feat: add destructuredArrayIgnorePattern option in no-unused-vars

docs/rules/no-unused-vars.md

@@ -238,6 +238,20 @@ function foo(x, _y) {
 foo();
 ```
 
+### destructuredArrayIgnorePattern
+
+The `destructuredArrayIgnorePattern` option specifies exceptions not to check for usage: destructuring assignments from an array whose names match a regexp pattern. For example, variables whose names begin with an underscore.
+
+Examples of **correct** code for the `{ "destructuredArrayIgnorePattern": "^_" }` option:
+
+```js
+/*eslint no-unused-vars: ["error", { "destructuredArrayIgnorePattern": "^_" }]*/
+
+const [a, _b, c] = ["a", "b", "c"]
+
+console.log(a + c);
+```
+
 ### caughtErrors
 
 The `caughtErrors` option is used for `catch` block arguments validation.

lib/rules/no-unused-vars.js

@@ -67,6 +67,9 @@ module.exports = {
                             },
                             caughtErrorsIgnorePattern: {
                                 type: "string"
+                            },
+                            destructuredArrayIgnorePattern: {
+                                type: "string"
                             }
                         },
                         additionalProperties: false
@@ -114,6 +117,10 @@ module.exports = {
                 if (firstOption.caughtErrorsIgnorePattern) {
                     config.caughtErrorsIgnorePattern = new RegExp(firstOption.caughtErrorsIgnorePattern, "u");
                 }
+
+                if (firstOption.destructuredArrayIgnorePattern) {
+                    config.destructuredArrayIgnorePattern = new RegExp(firstOption.destructuredArrayIgnorePattern, "u");
+                }
             }
         }
 
@@ -155,7 +162,16 @@ module.exports = {
          * @returns {UnusedVarMessageData} The message data to be used with this unused variable.
          */
         function getAssignedMessageData(unusedVar) {
-            const additional = config.varsIgnorePattern ? `. Allowed unused vars must match ${config.varsIgnorePattern.toString()}` : "";
+            const def = unusedVar.defs && unusedVar.defs[0];
+            let patternToMatch;
+
+            if (config.destructuredArrayIgnorePattern && def.type === "Variable" && def.node.id.type === "ArrayPattern") {
+                patternToMatch = config.destructuredArrayIgnorePattern;
+            } else if (config.varsIgnorePattern) {
+                patternToMatch = config.varsIgnorePattern;
+            }
+
+            const additional = patternToMatch ? `. Allowed unused vars must match ${patternToMatch.toString()}` : "";
 
             return {
                 varName: unusedVar.name,
@@ -624,6 +640,11 @@ module.exports = {
                             if (config.varsIgnorePattern && config.varsIgnorePattern.test(def.name.name)) {
                                 continue;
                             }
+
+                            // https://github.com/eslint/eslint/issues/15611
+                            if (type === "Variable" && def.node.id.type === "ArrayPattern" && config.destructuredArrayIgnorePattern && config.destructuredArrayIgnorePattern.test(def.name.name)) {
+                                continue;
+                            }
                         }
                     }
 

tests/lib/rules/no-unused-vars.js

@@ -163,6 +163,9 @@ ruleTester.run("no-unused-vars", rule, {
         { code: "function foo(a, _b) { return a; } foo();", options: [{ args: "after-used", argsIgnorePattern: "^_" }] },
         { code: "var [ firstItemIgnored, secondItem ] = items;\nconsole.log(secondItem);", options: [{ vars: "all", varsIgnorePattern: "[iI]gnored" }], parserOptions: { ecmaVersion: 6 } },
 
+        // https://github.com/eslint/eslint/issues/15611
+        { code: "const [ a, _b, c ] = items;\nconsole.log(a+c);", options: [{ destructuredArrayIgnorePattern: "^_" }], parserOptions: { ecmaVersion: 6 } },
+
         // for-in loops (see #2342)
         "(function(obj) { var name; for ( name in obj ) return; })({});",
         "(function(obj) { var name; for ( name in obj ) { return; } })({});",
@@ -463,6 +466,75 @@ ruleTester.run("no-unused-vars", rule, {
             }]
         },
 
+        // https://github.com/eslint/eslint/issues/15611
+        {
+            code: `
+            const array = ['a', 'b', 'c'];
+            const [a, _b, c] = array;
+            const newArray = [a, c];
+            `,
+            options: [{ destructuredArrayIgnorePattern: "^_" }],
+            parserOptions: { ecmaVersion: 2020 },
+            errors: [
+
+                // should report only `newArray`
+                { ...assignedError("newArray"), line: 4, column: 19 }
+            ]
+        },
+        {
+            code: `
+            const array = ['a', 'b', 'c', 'd', 'e'];
+            const [a, _b, c] = array;
+            `,
+            options: [{ destructuredArrayIgnorePattern: "^_" }],
+            parserOptions: { ecmaVersion: 2020 },
+            errors: [
+                {
+                    ...assignedError("a", ". Allowed unused vars must match /^_/u"),
+                    line: 3,
+                    column: 20
+                },
+                {
+                    ...assignedError("c", ". Allowed unused vars must match /^_/u"),
+                    line: 3,
+                    column: 27
+                }
+            ]
+        },
+        {
+            code: `
+            const array = ['a', 'b', 'c'];
+            const [a, _b, c] = array;
+            const fooArray = ['foo'];
+            const barArray = ['bar'];
+            const ignoreArray = ['ignore'];
+            `,
+            options: [{ destructuredArrayIgnorePattern: "^_", varsIgnorePattern: "ignore" }],
+            parserOptions: { ecmaVersion: 2020 },
+            errors: [
+                {
+                    ...assignedError("a", ". Allowed unused vars must match /^_/u"),
+                    line: 3,
+                    column: 20
+                },
+                {
+                    ...assignedError("c", ". Allowed unused vars must match /^_/u"),
+                    line: 3,
+                    column: 27
+                },
+                {
+                    ...assignedError("fooArray", ". Allowed unused vars must match /ignore/u"),
+                    line: 4,
+                    column: 19
+                },
+                {
+                    ...assignedError("barArray", ". Allowed unused vars must match /ignore/u"),
+                    line: 5,
+                    column: 19
+                }
+            ]
+        },
+
         // for-in loops (see #2342)
         {
             code: "(function(obj) { var name; for ( name in obj ) { i(); return; } })({});",