Fix false positive in prefer-for-of when array is in parentheses (#…

…1986)
palantir · Jan 5, 2017 · b20dfce · b20dfce
1 parent 9bb5d28
commit b20dfce
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/src/rules/preferForOfRule.ts b/src/rules/preferForOfRule.ts
@@ -17,7 +17,7 @@
 
 import * as ts from "typescript";
 import * as Lint from "../index";
-import { isAssignment } from "../language/utils";
+import { isAssignment, unwrapParentheses } from "../language/utils";
 
 export class Rule extends Lint.Rules.AbstractRule {
     /* tslint:disable:object-literal-sort-keys */
@@ -100,7 +100,7 @@ class PreferForOfWalker extends Lint.BlockScopeAwareRuleWalker<{}, IncrementorMa
                 // check if iterator is used for something other than reading data from array
                 if (node.parent != null && node.parent.kind === ts.SyntaxKind.ElementAccessExpression) {
                     const elementAccess = node.parent as ts.ElementAccessExpression;
-                    const arrayIdentifier = elementAccess.expression as ts.Identifier;
+                    const arrayIdentifier = unwrapParentheses(elementAccess.expression) as ts.Identifier;
                     if (incrementorState.arrayToken.text !== arrayIdentifier.text) {
                         // iterator used in array other than one iterated over
                         incrementorState.onlyArrayReadAccess = false;
@@ -155,7 +155,7 @@ class PreferForOfWalker extends Lint.BlockScopeAwareRuleWalker<{}, IncrementorMa
         if (conditionRight.kind === ts.SyntaxKind.PropertyAccessExpression) {
             const propertyAccess = conditionRight as ts.PropertyAccessExpression;
             if (indexVariable != null && propertyAccess.name.getText() === "length") {
-                return { indexVariable: indexVariable!, arrayToken: propertyAccess.expression };
+                return { indexVariable: indexVariable!, arrayToken: unwrapParentheses(propertyAccess.expression) };
             }
         }
 

diff --git a/test/rules/prefer-for-of/test.ts.lint b/test/rules/prefer-for-of/test.ts.lint
@@ -1,4 +1,10 @@
 function sampleFunc() {
+    // issue #1931, should not error
+    const value1 = [1];
+    const value2 = [2];
+    for (let i = 0; i < (value1).length; i++) {
+        const x = (value1)[i] === (value2)[i];
+    }
 
     // This loop only uses the iterator to access the array item, so we can recommend a for-of loop here
     for (var a = 0; a < obj.arr.length; a++) {