do not capture 'arguments' when property name 'arguments' is met (#13600)

do not capture 'arguments' when property name 'arguments' is met

Author: vladima

src/compiler/checker.ts

@@ -20222,7 +20222,8 @@ namespace ts {
             if (!isGeneratedIdentifier(node)) {
                 node = getParseTreeNode(node, isIdentifier);
                 if (node) {
-                    return getReferencedValueSymbol(node) === argumentsSymbol;
+                    const isPropertyName = node.parent.kind === SyntaxKind.PropertyAccessExpression && (<PropertyAccessExpression>node.parent).name === node;
+                    return !isPropertyName && getReferencedValueSymbol(node) === argumentsSymbol;
                 }
             }
 

src/compiler/transformers/es2015.ts

@@ -585,7 +585,7 @@ namespace ts {
             if (isGeneratedIdentifier(node)) {
                 return node;
             }
-            if (node.text !== "arguments" && !resolver.isArgumentsLocalBinding(node)) {
+            if (node.text !== "arguments" || !resolver.isArgumentsLocalBinding(node)) {
                 return node;
             }
             return convertedLoopState.argumentsName || (convertedLoopState.argumentsName = createUniqueName("arguments"));

tests/baselines/reference/argumentsAsPropertyName.js

@@ -0,0 +1,29 @@
+//// [argumentsAsPropertyName.ts]
+// target: es5
+type MyType = {
+    arguments: Array<string>
+}
+
+declare function use(s: any);
+
+function myFunction(myType: MyType) {
+    for (let i = 0; i < 10; i++) {
+        use(myType.arguments[i]);
+        // create closure so that tsc will turn loop body into function
+        const x = 5;
+        [1, 2, 3].forEach(function(j) { use(x); })
+    }
+}
+
+//// [argumentsAsPropertyName.js]
+function myFunction(myType) {
+    var _loop_1 = function (i) {
+        use(myType.arguments[i]);
+        // create closure so that tsc will turn loop body into function
+        var x = 5;
+        [1, 2, 3].forEach(function (j) { use(x); });
+    };
+    for (var i = 0; i < 10; i++) {
+        _loop_1(i);
+    }
+}

tests/baselines/reference/argumentsAsPropertyName.symbols

@@ -0,0 +1,43 @@
+=== tests/cases/compiler/argumentsAsPropertyName.ts ===
+// target: es5
+type MyType = {
+>MyType : Symbol(MyType, Decl(argumentsAsPropertyName.ts, 0, 0))
+
+    arguments: Array<string>
+>arguments : Symbol(arguments, Decl(argumentsAsPropertyName.ts, 1, 15))
+>Array : Symbol(Array, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+}
+
+declare function use(s: any);
+>use : Symbol(use, Decl(argumentsAsPropertyName.ts, 3, 1))
+>s : Symbol(s, Decl(argumentsAsPropertyName.ts, 5, 21))
+
+function myFunction(myType: MyType) {
+>myFunction : Symbol(myFunction, Decl(argumentsAsPropertyName.ts, 5, 29))
+>myType : Symbol(myType, Decl(argumentsAsPropertyName.ts, 7, 20))
+>MyType : Symbol(MyType, Decl(argumentsAsPropertyName.ts, 0, 0))
+
+    for (let i = 0; i < 10; i++) {
+>i : Symbol(i, Decl(argumentsAsPropertyName.ts, 8, 12))
+>i : Symbol(i, Decl(argumentsAsPropertyName.ts, 8, 12))
+>i : Symbol(i, Decl(argumentsAsPropertyName.ts, 8, 12))
+
+        use(myType.arguments[i]);
+>use : Symbol(use, Decl(argumentsAsPropertyName.ts, 3, 1))
+>myType.arguments : Symbol(arguments, Decl(argumentsAsPropertyName.ts, 1, 15))
+>myType : Symbol(myType, Decl(argumentsAsPropertyName.ts, 7, 20))
+>arguments : Symbol(arguments, Decl(argumentsAsPropertyName.ts, 1, 15))
+>i : Symbol(i, Decl(argumentsAsPropertyName.ts, 8, 12))
+
+        // create closure so that tsc will turn loop body into function
+        const x = 5;
+>x : Symbol(x, Decl(argumentsAsPropertyName.ts, 11, 13))
+
+        [1, 2, 3].forEach(function(j) { use(x); })
+>[1, 2, 3].forEach : Symbol(Array.forEach, Decl(lib.d.ts, --, --))
+>forEach : Symbol(Array.forEach, Decl(lib.d.ts, --, --))
+>j : Symbol(j, Decl(argumentsAsPropertyName.ts, 12, 35))
+>use : Symbol(use, Decl(argumentsAsPropertyName.ts, 3, 1))
+>x : Symbol(x, Decl(argumentsAsPropertyName.ts, 11, 13))
+    }
+}

tests/baselines/reference/argumentsAsPropertyName.types

@@ -0,0 +1,57 @@
+=== tests/cases/compiler/argumentsAsPropertyName.ts ===
+// target: es5
+type MyType = {
+>MyType : MyType
+
+    arguments: Array<string>
+>arguments : string[]
+>Array : T[]
+}
+
+declare function use(s: any);
+>use : (s: any) => any
+>s : any
+
+function myFunction(myType: MyType) {
+>myFunction : (myType: MyType) => void
+>myType : MyType
+>MyType : MyType
+
+    for (let i = 0; i < 10; i++) {
+>i : number
+>0 : 0
+>i < 10 : boolean
+>i : number
+>10 : 10
+>i++ : number
+>i : number
+
+        use(myType.arguments[i]);
+>use(myType.arguments[i]) : any
+>use : (s: any) => any
+>myType.arguments[i] : string
+>myType.arguments : string[]
+>myType : MyType
+>arguments : string[]
+>i : number
+
+        // create closure so that tsc will turn loop body into function
+        const x = 5;
+>x : 5
+>5 : 5
+
+        [1, 2, 3].forEach(function(j) { use(x); })
+>[1, 2, 3].forEach(function(j) { use(x); }) : void
+>[1, 2, 3].forEach : (callbackfn: (value: number, index: number, array: number[]) => void, thisArg?: any) => void
+>[1, 2, 3] : number[]
+>1 : 1
+>2 : 2
+>3 : 3
+>forEach : (callbackfn: (value: number, index: number, array: number[]) => void, thisArg?: any) => void
+>function(j) { use(x); } : (j: number) => void
+>j : number
+>use(x) : any
+>use : (s: any) => any
+>x : 5
+    }
+}

tests/cases/compiler/argumentsAsPropertyName.ts

@@ -0,0 +1,15 @@
+// target: es5
+type MyType = {
+    arguments: Array<string>
+}
+
+declare function use(s: any);
+
+function myFunction(myType: MyType) {
+    for (let i = 0; i < 10; i++) {
+        use(myType.arguments[i]);
+        // create closure so that tsc will turn loop body into function
+        const x = 5;
+        [1, 2, 3].forEach(function(j) { use(x); })
+    }
+}