From 723ffab8df671a7960bf05e2711f43f9de2398a6 Mon Sep 17 00:00:00 2001
From: Kitson Kelly <me@kitsonkelly.com>
Date: Wed, 28 Sep 2016 21:50:33 +0100
Subject: [PATCH] Improve Array.prototype.slice typing

---
 src/lib/es5.d.ts                              |  3 ++-
 tests/baselines/reference/arraySlice.js       |  8 ++++++++
 tests/baselines/reference/arraySlice.symbols  |  9 +++++++++
 tests/baselines/reference/arraySlice.types    | 12 +++++++++++
 tests/baselines/reference/invalidSplice.types |  4 ++--
 ...ymousTypeNotReferencingTypeParameter.types | 20 +++++++++----------
 tests/cases/compiler/arraySlice.ts            |  2 ++
 7 files changed, 45 insertions(+), 13 deletions(-)
 create mode 100644 tests/baselines/reference/arraySlice.js
 create mode 100644 tests/baselines/reference/arraySlice.symbols
 create mode 100644 tests/baselines/reference/arraySlice.types
 create mode 100644 tests/cases/compiler/arraySlice.ts

diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index ce719668acf..8a9eeaba57c 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -1156,8 +1156,9 @@ interface Array<T> {
     /**
       * Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements.
       * @param start The zero-based location in the array from which to start removing elements.
+      * @param deleteCount The number of elements to remove.
       */
-    splice(start: number): T[];
+    splice(start: number, deleteCount?: number): T[];
     /**
       * Removes elements from an array and, if necessary, inserts new elements in their place, returning the deleted elements.
       * @param start The zero-based location in the array from which to start removing elements.
diff --git a/tests/baselines/reference/arraySlice.js b/tests/baselines/reference/arraySlice.js
new file mode 100644
index 00000000000..a5e4ba1546e
--- /dev/null
+++ b/tests/baselines/reference/arraySlice.js
@@ -0,0 +1,8 @@
+//// [arraySlice.ts]
+var arr: string[] | number[];
+arr.splice(1, 1);
+
+
+//// [arraySlice.js]
+var arr;
+arr.splice(1, 1);
diff --git a/tests/baselines/reference/arraySlice.symbols b/tests/baselines/reference/arraySlice.symbols
new file mode 100644
index 00000000000..3b6545f9349
--- /dev/null
+++ b/tests/baselines/reference/arraySlice.symbols
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/arraySlice.ts ===
+var arr: string[] | number[];
+>arr : Symbol(arr, Decl(arraySlice.ts, 0, 3))
+
+arr.splice(1, 1);
+>arr.splice : Symbol(splice, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>arr : Symbol(arr, Decl(arraySlice.ts, 0, 3))
+>splice : Symbol(splice, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+
diff --git a/tests/baselines/reference/arraySlice.types b/tests/baselines/reference/arraySlice.types
new file mode 100644
index 00000000000..d1ee482ccaa
--- /dev/null
+++ b/tests/baselines/reference/arraySlice.types
@@ -0,0 +1,12 @@
+=== tests/cases/compiler/arraySlice.ts ===
+var arr: string[] | number[];
+>arr : string[] | number[]
+
+arr.splice(1, 1);
+>arr.splice(1, 1) : string[] | number[]
+>arr.splice : { (start: number, deleteCount?: number): string[]; (start: number, deleteCount: number, ...items: string[]): string[]; } | { (start: number, deleteCount?: number): number[]; (start: number, deleteCount: number, ...items: number[]): number[]; }
+>arr : string[] | number[]
+>splice : { (start: number, deleteCount?: number): string[]; (start: number, deleteCount: number, ...items: string[]): string[]; } | { (start: number, deleteCount?: number): number[]; (start: number, deleteCount: number, ...items: number[]): number[]; }
+>1 : 1
+>1 : 1
+
diff --git a/tests/baselines/reference/invalidSplice.types b/tests/baselines/reference/invalidSplice.types
index 876846d3da9..9ff59021725 100644
--- a/tests/baselines/reference/invalidSplice.types
+++ b/tests/baselines/reference/invalidSplice.types
@@ -2,9 +2,9 @@
 var arr = [].splice(0,3,4,5);
 >arr : any[]
 >[].splice(0,3,4,5) : any[]
->[].splice : { (start: number): any[]; (start: number, deleteCount: number, ...items: any[]): any[]; }
+>[].splice : { (start: number, deleteCount?: number): any[]; (start: number, deleteCount: number, ...items: any[]): any[]; }
 >[] : undefined[]
->splice : { (start: number): any[]; (start: number, deleteCount: number, ...items: any[]): any[]; }
+>splice : { (start: number, deleteCount?: number): any[]; (start: number, deleteCount: number, ...items: any[]): any[]; }
 >0 : 0
 >3 : 3
 >4 : 4
diff --git a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
index f2bd83674cd..127a8d930c5 100644
--- a/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
+++ b/tests/baselines/reference/staticAnonymousTypeNotReferencingTypeParameter.types
@@ -364,9 +364,9 @@ class ListWrapper {
 >value : T
 >T : T
 >list.splice(index, 0, value) : T[]
->list.splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>list.splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >list : T[]
->splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >index : number
 >0 : 0
 >value : T
@@ -389,9 +389,9 @@ class ListWrapper {
 
     list.splice(index, 1);
 >list.splice(index, 1) : T[]
->list.splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>list.splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >list : T[]
->splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >index : number
 >1 : 1
 
@@ -431,9 +431,9 @@ class ListWrapper {
 
       list.splice(index, 1);
 >list.splice(index, 1) : T[]
->list.splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>list.splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >list : T[]
->splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >index : number
 >1 : 1
     }
@@ -464,9 +464,9 @@ class ListWrapper {
 
       list.splice(index, 1);
 >list.splice(index, 1) : T[]
->list.splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>list.splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >list : T[]
->splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >index : number
 >1 : 1
 
@@ -603,9 +603,9 @@ class ListWrapper {
 >length : number
 >T : T
 >l.splice(from, length) : T[]
->l.splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>l.splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >l : T[]
->splice : { (start: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
+>splice : { (start: number, deleteCount?: number): T[]; (start: number, deleteCount: number, ...items: T[]): T[]; }
 >from : number
 >length : number
 
diff --git a/tests/cases/compiler/arraySlice.ts b/tests/cases/compiler/arraySlice.ts
new file mode 100644
index 00000000000..d2c5c974a23
--- /dev/null
+++ b/tests/cases/compiler/arraySlice.ts
@@ -0,0 +1,2 @@
+var arr: string[] | number[];
+arr.splice(1, 1);