Don't autoload when checking property types

Noticed while working on union types: We do not load argument and
return types during type checks, but we do load property types.

I'm normalizing the behavior towards the existing status quo (not
loading), though we may consider loading everywhere (all types,
and instanceof) in order to properly support class aliases.

Zend/tests/type_declarations/typed_properties_class_loading.phpt

@@ -0,0 +1,51 @@
+--TEST--
+Typed properties do not invoke the autoloader
+--FILE--
+<?php
+
+class Test {
+    public X $propX;
+    public ?Y $propY;
+}
+
+spl_autoload_register(function($class) {
+    echo "Loading $class\n";
+});
+
+$test = new Test;
+try {
+    $test->propX = new stdClass;
+} catch (TypeError $e) {
+    echo $e->getMessage(), "\n";
+}
+
+if (true) {
+    class X {}
+}
+
+$test->propX = new X;
+var_dump($test->propX);
+
+$test->propY = null;
+$r =& $test->propY;
+try {
+    $test->propY = new stdClass;
+} catch (TypeError $e) {
+    echo $e->getMessage(), "\n";
+}
+
+if (true) {
+    class Y {}
+}
+
+$r = new Y;
+var_dump($test->propY);
+
+?>
+--EXPECT--
+Typed property Test::$propX must be an instance of X, stdClass used
+object(X)#3 (0) {
+}
+Typed property Test::$propY must be an instance of Y or null, stdClass used
+object(Y)#4 (0) {
+}

Zend/zend_execute.c

@@ -941,7 +941,7 @@ static zend_bool zend_resolve_class_type(zend_type *type, zend_class_entry *self
 		}
 		ce = self_ce->parent;
 	} else {
-		ce = zend_lookup_class(name);
+		ce = zend_lookup_class_ex(name, NULL, ZEND_FETCH_CLASS_NO_AUTOLOAD);
 		if (UNEXPECTED(!ce)) {
 			return 0;
 		}