From 171a5f8098831990e8829f5ced2b3cc8827cbea0 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Thu, 12 Mar 2015 10:58:16 -0700
Subject: [PATCH 1/2] correctly parse destructuring in let outside of strict
 mode

---
 src/compiler/parser.ts                             |  9 +++++++--
 tests/baselines/reference/letInNonStrictMode.js    | 11 +++++++++++
 tests/baselines/reference/letInNonStrictMode.types | 11 +++++++++++
 tests/cases/compiler/letInNonStrictMode.ts         |  2 ++
 4 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/letInNonStrictMode.js
 create mode 100644 tests/baselines/reference/letInNonStrictMode.types
 create mode 100644 tests/cases/compiler/letInNonStrictMode.ts

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 6e444eb23c7f5..7656e2eb2c9eb 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -2975,6 +2975,11 @@ module ts {
             return !scanner.hasPrecedingLineBreak() && isIdentifier()
         }
 
+        function netTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() {
+            nextToken();
+            return !scanner.hasPrecedingLineBreak() && (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken)
+        }
+
         function parseYieldExpression(): YieldExpression {
             var node = <YieldExpression>createNode(SyntaxKind.YieldExpression);
 
@@ -4873,9 +4878,9 @@ module ts {
         }
 
         function isLetDeclaration() {
-            // It is let declaration if in strict mode or next token is identifier on same line.
+            // It is let declaration if in strict mode or next token is identifier\open brace\open curly on same line.
             // otherwise it needs to be treated like identifier
-            return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOnSameLine);
+            return inStrictModeContext() || lookAhead(netTokenIsIdentifierOrStartOfDestructuringOnTheSameLine);
         }
 
         function isDeclarationStart(): boolean {
diff --git a/tests/baselines/reference/letInNonStrictMode.js b/tests/baselines/reference/letInNonStrictMode.js
new file mode 100644
index 0000000000000..af21ce3281c39
--- /dev/null
+++ b/tests/baselines/reference/letInNonStrictMode.js
@@ -0,0 +1,11 @@
+//// [letInNonStrictMode.ts]
+let [x] = [1];
+let {a: y} = {a: 1};
+
+//// [letInNonStrictMode.js]
+var x = ([
+    1
+])[0];
+var y = ({
+    a: 1
+}).a;
diff --git a/tests/baselines/reference/letInNonStrictMode.types b/tests/baselines/reference/letInNonStrictMode.types
new file mode 100644
index 0000000000000..4f2cbe4a70386
--- /dev/null
+++ b/tests/baselines/reference/letInNonStrictMode.types
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/letInNonStrictMode.ts ===
+let [x] = [1];
+>x : number
+>[1] : [number]
+
+let {a: y} = {a: 1};
+>a : unknown
+>y : number
+>{a: 1} : { a: number; }
+>a : number
+
diff --git a/tests/cases/compiler/letInNonStrictMode.ts b/tests/cases/compiler/letInNonStrictMode.ts
new file mode 100644
index 0000000000000..576246e76a1b5
--- /dev/null
+++ b/tests/cases/compiler/letInNonStrictMode.ts
@@ -0,0 +1,2 @@
+let [x] = [1];
+let {a: y} = {a: 1};
\ No newline at end of file

From e46442f45f99f3277d6e2fc222402c5051379c6f Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Fri, 13 Mar 2015 12:08:58 -0700
Subject: [PATCH 2/2] addressed PR feedback: fixed typo in function name

---
 src/compiler/parser.ts | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 7656e2eb2c9eb..2620c23398bec 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -2975,9 +2975,10 @@ module ts {
             return !scanner.hasPrecedingLineBreak() && isIdentifier()
         }
 
-        function netTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() {
+        function nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() {
             nextToken();
-            return !scanner.hasPrecedingLineBreak() && (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken)
+            return !scanner.hasPrecedingLineBreak() &&
+                (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken);
         }
 
         function parseYieldExpression(): YieldExpression {
@@ -4878,9 +4879,9 @@ module ts {
         }
 
         function isLetDeclaration() {
-            // It is let declaration if in strict mode or next token is identifier\open brace\open curly on same line.
+            // It is let declaration if in strict mode or next token is identifier\open bracket\open curly on same line.
             // otherwise it needs to be treated like identifier
-            return inStrictModeContext() || lookAhead(netTokenIsIdentifierOrStartOfDestructuringOnTheSameLine);
+            return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine);
         }
 
         function isDeclarationStart(): boolean {