Merge branch 'PHP-8.4'

* PHP-8.4:
  Reapply GH-17712 with a fix for internal class constants (#18464)

Author: DanielEScherzer

NEWS

@@ -49,6 +49,9 @@ PHP                                                                        NEWS
   . Added get_error_handler(), get_exception_handler() functions. (Arnaud)
   . Fixed bug GH-15753 and GH-16198 (Bind traits before parent class). (ilutov)
   . Added support for casts in constant expressions. (nielsdos)
+  . Fixed bugs GH-17711 and GH-18022 (Infinite recursion on deprecated attribute
+    evaluation) and GH-18464 (Recursion protection for deprecation constants not
+    released on bailout). (DanielEScherzer and ilutov)
 
 - Curl:
   . Added curl_multi_get_handles(). (timwolla)

Zend/tests/constants/gh18463-class-constant.phpt

@@ -0,0 +1,20 @@
+--TEST--
+GH-18463: Recursion protection should not be applied to internal class constants
+--EXTENSIONS--
+zend_test
+--FILE--
+<?php
+
+function handler($errno, $errstr, $errfile, $errline) {
+	echo "$errstr in $errfile on line $errline\n";
+	eval('class string {}');
+}
+
+set_error_handler('handler');
+
+var_dump(_ZendTestClass::ZEND_TEST_DEPRECATED);
+?>
+--EXPECTF--
+Constant _ZendTestClass::ZEND_TEST_DEPRECATED is deprecated in %s on line %d
+
+Fatal error: Cannot use "string" as a class name as it is reserved in %s(%d) : eval()'d code on line %d

Zend/zend_constants.c

@@ -373,9 +373,15 @@ ZEND_API zval *zend_get_class_constant_ex(zend_string *class_name, zend_string *
 
 			if (UNEXPECTED(ZEND_CLASS_CONST_FLAGS(c) & ZEND_ACC_DEPRECATED)) {
 				if ((flags & ZEND_FETCH_CLASS_SILENT) == 0 && !CONST_IS_RECURSIVE(c)) {
+					if (c->ce->type == ZEND_USER_CLASS) {
+						/* Recursion protection only applied to user constants, GH-18463 */
+						CONST_PROTECT_RECURSION(c);
+					}
 					CONST_PROTECT_RECURSION(c);
 					zend_deprecated_class_constant(c, constant_name);
-					CONST_UNPROTECT_RECURSION(c);
+					if (c->ce->type == ZEND_USER_CLASS) {
+						CONST_UNPROTECT_RECURSION(c);
+					}
 					if (EG(exception)) {
 						goto failure;
 					}

Zend/zend_vm_def.h

@@ -6156,10 +6156,15 @@ ZEND_VM_HANDLER(181, ZEND_FETCH_CLASS_CONSTANT, VAR|CONST|UNUSED|CLASS_FETCH, CO
 			}
 
 			bool is_constant_deprecated = ZEND_CLASS_CONST_FLAGS(c) & ZEND_ACC_DEPRECATED;
-			if (UNEXPECTED(is_constant_deprecated) && !CONST_IS_RECURSIVE(c)) {
-				CONST_PROTECT_RECURSION(c);
+			if (UNEXPECTED(is_constant_deprecated) && !CONST_IS_RECURSIVE(c)) {			
+				if (c->ce->type == ZEND_USER_CLASS) {
+					/* Recursion protection only applied to user constants, GH-18463 */
+					CONST_PROTECT_RECURSION(c);
+				}
 				zend_deprecated_class_constant(c, constant_name);
-				CONST_UNPROTECT_RECURSION(c);
+				if (c->ce->type == ZEND_USER_CLASS) {
+					CONST_UNPROTECT_RECURSION(c);
+				}
 
 				if (EG(exception)) {
 					ZVAL_UNDEF(EX_VAR(opline->result.var));