Privacy: Reset wp_page_for_privacy_policy when the page is trashed or deleted

src/wp-admin/includes/class-wp-privacy-policy-content.php

@@ -329,6 +329,12 @@ public static function notice( $post = null ) {
 		$current_screen = get_current_screen();
 		$policy_page_id = (int) get_option( 'wp_page_for_privacy_policy' );
 
+		// If the privacy policy page has been deleted, reset the option and bail.
+		if ( $policy_page_id && ! get_post( $policy_page_id ) ) {
+			update_option( 'wp_page_for_privacy_policy', 0 );
+			return;
+		}
+
 		if ( 'post' !== $current_screen->base || $policy_page_id !== $post->ID ) {
 			return;
 		}

src/wp-admin/options-privacy.php

@@ -127,20 +127,7 @@ static function ( $body_class ) {
 			'error'
 		);
 	} else {
-		if ( 'trash' === $privacy_policy_page->post_status ) {
-			add_settings_error(
-				'page_for_privacy_policy',
-				'page_for_privacy_policy',
-				sprintf(
-					/* translators: %s: URL to Pages Trash. */
-					__( 'The currently selected Privacy Policy page is in the Trash. Please create or select a new Privacy Policy page or <a href="%s">restore the current page</a>.' ),
-					'edit.php?post_status=trash&post_type=page'
-				),
-				'error'
-			);
-		} else {
-			$privacy_policy_page_exists = true;
-		}
+		$privacy_policy_page_exists = true;
 	}
 }
 

src/wp-includes/default-filters.php

@@ -577,7 +577,9 @@
 add_action( 'init', 'create_initial_post_types', 0 ); // Highest priority.
 add_action( 'admin_menu', '_add_post_type_submenus' );
 add_action( 'before_delete_post', '_reset_front_page_settings_for_post' );
+add_action( 'before_delete_post', '_reset_privacy_policy_page_for_post' );
 add_action( 'wp_trash_post', '_reset_front_page_settings_for_post' );
+add_action( 'wp_trash_post', '_reset_privacy_policy_page_for_post' );
 add_action( 'change_locale', 'create_initial_post_types' );
 
 // Post Formats.

src/wp-includes/post.php

@@ -4027,6 +4027,22 @@ function _reset_front_page_settings_for_post( $post_id ) {
 	unstick_post( $post->ID );
 }
 
+/**
+ * Resets the Privacy Policy page ID option when the Privacy Policy page
+ * is deleted or trashed, to prevent uncached database queries for a
+ * non-existent page.
+ *
+ * @since 7.1.0
+ * @access private
+ *
+ * @param int $post_id The ID of the post being deleted or trashed.
+ */
+function _reset_privacy_policy_page_for_post( int $post_id ): void {
+	if ( 'page' === get_post_type( $post_id ) && ( (int) get_option( 'wp_page_for_privacy_policy' ) === $post_id ) ) {
+		update_option( 'wp_page_for_privacy_policy', 0 );
+	}
+}
+
 /**
  * Moves a post or page to the Trash
  *

tests/phpunit/tests/privacy/wpPrivacyResetPolicyPageForPost.php

@@ -0,0 +1,145 @@
+<?php
+/**
+ * Tests for _reset_privacy_policy_page_for_post() and the self-healing
+ * check in WP_Privacy_Policy_Content::notice().
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 7.1.0
+ *
+ * @group privacy
+ *
+ * @covers ::_reset_privacy_policy_page_for_post
+ */
+class Tests_Privacy_WpPrivacyResetPolicyPageForPost extends WP_UnitTestCase {
+	/**
+	 * ID of the page set as the Privacy Policy page.
+	 *
+	 * @var int
+	 */
+	private $policy_page_id;
+
+	public function set_up() {
+		parent::set_up();
+
+		$this->policy_page_id = self::factory()->post->create( array( 'post_type' => 'page' ) );
+		update_option( 'wp_page_for_privacy_policy', $this->policy_page_id );
+	}
+
+	public function tear_down() {
+		delete_option( 'wp_page_for_privacy_policy' );
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests that trashing the Privacy Policy page resets the option to 0.
+	 *
+	 * @ticket 56694
+	 */
+	public function test_trashing_privacy_policy_page_resets_option() {
+		wp_trash_post( $this->policy_page_id );
+
+		$this->assertSame( 0, (int) get_option( 'wp_page_for_privacy_policy' ) );
+	}
+
+	/**
+	 * Tests that permanently deleting the Privacy Policy page resets the option to 0.
+	 *
+	 * @ticket 56694
+	 */
+	public function test_deleting_privacy_policy_page_resets_option() {
+		wp_delete_post( $this->policy_page_id, true );
+
+		$this->assertSame( 0, (int) get_option( 'wp_page_for_privacy_policy' ) );
+	}
+
+	/**
+	 * Tests that trashing a different page does not change the option.
+	 *
+	 * @ticket 56694
+	 */
+	public function test_trashing_a_different_page_does_not_reset_option() {
+		$other_page_id = self::factory()->post->create( array( 'post_type' => 'page' ) );
+		wp_trash_post( $other_page_id );
+
+		$this->assertSame(
+			$this->policy_page_id,
+			(int) get_option( 'wp_page_for_privacy_policy' ),
+			'Trashing an unrelated page should not reset wp_page_for_privacy_policy.'
+		);
+	}
+
+	/**
+	 * Tests that deleting a non-page post type does not change the option.
+	 *
+	 * @ticket 56694
+	 */
+	public function test_deleting_non_page_post_type_does_not_reset_option() {
+		$post_id = self::factory()->post->create( array( 'post_type' => 'post' ) );
+		wp_delete_post( $post_id, true );
+
+		$this->assertSame(
+			$this->policy_page_id,
+			(int) get_option( 'wp_page_for_privacy_policy' ),
+			'Deleting a non-page post should not reset wp_page_for_privacy_policy.'
+		);
+	}
+
+	/**
+	 * Tests that WP_Privacy_Policy_Content::notice() resets the option to 0
+	 * when the stored ID points to a page that no longer exists.
+	 *
+	 * @ticket 56694
+	 *
+	 * @covers WP_Privacy_Policy_Content::notice
+	 */
+	public function test_notice_self_heals_when_policy_page_does_not_exist() {
+		require_once ABSPATH . 'wp-admin/includes/class-wp-privacy-policy-content.php';
+
+		update_option( 'wp_page_for_privacy_policy', 99999 );
+
+		$user_id = self::factory()->user->create( array( 'role' => 'administrator' ) );
+		wp_set_current_user( $user_id );
+		if ( is_multisite() ) {
+			grant_super_admin( $user_id );
+		}
+		set_current_screen( 'post' );
+
+		$post = self::factory()->post->create_and_get( array( 'post_type' => 'page' ) );
+		WP_Privacy_Policy_Content::notice( $post );
+
+		$this->assertSame(
+			0,
+			(int) get_option( 'wp_page_for_privacy_policy' ),
+			'notice() should reset the option to 0 when the stored page does not exist.'
+		);
+	}
+
+	/**
+	 * Tests that _reset_privacy_policy_page_for_post() does not call
+	 * update_option() when wp_page_for_privacy_policy is already 0.
+	 *
+	 * @ticket 56694
+	 */
+	public function test_no_update_option_when_policy_page_already_zero() {
+		update_option( 'wp_page_for_privacy_policy', 0 );
+
+		$call_count = 0;
+		add_filter(
+			'pre_update_option_wp_page_for_privacy_policy',
+			static function ( $value ) use ( &$call_count ) {
+				++$call_count;
+				return $value;
+			}
+		);
+
+		$other_page_id = self::factory()->post->create( array( 'post_type' => 'page' ) );
+		wp_trash_post( $other_page_id );
+
+		$this->assertSame(
+			0,
+			$call_count,
+			'update_option() should not be called when wp_page_for_privacy_policy is already 0.'
+		);
+	}
+}