diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index e08534d8ba9..fd2ae5b3fdf 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -1050,7 +1050,8 @@ interface ReadonlyArray<T> {
       * @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
       * @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
       */
-    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T, initialValue?: T): T;
+    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T): T;
+    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T, initialValue: T): T;
     /**
       * Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
       * @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
@@ -1062,7 +1063,8 @@ interface ReadonlyArray<T> {
       * @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
       * @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T, initialValue?: T): T;
+    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T): T;
+    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => T, initialValue: T): T;
     /**
       * Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
       * @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
@@ -1200,7 +1202,8 @@ interface Array<T> {
       * @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
       * @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
       */
-    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T;
+    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T;
+    reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T;
     /**
       * Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
       * @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
@@ -1212,7 +1215,8 @@ interface Array<T> {
       * @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
       * @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T;
+    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T;
+    reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T;
     /**
       * Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
       * @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
@@ -1647,7 +1651,8 @@ interface Int8Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -1671,7 +1676,8 @@ interface Int8Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int8Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -1914,7 +1920,8 @@ interface Uint8Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -1938,7 +1945,8 @@ interface Uint8Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -2181,7 +2189,8 @@ interface Uint8ClampedArray {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -2205,7 +2214,8 @@ interface Uint8ClampedArray {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint8ClampedArray) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -2446,7 +2456,8 @@ interface Int16Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -2470,7 +2481,8 @@ interface Int16Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int16Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -2714,7 +2726,8 @@ interface Uint16Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -2738,7 +2751,8 @@ interface Uint16Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint16Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -2981,7 +2995,8 @@ interface Int32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -3005,7 +3020,8 @@ interface Int32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Int32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -3247,7 +3263,8 @@ interface Uint32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -3271,7 +3288,8 @@ interface Uint32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Uint32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -3514,7 +3532,8 @@ interface Float32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -3538,7 +3557,8 @@ interface Float32Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float32Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
@@ -3782,7 +3802,8 @@ interface Float64Array {
       * the accumulation. The first call to the callbackfn function provides this value as an argument
       * instead of an array value.
       */
-    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number, initialValue?: number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number): number;
+    reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array. The return value of
@@ -3806,7 +3827,8 @@ interface Float64Array {
       * the accumulation. The first call to the callbackfn function provides this value as an
       * argument instead of an array value.
       */
-    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number, initialValue?: number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number): number;
+    reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: Float64Array) => number, initialValue: number): number;
 
     /**
       * Calls the specified callback function for all the elements in an array, in descending order.
diff --git a/tests/baselines/reference/anyInferenceAnonymousFunctions.symbols b/tests/baselines/reference/anyInferenceAnonymousFunctions.symbols
index c1b5df88fb0..4aad165f40a 100644
--- a/tests/baselines/reference/anyInferenceAnonymousFunctions.symbols
+++ b/tests/baselines/reference/anyInferenceAnonymousFunctions.symbols
@@ -3,9 +3,9 @@ var paired: any[];
 >paired : Symbol(paired, Decl(anyInferenceAnonymousFunctions.ts, 0, 3))
 
 paired.reduce(function (a1, a2) {
->paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >paired : Symbol(paired, Decl(anyInferenceAnonymousFunctions.ts, 0, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >a1 : Symbol(a1, Decl(anyInferenceAnonymousFunctions.ts, 2, 24))
 >a2 : Symbol(a2, Decl(anyInferenceAnonymousFunctions.ts, 2, 27))
 
@@ -15,9 +15,9 @@ paired.reduce(function (a1, a2) {
 } , []);
 
 paired.reduce((b1, b2) => {
->paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >paired : Symbol(paired, Decl(anyInferenceAnonymousFunctions.ts, 0, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b1 : Symbol(b1, Decl(anyInferenceAnonymousFunctions.ts, 8, 15))
 >b2 : Symbol(b2, Decl(anyInferenceAnonymousFunctions.ts, 8, 18))
 
@@ -27,9 +27,9 @@ paired.reduce((b1, b2) => {
 } , []);
 
 paired.reduce((b3, b4) => b3.concat({}), []);
->paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>paired.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >paired : Symbol(paired, Decl(anyInferenceAnonymousFunctions.ts, 0, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b3 : Symbol(b3, Decl(anyInferenceAnonymousFunctions.ts, 13, 15))
 >b4 : Symbol(b4, Decl(anyInferenceAnonymousFunctions.ts, 13, 18))
 >b3 : Symbol(b3, Decl(anyInferenceAnonymousFunctions.ts, 13, 15))
diff --git a/tests/baselines/reference/anyInferenceAnonymousFunctions.types b/tests/baselines/reference/anyInferenceAnonymousFunctions.types
index 8dc7fdcb90f..d5f693b5453 100644
--- a/tests/baselines/reference/anyInferenceAnonymousFunctions.types
+++ b/tests/baselines/reference/anyInferenceAnonymousFunctions.types
@@ -4,9 +4,9 @@ var paired: any[];
 
 paired.reduce(function (a1, a2) {
 >paired.reduce(function (a1, a2) {    return a1.concat({});} , []) : any
->paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >paired : any[]
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >function (a1, a2) {    return a1.concat({});} : (a1: any, a2: any) => any
 >a1 : any
 >a2 : any
@@ -23,9 +23,9 @@ paired.reduce(function (a1, a2) {
 
 paired.reduce((b1, b2) => {
 >paired.reduce((b1, b2) => {    return b1.concat({});} , []) : any
->paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >paired : any[]
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >(b1, b2) => {    return b1.concat({});} : (b1: any, b2: any) => any
 >b1 : any
 >b2 : any
@@ -42,9 +42,9 @@ paired.reduce((b1, b2) => {
 
 paired.reduce((b3, b4) => b3.concat({}), []);
 >paired.reduce((b3, b4) => b3.concat({}), []) : any
->paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>paired.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >paired : any[]
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >(b3, b4) => b3.concat({}) : (b3: any, b4: any) => any
 >b3 : any
 >b4 : any
diff --git a/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.symbols b/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.symbols
index 02589e011c4..31efb739e4c 100644
--- a/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.symbols
+++ b/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.symbols
@@ -4,7 +4,7 @@ interface Array<T> {
 >T : Symbol(T, Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 16))
 
     reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T,
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
 >callbackfn : Symbol(callbackfn, Decl(duplicateOverloadInTypeAugmentation1.ts, 1, 11))
 >previousValue : Symbol(previousValue, Decl(duplicateOverloadInTypeAugmentation1.ts, 1, 24))
 >T : Symbol(T, Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 16))
@@ -21,7 +21,7 @@ interface Array<T> {
 >T : Symbol(T, Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 16))
 
     reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U,
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
 >U : Symbol(U, Decl(duplicateOverloadInTypeAugmentation1.ts, 3, 11))
 >callbackfn : Symbol(callbackfn, Decl(duplicateOverloadInTypeAugmentation1.ts, 3, 14))
 >previousValue : Symbol(previousValue, Decl(duplicateOverloadInTypeAugmentation1.ts, 3, 27))
@@ -44,9 +44,9 @@ var a: Array<string>;
 
 var r5 = a.reduce((x, y) => x + y);
 >r5 : Symbol(r5, Decl(duplicateOverloadInTypeAugmentation1.ts, 7, 3))
->a.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
+>a.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
 >a : Symbol(a, Decl(duplicateOverloadInTypeAugmentation1.ts, 6, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(duplicateOverloadInTypeAugmentation1.ts, 0, 20), Decl(duplicateOverloadInTypeAugmentation1.ts, 2, 29))
 >x : Symbol(x, Decl(duplicateOverloadInTypeAugmentation1.ts, 7, 19))
 >y : Symbol(y, Decl(duplicateOverloadInTypeAugmentation1.ts, 7, 21))
 >x : Symbol(x, Decl(duplicateOverloadInTypeAugmentation1.ts, 7, 19))
diff --git a/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.types b/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.types
index bc7214eb6b9..ea07ece4314 100644
--- a/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.types
+++ b/tests/baselines/reference/duplicateOverloadInTypeAugmentation1.types
@@ -4,7 +4,7 @@ interface Array<T> {
 >T : T
 
     reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T,
->reduce : { (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
 >callbackfn : (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T
 >previousValue : T
 >T : T
@@ -21,7 +21,7 @@ interface Array<T> {
 >T : T
 
     reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U,
->reduce : { (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; (callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; <U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
 >U : U
 >callbackfn : (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U
 >previousValue : U
@@ -45,9 +45,9 @@ var a: Array<string>;
 var r5 = a.reduce((x, y) => x + y);
 >r5 : string
 >a.reduce((x, y) => x + y) : string
->a.reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
+>a.reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string): string; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
 >a : string[]
->reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string): string; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
 >(x, y) => x + y : (x: string, y: string) => string
 >x : string
 >y : string
diff --git a/tests/baselines/reference/genericContextualTypingSpecialization.symbols b/tests/baselines/reference/genericContextualTypingSpecialization.symbols
index b244ab496be..0dcc8cb5899 100644
--- a/tests/baselines/reference/genericContextualTypingSpecialization.symbols
+++ b/tests/baselines/reference/genericContextualTypingSpecialization.symbols
@@ -3,9 +3,9 @@ var b: number[];
 >b : Symbol(b, Decl(genericContextualTypingSpecialization.ts, 0, 3))
 
 b.reduce<number>((c, d) => c + d, 0); // should not error on '+'
->b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b : Symbol(b, Decl(genericContextualTypingSpecialization.ts, 0, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >c : Symbol(c, Decl(genericContextualTypingSpecialization.ts, 1, 18))
 >d : Symbol(d, Decl(genericContextualTypingSpecialization.ts, 1, 20))
 >c : Symbol(c, Decl(genericContextualTypingSpecialization.ts, 1, 18))
diff --git a/tests/baselines/reference/genericContextualTypingSpecialization.types b/tests/baselines/reference/genericContextualTypingSpecialization.types
index 82255020347..d7d61010507 100644
--- a/tests/baselines/reference/genericContextualTypingSpecialization.types
+++ b/tests/baselines/reference/genericContextualTypingSpecialization.types
@@ -4,9 +4,9 @@ var b: number[];
 
 b.reduce<number>((c, d) => c + d, 0); // should not error on '+'
 >b.reduce<number>((c, d) => c + d, 0) : number
->b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >b : number[]
->reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >(c, d) => c + d : (c: number, d: number) => number
 >c : number
 >d : number
diff --git a/tests/baselines/reference/genericReduce.symbols b/tests/baselines/reference/genericReduce.symbols
index f220972a350..a939c5cf92d 100644
--- a/tests/baselines/reference/genericReduce.symbols
+++ b/tests/baselines/reference/genericReduce.symbols
@@ -14,9 +14,9 @@ var b = a.map(s => s.length);
 
 var n1 = b.reduce((x, y) => x + y);
 >n1 : Symbol(n1, Decl(genericReduce.ts, 2, 3))
->b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b : Symbol(b, Decl(genericReduce.ts, 1, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >x : Symbol(x, Decl(genericReduce.ts, 2, 19))
 >y : Symbol(y, Decl(genericReduce.ts, 2, 21))
 >x : Symbol(x, Decl(genericReduce.ts, 2, 19))
@@ -24,9 +24,9 @@ var n1 = b.reduce((x, y) => x + y);
 
 var n2 = b.reduceRight((x, y) => x + y);
 >n2 : Symbol(n2, Decl(genericReduce.ts, 3, 3))
->b.reduceRight : Symbol(Array.reduceRight, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>b.reduceRight : Symbol(Array.reduceRight, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b : Symbol(b, Decl(genericReduce.ts, 1, 3))
->reduceRight : Symbol(Array.reduceRight, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduceRight : Symbol(Array.reduceRight, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >x : Symbol(x, Decl(genericReduce.ts, 3, 24))
 >y : Symbol(y, Decl(genericReduce.ts, 3, 26))
 >x : Symbol(x, Decl(genericReduce.ts, 3, 24))
@@ -50,9 +50,9 @@ n2.toExponential(2); // should not error if 'n2' is correctly number.
 
 var n3 = b.reduce<string>( (x, y) => x + y, ""); // Initial value is of type string
 >n3 : Symbol(n3, Decl(genericReduce.ts, 10, 3))
->b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>b.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >b : Symbol(b, Decl(genericReduce.ts, 1, 3))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >x : Symbol(x, Decl(genericReduce.ts, 10, 28))
 >y : Symbol(y, Decl(genericReduce.ts, 10, 30))
 >x : Symbol(x, Decl(genericReduce.ts, 10, 28))
diff --git a/tests/baselines/reference/genericReduce.types b/tests/baselines/reference/genericReduce.types
index 628398f86fd..65a069426a7 100644
--- a/tests/baselines/reference/genericReduce.types
+++ b/tests/baselines/reference/genericReduce.types
@@ -22,9 +22,9 @@ var b = a.map(s => s.length);
 var n1 = b.reduce((x, y) => x + y);
 >n1 : number
 >b.reduce((x, y) => x + y) : number
->b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >b : number[]
->reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >(x, y) => x + y : (x: number, y: number) => number
 >x : number
 >y : number
@@ -35,9 +35,9 @@ var n1 = b.reduce((x, y) => x + y);
 var n2 = b.reduceRight((x, y) => x + y);
 >n2 : number
 >b.reduceRight((x, y) => x + y) : number
->b.reduceRight : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>b.reduceRight : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >b : number[]
->reduceRight : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>reduceRight : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >(x, y) => x + y : (x: number, y: number) => number
 >x : number
 >y : number
@@ -76,9 +76,9 @@ n2.toExponential(2); // should not error if 'n2' is correctly number.
 var n3 = b.reduce<string>( (x, y) => x + y, ""); // Initial value is of type string
 >n3 : string
 >b.reduce<string>( (x, y) => x + y, "") : string
->b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>b.reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >b : number[]
->reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >(x, y) => x + y : (x: string, y: number) => string
 >x : string
 >y : number
diff --git a/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.symbols b/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.symbols
index e18c80afcde..3060f44009b 100644
--- a/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.symbols
+++ b/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.symbols
@@ -124,9 +124,9 @@ function compose<T>(...fns: ((x: T) => T)[]): (x: T) => T {
   return (x: T) => fns.reduce((prev, fn) => fn(prev), x);
 >x : Symbol(x, Decl(inferFromGenericFunctionReturnTypes1.ts, 27, 10))
 >T : Symbol(T, Decl(inferFromGenericFunctionReturnTypes1.ts, 26, 17))
->fns.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>fns.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >fns : Symbol(fns, Decl(inferFromGenericFunctionReturnTypes1.ts, 26, 20))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prev : Symbol(prev, Decl(inferFromGenericFunctionReturnTypes1.ts, 27, 31))
 >fn : Symbol(fn, Decl(inferFromGenericFunctionReturnTypes1.ts, 27, 36))
 >fn : Symbol(fn, Decl(inferFromGenericFunctionReturnTypes1.ts, 27, 36))
diff --git a/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.types b/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.types
index dfbe6c2f2b6..9484b3aaa19 100644
--- a/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.types
+++ b/tests/baselines/reference/inferFromGenericFunctionReturnTypes1.types
@@ -131,9 +131,9 @@ function compose<T>(...fns: ((x: T) => T)[]): (x: T) => T {
 >x : T
 >T : T
 >fns.reduce((prev, fn) => fn(prev), x) : T
->fns.reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue?: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
+>fns.reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T): (x: T) => T; (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
 >fns : ((x: T) => T)[]
->reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue?: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T): (x: T) => T; (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
 >(prev, fn) => fn(prev) : (prev: T, fn: (x: T) => T) => T
 >prev : T
 >fn : (x: T) => T
diff --git a/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.symbols b/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.symbols
index 7e4fe043b93..f7189682273 100644
--- a/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.symbols
+++ b/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.symbols
@@ -292,9 +292,9 @@ function compose<T>(...fns: ((x: T) => T)[]): (x: T) => T {
   return (x: T) => fns.reduce((prev, fn) => fn(prev), x);
 >x : Symbol(x, Decl(inferFromGenericFunctionReturnTypes2.ts, 49, 10))
 >T : Symbol(T, Decl(inferFromGenericFunctionReturnTypes2.ts, 48, 17))
->fns.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>fns.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >fns : Symbol(fns, Decl(inferFromGenericFunctionReturnTypes2.ts, 48, 20))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prev : Symbol(prev, Decl(inferFromGenericFunctionReturnTypes2.ts, 49, 31))
 >fn : Symbol(fn, Decl(inferFromGenericFunctionReturnTypes2.ts, 49, 36))
 >fn : Symbol(fn, Decl(inferFromGenericFunctionReturnTypes2.ts, 49, 36))
diff --git a/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.types b/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.types
index cf7752e237e..a36b7ed35be 100644
--- a/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.types
+++ b/tests/baselines/reference/inferFromGenericFunctionReturnTypes2.types
@@ -358,9 +358,9 @@ function compose<T>(...fns: ((x: T) => T)[]): (x: T) => T {
 >x : T
 >T : T
 >fns.reduce((prev, fn) => fn(prev), x) : T
->fns.reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue?: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
+>fns.reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T): (x: T) => T; (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
 >fns : ((x: T) => T)[]
->reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue?: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T): (x: T) => T; (callbackfn: (previousValue: (x: T) => T, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => (x: T) => T, initialValue: (x: T) => T): (x: T) => T; <U>(callbackfn: (previousValue: U, currentValue: (x: T) => T, currentIndex: number, array: ((x: T) => T)[]) => U, initialValue: U): U; }
 >(prev, fn) => fn(prev) : (prev: T, fn: (x: T) => T) => T
 >prev : T
 >fn : (x: T) => T
diff --git a/tests/baselines/reference/parserharness.symbols b/tests/baselines/reference/parserharness.symbols
index 94ae5c87901..8382d6ab41a 100644
--- a/tests/baselines/reference/parserharness.symbols
+++ b/tests/baselines/reference/parserharness.symbols
@@ -4692,7 +4692,7 @@ module Harness {
 
             var minDistFromStart = entries.map(x => x.editRange.minChar).reduce((prev, current) => Math.min(prev, current));
 >minDistFromStart : Symbol(minDistFromStart, Decl(parserharness.ts, 1595, 15))
->entries.map(x => x.editRange.minChar).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>entries.map(x => x.editRange.minChar).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >entries.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
 >entries : Symbol(entries, Decl(parserharness.ts, 1593, 15))
 >map : Symbol(Array.map, Decl(lib.d.ts, --, --))
@@ -4700,7 +4700,7 @@ module Harness {
 >x.editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
 >x : Symbol(x, Decl(parserharness.ts, 1595, 47))
 >editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prev : Symbol(prev, Decl(parserharness.ts, 1595, 81))
 >current : Symbol(current, Decl(parserharness.ts, 1595, 86))
 >Math.min : Symbol(Math.min, Decl(lib.d.ts, --, --))
@@ -4711,7 +4711,7 @@ module Harness {
 
             var minDistFromEnd = entries.map(x => x.length - x.editRange.limChar).reduce((prev, current) => Math.min(prev, current));
 >minDistFromEnd : Symbol(minDistFromEnd, Decl(parserharness.ts, 1596, 15))
->entries.map(x => x.length - x.editRange.limChar).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>entries.map(x => x.length - x.editRange.limChar).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >entries.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
 >entries : Symbol(entries, Decl(parserharness.ts, 1593, 15))
 >map : Symbol(Array.map, Decl(lib.d.ts, --, --))
@@ -4722,7 +4722,7 @@ module Harness {
 >x.editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
 >x : Symbol(x, Decl(parserharness.ts, 1596, 45))
 >editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prev : Symbol(prev, Decl(parserharness.ts, 1596, 90))
 >current : Symbol(current, Decl(parserharness.ts, 1596, 95))
 >Math.min : Symbol(Math.min, Decl(lib.d.ts, --, --))
@@ -4733,7 +4733,7 @@ module Harness {
 
             var aggDelta = entries.map(x => x.editRange.delta).reduce((prev, current) => prev + current);
 >aggDelta : Symbol(aggDelta, Decl(parserharness.ts, 1597, 15))
->entries.map(x => x.editRange.delta).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>entries.map(x => x.editRange.delta).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >entries.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
 >entries : Symbol(entries, Decl(parserharness.ts, 1593, 15))
 >map : Symbol(Array.map, Decl(lib.d.ts, --, --))
@@ -4741,7 +4741,7 @@ module Harness {
 >x.editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
 >x : Symbol(x, Decl(parserharness.ts, 1597, 39))
 >editRange : Symbol(editRange, Decl(parserharness.ts, 1547, 44))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prev : Symbol(prev, Decl(parserharness.ts, 1597, 71))
 >current : Symbol(current, Decl(parserharness.ts, 1597, 76))
 >prev : Symbol(prev, Decl(parserharness.ts, 1597, 71))
diff --git a/tests/baselines/reference/parserharness.types b/tests/baselines/reference/parserharness.types
index 2fd260f5d2b..6ea78e22f2f 100644
--- a/tests/baselines/reference/parserharness.types
+++ b/tests/baselines/reference/parserharness.types
@@ -6604,7 +6604,7 @@ module Harness {
             var minDistFromStart = entries.map(x => x.editRange.minChar).reduce((prev, current) => Math.min(prev, current));
 >minDistFromStart : any
 >entries.map(x => x.editRange.minChar).reduce((prev, current) => Math.min(prev, current)) : any
->entries.map(x => x.editRange.minChar).reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>entries.map(x => x.editRange.minChar).reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >entries.map(x => x.editRange.minChar) : any[]
 >entries.map : <U>(callbackfn: (value: { length: number; editRange: any; }, index: number, array: { length: number; editRange: any; }[]) => U, thisArg?: any) => U[]
 >entries : { length: number; editRange: any; }[]
@@ -6616,7 +6616,7 @@ module Harness {
 >x : { length: number; editRange: any; }
 >editRange : any
 >minChar : any
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >(prev, current) => Math.min(prev, current) : (prev: any, current: any) => number
 >prev : any
 >current : any
@@ -6630,7 +6630,7 @@ module Harness {
             var minDistFromEnd = entries.map(x => x.length - x.editRange.limChar).reduce((prev, current) => Math.min(prev, current));
 >minDistFromEnd : number
 >entries.map(x => x.length - x.editRange.limChar).reduce((prev, current) => Math.min(prev, current)) : number
->entries.map(x => x.length - x.editRange.limChar).reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>entries.map(x => x.length - x.editRange.limChar).reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >entries.map(x => x.length - x.editRange.limChar) : number[]
 >entries.map : <U>(callbackfn: (value: { length: number; editRange: any; }, index: number, array: { length: number; editRange: any; }[]) => U, thisArg?: any) => U[]
 >entries : { length: number; editRange: any; }[]
@@ -6646,7 +6646,7 @@ module Harness {
 >x : { length: number; editRange: any; }
 >editRange : any
 >limChar : any
->reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue?: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number, initialValue: number): number; <U>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: number[]) => U, initialValue: U): U; }
 >(prev, current) => Math.min(prev, current) : (prev: number, current: number) => number
 >prev : number
 >current : number
@@ -6660,7 +6660,7 @@ module Harness {
             var aggDelta = entries.map(x => x.editRange.delta).reduce((prev, current) => prev + current);
 >aggDelta : any
 >entries.map(x => x.editRange.delta).reduce((prev, current) => prev + current) : any
->entries.map(x => x.editRange.delta).reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>entries.map(x => x.editRange.delta).reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >entries.map(x => x.editRange.delta) : any[]
 >entries.map : <U>(callbackfn: (value: { length: number; editRange: any; }, index: number, array: { length: number; editRange: any; }[]) => U, thisArg?: any) => U[]
 >entries : { length: number; editRange: any; }[]
@@ -6672,7 +6672,7 @@ module Harness {
 >x : { length: number; editRange: any; }
 >editRange : any
 >delta : any
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >(prev, current) => prev + current : (prev: any, current: any) => any
 >prev : any
 >current : any
diff --git a/tests/baselines/reference/recursiveTypeRelations.symbols b/tests/baselines/reference/recursiveTypeRelations.symbols
index 9f656a789ed..2c940df2487 100644
--- a/tests/baselines/reference/recursiveTypeRelations.symbols
+++ b/tests/baselines/reference/recursiveTypeRelations.symbols
@@ -89,12 +89,12 @@ export function css<S extends { [K in keyof S]: string }>(styles: S, ...classNam
 >arg : Symbol(arg, Decl(recursiveTypeRelations.ts, 18, 30))
 
       return Object.keys(arg).reduce<ClassNameObject>((obj: ClassNameObject, key: keyof S) => {
->Object.keys(arg).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>Object.keys(arg).reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >Object.keys : Symbol(ObjectConstructor.keys, Decl(lib.d.ts, --, --))
 >Object : Symbol(Object, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >keys : Symbol(ObjectConstructor.keys, Decl(lib.d.ts, --, --))
 >arg : Symbol(arg, Decl(recursiveTypeRelations.ts, 18, 30))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >obj : Symbol(obj, Decl(recursiveTypeRelations.ts, 26, 55))
 >key : Symbol(key, Decl(recursiveTypeRelations.ts, 26, 76))
 >S : Symbol(S, Decl(recursiveTypeRelations.ts, 17, 20))
diff --git a/tests/baselines/reference/recursiveTypeRelations.types b/tests/baselines/reference/recursiveTypeRelations.types
index 6def28d4461..110ff8175c4 100644
--- a/tests/baselines/reference/recursiveTypeRelations.types
+++ b/tests/baselines/reference/recursiveTypeRelations.types
@@ -102,13 +102,13 @@ export function css<S extends { [K in keyof S]: string }>(styles: S, ...classNam
 
       return Object.keys(arg).reduce<ClassNameObject>((obj: ClassNameObject, key: keyof S) => {
 >Object.keys(arg).reduce<ClassNameObject>((obj: ClassNameObject, key: keyof S) => {        const exportedClassName = styles[key];        obj[exportedClassName] = (arg as ClassNameMap<S>)[key];         return obj;      }, {}) : any
->Object.keys(arg).reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
+>Object.keys(arg).reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string): string; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
 >Object.keys(arg) : string[]
 >Object.keys : (o: {}) => string[]
 >Object : ObjectConstructor
 >keys : (o: {}) => string[]
 >arg : keyof S | (object & { [K in keyof S]?: boolean; })
->reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue?: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string): string; (callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue: string): string; <U>(callbackfn: (previousValue: U, currentValue: string, currentIndex: number, array: string[]) => U, initialValue: U): U; }
 >ClassNameObject : No type information available!
 >(obj: ClassNameObject, key: keyof S) => {        const exportedClassName = styles[key];        obj[exportedClassName] = (arg as ClassNameMap<S>)[key];         return obj;      } : (obj: any, key: keyof S) => any
 >obj : any
diff --git a/tests/baselines/reference/restInvalidArgumentType.types b/tests/baselines/reference/restInvalidArgumentType.types
index 28162bcc7cc..39495008877 100644
--- a/tests/baselines/reference/restInvalidArgumentType.types
+++ b/tests/baselines/reference/restInvalidArgumentType.types
@@ -87,7 +87,7 @@ function f<T extends { b: string }>(p1: T, p2: T[]) {
 >p1 : T
 
     var {...r2} = p2;   // OK
->r2 : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
+>r2 : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
 >p2 : T[]
 
     var {...r3} = t;   // Error, generic type paramter
diff --git a/tests/baselines/reference/returnTypeParameterWithModules.symbols b/tests/baselines/reference/returnTypeParameterWithModules.symbols
index 7f8fab382a3..eb56940b604 100644
--- a/tests/baselines/reference/returnTypeParameterWithModules.symbols
+++ b/tests/baselines/reference/returnTypeParameterWithModules.symbols
@@ -13,11 +13,11 @@ module M1 {
 
         return Array.prototype.reduce.apply(ar, e ? [f, e] : [f]);
 >Array.prototype.reduce.apply : Symbol(Function.apply, Decl(lib.d.ts, --, --))
->Array.prototype.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>Array.prototype.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, --, --))
 >Array : Symbol(Array, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, --, --))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >apply : Symbol(Function.apply, Decl(lib.d.ts, --, --))
 >ar : Symbol(ar, Decl(returnTypeParameterWithModules.ts, 1, 30))
 >e : Symbol(e, Decl(returnTypeParameterWithModules.ts, 1, 36))
diff --git a/tests/baselines/reference/returnTypeParameterWithModules.types b/tests/baselines/reference/returnTypeParameterWithModules.types
index 584c962a170..3aec0f14fcf 100644
--- a/tests/baselines/reference/returnTypeParameterWithModules.types
+++ b/tests/baselines/reference/returnTypeParameterWithModules.types
@@ -14,11 +14,11 @@ module M1 {
         return Array.prototype.reduce.apply(ar, e ? [f, e] : [f]);
 >Array.prototype.reduce.apply(ar, e ? [f, e] : [f]) : any
 >Array.prototype.reduce.apply : (this: Function, thisArg: any, argArray?: any) => any
->Array.prototype.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>Array.prototype.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >Array.prototype : any[]
 >Array : ArrayConstructor
 >prototype : any[]
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >apply : (this: Function, thisArg: any, argArray?: any) => any
 >ar : any
 >e ? [f, e] : [f] : any[]
diff --git a/tests/baselines/reference/spreadInvalidArgumentType.types b/tests/baselines/reference/spreadInvalidArgumentType.types
index 1eebc00850f..244d8515893 100644
--- a/tests/baselines/reference/spreadInvalidArgumentType.types
+++ b/tests/baselines/reference/spreadInvalidArgumentType.types
@@ -89,8 +89,8 @@ function f<T extends { b: string }>(p1: T, p2: T[]) {
 >p1 : T
 
     var o2 = { ...p2 };   // OK
->o2 : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
->{ ...p2 } : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue?: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
+>o2 : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
+>{ ...p2 } : { [n: number]: T; length: number; toString(): string; toLocaleString(): string; push(...items: T[]): number; pop(): T; concat(...items: ReadonlyArray<T>[]): T[]; concat(...items: (T | ReadonlyArray<T>)[]): T[]; join(separator?: string): string; reverse(): T[]; shift(): T; slice(start?: number, end?: number): T[]; sort(compareFn?: (a: T, b: T) => number): T[]; splice(start: number, deleteCount?: number): T[]; splice(start: number, deleteCount: number, ...items: T[]): T[]; unshift(...items: T[]): number; indexOf(searchElement: T, fromIndex?: number): number; lastIndexOf(searchElement: T, fromIndex?: number): number; every(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; some(callbackfn: (value: T, index: number, array: T[]) => boolean, thisArg?: any): boolean; forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void; map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[]; filter<S extends T>(callbackfn: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[]; filter(callbackfn: (value: T, index: number, array: T[]) => any, thisArg?: any): T[]; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T; reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T; reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U; }
 >p2 : T[]
 
     var o3 = { ...t };   // Error, generic type paramter
diff --git a/tests/baselines/reference/unknownSymbolOffContextualType1.symbols b/tests/baselines/reference/unknownSymbolOffContextualType1.symbols
index 1e19afeb6a0..3acf34ec9bf 100644
--- a/tests/baselines/reference/unknownSymbolOffContextualType1.symbols
+++ b/tests/baselines/reference/unknownSymbolOffContextualType1.symbols
@@ -61,9 +61,9 @@ function getMaxWidth(elementNames: string[]) {
     });
     var maxWidth = widths.reduce(function (a, b) {
 >maxWidth : Symbol(maxWidth, Decl(unknownSymbolOffContextualType1.ts, 17, 7))
->widths.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>widths.reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >widths : Symbol(widths, Decl(unknownSymbolOffContextualType1.ts, 14, 7))
->reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>reduce : Symbol(Array.reduce, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
 >a : Symbol(a, Decl(unknownSymbolOffContextualType1.ts, 17, 43))
 >b : Symbol(b, Decl(unknownSymbolOffContextualType1.ts, 17, 45))
 
diff --git a/tests/baselines/reference/unknownSymbolOffContextualType1.types b/tests/baselines/reference/unknownSymbolOffContextualType1.types
index c6f05b69b74..7df3bd52cc9 100644
--- a/tests/baselines/reference/unknownSymbolOffContextualType1.types
+++ b/tests/baselines/reference/unknownSymbolOffContextualType1.types
@@ -72,9 +72,9 @@ function getMaxWidth(elementNames: string[]) {
     var maxWidth = widths.reduce(function (a, b) {
 >maxWidth : any
 >widths.reduce(function (a, b) {        return a > b ? a : b;    }) : any
->widths.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>widths.reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >widths : any[]
->reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue?: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
+>reduce : { (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any): any; (callbackfn: (previousValue: any, currentValue: any, currentIndex: number, array: any[]) => any, initialValue: any): any; <U>(callbackfn: (previousValue: U, currentValue: any, currentIndex: number, array: any[]) => U, initialValue: U): U; }
 >function (a, b) {        return a > b ? a : b;    } : (a: any, b: any) => any
 >a : any
 >b : any