From ce366328e4b9518ef9f122e20b051d9cb49aa0dd Mon Sep 17 00:00:00 2001
From: Gina Peter Bnayard <girgias@php.net>
Date: Mon, 12 Aug 2024 14:20:14 +0200
Subject: [PATCH] Deprecate using "_" as a class name

RFC: https://wiki.php.net/rfc/deprecations_php_8_4#deprecate_using_a_single_underscore_as_a_class_name
---
 NEWS                                     |  1 +
 UPGRADING                                |  2 ++
 Zend/tests/class_underscore_as_name.phpt | 18 ++++++++++++++++++
 Zend/zend_compile.c                      |  3 +++
 4 files changed, 24 insertions(+)
 create mode 100644 Zend/tests/class_underscore_as_name.phpt

diff --git a/NEWS b/NEWS
index 1656b8bba2683..d72818363ab5a 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ PHP                                                                        NEWS
   . Fixed bug GH-15181 (Disabled output handler is flushed again). (cmb)
   . Passing E_USER_ERROR to trigger_error() is now deprecated. (Girgias)
   . Fixed bug GH-15292 (Dynamic AVX detection is broken for MSVC). (nielsdos)
+  . Using "_" as a class name is now deprecated. (Girgias)
 
 - Date:
   . Constants SUNFUNCS_RET_TIMESTAMP, SUNFUNCS_RET_STRING, and SUNFUNCS_RET_DOUBLE
diff --git a/UPGRADING b/UPGRADING
index 544a25c6fbeb8..eb77915769279 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -408,6 +408,8 @@ PHP 8.4 UPGRADE NOTES
     RFC: https://wiki.php.net/rfc/deprecate-implicitly-nullable-types
   . Passing E_USER_ERROR to trigger_error() is now deprecated.
     RFC: https://wiki.php.net/rfc/deprecations_php_8_4#deprecate_passing_e_user_error_to_trigger_error
+  . Using "_" as a class name is now deprecated.
+    RFC: https://wiki.php.net/rfc/deprecations_php_8_4#deprecate_using_a_single_underscore_as_a_class_name
 
 - Curl:
   . The CURLOPT_BINARYTRANSFER constant is deprecated.
diff --git a/Zend/tests/class_underscore_as_name.phpt b/Zend/tests/class_underscore_as_name.phpt
new file mode 100644
index 0000000000000..7e7e37a0384f3
--- /dev/null
+++ b/Zend/tests/class_underscore_as_name.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Using "_" as a class name is deprecated
+--FILE--
+<?php
+
+namespace Foo\Bar {
+    class _ {}
+}
+
+namespace {
+    class _ {}
+}
+
+?>
+--EXPECTF--
+Deprecated: Using "_" as a class name is deprecated since 8.4 in %s on line %d
+
+Deprecated: Using "_" as a class name is deprecated since 8.4 in %s on line %d
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 307bcab819c40..590f8901df5de 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -243,6 +243,9 @@ void zend_assert_valid_class_name(const zend_string *name) /* {{{ */
 		zend_error_noreturn(E_COMPILE_ERROR,
 			"Cannot use '%s' as class name as it is reserved", ZSTR_VAL(name));
 	}
+	if (zend_string_equals_literal(name, "_")) {
+		zend_error(E_DEPRECATED, "Using \"_\" as a class name is deprecated since 8.4");
+	}
 }
 /* }}} */