Fix phpGH-16574: Incorrect error "undefined method" messages

The `get_method` object handler may change the object pointer. SPL does
this in its iterator implementations. This causes the error message
to change to another class which is confusing to the user. JIT handles
this correctly. This patch aligns behaviour with JIT.

Closes phpGH-16576.

Author: nielsdos

NEWS

@@ -2,6 +2,10 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.4.0RC4
 
+- Core:
+  . Fixed bug GH-16574 (Incorrect error "undefined method" messages).
+    (nielsdos)
+
 - GD:
   . Fixed bug GH-16559 (UBSan abort in ext/gd/libgd/gd_interpolation.c:1007).
     (nielsdos)

Zend/zend_vm_def.h

@@ -3625,7 +3625,7 @@ ZEND_VM_HOT_OBJ_HANDLER(112, ZEND_INIT_METHOD_CALL, CONST|TMPVAR|UNUSED|THIS|CV,
 		fbc = obj->handlers->get_method(&obj, Z_STR_P(function_name), ((OP2_TYPE == IS_CONST) ? (RT_CONSTANT(opline, opline->op2) + 1) : NULL));
 		if (UNEXPECTED(fbc == NULL)) {
 			if (EXPECTED(!EG(exception))) {
-				zend_undefined_method(obj->ce, Z_STR_P(function_name));
+				zend_undefined_method(orig_obj->ce, Z_STR_P(function_name));
 			}
 			FREE_OP2();
 			if ((OP1_TYPE & (IS_VAR|IS_TMP_VAR)) && GC_DELREF(orig_obj) == 0) {

Zend/zend_vm_execute.h

@@ -0,0 +1,15 @@
+--TEST--
+GH-16574 (Incorrect error "undefined method" messages)
+--CREDITS--
+YuanchengJiang
+--FILE--
+<?php
+$i = new ArrayIterator([1,1,1,1,1]);
+$i = new CachingIterator($i, CachingIterator::FULL_CACHE);
+$i->doesnotexist("x");
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Call to undefined method CachingIterator::doesnotexist() in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d