From d2342e75d0754c798bdd7316e2b93e239a2eb29f Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Mon, 16 Jul 2018 14:14:27 +0000
Subject: [PATCH] Login and Registration: Set a better default value for
 `$wp_error` parameter in `login_header()`.

To prevent someone from passing a string (which would not be added to a new `WP_Error` instance), check for `is_wp_error()` explicitly.

Props desrosj, chetan200891, spyderbytes, lbenicio, sebastien@thivinfo.com, abdullahramzan.
Merges [43457] to the 4.9 branch.
Fixes #44052.
Built from https://develop.svn.wordpress.org/branches/4.9@43458


git-svn-id: http://core.svn.wordpress.org/branches/4.9@43285 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/version.php | 2 +-
 wp-login.php            | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/wp-includes/version.php b/wp-includes/version.php
index bfb83d5708..08a7f07637 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.8-alpha-43456';
+$wp_version = '4.9.8-alpha-43458';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-login.php b/wp-login.php
index 95c046f8a3..ffd86c1e20 100644
--- a/wp-login.php
+++ b/wp-login.php
@@ -28,9 +28,9 @@ if ( force_ssl_admin() && ! is_ssl() ) {
  * @param string   $title    Optional. WordPress login Page title to display in the `<title>` element.
  *                           Default 'Log In'.
  * @param string   $message  Optional. Message to display in header. Default empty.
- * @param WP_Error $wp_error Optional. The error to pass. Default empty.
+ * @param WP_Error $wp_error Optional. The error to pass. Default is a WP_Error instance.
  */
-function login_header( $title = 'Log In', $message = '', $wp_error = '' ) {
+function login_header( $title = 'Log In', $message = '', $wp_error = null ) {
 	global $error, $interim_login, $action;
 
 	// Don't index any of these forms
@@ -38,8 +38,9 @@ function login_header( $title = 'Log In', $message = '', $wp_error = '' ) {
 
 	add_action( 'login_head', 'wp_login_viewport_meta' );
 
-	if ( empty($wp_error) )
+	if ( ! is_wp_error( $wp_error ) ) {
 		$wp_error = new WP_Error();
+	}
 
 	// Shake it!
 	$shake_error_codes = array( 'empty_password', 'empty_email', 'invalid_email', 'invalidcombo', 'empty_username', 'invalid_username', 'incorrect_password' );