From c4d8b0db62b859e721105d4bc0f4044ce346995e Mon Sep 17 00:00:00 2001
From: YeonJuan <yeonjuan93@naver.com>
Date: Sun, 4 Apr 2021 08:32:03 +0900
Subject: [PATCH] Fix: no-unused-vars ignoreRestSiblings check assignments
 (fixes #14163) (#14264)

* Fix: Check assignment reference in no-unused-vars (fixes #14163)

* rename variables

* add example
---
 docs/rules/no-unused-vars.md      |  7 +++++--
 lib/rules/no-unused-vars.js       | 25 +++++++++++++++----------
 tests/lib/rules/no-unused-vars.js | 24 ++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/docs/rules/no-unused-vars.md b/docs/rules/no-unused-vars.md
index f730e666178..30647031eb1 100644
--- a/docs/rules/no-unused-vars.md
+++ b/docs/rules/no-unused-vars.md
@@ -214,8 +214,11 @@ Examples of **correct** code for the `{ "ignoreRestSiblings": true }` option:
 
 ```js
 /*eslint no-unused-vars: ["error", { "ignoreRestSiblings": true }]*/
-// 'type' is ignored because it has a rest property sibling.
-var { type, ...coords } = data;
+// 'foo' and 'bar' were ignored because they have a rest property sibling.
+var { foo, ...coords } = data;
+
+var bar;
+({ bar, ...coords } = data);
 ```
 
 ### argsIgnorePattern
diff --git a/lib/rules/no-unused-vars.js b/lib/rules/no-unused-vars.js
index 4dc6dc2bab3..32589099cf4 100644
--- a/lib/rules/no-unused-vars.js
+++ b/lib/rules/no-unused-vars.js
@@ -196,6 +196,17 @@ module.exports = {
 
         }
 
+        /**
+         * Checks whether a node is a sibling of the rest property or not.
+         * @param {ASTNode} node a node to check
+         * @returns {boolean} True if the node is a sibling of the rest property, otherwise false.
+         */
+        function hasRestSibling(node) {
+            return node.type === "Property" &&
+                node.parent.type === "ObjectPattern" &&
+                REST_PROPERTY_TYPE.test(node.parent.properties[node.parent.properties.length - 1].type);
+        }
+
         /**
          * Determines if a variable has a sibling rest property
          * @param {Variable} variable eslint-scope variable object.
@@ -204,16 +215,10 @@ module.exports = {
          */
         function hasRestSpreadSibling(variable) {
             if (config.ignoreRestSiblings) {
-                return variable.defs.some(def => {
-                    const propertyNode = def.name.parent;
-                    const patternNode = propertyNode.parent;
-
-                    return (
-                        propertyNode.type === "Property" &&
-                        patternNode.type === "ObjectPattern" &&
-                        REST_PROPERTY_TYPE.test(patternNode.properties[patternNode.properties.length - 1].type)
-                    );
-                });
+                const hasRestSiblingDefinition = variable.defs.some(def => hasRestSibling(def.name.parent));
+                const hasRestSiblingReference = variable.references.some(ref => hasRestSibling(ref.identifier.parent));
+
+                return hasRestSiblingDefinition || hasRestSiblingReference;
             }
 
             return false;
diff --git a/tests/lib/rules/no-unused-vars.js b/tests/lib/rules/no-unused-vars.js
index 061ac08d51f..db041d46b89 100644
--- a/tests/lib/rules/no-unused-vars.js
+++ b/tests/lib/rules/no-unused-vars.js
@@ -291,6 +291,13 @@ ruleTester.run("no-unused-vars", rule, {
             parserOptions: { ecmaVersion: 2018 }
         },
 
+        // https://github.com/eslint/eslint/issues/14163
+        {
+            code: "let foo, rest;\n({ foo, ...rest } = something);\nconsole.log(rest);",
+            options: [{ ignoreRestSiblings: true }],
+            parserOptions: { ecmaVersion: 2020 }
+        },
+
         // https://github.com/eslint/eslint/issues/10952
         "/*eslint use-every-a:1*/ !function(b, a) { return 1 }",
 
@@ -588,6 +595,23 @@ ruleTester.run("no-unused-vars", rule, {
                 }
             ]
         },
+        {
+            code: "let type, coords;\n({ type, ...coords } = data);\n console.log(type)",
+            options: [{ ignoreRestSiblings: true }],
+            parserOptions: { ecmaVersion: 2018 },
+            errors: [
+                {
+                    line: 2,
+                    column: 13,
+                    messageId: "unusedVar",
+                    data: {
+                        varName: "coords",
+                        action: "assigned a value",
+                        additional: ""
+                    }
+                }
+            ]
+        },
 
         // Unused rest property without ignoreRestSiblings
         {