Avoid cloning uncloneables

src/Doctrine/Instantiator/Instantiator.php

@@ -69,8 +69,7 @@ public function instantiate($className)
         $instance   = $factory();
         $reflection = new ReflectionClass($instance);
 
-        // not cloneable if it implements `__clone`, as we want to avoid calling it
-        if (! $reflection->hasMethod('__clone')) {
+        if ($this->isSafeToClone($reflection)) {
             self::$cachedCloneables[$className] = clone $instance;
         }
 
@@ -235,4 +234,21 @@ private function isPhpVersionWithBrokenSerializationFormat()
     {
         return PHP_VERSION_ID === 50429 || PHP_VERSION_ID === 50513;
     }
+
+    /**
+     * Checks if a class is cloneable
+     *
+     * @param ReflectionClass $reflection
+     *
+     * @return bool
+     */
+    private function isSafeToClone(ReflectionClass $reflection)
+    {
+        if (method_exists($reflection, 'isCloneable') && ! $reflection->isCloneable()) {
+            return false;
+        }
+
+        // not cloneable if it implements `__clone`, as we want to avoid calling it
+        return ! $reflection->hasMethod('__clone');
+    }
 }

tests/DoctrineTest/InstantiatorTest/InstantiatorTest.php

@@ -169,6 +169,7 @@ public function getInstantiableClasses()
             array('DoctrineTest\\InstantiatorTestAsset\\SimpleSerializableAsset'),
             array('DoctrineTest\\InstantiatorTestAsset\\PharExceptionAsset'),
             array('DoctrineTest\\InstantiatorTestAsset\\UnCloneableAsset'),
+            array('DoctrineTest\\InstantiatorTestAsset\\XMLReaderAsset'),
         );
 
         if (\PHP_VERSION_ID === 50429 || \PHP_VERSION_ID === 50513) {

tests/DoctrineTest/InstantiatorTestAsset/XMLReaderAsset.php

@@ -0,0 +1,41 @@
+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the MIT license. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace DoctrineTest\InstantiatorTestAsset;
+
+use BadMethodCallException;
+use XMLReader;
+
+/**
+ * Test asset that extends an internal PHP class
+ *
+ * @author Dave Marshall <dave@atst.io>
+ */
+class XMLReaderAsset extends XMLReader
+{
+    /**
+     * Constructor - should not be called
+     *
+     * @throws BadMethodCallException
+     */
+    public function __construct()
+    {
+        throw new BadMethodCallException('Not supposed to be called!');
+    }
+}