Mark array_walk $userdata arg as UNKNOWN

It makes a difference whether this arg is not passed or is null.

Author: nikic

ext/standard/basic_functions.stub.php

@@ -120,9 +120,9 @@ function min($arg, ...$args) {}
 /** @return mixed */
 function max($arg, ...$args) {}
 
-function array_walk(array|object &$input, callable $funcname, $userdata = null): bool {}
+function array_walk(array|object &$input, callable $funcname, $userdata = UNKNOWN): bool {}
 
-function array_walk_recursive(array|object &$input, callable $funcname, $userdata = null): bool {}
+function array_walk_recursive(array|object &$input, callable $funcname, $userdata = UNKNOWN): bool {}
 
 function in_array($needle, array $haystack, bool $strict = false): bool {}
 

ext/standard/basic_functions_arginfo.h

@@ -140,7 +140,7 @@ ZEND_END_ARG_INFO()
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_array_walk, 0, 2, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_MASK(1, input, MAY_BE_ARRAY|MAY_BE_OBJECT, NULL)
 	ZEND_ARG_TYPE_INFO(0, funcname, IS_CALLABLE, 0)
-	ZEND_ARG_INFO_WITH_DEFAULT_VALUE(0, userdata, "null")
+	ZEND_ARG_INFO(0, userdata)
 ZEND_END_ARG_INFO()
 
 #define arginfo_array_walk_recursive arginfo_array_walk