++++++++-
 .../reference/mappedTypeModifiers.symbols     | 77 ++++++++++++++++
 .../reference/mappedTypeModifiers.types       | 92 +++++++++++++++++++
 5 files changed, 255 insertions(+), 4 deletions(-)

diff --git a/tests/baselines/reference/mappedTypeErrors.errors.txt b/tests/baselines/reference/mappedTypeErrors.errors.txt
index 17c77fa50a0..f98a11dbaf9 100644
--- a/tests/baselines/reference/mappedTypeErrors.errors.txt
+++ b/tests/baselines/reference/mappedTypeErrors.errors.txt
@@ -36,9 +36,18 @@ tests/cases/conformance/types/mapped/mappedTypeErrors.ts(124,12): error TS2345:
     Type 'undefined' is not assignable to type 'string'.
 tests/cases/conformance/types/mapped/mappedTypeErrors.ts(125,14): error TS2345: Argument of type '{ c: boolean; }' is not assignable to parameter of type 'Pick<Foo, "a" | "b">'.
   Object literal may only specify known properties, and 'c' does not exist in type 'Pick<Foo, "a" | "b">'.
+tests/cases/conformance/types/mapped/mappedTypeErrors.ts(129,5): error TS2322: Type '{ a: string; }' is not assignable to type 'T2'.
+  Types of property 'a' are incompatible.
+    Type 'string' is not assignable to type 'number | undefined'.
+tests/cases/conformance/types/mapped/mappedTypeErrors.ts(130,5): error TS2322: Type '{ a: string; }' is not assignable to type 'Partial<T2>'.
+  Types of property 'a' are incompatible.
+    Type 'string' is not assignable to type 'number | undefined'.
+tests/cases/conformance/types/mapped/mappedTypeErrors.ts(131,5): error TS2322: Type '{ a: string; }' is not assignable to type '{ [x: string]: any; a?: number | undefined; }'.
+  Types of property 'a' are incompatible.
+    Type 'string' is not assignable to type 'number | undefined'.
 
 
-==== tests/cases/conformance/types/mapped/mappedTypeErrors.ts (21 errors) ====
+==== tests/cases/conformance/types/mapped/mappedTypeErrors.ts (24 errors) ====
     
     interface Shape {
         name: string;
@@ -223,4 +232,21 @@ tests/cases/conformance/types/mapped/mappedTypeErrors.ts(125,14): error TS2345:
                  ~~~~~~~
 !!! error TS2345: Argument of type '{ c: boolean; }' is not assignable to parameter of type 'Pick<Foo, "a" | "b">'.
 !!! error TS2345:   Object literal may only specify known properties, and 'c' does not exist in type 'Pick<Foo, "a" | "b">'.
-    
\ No newline at end of file
+    
+    type T2 = { a?: number, [key: string]: any };
+    
+    let x1: T2 = { a: 'no' };  // Error
+        ~~
+!!! error TS2322: Type '{ a: string; }' is not assignable to type 'T2'.
+!!! error TS2322:   Types of property 'a' are incompatible.
+!!! error TS2322:     Type 'string' is not assignable to type 'number | undefined'.
+    let x2: Partial<T2> = { a: 'no' }; // Error
+        ~~
+!!! error TS2322: Type '{ a: string; }' is not assignable to type 'Partial<T2>'.
+!!! error TS2322:   Types of property 'a' are incompatible.
+!!! error TS2322:     Type 'string' is not assignable to type 'number | undefined'.
+    let x3: { [P in keyof T2]: T2[P]} = { a: 'no' };  // Error
+        ~~
+!!! error TS2322: Type '{ a: string; }' is not assignable to type '{ [x: string]: any; a?: number | undefined; }'.
+!!! error TS2322:   Types of property 'a' are incompatible.
+!!! error TS2322:     Type 'string' is not assignable to type 'number | undefined'.
\ No newline at end of file
diff --git a/tests/baselines/reference/mappedTypeErrors.js b/tests/baselines/reference/mappedTypeErrors.js
index e1b458565bb..83dc235c705 100644
--- a/tests/baselines/reference/mappedTypeErrors.js
+++ b/tests/baselines/reference/mappedTypeErrors.js
@@ -124,7 +124,12 @@ c.setState({ });
 c.setState(foo);
 c.setState({ a: undefined });  // Error
 c.setState({ c: true });  // Error
-
+
+type T2 = { a?: number, [key: string]: any };
+
+let x1: T2 = { a: 'no' };  // Error
+let x2: Partial<T2> = { a: 'no' }; // Error
+let x3: { [P in keyof T2]: T2[P]} = { a: 'no' };  // Error
 
 //// [mappedTypeErrors.js]
 function f1(x) {
@@ -196,6 +201,9 @@ c.setState({});
 c.setState(foo);
 c.setState({ a: undefined }); // Error
 c.setState({ c: true }); // Error
+var x1 = { a: 'no' }; // Error
+var x2 = { a: 'no' }; // Error
+var x3 = { a: 'no' }; // Error
 
 
 //// [mappedTypeErrors.d.ts]
@@ -251,3 +259,12 @@ declare class C<T> {
     setState<K extends keyof T>(props: Pick<T, K>): void;
 }
 declare let c: C<Foo>;
+declare type T2 = {
+    a?: number;
+    [key: string]: any;
+};
+declare let x1: T2;
+declare let x2: Partial<T2>;
+declare let x3: {
+    [P in keyof T2]: T2[P];
+};
diff --git a/tests/baselines/reference/mappedTypeModifiers.js b/tests/baselines/reference/mappedTypeModifiers.js
index 6291fb9c42b..a247d18f2d4 100644
--- a/tests/baselines/reference/mappedTypeModifiers.js
+++ b/tests/baselines/reference/mappedTypeModifiers.js
@@ -74,7 +74,30 @@ var b04: Readonly<BP>;
 var b04: Partial<Readonly<B>>;
 var b04: Readonly<Partial<B>>;
 var b04: { [P in keyof BPR]: BPR[P] }
-var b04: Pick<BPR, keyof BPR>;
+var b04: Pick<BPR, keyof BPR>;
+
+type Foo = { prop: number, [x: string]: number };
+
+function f1(x: Partial<Foo>) {
+    x.prop; // ok
+    (x["other"] || 0).toFixed();
+}
+
+function f2(x: Readonly<Foo>) {
+    x.prop; // ok
+    x["other"].toFixed();
+}
+
+function f3(x: Boxified<Foo>) {
+    x.prop; // ok
+    x["other"].x.toFixed();
+}
+
+function f4(x: { [P in keyof Foo]: Foo[P] }) {
+    x.prop; // ok
+    x["other"].toFixed();
+}
+
 
 //// [mappedTypeModifiers.js]
 var v00;
@@ -131,3 +154,19 @@ var b04;
 var b04;
 var b04;
 var b04;
+function f1(x) {
+    x.prop; // ok
+    (x["other"] || 0).toFixed();
+}
+function f2(x) {
+    x.prop; // ok
+    x["other"].toFixed();
+}
+function f3(x) {
+    x.prop; // ok
+    x["other"].x.toFixed();
+}
+function f4(x) {
+    x.prop; // ok
+    x["other"].toFixed();
+}
diff --git a/tests/baselines/reference/mappedTypeModifiers.symbols b/tests/baselines/reference/mappedTypeModifiers.symbols
index 5138055d08b..b2b8faed4cf 100644
--- a/tests/baselines/reference/mappedTypeModifiers.symbols
+++ b/tests/baselines/reference/mappedTypeModifiers.symbols
@@ -353,3 +353,80 @@ var b04: Pick<BPR, keyof BPR>;
 >BPR : Symbol(BPR, Decl(mappedTypeModifiers.ts, 42, 67))
 >BPR : Symbol(BPR, Decl(mappedTypeModifiers.ts, 42, 67))
 
+type Foo = { prop: number, [x: string]: number };
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+>prop : Symbol(prop, Decl(mappedTypeModifiers.ts, 77, 12))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 77, 28))
+
+function f1(x: Partial<Foo>) {
+>f1 : Symbol(f1, Decl(mappedTypeModifiers.ts, 77, 49))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 79, 12))
+>Partial : Symbol(Partial, Decl(lib.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+
+    x.prop; // ok
+>x.prop : Symbol(prop)
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 79, 12))
+>prop : Symbol(prop)
+
+    (x["other"] || 0).toFixed();
+>(x["other"] || 0).toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 79, 12))
+>toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+}
+
+function f2(x: Readonly<Foo>) {
+>f2 : Symbol(f2, Decl(mappedTypeModifiers.ts, 82, 1))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 84, 12))
+>Readonly : Symbol(Readonly, Decl(lib.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+
+    x.prop; // ok
+>x.prop : Symbol(prop)
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 84, 12))
+>prop : Symbol(prop)
+
+    x["other"].toFixed();
+>x["other"].toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 84, 12))
+>toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+}
+
+function f3(x: Boxified<Foo>) {
+>f3 : Symbol(f3, Decl(mappedTypeModifiers.ts, 87, 1))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 89, 12))
+>Boxified : Symbol(Boxified, Decl(mappedTypeModifiers.ts, 36, 28))
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+
+    x.prop; // ok
+>x.prop : Symbol(prop)
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 89, 12))
+>prop : Symbol(prop)
+
+    x["other"].x.toFixed();
+>x["other"].x.toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+>x["other"].x : Symbol(x, Decl(mappedTypeModifiers.ts, 38, 38))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 89, 12))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 38, 38))
+>toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+}
+
+function f4(x: { [P in keyof Foo]: Foo[P] }) {
+>f4 : Symbol(f4, Decl(mappedTypeModifiers.ts, 92, 1))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 94, 12))
+>P : Symbol(P, Decl(mappedTypeModifiers.ts, 94, 18))
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+>Foo : Symbol(Foo, Decl(mappedTypeModifiers.ts, 75, 30))
+>P : Symbol(P, Decl(mappedTypeModifiers.ts, 94, 18))
+
+    x.prop; // ok
+>x.prop : Symbol(prop)
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 94, 12))
+>prop : Symbol(prop)
+
+    x["other"].toFixed();
+>x["other"].toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+>x : Symbol(x, Decl(mappedTypeModifiers.ts, 94, 12))
+>toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, --, --))
+}
+
diff --git a/tests/baselines/reference/mappedTypeModifiers.types b/tests/baselines/reference/mappedTypeModifiers.types
index 7a30e227bd6..7771de023f1 100644
--- a/tests/baselines/reference/mappedTypeModifiers.types
+++ b/tests/baselines/reference/mappedTypeModifiers.types
@@ -353,3 +353,95 @@ var b04: Pick<BPR, keyof BPR>;
 >BPR : BPR
 >BPR : BPR
 
+type Foo = { prop: number, [x: string]: number };
+>Foo : Foo
+>prop : number
+>x : string
+
+function f1(x: Partial<Foo>) {
+>f1 : (x: Partial<Foo>) => void
+>x : Partial<Foo>
+>Partial : Partial<T>
+>Foo : Foo
+
+    x.prop; // ok
+>x.prop : number | undefined
+>x : Partial<Foo>
+>prop : number | undefined
+
+    (x["other"] || 0).toFixed();
+>(x["other"] || 0).toFixed() : string
+>(x["other"] || 0).toFixed : (fractionDigits?: number | undefined) => string
+>(x["other"] || 0) : number
+>x["other"] || 0 : number
+>x["other"] : number | undefined
+>x : Partial<Foo>
+>"other" : "other"
+>0 : 0
+>toFixed : (fractionDigits?: number | undefined) => string
+}
+
+function f2(x: Readonly<Foo>) {
+>f2 : (x: Readonly<Foo>) => void
+>x : Readonly<Foo>
+>Readonly : Readonly<T>
+>Foo : Foo
+
+    x.prop; // ok
+>x.prop : number
+>x : Readonly<Foo>
+>prop : number
+
+    x["other"].toFixed();
+>x["other"].toFixed() : string
+>x["other"].toFixed : (fractionDigits?: number | undefined) => string
+>x["other"] : number
+>x : Readonly<Foo>
+>"other" : "other"
+>toFixed : (fractionDigits?: number | undefined) => string
+}
+
+function f3(x: Boxified<Foo>) {
+>f3 : (x: Boxified<Foo>) => void
+>x : Boxified<Foo>
+>Boxified : Boxified<T>
+>Foo : Foo
+
+    x.prop; // ok
+>x.prop : { x: number; }
+>x : Boxified<Foo>
+>prop : { x: number; }
+
+    x["other"].x.toFixed();
+>x["other"].x.toFixed() : string
+>x["other"].x.toFixed : (fractionDigits?: number | undefined) => string
+>x["other"].x : number
+>x["other"] : { x: number; }
+>x : Boxified<Foo>
+>"other" : "other"
+>x : number
+>toFixed : (fractionDigits?: number | undefined) => string
+}
+
+function f4(x: { [P in keyof Foo]: Foo[P] }) {
+>f4 : (x: { [x: string]: number; prop: number; }) => void
+>x : { [x: string]: number; prop: number; }
+>P : P
+>Foo : Foo
+>Foo : Foo
+>P : P
+
+    x.prop; // ok
+>x.prop : number
+>x : { [x: string]: number; prop: number; }
+>prop : number
+
+    x["other"].toFixed();
+>x["other"].toFixed() : string
+>x["other"].toFixed : (fractionDigits?: number | undefined) => string
+>x["other"] : number
+>x : { [x: string]: number; prop: number; }
+>"other" : "other"
+>toFixed : (fractionDigits?: number | undefined) => string
+}
+

From b0f42f04eea70f4912fd85ef8d48cafda31e3107 Mon Sep 17 00:00:00 2001
From: Bill Ticehurst <billti@hotmail.com>
Date: Mon, 12 Dec 2016 18:20:09 -0800
Subject: [PATCH 4/4] Fix __awaiter helper for IE8 compat

---
 src/compiler/transformers/es2017.ts                           | 2 +-
 tests/baselines/reference/asyncAwaitIsolatedModules_es5.js    | 2 +-
 tests/baselines/reference/asyncAwaitIsolatedModules_es6.js    | 2 +-
 tests/baselines/reference/asyncAwait_es5.js                   | 2 +-
 tests/baselines/reference/asyncAwait_es6.js                   | 2 +-
 tests/baselines/reference/asyncFunctionNoReturnType.js        | 2 +-
 tests/baselines/reference/asyncFunctionReturnType.js          | 2 +-
 tests/baselines/reference/asyncFunctionsAcrossFiles.js        | 4 ++--
 .../baselines/reference/asyncFunctionsAndStrictNullChecks.js  | 2 +-
 tests/baselines/reference/asyncIIFE.js                        | 2 +-
 tests/baselines/reference/asyncImportedPromise_es5.js         | 2 +-
 tests/baselines/reference/asyncImportedPromise_es6.js         | 2 +-
 tests/baselines/reference/asyncMultiFile_es5.js               | 2 +-
 tests/baselines/reference/asyncMultiFile_es6.js               | 2 +-
 tests/baselines/reference/await_unaryExpression_es6.js        | 2 +-
 tests/baselines/reference/await_unaryExpression_es6_1.js      | 2 +-
 tests/baselines/reference/await_unaryExpression_es6_2.js      | 2 +-
 tests/baselines/reference/await_unaryExpression_es6_3.js      | 2 +-
 tests/baselines/reference/castOfAwait.js                      | 2 +-
 tests/baselines/reference/declarationEmitPromise.js           | 2 +-
 tests/baselines/reference/decoratorMetadataPromise.js         | 2 +-
 tests/baselines/reference/defaultExportInAwaitExpression01.js | 2 +-
 tests/baselines/reference/defaultExportInAwaitExpression02.js | 2 +-
 tests/baselines/reference/es5-asyncFunction.js                | 2 +-
 tests/baselines/reference/es5-importHelpersAsyncFunctions.js  | 2 +-
 tests/baselines/reference/exportDefaultAsyncFunction.js       | 2 +-
 tests/baselines/reference/exportDefaultAsyncFunction2.js      | 2 +-
 tests/baselines/reference/inferenceLimit.js                   | 2 +-
 .../modularizeLibrary_NoErrorDuplicateLibOptions1.js          | 2 +-
 .../modularizeLibrary_NoErrorDuplicateLibOptions2.js          | 2 +-
 .../reference/modularizeLibrary_TargetES5UsingES6Lib.js       | 2 +-
 tests/baselines/reference/noImplicitReturnsInAsync1.js        | 2 +-
 tests/baselines/reference/noImplicitReturnsInAsync2.js        | 2 +-
 tests/baselines/reference/objectRest2.js                      | 2 +-
 tests/baselines/reference/promiseType.js                      | 2 +-
 tests/baselines/reference/promiseTypeStrictNull.js            | 2 +-
 tests/baselines/reference/reachabilityChecks7.js              | 2 +-
 tests/baselines/reference/transformNestedGeneratorsWithTry.js | 2 +-
 38 files changed, 39 insertions(+), 39 deletions(-)

diff --git a/src/compiler/transformers/es2017.ts b/src/compiler/transformers/es2017.ts
index 14f840f2e66..c87dbe32518 100644
--- a/src/compiler/transformers/es2017.ts
+++ b/src/compiler/transformers/es2017.ts
@@ -494,7 +494,7 @@ namespace ts {
                     function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
                     function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
                     function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-                    step((generator = generator.apply(thisArg, _arguments)).next());
+                    step((generator = generator.apply(thisArg, _arguments || [])).next());
                 });
             };`
     };
diff --git a/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js b/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
index 2f11dddf7de..49404267009 100644
--- a/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
+++ b/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
@@ -46,7 +46,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/asyncAwaitIsolatedModules_es6.js b/tests/baselines/reference/asyncAwaitIsolatedModules_es6.js
index 98d11d72bfb..046b74e6569 100644
--- a/tests/baselines/reference/asyncAwaitIsolatedModules_es6.js
+++ b/tests/baselines/reference/asyncAwaitIsolatedModules_es6.js
@@ -45,7 +45,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function f0() {
diff --git a/tests/baselines/reference/asyncAwait_es5.js b/tests/baselines/reference/asyncAwait_es5.js
index 043e68abeab..e4dc62ea1cf 100644
--- a/tests/baselines/reference/asyncAwait_es5.js
+++ b/tests/baselines/reference/asyncAwait_es5.js
@@ -45,7 +45,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/asyncAwait_es6.js b/tests/baselines/reference/asyncAwait_es6.js
index 4ba9e096e10..d6635098aed 100644
--- a/tests/baselines/reference/asyncAwait_es6.js
+++ b/tests/baselines/reference/asyncAwait_es6.js
@@ -45,7 +45,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function f0() {
diff --git a/tests/baselines/reference/asyncFunctionNoReturnType.js b/tests/baselines/reference/asyncFunctionNoReturnType.js
index fd39fc74d0e..b1c55416566 100644
--- a/tests/baselines/reference/asyncFunctionNoReturnType.js
+++ b/tests/baselines/reference/asyncFunctionNoReturnType.js
@@ -11,7 +11,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/asyncFunctionReturnType.js b/tests/baselines/reference/asyncFunctionReturnType.js
index 76f9952ab9f..dcdead47c6b 100644
--- a/tests/baselines/reference/asyncFunctionReturnType.js
+++ b/tests/baselines/reference/asyncFunctionReturnType.js
@@ -16,7 +16,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function fAsync() {
diff --git a/tests/baselines/reference/asyncFunctionsAcrossFiles.js b/tests/baselines/reference/asyncFunctionsAcrossFiles.js
index e9b5710dc07..b1a766e4e41 100644
--- a/tests/baselines/reference/asyncFunctionsAcrossFiles.js
+++ b/tests/baselines/reference/asyncFunctionsAcrossFiles.js
@@ -21,7 +21,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 import { a } from './a';
@@ -36,7 +36,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 import { b } from './b';
diff --git a/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
index ac9a558a53f..50ecbbb2beb 100644
--- a/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
+++ b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
@@ -32,7 +32,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function sample(promise) {
diff --git a/tests/baselines/reference/asyncIIFE.js b/tests/baselines/reference/asyncIIFE.js
index 79779af62f3..2460dbdf26b 100644
--- a/tests/baselines/reference/asyncIIFE.js
+++ b/tests/baselines/reference/asyncIIFE.js
@@ -16,7 +16,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function f1() {
diff --git a/tests/baselines/reference/asyncImportedPromise_es5.js b/tests/baselines/reference/asyncImportedPromise_es5.js
index e5c28eb2dc1..641b8e0381f 100644
--- a/tests/baselines/reference/asyncImportedPromise_es5.js
+++ b/tests/baselines/reference/asyncImportedPromise_es5.js
@@ -31,7 +31,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/asyncImportedPromise_es6.js b/tests/baselines/reference/asyncImportedPromise_es6.js
index 17c9de51ee6..6c6e34e7b1d 100644
--- a/tests/baselines/reference/asyncImportedPromise_es6.js
+++ b/tests/baselines/reference/asyncImportedPromise_es6.js
@@ -21,7 +21,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 class Test {
diff --git a/tests/baselines/reference/asyncMultiFile_es5.js b/tests/baselines/reference/asyncMultiFile_es5.js
index 6b44f5393fc..547135e5c19 100644
--- a/tests/baselines/reference/asyncMultiFile_es5.js
+++ b/tests/baselines/reference/asyncMultiFile_es5.js
@@ -11,7 +11,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/asyncMultiFile_es6.js b/tests/baselines/reference/asyncMultiFile_es6.js
index 0c45aa6c8a3..e7dd854b95b 100644
--- a/tests/baselines/reference/asyncMultiFile_es6.js
+++ b/tests/baselines/reference/asyncMultiFile_es6.js
@@ -11,7 +11,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function f() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6.js b/tests/baselines/reference/await_unaryExpression_es6.js
index 6609cc6f3f4..f9183f7af3e 100644
--- a/tests/baselines/reference/await_unaryExpression_es6.js
+++ b/tests/baselines/reference/await_unaryExpression_es6.js
@@ -22,7 +22,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function bar() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_1.js b/tests/baselines/reference/await_unaryExpression_es6_1.js
index 48f50d76f4a..948e537cb01 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_1.js
+++ b/tests/baselines/reference/await_unaryExpression_es6_1.js
@@ -26,7 +26,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function bar() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_2.js b/tests/baselines/reference/await_unaryExpression_es6_2.js
index 5e9d63a21d2..4b4c1cd6513 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_2.js
+++ b/tests/baselines/reference/await_unaryExpression_es6_2.js
@@ -18,7 +18,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function bar1() {
diff --git a/tests/baselines/reference/await_unaryExpression_es6_3.js b/tests/baselines/reference/await_unaryExpression_es6_3.js
index 469c8ea3ee9..6db5d5a7c31 100644
--- a/tests/baselines/reference/await_unaryExpression_es6_3.js
+++ b/tests/baselines/reference/await_unaryExpression_es6_3.js
@@ -24,7 +24,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function bar1() {
diff --git a/tests/baselines/reference/castOfAwait.js b/tests/baselines/reference/castOfAwait.js
index 1f66d49e0f3..9f67f74b11b 100644
--- a/tests/baselines/reference/castOfAwait.js
+++ b/tests/baselines/reference/castOfAwait.js
@@ -14,7 +14,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function f() {
diff --git a/tests/baselines/reference/declarationEmitPromise.js b/tests/baselines/reference/declarationEmitPromise.js
index e6f3f922b46..9e820a789c9 100644
--- a/tests/baselines/reference/declarationEmitPromise.js
+++ b/tests/baselines/reference/declarationEmitPromise.js
@@ -29,7 +29,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 class bluebird {
diff --git a/tests/baselines/reference/decoratorMetadataPromise.js b/tests/baselines/reference/decoratorMetadataPromise.js
index 52449f91755..23491449dfa 100644
--- a/tests/baselines/reference/decoratorMetadataPromise.js
+++ b/tests/baselines/reference/decoratorMetadataPromise.js
@@ -27,7 +27,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 class A {
diff --git a/tests/baselines/reference/defaultExportInAwaitExpression01.js b/tests/baselines/reference/defaultExportInAwaitExpression01.js
index a16e2f07f5f..9a122ae99c5 100644
--- a/tests/baselines/reference/defaultExportInAwaitExpression01.js
+++ b/tests/baselines/reference/defaultExportInAwaitExpression01.js
@@ -32,7 +32,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 (function (dependencies, factory) {
diff --git a/tests/baselines/reference/defaultExportInAwaitExpression02.js b/tests/baselines/reference/defaultExportInAwaitExpression02.js
index db05d62a2ad..8499164f675 100644
--- a/tests/baselines/reference/defaultExportInAwaitExpression02.js
+++ b/tests/baselines/reference/defaultExportInAwaitExpression02.js
@@ -24,7 +24,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 const a_1 = require("./a");
diff --git a/tests/baselines/reference/es5-asyncFunction.js b/tests/baselines/reference/es5-asyncFunction.js
index 5123566dc8c..6f04c7ed7ef 100644
--- a/tests/baselines/reference/es5-asyncFunction.js
+++ b/tests/baselines/reference/es5-asyncFunction.js
@@ -14,7 +14,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/es5-importHelpersAsyncFunctions.js b/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
index 0fd308cee3b..71c4af8d559 100644
--- a/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
+++ b/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
@@ -34,7 +34,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
diff --git a/tests/baselines/reference/exportDefaultAsyncFunction.js b/tests/baselines/reference/exportDefaultAsyncFunction.js
index 22f686b6ec8..9931d1f1eea 100644
--- a/tests/baselines/reference/exportDefaultAsyncFunction.js
+++ b/tests/baselines/reference/exportDefaultAsyncFunction.js
@@ -9,7 +9,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 export default function foo() {
diff --git a/tests/baselines/reference/exportDefaultAsyncFunction2.js b/tests/baselines/reference/exportDefaultAsyncFunction2.js
index aed6eb6c879..7b79bed9408 100644
--- a/tests/baselines/reference/exportDefaultAsyncFunction2.js
+++ b/tests/baselines/reference/exportDefaultAsyncFunction2.js
@@ -40,7 +40,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 export default () => __awaiter(this, void 0, void 0, function* () { return 0; });
diff --git a/tests/baselines/reference/inferenceLimit.js b/tests/baselines/reference/inferenceLimit.js
index b9423ebd655..84f0989e987 100644
--- a/tests/baselines/reference/inferenceLimit.js
+++ b/tests/baselines/reference/inferenceLimit.js
@@ -49,7 +49,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 class BrokenClass {
diff --git a/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions1.js b/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions1.js
index 180b53028ff..b83efdce890 100644
--- a/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions1.js
+++ b/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions1.js
@@ -87,7 +87,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 // Using Es6 array
diff --git a/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions2.js b/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions2.js
index cf69f260223..32d7135916b 100644
--- a/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions2.js
+++ b/tests/baselines/reference/modularizeLibrary_NoErrorDuplicateLibOptions2.js
@@ -87,7 +87,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 // Using Es6 array
diff --git a/tests/baselines/reference/modularizeLibrary_TargetES5UsingES6Lib.js b/tests/baselines/reference/modularizeLibrary_TargetES5UsingES6Lib.js
index 350113ec6a0..d0de3c93da0 100644
--- a/tests/baselines/reference/modularizeLibrary_TargetES5UsingES6Lib.js
+++ b/tests/baselines/reference/modularizeLibrary_TargetES5UsingES6Lib.js
@@ -87,7 +87,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 // Using Es6 array
diff --git a/tests/baselines/reference/noImplicitReturnsInAsync1.js b/tests/baselines/reference/noImplicitReturnsInAsync1.js
index 5274264a6b1..5ab86a91d3b 100644
--- a/tests/baselines/reference/noImplicitReturnsInAsync1.js
+++ b/tests/baselines/reference/noImplicitReturnsInAsync1.js
@@ -13,7 +13,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function test(isError = false) {
diff --git a/tests/baselines/reference/noImplicitReturnsInAsync2.js b/tests/baselines/reference/noImplicitReturnsInAsync2.js
index 93f8c97d1fb..7e7f22bd691 100644
--- a/tests/baselines/reference/noImplicitReturnsInAsync2.js
+++ b/tests/baselines/reference/noImplicitReturnsInAsync2.js
@@ -42,7 +42,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 // Should be an error, Promise<number>, currently retorted correctly 
diff --git a/tests/baselines/reference/objectRest2.js b/tests/baselines/reference/objectRest2.js
index e21c8c79853..6abff9e56a1 100644
--- a/tests/baselines/reference/objectRest2.js
+++ b/tests/baselines/reference/objectRest2.js
@@ -28,7 +28,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 function rootConnection(name) {
diff --git a/tests/baselines/reference/promiseType.js b/tests/baselines/reference/promiseType.js
index 9fbdb2ab2b6..4e42ea24073 100644
--- a/tests/baselines/reference/promiseType.js
+++ b/tests/baselines/reference/promiseType.js
@@ -161,7 +161,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 const a = p.then();
diff --git a/tests/baselines/reference/promiseTypeStrictNull.js b/tests/baselines/reference/promiseTypeStrictNull.js
index 8c5cef4c7c4..4aefeb3403e 100644
--- a/tests/baselines/reference/promiseTypeStrictNull.js
+++ b/tests/baselines/reference/promiseTypeStrictNull.js
@@ -161,7 +161,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 const a = p.then();
diff --git a/tests/baselines/reference/reachabilityChecks7.js b/tests/baselines/reference/reachabilityChecks7.js
index b8334f4276b..c17472205a4 100644
--- a/tests/baselines/reference/reachabilityChecks7.js
+++ b/tests/baselines/reference/reachabilityChecks7.js
@@ -36,7 +36,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 // async function without return type annotation - error
diff --git a/tests/baselines/reference/transformNestedGeneratorsWithTry.js b/tests/baselines/reference/transformNestedGeneratorsWithTry.js
index 69273e62633..7c3597ddc4b 100644
--- a/tests/baselines/reference/transformNestedGeneratorsWithTry.js
+++ b/tests/baselines/reference/transformNestedGeneratorsWithTry.js
@@ -29,7 +29,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
         function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
         function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments)).next());
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {