Merge branch 'master' of https://github.com/Microsoft/TypeScript

Author: CyrusNajmabadi

src/compiler/checker.ts

@@ -11072,7 +11072,7 @@ module ts {
 
             var symbol = declarationSymbol ||
                 getNodeLinks(n).resolvedSymbol ||
-                resolveName(n, n.text, SymbolFlags.BlockScopedVariable | SymbolFlags.Alias, /*nodeNotFoundMessage*/ undefined, /*nameArg*/ undefined);
+                resolveName(n, n.text, SymbolFlags.Value | SymbolFlags.Alias, /*nodeNotFoundMessage*/ undefined, /*nameArg*/ undefined);
 
             var isLetOrConst =
                 symbol &&

src/compiler/parser.ts

@@ -2975,6 +2975,12 @@ module ts {
             return !scanner.hasPrecedingLineBreak() && isIdentifier()
         }
 
+        function nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() {
+            nextToken();
+            return !scanner.hasPrecedingLineBreak() &&
+                (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken);
+        }
+
         function parseYieldExpression(): YieldExpression {
             var node = <YieldExpression>createNode(SyntaxKind.YieldExpression);
 
@@ -4873,9 +4879,9 @@ 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 bracket\open curly on same line.
             // otherwise it needs to be treated like identifier
-            return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOnSameLine);
+            return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine);
         }
 
         function isDeclarationStart(): boolean {

tests/baselines/reference/letConstMatchingParameterNames.js

@@ -0,0 +1,28 @@
+//// [letConstMatchingParameterNames.ts]
+let parent = true;
+const parent2 = true;
+declare function use(a: any);
+
+function a() {
+    
+    let parent = 1;
+    const parent2 = 2;
+
+    function b(parent: string, parent2: number) {
+        use(parent);
+        use(parent2);
+    }
+}
+
+
+//// [letConstMatchingParameterNames.js]
+var parent = true;
+var parent2 = true;
+function a() {
+    var _parent = 1;
+    var _parent2 = 2;
+    function b(parent, parent2) {
+        use(parent);
+        use(parent2);
+    }
+}

tests/baselines/reference/letConstMatchingParameterNames.types

@@ -0,0 +1,37 @@
+=== tests/cases/compiler/letConstMatchingParameterNames.ts ===
+let parent = true;
+>parent : boolean
+
+const parent2 = true;
+>parent2 : boolean
+
+declare function use(a: any);
+>use : (a: any) => any
+>a : any
+
+function a() {
+>a : () => void
+    
+    let parent = 1;
+>parent : number
+
+    const parent2 = 2;
+>parent2 : number
+
+    function b(parent: string, parent2: number) {
+>b : (parent: string, parent2: number) => void
+>parent : string
+>parent2 : number
+
+        use(parent);
+>use(parent) : any
+>use : (a: any) => any
+>parent : string
+
+        use(parent2);
+>use(parent2) : any
+>use : (a: any) => any
+>parent2 : number
+    }
+}
+

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;

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
+

tests/cases/compiler/letConstMatchingParameterNames.ts

@@ -0,0 +1,15 @@
+// @target: es5
+let parent = true;
+const parent2 = true;
+declare function use(a: any);
+
+function a() {
+    
+    let parent = 1;
+    const parent2 = 2;
+
+    function b(parent: string, parent2: number) {
+        use(parent);
+        use(parent2);
+    }
+}

tests/cases/compiler/letInNonStrictMode.ts

@@ -0,0 +1,2 @@
+let [x] = [1];
+let {a: y} = {a: 1};