Fix PHPStan level 0 issues for Customizer setting subclasses by returning correct types

src/wp-includes/class-wp-customize-setting.php

@@ -708,7 +708,7 @@ protected function update( $value ) {
 			 */
 			do_action( "customize_update_{$this->type}", $value, $this );
 
-			return has_action( "customize_update_{$this->type}" );
+			return (bool) has_action( "customize_update_{$this->type}" );
 		}
 	}
 

src/wp-includes/customize/class-wp-customize-background-image-setting.php

@@ -26,10 +26,13 @@ final class WP_Customize_Background_Image_Setting extends WP_Customize_Setting {
 
 	/**
 	 * @since 3.4.0
+	 * @since 7.0.0 Return type updated from void to true for compatibility with base class.
 	 *
 	 * @param mixed $value The value to update. Not used.
+	 * @return true Always returns true.
 	 */
 	public function update( $value ) {
 		remove_theme_mod( 'background_image_thumb' );
+		return true;
 	}
 }

src/wp-includes/customize/class-wp-customize-filter-setting.php

@@ -22,8 +22,12 @@ class WP_Customize_Filter_Setting extends WP_Customize_Setting {
 	 * Saves the value of the setting, using the related API.
 	 *
 	 * @since 3.4.0
+	 * @since 7.0.0 Return type updated from void to true for compatibility with base class.
 	 *
 	 * @param mixed $value The value to update.
+	 * @return true Always returns true.
 	 */
-	public function update( $value ) {}
+	public function update( $value ) {
+		return true;
+	}
 }

src/wp-includes/customize/class-wp-customize-header-image-setting.php

@@ -28,10 +28,12 @@ final class WP_Customize_Header_Image_Setting extends WP_Customize_Setting {
 
 	/**
 	 * @since 3.4.0
+	 * @since 7.0.0 Return type updated from void to true for compatibility with base class.
 	 *
 	 * @global Custom_Image_Header $custom_image_header
 	 *
 	 * @param mixed $value The value to update.
+	 * @return true Always returns true.
 	 */
 	public function update( $value ) {
 		global $custom_image_header;
@@ -58,5 +60,6 @@ public function update( $value ) {
 		} else {
 			$custom_image_header->set_header_image( $value );
 		}
+		return true;
 	}
 }

src/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php

@@ -759,17 +759,18 @@ public function sanitize( $value ) {
 	 * To delete a menu, the client can send false as the value.
 	 *
 	 * @since 4.3.0
+	 * @since 7.0.0 Return type updated from null|void to bool for compatibility with base class.
 	 *
 	 * @see wp_update_nav_menu_item()
 	 *
 	 * @param array|false $value The menu item array to update. If false, then the menu item will be deleted
 	 *                           entirely. See WP_Customize_Nav_Menu_Item_Setting::$default for what the value
 	 *                           should consist of.
-	 * @return null|void
+	 * @return bool Whether updated.
 	 */
 	protected function update( $value ) {
 		if ( $this->is_updated ) {
-			return;
+			return ( 'error' !== $this->update_status );
 		}
 
 		$this->is_updated = true;
@@ -806,19 +807,19 @@ protected function update( $value ) {
 				if ( ! $nav_menu_setting || ! ( $nav_menu_setting instanceof WP_Customize_Nav_Menu_Setting ) ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'unexpected_nav_menu_setting' );
-					return;
+					return false;
 				}
 
 				if ( false === $nav_menu_setting->save() ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'nav_menu_setting_failure' );
-					return;
+					return false;
 				}
 
 				if ( (int) $value['nav_menu_term_id'] !== $nav_menu_setting->previous_term_id ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'unexpected_previous_term_id' );
-					return;
+					return false;
 				}
 
 				$value['nav_menu_term_id'] = $nav_menu_setting->term_id;
@@ -832,19 +833,19 @@ protected function update( $value ) {
 				if ( ! $parent_nav_menu_item_setting || ! ( $parent_nav_menu_item_setting instanceof WP_Customize_Nav_Menu_Item_Setting ) ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'unexpected_nav_menu_item_setting' );
-					return;
+					return false;
 				}
 
 				if ( false === $parent_nav_menu_item_setting->save() ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'nav_menu_item_setting_failure' );
-					return;
+					return false;
 				}
 
 				if ( (int) $value['menu_item_parent'] !== $parent_nav_menu_item_setting->previous_post_id ) {
 					$this->update_status = 'error';
 					$this->update_error  = new WP_Error( 'unexpected_previous_post_id' );
-					return;
+					return false;
 				}
 
 				$value['menu_item_parent'] = $parent_nav_menu_item_setting->post_id;
@@ -886,6 +887,8 @@ protected function update( $value ) {
 				}
 			}
 		}
+
+		return ( 'error' !== $this->update_status );
 	}
 
 	/**

src/wp-includes/customize/class-wp-customize-nav-menu-setting.php

@@ -466,6 +466,7 @@ public function sanitize( $value ) {
 	 * To delete a menu, the client can send false as the value.
 	 *
 	 * @since 4.3.0
+	 * @since 7.0.0 Return type updated from null|void to bool for compatibility with base class.
 	 *
 	 * @see wp_update_nav_menu_object()
 	 *
@@ -478,11 +479,11 @@ public function sanitize( $value ) {
 	 *     @type int    $parent      The id of the parent term. Default 0.
 	 *     @type bool   $auto_add    Whether pages will auto_add to this menu. Default false.
 	 * }
-	 * @return null|void
+	 * @return bool Whether updated.
 	 */
 	protected function update( $value ) {
 		if ( $this->is_updated ) {
-			return;
+			return ( 'error' !== $this->update_status );
 		}
 
 		$this->is_updated = true;
@@ -582,6 +583,8 @@ protected function update( $value ) {
 				$this->_widget_nav_menu_updates[ $nav_menu_widget_setting->id ] = $updated_widget_instance;
 			}
 		}
+
+		return ( 'error' !== $this->update_status );
 	}
 
 	/**