Throw error if user want to access message properties (#4603)

* Throw error if user want to access message properties

* Fix typo

php/ext/google/protobuf/message.c

@@ -222,7 +222,13 @@ static zval* message_get_property_ptr_ptr(zval* object, zval* member, int type,
 }
 
 static HashTable* message_get_properties(zval* object TSRMLS_DC) {
-  return NULL;
+  // User cannot get property directly (e.g., $a = $m->a)
+  zend_error(E_USER_ERROR, "Cannot access private properties.");
+#if PHP_MAJOR_VERSION < 7
+  return zend_std_get_properties(object TSRMLS_CC);
+#else
+  return zend_std_get_properties(object);
+#endif
 }
 
 static HashTable* message_get_gc(zval* object, CACHED_VALUE** table,

php/tests/test.sh

@@ -21,7 +21,7 @@ do
   echo "****************************"
   echo "* $t"
   echo "****************************"
-  # php -dextension=../ext/google/protobuf/modules/protobuf.so `which phpunit` --bootstrap autoload.php $t
+  php -dextension=../ext/google/protobuf/modules/protobuf.so `which phpunit` --bootstrap autoload.php $t
   echo ""
 done