Follow-up fix for GH-9655

Type needs to be rendered as a DNF type and not X&Y|null

Author: Girgias

Zend/tests/type_declarations/intersection_types/implicit_nullable_intersection_type.phpt

@@ -10,5 +10,5 @@ function foo(X&Y $foo = null) {
 foo(null);
 
 ?>
---EXPECTF--
+--EXPECT--
 NULL

Zend/tests/type_declarations/intersection_types/implicit_nullable_intersection_type_error.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Verify type rendering in type error for implicitly nullable intersection types
+--FILE--
+<?php
+
+function foo(X&Y $foo = null) {
+    var_dump($foo);
+}
+
+try {
+    foo(5);
+} catch (\TypeError $e) {
+    echo $e->getMessage(), \PHP_EOL;
+}
+
+?>
+--EXPECTF--
+foo(): Argument #1 ($foo) must be of type (X&Y)|null, int given, called in %s on line %d

Zend/zend_compile.c

@@ -1230,7 +1230,12 @@ zend_string *zend_type_to_string_resolved(zend_type type, zend_class_entry *scop
 	/* Pure intersection type */
 	if (ZEND_TYPE_IS_INTERSECTION(type)) {
 		ZEND_ASSERT(!ZEND_TYPE_IS_UNION(type));
-		str = add_intersection_type(str, ZEND_TYPE_LIST(type), scope, /* is_bracketed */ false);
+		bool is_bracketed = false;
+		/* Shim for implicitly nullable pure intersection types */
+		if (UNEXPECTED(ZEND_TYPE_PURE_MASK(type) & MAY_BE_NULL)) {
+			is_bracketed = true;
+		}
+		str = add_intersection_type(str, ZEND_TYPE_LIST(type), scope, is_bracketed);
 	} else if (ZEND_TYPE_HAS_LIST(type)) {
 		/* A union type might not be a list */
 		zend_type *list_type;