Add tests for relative class types

Author: Girgias

Zend/tests/type_declarations/relative_class_types/invalid_types/invalid_parent_type_outside_class.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Cannot use parent type outside a class
+--FILE--
+<?php
+
+function foo($x): parent {};
+
+?>
+--EXPECTF--
+Fatal error: Cannot use "parent" when no class scope is active in %s on line %d

Zend/tests/type_declarations/relative_class_types/invalid_types/invalid_self_type_outside_class.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Cannot use self type outside a class
+--FILE--
+<?php
+
+function foo($x): self {};
+
+?>
+--EXPECTF--
+Fatal error: Cannot use "self" when no class scope is active in %s on line %d

Zend/tests/type_declarations/relative_class_types/invalid_types/invalid_static_type_outside_class.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Cannot use static type outside a class
+--FILE--
+<?php
+
+function foo($x): static {};
+
+?>
+--EXPECTF--
+Fatal error: Cannot use "static" when no class scope is active in %s on line %d

Zend/tests/type_declarations/relative_class_types/relative_type_in_closures.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Relative class types can be used for closures as it may be bound to a class
+--FILE--
+<?php
+
+$fn1 = function($x): self {};
+$fn2 = function($x): parent {};
+$fn3 = function($x): static {};
+
+?>
+DONE
+--EXPECT--
+DONE