Fixed bug #79683

Reset fake_scope during __toString() call.

I'll check if we can solve this more globally in master, by
resetting fake_scope in zend_call_function.

Author: nikic

NEWS

@@ -9,6 +9,7 @@ PHP                                                                        NEWS
     Nikita)
   . Fixed bug #79657 ("yield from" hangs when invalid value encountered).
     (Nikita)
+  . Fixed bug #79683 (Fake reflection scope affects __toString()). (Nikita)
 
 - Filter:
   . Fixed bug #73527 (Invalid memory access in php_filter_strip). (cmb)

Zend/zend_object_handlers.c

@@ -1796,7 +1796,10 @@ ZEND_API int zend_std_cast_object_tostring(zval *readobj, zval *writeobj, int ty
 		case IS_STRING:
 			ce = Z_OBJCE_P(readobj);
 			if (ce->__tostring) {
+				zend_class_entry *fake_scope = EG(fake_scope);
+				EG(fake_scope) = NULL;
 				zend_call_method_with_0_params(readobj, ce, &ce->__tostring, "__tostring", &retval);
+				EG(fake_scope) = fake_scope;
 				if (EXPECTED(Z_TYPE(retval) == IS_STRING)) {
 					ZVAL_COPY_VALUE(writeobj, &retval);
 					return SUCCESS;

ext/reflection/tests/bug79683.phpt

@@ -0,0 +1,35 @@
+--TEST--
+Bug #79683: Fake reflection scope affects __toString()
+--FILE--
+<?php
+
+class A
+{
+    private string $prop1 = '123';
+
+    public function __toString()
+    {
+        return $this->prop1;
+    }
+}
+
+class B
+{
+    private string $prop2;
+}
+
+$b = new B();
+
+$reflector = new ReflectionClass($b);
+$property = $reflector->getProperty('prop2');
+$property->setAccessible(true);
+$property->setValue($b, new A());
+
+var_dump($b);
+
+?>
+--EXPECT--
+object(B)#1 (1) {
+  ["prop2":"B":private]=>
+  string(3) "123"
+}