From 4d2abda74a8bb70b65b94bd3d03bb5ac10d2fb3c Mon Sep 17 00:00:00 2001
From: Peter Wilson <wilson@peterwilson.cc>
Date: Thu, 4 Mar 2021 00:14:04 +0000
Subject: [PATCH] Roles/Caps: Return same result from `current_user_can` and
 `user_can()`.

Ensure `current_user_can()` and `user_can()` return the same results for logged out users. For core capabilities this changes `user_can( 0, 'exist' )` to return `true` rather than `false` in line with `current_user_can( 'exist' )` for logged out users.

Convert `current_user_can()` and `current_user_can_for_blog()` to wrapper functions ultimately calling `user_can()`.

Add anonymous user to primitive capability checks as appropriate. Convert `Tests_User_Capabilities::test_other_caps_for_all_roles()` to use a data provider and add tests to check whether user exists in the database (`WP_User::exists()`) as that intentionally differs from the `exist` capability.

Props jjj, johnbillion, peterwilsoncc, SergeyBiryukov, TimothyBlynJacobs.
Fixes #52076.


Built from https://develop.svn.wordpress.org/trunk@50490


git-svn-id: http://core.svn.wordpress.org/trunk@50103 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/capabilities.php  | 27 ++++++++-------------------
 wp-includes/class-wp-user.php |  3 +++
 wp-includes/version.php       |  2 +-
 3 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/wp-includes/capabilities.php b/wp-includes/capabilities.php
index f7ff5cbab2..3ff0481fd4 100644
--- a/wp-includes/capabilities.php
+++ b/wp-includes/capabilities.php
@@ -679,6 +679,7 @@ function map_meta_cap( $cap, $user_id, ...$args ) {
  * @since 2.0.0
  * @since 5.3.0 Formalized the existing and already documented `...$args` parameter
  *              by adding it to the function signature.
+ * @since 5.8.0 Converted to wrapper for the user_can() function.
  *
  * @see WP_User::has_cap()
  * @see map_meta_cap()
@@ -689,13 +690,7 @@ function map_meta_cap( $cap, $user_id, ...$args ) {
  *              passed, whether the current user has the given meta capability for the given object.
  */
 function current_user_can( $capability, ...$args ) {
-	$current_user = wp_get_current_user();
-
-	if ( empty( $current_user ) ) {
-		return false;
-	}
-
-	return $current_user->has_cap( $capability, ...$args );
+	return user_can( wp_get_current_user(), $capability, ...$args );
 }
 
 /**
@@ -714,6 +709,7 @@ function current_user_can( $capability, ...$args ) {
  * @since 3.0.0
  * @since 5.3.0 Formalized the existing and already documented `...$args` parameter
  *              by adding it to the function signature.
+ * @since 5.8.0 Wraps current_user_can() after switching to blog.
  *
  * @param int    $blog_id    Site ID.
  * @param string $capability Capability name.
@@ -723,16 +719,7 @@ function current_user_can( $capability, ...$args ) {
 function current_user_can_for_blog( $blog_id, $capability, ...$args ) {
 	$switched = is_multisite() ? switch_to_blog( $blog_id ) : false;
 
-	$current_user = wp_get_current_user();
-
-	if ( empty( $current_user ) ) {
-		if ( $switched ) {
-			restore_current_blog();
-		}
-		return false;
-	}
-
-	$can = $current_user->has_cap( $capability, ...$args );
+	$can = current_user_can( $capability, ...$args );
 
 	if ( $switched ) {
 		restore_current_blog();
@@ -805,8 +792,10 @@ function user_can( $user, $capability, ...$args ) {
 		$user = get_userdata( $user );
 	}
 
-	if ( ! $user || ! $user->exists() ) {
-		return false;
+	if ( empty( $user ) ) {
+		// User is logged out, create anonymous user object.
+		$user = new WP_User( 0 );
+		$user->init( new stdClass );
 	}
 
 	return $user->has_cap( $capability, ...$args );
diff --git a/wp-includes/class-wp-user.php b/wp-includes/class-wp-user.php
index 87518c45c8..195bc24341 100644
--- a/wp-includes/class-wp-user.php
+++ b/wp-includes/class-wp-user.php
@@ -167,6 +167,9 @@ class WP_User {
 	 * @param int    $site_id Optional. The site ID to initialize for.
 	 */
 	public function init( $data, $site_id = '' ) {
+		if ( ! isset( $data->ID ) ) {
+			$data->ID = 0;
+		}
 		$this->data = $data;
 		$this->ID   = (int) $data->ID;
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3541c83d2e..dfaecb3319 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50488';
+$wp_version = '5.8-alpha-50490';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.