From 6f87db7c318225e48ccbbf0bec8b3758ea839b82 Mon Sep 17 00:00:00 2001
From: Milos Djermanovic <milos.djermanovic@gmail.com>
Date: Fri, 11 Sep 2020 17:12:37 +0200
Subject: [PATCH] Update: fix id-length false negatives on Object.prototype
 property names (#13670)

---
 lib/rules/id-length.js       |  9 ++-------
 tests/lib/rules/id-length.js | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/lib/rules/id-length.js b/lib/rules/id-length.js
index b97f32b9787..4df081ff9fe 100644
--- a/lib/rules/id-length.js
+++ b/lib/rules/id-length.js
@@ -64,12 +64,7 @@ module.exports = {
         const minLength = typeof options.min !== "undefined" ? options.min : 2;
         const maxLength = typeof options.max !== "undefined" ? options.max : Infinity;
         const properties = options.properties !== "never";
-        const exceptions = (options.exceptions ? options.exceptions : [])
-            .reduce((obj, item) => {
-                obj[item] = true;
-
-                return obj;
-            }, {});
+        const exceptions = new Set(options.exceptions);
         const exceptionPatterns = (options.exceptionPatterns || []).map(pattern => new RegExp(pattern, "u"));
         const reportedNode = new Set();
 
@@ -130,7 +125,7 @@ module.exports = {
                 const isShort = name.length < minLength;
                 const isLong = name.length > maxLength;
 
-                if (!(isShort || isLong) || exceptions[name] || matchesExceptionPattern(name)) {
+                if (!(isShort || isLong) || exceptions.has(name) || matchesExceptionPattern(name)) {
                     return; // Nothing to report
                 }
 
diff --git a/tests/lib/rules/id-length.js b/tests/lib/rules/id-length.js
index 655b6e34f18..99a3957939c 100644
--- a/tests/lib/rules/id-length.js
+++ b/tests/lib/rules/id-length.js
@@ -112,6 +112,13 @@ ruleTester.run("id-length", rule, {
                 tooLongError
             ]
         },
+        {
+            code: "var toString;",
+            options: [{ max: 5 }],
+            errors: [
+                tooLongError
+            ]
+        },
         {
             code: "(a) => { a * a };",
             parserOptions: { ecmaVersion: 6 },
@@ -202,6 +209,19 @@ ruleTester.run("id-length", rule, {
                 }
             ]
         },
+        {
+            code: "var hasOwnProperty;",
+            options: [{ max: 10, exceptions: [] }],
+            errors: [
+                {
+                    messageId: "tooLong",
+                    data: { name: "hasOwnProperty", max: 10 },
+                    line: 1,
+                    column: 5,
+                    type: "Identifier"
+                }
+            ]
+        },
         {
             code: "function foo({ a: { b: { c: d, e } } }) { }",
             parserOptions: { ecmaVersion: 6 },