--- /dev/null
+/**
+ * @fileoverview Disallow renaming import, export, and destructured assignments to the same name.
+ * @author Kai Cataldo
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "suggestion",
+
+ docs: {
+ description: "disallow renaming import, export, and destructured assignments to the same name",
+ category: "ECMAScript 6",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/no-useless-rename"
+ },
+
+ fixable: "code",
+
+ schema: [
+ {
+ type: "object",
+ properties: {
+ ignoreDestructuring: { type: "boolean", default: false },
+ ignoreImport: { type: "boolean", default: false },
+ ignoreExport: { type: "boolean", default: false }
+ },
+ additionalProperties: false
+ }
+ ],
+
+ messages: {
+ unnecessarilyRenamed: "{{type}} {{name}} unnecessarily renamed."
+ }
+ },
+
+ create(context) {
+ const sourceCode = context.getSourceCode(),
+ options = context.options[0] || {},
+ ignoreDestructuring = options.ignoreDestructuring === true,
+ ignoreImport = options.ignoreImport === true,
+ ignoreExport = options.ignoreExport === true;
+
+ //--------------------------------------------------------------------------
+ // Helpers
+ //--------------------------------------------------------------------------
+
+ /**
+ * Reports error for unnecessarily renamed assignments
+ * @param {ASTNode} node node to report
+ * @param {ASTNode} initial node with initial name value
+ * @param {string} type the type of the offending node
+ * @returns {void}
+ */
+ function reportError(node, initial, type) {
+ const name = initial.type === "Identifier" ? initial.name : initial.value;
+
+ return context.report({
+ node,
+ messageId: "unnecessarilyRenamed",
+ data: {
+ name,
+ type
+ },
+ fix(fixer) {
+ const replacementNode = node.type === "Property" ? node.value : node.local;
+
+ if (sourceCode.getCommentsInside(node).length > sourceCode.getCommentsInside(replacementNode).length) {
+ return null;
+ }
+
+ // Don't autofix code such as `({foo: (foo) = a} = obj);`, parens are not allowed in shorthand properties.
+ if (
+ replacementNode.type === "AssignmentPattern" &&
+ astUtils.isParenthesised(sourceCode, replacementNode.left)
+ ) {
+ return null;
+ }
+
+ return fixer.replaceText(node, sourceCode.getText(replacementNode));
+ }
+ });
+ }
+
+ /**
+ * Checks whether a destructured assignment is unnecessarily renamed
+ * @param {ASTNode} node node to check
+ * @returns {void}
+ */
+ function checkDestructured(node) {
+ if (ignoreDestructuring) {
+ return;
+ }
+
+ for (const property of node.properties) {
+
+ /**
+ * Properties using shorthand syntax and rest elements can not be renamed.
+ * If the property is computed, we have no idea if a rename is useless or not.
+ */
+ if (property.type !== "Property" || property.shorthand || property.computed) {
+ continue;
+ }
+
+ const key = (property.key.type === "Identifier" && property.key.name) || (property.key.type === "Literal" && property.key.value);
+ const renamedKey = property.value.type === "AssignmentPattern" ? property.value.left.name : property.value.name;
+
+ if (key === renamedKey) {
+ reportError(property, property.key, "Destructuring assignment");
+ }
+ }
+ }
+
+ /**
+ * Checks whether an import is unnecessarily renamed
+ * @param {ASTNode} node node to check
+ * @returns {void}
+ */
+ function checkImport(node) {
+ if (ignoreImport) {
+ return;
+ }
+
+ if (node.imported.name === node.local.name &&
+ node.imported.range[0] !== node.local.range[0]) {
+ reportError(node, node.imported, "Import");
+ }
+ }
+
+ /**
+ * Checks whether an export is unnecessarily renamed
+ * @param {ASTNode} node node to check
+ * @returns {void}
+ */
+ function checkExport(node) {
+ if (ignoreExport) {
+ return;
+ }
+
+ if (node.local.name === node.exported.name &&
+ node.local.range[0] !== node.exported.range[0]) {
+ reportError(node, node.local, "Export");
+ }
+
+ }
+
+ //--------------------------------------------------------------------------
+ // Public
+ //--------------------------------------------------------------------------
+
+ return {
+ ObjectPattern: checkDestructured,
+ ImportSpecifier: checkImport,
+ ExportSpecifier: checkExport
+ };
+ }
+};