util: isRegExp() should not call toString() on its argument

An overloaded toString() method may have side effects
so don't call it for a simple type check.

lib/util.js

@@ -326,15 +326,8 @@ function isArray(ar) {
 
 
 function isRegExp(re) {
-  return re instanceof RegExp || // easy case
-         // duck-type for context-switching evalcx case
-         typeof(re) === 'object' &&
-         re.constructor &&
-         re.constructor.name === 'RegExp' &&
-         re.compile &&
-         re.test &&
-         re.exec &&
-         ('' + re).match(/^\/.*\/[gim]{0,3}$/);
+  return re instanceof RegExp ||
+    (typeof re === 'object' && Object.prototype.toString.call(re) === '[object RegExp]');
 }
 
 

test/simple/test-console-not-call-toString.js

@@ -0,0 +1,33 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var func = function () {};
+var toStringCalled = false;
+func.toString = function () {
+  toStringCalled = true;
+};
+
+require('util').inspect(func);
+
+assert.ok(!toStringCalled);