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qwen/nodejs/node_modules/eslint/lib/rules/no-dupe-args.js

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+/**
+ * @fileoverview Rule to flag duplicate arguments
+ * @author Jamund Ferguson
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "problem",
+
+        docs: {
+            description: "Disallow duplicate arguments in `function` definitions",
+            recommended: true,
+            url: "https://eslint.org/docs/latest/rules/no-dupe-args"
+        },
+
+        schema: [],
+
+        messages: {
+            unexpected: "Duplicate param '{{name}}'."
+        }
+    },
+
+    create(context) {
+
+        const sourceCode = context.sourceCode;
+
+        //--------------------------------------------------------------------------
+        // Helpers
+        //--------------------------------------------------------------------------
+
+        /**
+         * Checks whether or not a given definition is a parameter's.
+         * @param {eslint-scope.DefEntry} def A definition to check.
+         * @returns {boolean} `true` if the definition is a parameter's.
+         */
+        function isParameter(def) {
+            return def.type === "Parameter";
+        }
+
+        /**
+         * Determines if a given node has duplicate parameters.
+         * @param {ASTNode} node The node to check.
+         * @returns {void}
+         * @private
+         */
+        function checkParams(node) {
+            const variables = sourceCode.getDeclaredVariables(node);
+
+            for (let i = 0; i < variables.length; ++i) {
+                const variable = variables[i];
+
+                // Checks and reports duplications.
+                const defs = variable.defs.filter(isParameter);
+
+                if (defs.length >= 2) {
+                    context.report({
+                        node,
+                        messageId: "unexpected",
+                        data: { name: variable.name }
+                    });
+                }
+            }
+        }
+
+        //--------------------------------------------------------------------------
+        // Public API
+        //--------------------------------------------------------------------------
+
+        return {
+            FunctionDeclaration: checkParams,
+            FunctionExpression: checkParams
+        };
+
+    }
+};