Fix copying of functions in variance obligations

Only copy sizeof(zend_internal_function) for internal functions.

Author: nikic

Zend/tests/type_declarations/variance/internal_parent.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Internal class as parent
+--FILE--
+<?php
+
+class Test extends DateTime {
+    public static function createFromFormat($format, $time, Wrong $timezone = null) { }
+}
+
+?>
+--EXPECTF--
+Warning: Could not check compatibility between Test::createFromFormat($format, $time, ?Wrong $timezone = NULL) and DateTime::createFromFormat($format, $time, ?DateTimeZone $object = NULL), because class Wrong is not available in %s on line %d

Zend/zend_inheritance.c

@@ -2294,8 +2294,17 @@ static void add_compatibility_obligation(
 	HashTable *obligations = get_or_init_obligations_for_class(ce);
 	variance_obligation *obligation = emalloc(sizeof(variance_obligation));
 	obligation->type = OBLIGATION_COMPATIBILITY;
-	obligation->child_fn = *child_fn;
-	obligation->parent_fn = *parent_fn;
+	/* Copy functions, because they may be stack-allocated in the case of traits. */
+	if (child_fn->common.type == ZEND_INTERNAL_FUNCTION) {
+		memcpy(&obligation->child_fn, child_fn, sizeof(zend_internal_function));
+	} else {
+		memcpy(&obligation->child_fn, child_fn, sizeof(zend_op_array));
+	}
+	if (parent_fn->common.type == ZEND_INTERNAL_FUNCTION) {
+		memcpy(&obligation->parent_fn, parent_fn, sizeof(zend_internal_function));
+	} else {
+		memcpy(&obligation->parent_fn, parent_fn, sizeof(zend_op_array));
+	}
 	obligation->always_error = always_error;
 	zend_hash_next_index_insert_ptr(obligations, obligation);
 }