fix: avoid naming collision with default array element variable in au…

…tofix for `no-for-loop` rule

rules/no-for-loop.js

@@ -2,6 +2,7 @@
 const getDocumentationUrl = require('./utils/get-documentation-url');
 const isLiteralValue = require('./utils/is-literal-value');
 const {flatten} = require('lodash');
+const avoidCapture = require('./utils/avoid-capture');
 
 const defaultElementName = 'element';
 const isLiteralZero = node => isLiteralValue(node, 0);
@@ -335,7 +336,7 @@ const create = context => {
 					const shouldGenerateIndex = isIndexVariableUsedElsewhereInTheLoopBody(indexVariable, bodyScope, arrayIdentifierName);
 
 					const index = indexIdentifierName;
-					const element = elementIdentifierName || defaultElementName;
+					const element = elementIdentifierName || avoidCapture(defaultElementName, [bodyScope], context.parserOptions.ecmaVersion);
 					const array = arrayIdentifierName;
 
 					let declarationElement = element;

test/no-for-loop.js

@@ -482,6 +482,40 @@ ruleTester.run('no-for-loop', rule, {
 				const [ a, b ] = element;
 				console.log(a, b, element);
 			}
+		`),
+
+		// Avoid naming collision when using default element name.
+		testCase(outdent`
+			for (let i = 0; i < arr.length; i += 1) {
+				console.log(arr[i]);
+				const element = foo();
+				console.log(element);
+			}
+		`, outdent`
+			for (const element_ of arr) {
+				console.log(element_);
+				const element = foo();
+				console.log(element);
+			}
+		`),
+
+		// Avoid naming collision when using default element name (multiple collisions).
+		testCase(outdent`
+			for (let i = 0; i < arr.length; i += 1) {
+				console.log(arr[i]);
+				const element = foo();
+				const element_ = foo();
+				console.log(element);
+				console.log(element_);
+			}
+		`, outdent`
+			for (const element__ of arr) {
+				console.log(element__);
+				const element = foo();
+				const element_ = foo();
+				console.log(element);
+				console.log(element_);
+			}
 		`)
 	]
 });