From c9df4f75a22f9ffd14753fdc84919d6e48dad6d9 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Mon, 16 Aug 2021 15:22:38 +0000
Subject: [PATCH] Code Modernization: Check the return type of
 `_get_cron_array()` in `wp_schedule_event()`.

This fixes a "Deprecated: Automatic conversion of false to array is deprecated" warning on PHP 8.1.

In `wp_schedule_event()`, the cron info array is retrieved via a call to `_get_cron_array()`, but as the documentation (correctly) states, the return type of that function is `array|false`, where `false` is returned for a virgin site, with no cron jobs scheduled yet.

However, no type check is done on the return value, and the `wp_schedule_event()` function just blindly continues by assigning a value to a subkey of the `$crons` "array".

Fixed by adding validation for the returned value from `_get_cron_array()` and initializing an empty array if `false` was returned.

Reference: [https://developer.wordpress.org/reference/functions/_get_cron_array/ WordPress Developer Resources: _get_cron_array()]

Props jrf, hellofromTonya, lucatume, pbearne, iluy, pedromendonca, SergeyBiryukov.
See #53635.

git-svn-id: https://develop.svn.wordpress.org/trunk@51619 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/cron.php     |  7 +++++--
 tests/phpunit/tests/cron.php | 24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/cron.php b/src/wp-includes/cron.php
index 1666a09b27..18fe14196e 100644
--- a/src/wp-includes/cron.php
+++ b/src/wp-includes/cron.php
@@ -302,6 +302,10 @@ function wp_schedule_event( $timestamp, $recurrence, $hook, $args = array(), $wp
 	$key = md5( serialize( $event->args ) );
 
 	$crons = _get_cron_array();
+	if ( ! is_array( $crons ) ) {
+		$crons = array();
+	}
+
 	$crons[ $event->timestamp ][ $event->hook ][ $key ] = array(
 		'schedule' => $event->schedule,
 		'args'     => $event->args,
@@ -1125,8 +1129,7 @@ function wp_get_ready_cron_jobs() {
 	}
 
 	$crons = _get_cron_array();
-
-	if ( false === $crons ) {
+	if ( ! is_array( $crons ) ) {
 		return array();
 	}
 
diff --git a/tests/phpunit/tests/cron.php b/tests/phpunit/tests/cron.php
index e0f973d51e..9b9c475954 100644
--- a/tests/phpunit/tests/cron.php
+++ b/tests/phpunit/tests/cron.php
@@ -98,7 +98,31 @@ class Tests_Cron extends WP_UnitTestCase {
 		$this->assertFalse( wp_next_scheduled( $hook, array( 'bar' ) ) );
 
 		$this->assertSame( $recur, wp_get_schedule( $hook, $args ) );
+	}
 
+
+	/**
+	 * Tests that a call to wp_schedule_event() on a site without any scheduled events
+	 * does not result in a PHP deprecation warning on PHP 8.1 or higher.
+	 *
+	 * The warning that we should not see:
+	 * `Deprecated: Automatic conversion of false to array is deprecated`.
+	 *
+	 * @ticket 53635
+	 *
+	 * @covers ::wp_schedule_event
+	 */
+	function test_wp_schedule_event_without_cron_option_does_not_throw_warning() {
+		delete_option( 'cron' );
+
+		// Verify that the cause of the error is in place.
+		$this->assertFalse( _get_cron_array(), '_get_cron_array() does not return false' );
+
+		$hook      = __FUNCTION__;
+		$timestamp = strtotime( '+10 minutes' );
+
+		// Add an event.
+		$this->assertTrue( wp_schedule_event( $timestamp, 'daily', $hook ) );
 	}
 
 	function test_unschedule_event() {