feat: add ESLint v9 compatibility layer

Author: MichaelDeBoey

lib/eslint-compat.js

@@ -0,0 +1,14 @@
+const getDeclaredVariables = (context, node) =>
+    getSourceCode(context).getDeclaredVariables?.(node) ??
+    context.getDeclaredVariables(node)
+
+const getSourceCode = (context) => context.sourceCode ?? context.getSourceCode()
+
+const getScope = (context, node) =>
+    getSourceCode(context).getScope?.(node) ?? context.getScope()
+
+module.exports = {
+    getDeclaredVariables,
+    getSourceCode,
+    getScope,
+}

lib/rules/arrow-parens.js

@@ -1,12 +1,9 @@
-/**
- * @author Toru Nagashima
- * @copyright 2015 Toru Nagashima. All rights reserved.
- * See LICENSE file in root directory for full license.
- */
 "use strict"
 
+const { getSourceCode } = require("../eslint-compat")
+
 /**
- * Checks whether or not a given token is `(`.
+ * Checks whether a given token is `(`.
  * @param {Token} token - A token to check.
  * @returns {boolean} `true` when the token is `(`.
  */
@@ -15,7 +12,7 @@ function isOpenParen(token) {
 }
 
 /**
- * Checks whether or not given two tokens are at a same line.
+ * Checks whether given two tokens are at a same line.
  * @param {Token} a - A left token.
  * @param {Token} b - A right token.
  * @returns {boolean} `true` when the tokens are at a same line.
@@ -43,12 +40,11 @@ module.exports = {
         type: "suggestion",
     },
     create(context) {
+        const sourceCode = getSourceCode(context)
         return {
             ArrowFunctionExpression(node) {
-                const first = context
-                    .getSourceCode()
-                    .getFirstToken(node, node.async ? 1 : 0)
-                const before = context.getSourceCode().getTokenBefore(first)
+                const first = sourceCode.getFirstToken(node, node.async ? 1 : 0)
+                const before = sourceCode.getTokenBefore(first)
 
                 if (isOpenParen(first)) {
                     if (
@@ -63,9 +59,8 @@ module.exports = {
                             fix(fixer) {
                                 const id = node.params[0]
                                 const begin = first.range[0]
-                                const end = context
-                                    .getSourceCode()
-                                    .getTokenAfter(id).range[1]
+                                const end =
+                                    sourceCode.getTokenAfter(id).range[1]
 
                                 return fixer.replaceTextRange(
                                     [begin, end],

lib/rules/block-scoped-var.js

@@ -1,10 +1,7 @@
-/**
- * @author Toru Nagashima
- * @copyright 2015 Toru Nagashima. All rights reserved.
- * See LICENSE file in root directory for full license.
- */
 "use strict"
 
+const { getDeclaredVariables } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
@@ -15,7 +12,7 @@ const containerNodeType =
     /^(?:For(?:In|Of)?Statement|(?:Arrow)?Function(?:Declaration|Expression))$/u
 
 /**
- * Checks whether or not a given definition should be skipped.
+ * Checks whether a given definition should be skipped.
  * @param {escope.Variable.DefEntry} def - A definition to check.
  * @param {escope.Variable.DefEntry[]} defs - A definition list which includes `def`.
  * @param {escope.Variable} variable - A variable which is defined by the definition.
@@ -180,7 +177,7 @@ class PseudoScope {
     }
 
     /**
-     * Turns an used flag on.
+     * Turns a used flag on.
      * @returns {void}
      */
     markAsUsed() {
@@ -213,12 +210,12 @@ module.exports = {
     },
     create(context) {
         /**
-         * Finds and reports references which are outside of valid scopes.
+         * Finds and reports references which are outside valid scopes.
          * @param {ASTNode} node - A node to get variables.
          * @returns {void}
          */
         function checkForVariables(node) {
-            const variables = context.getDeclaredVariables(node)
+            const variables = getDeclaredVariables(context, node)
             for (const variable of variables) {
                 const defs = variable.defs
                 const lastDef = defs[defs.length - 1]
@@ -235,7 +232,7 @@ module.exports = {
                     continue
                 }
 
-                // Check whether or not any reading reference exists.
+                // Check whether any reading reference exists.
                 // And while it does, warn references which does not belong to any
                 // scope.
                 let hasReadRef = false

lib/rules/no-instanceof-array.js

@@ -1,10 +1,7 @@
-/**
- * @author Toru Nagashima
- * @copyright 2016 Toru Nagashima. All rights reserved.
- * See LICENSE file in root directory for full license.
- */
 "use strict"
 
+const { getScope, getSourceCode } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
@@ -26,7 +23,7 @@ module.exports = {
     },
 
     create(context) {
-        const sourceCode = context.getSourceCode()
+        const sourceCode = getSourceCode(context)
 
         /**
          * Checks whether the given node is RHS of instanceof.
@@ -43,8 +40,8 @@ module.exports = {
         }
 
         return {
-            "Program:exit"() {
-                const globalScope = context.getScope()
+            "Program:exit"(node) {
+                const globalScope = getScope(context, node)
                 const variable = globalScope.set.get("Array")
 
                 // Skip if undefined or shadowed

lib/rules/no-instanceof-wrapper.js

@@ -1,10 +1,7 @@
-/**
- * @author Toru Nagashima
- * @copyright 2016 Toru Nagashima. All rights reserved.
- * See LICENSE file in root directory for full license.
- */
 "use strict"
 
+const { getScope, getSourceCode } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
@@ -26,7 +23,7 @@ module.exports = {
     },
 
     create(context) {
-        const sourceCode = context.getSourceCode()
+        const sourceCode = getSourceCode(context)
         const targetTypes = [
             "Boolean",
             "Number",
@@ -51,8 +48,8 @@ module.exports = {
         }
 
         return {
-            "Program:exit"() {
-                const globalScope = context.getScope()
+            "Program:exit"(node) {
+                const globalScope = getScope(context, node)
 
                 for (const ctorName of targetTypes) {
                     const typeName = ctorName.toLowerCase()

lib/rules/no-this-in-static.js

@@ -1,10 +1,7 @@
-/**
- * @author Toru Nagashima
- * @copyright 2016 Toru Nagashima. All rights reserved.
- * See LICENSE file in root directory for full license.
- */
 "use strict"
 
+const { getSourceCode } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
@@ -25,7 +22,7 @@ module.exports = {
     },
 
     create(context) {
-        const sourceCode = context.getSourceCode()
+        const sourceCode = getSourceCode(context)
         let funcInfo = null
 
         /**
@@ -65,7 +62,7 @@ module.exports = {
         }
 
         /**
-         * Reports the `this`/`super` node if this is inside of a static method.
+         * Reports the `this`/`super` node if this is inside a static method.
          *
          * @param {ASTNode} node - The node to report.
          * @returns {void}

lib/rules/no-use-ignored-vars.js

@@ -1,9 +1,7 @@
-/**
- * @fileoverview Rule to disallow a use of ignored variables.
- * @author Toru Nagashima
- */
 "use strict"
 
+const { getScope } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
@@ -84,8 +82,8 @@ module.exports = {
         }
 
         return {
-            "Program:exit"() {
-                const queue = [context.getScope()]
+            "Program:exit"(node) {
+                const queue = [getScope(context, node)]
                 let scope = null
 
                 while ((scope = queue.pop()) != null) {

lib/rules/no-useless-rest-spread.js

@@ -1,9 +1,7 @@
-/**
- * @fileoverview Rule to disallow unnecessary spread operators.
- * @author Toru Nagashima
- */
 "use strict"
 
+const { getSourceCode } = require("../eslint-compat")
+
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
@@ -109,7 +107,7 @@ module.exports = {
     },
 
     create(context) {
-        const sourceCode = context.getSourceCode()
+        const sourceCode = getSourceCode(context)
 
         /**
          * Verify the given SpreadElement or RestElement.
@@ -133,12 +131,11 @@ module.exports = {
                 const isRestParameter =
                     nodeType === "RestElement" && argumentType !== parentType
                 const type1 = nodeType === "RestElement" ? "rest" : "spread"
-                const type2 =
-                    /* eslint-disable @eslint-community/mysticatea/prettier */
-                    isRestParameter ? "parameter" :
-                    isArray ? "element" :
-                    /* otherwise */ "property"
-                    /* eslint-enable @eslint-community/mysticatea/prettier */
+                const type2 = isRestParameter
+                    ? "parameter"
+                    : isArray
+                    ? "element"
+                    : /* otherwise */ "property"
 
                 context.report({
                     node,