Make _.isNative throw if core-js is detected.

lodash.js

@@ -1233,11 +1233,12 @@
         objectProto = context.Object.prototype,
         stringProto = context.String.prototype;
 
-    /** Used to detect methods masquerading as native. */
-    var fakeSrcKey = (function() {
-      var shared = context['__core-js_shared__'],
-          uid = /[^.]+$/.exec(shared && shared.keys && shared.keys.IE_PROTO || '');
+    /** Used to detect overreaching core-js shims. */
+    var coreJsData = context['__core-js_shared__'];
 
+    /** Used to detect methods masquerading as native. */
+    var maskSrcKey = (function() {
+      var uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || '');
       return uid ? ('Symbol(src)_1.' + uid) : '';
     }());
 
@@ -2994,6 +2995,22 @@
       return true;
     }
 
+    /**
+     * The base implementation of `_.isNative` without bad shim checks.
+     *
+     * @private
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is a native function,
+     *  else `false`.
+     */
+    function baseIsNative(value) {
+      if (!isObject(value) || isMasked(value)) {
+        return false;
+      }
+      var pattern = (isFunction(value) || isHostObject(value)) ? reIsNative : reIsHostCtor;
+      return pattern.test(toSource(value));
+    }
+
     /**
      * The base implementation of `_.iteratee`.
      *
@@ -5377,7 +5394,7 @@
      */
     function getNative(object, key) {
       var value = object[key];
-      return isNative(value) ? value : undefined;
+      return (isMaskable(value) ? baseIsNative : isNative)(value) ? value : undefined;
     }
 
     /**
@@ -5738,6 +5755,28 @@
       return !!data && func === data[0];
     }
 
+    /**
+     * Checks if `func` has its source masked.
+     *
+     * @private
+     * @param {Function} func The function to check.
+     * @returns {boolean} Returns `true` if `func` is masked, else `false`.
+     */
+    function isMasked(func) {
+      return maskSrcKey in func;
+    }
+
+    /**
+     * Checks if `func` is capable of being masked.
+     *
+     * @private
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `func` is maskable, else `false`.
+     */
+    function isMaskable(value) {
+      return !!coreJsData && isFunction(value);
+    }
+
     /**
      * Checks if `value` is likely a prototype object.
      *
@@ -11138,7 +11177,7 @@
     }
 
     /**
-     * Checks if `value` is a native function.
+     * Checks if `value` is a pristine native function.
      *
      * @static
      * @memberOf _
@@ -11156,11 +11195,10 @@
      * // => false
      */
     function isNative(value) {
-      if (!isObject(value) || (fakeSrcKey && fakeSrcKey in value)) {
-        return false;
+      if (isMaskable(value)) {
+        throw Error('This method is not supported with core-js. Try https://github.com/es-shims.');
       }
-      var pattern = (isFunction(value) || isHostObject(value)) ? reIsNative : reIsHostCtor;
-      return pattern.test(toSource(value));
+      return baseIsNative(value);
     }
 
     /**

test/test.js

@@ -11014,6 +11014,48 @@
         skipAssert(assert);
       }
     });
+
+    QUnit.test('should throw an error if core-js is detected', function(assert) {
+      assert.expect(1);
+
+      if (!isModularize) {
+        var lodash = _.runInContext({
+          '__core-js_shared__': {}
+        });
+
+        assert.raises(function() { lodash.isNative(noop); });
+      }
+      else {
+        skipAssert(assert);
+      }
+    });
+
+    QUnit.test('should detect methods masquerading as native', function(assert) {
+      assert.expect(2);
+
+      if (_._baseEach) {
+        var path = require('path'),
+            basePath = path.dirname(filePath),
+            uid = 'e0gvgyrad1jor',
+            coreKey = '__core-js_shared__',
+            fakeSrcKey = 'Symbol(src)_1.' + uid;
+
+        root[coreKey] = { 'keys': { 'IE_PROTO': 'Symbol(IE_PROTO)_3.' + uid } };
+        emptyObject(require.cache);
+
+        var baseIsNative = require(path.join(basePath, '_baseIsNative'));
+        assert.strictEqual(baseIsNative(slice), true);
+
+        slice[fakeSrcKey] = slice + '';
+        assert.strictEqual(baseIsNative(slice), false);
+
+        delete slice[fakeSrcKey];
+        delete root[coreKey];
+      }
+      else {
+        skipAssert(assert, 2);
+      }
+    });
   }(1, 2, 3));
 
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