Test and simplicifation for nullable intersection type

Author: Girgias

Zend/tests/type_declarations/intersection_types/invalid_nullable_type.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Intersection type cannot be nullable
+--FILE--
+<?php
+
+function foo(): ?Countable&Iterator {}
+
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected token "&", expecting "{" in %s on line %d

Zend/zend_compile.c

@@ -6293,10 +6293,6 @@ static zend_type zend_compile_typename(
 		zend_ast_list *list = zend_ast_get_list(ast);
 		zend_type_list *type_list;
 
-		if (allow_null) {
-			zend_error_noreturn(E_COMPILE_ERROR, "Nullable type cannot be part of an intersection type");
-		}
-
 		/* Allocate the type list directly on the arena as it must be a type
 		 * list of the same number of elements as the AST list has children */
 		type_list = zend_arena_alloc(&CG(arena), ZEND_TYPE_LIST_SIZE(list->children));