Generally, the extension uses zend_string_release() to free zend_string objects after use, which only frees the string's memory if its reference count dips below 1.

That said, a few places are still using zend_string_free(), which always asserts that the reference count is zero before freeing the string's memory. Two such occurrences are when freeing the zend_string created to fetch a zend_class_entry for a type map class and "__pclass" field. This is problematic if a custom autoloader adds a reference to the class name, which is exactly what Composer does to cache missing classes.

Whenever possible, we should use zend_string_release() to free zend_string objects.