Fix "strtolower(): Passing null to parameter #1 ($string) of type string is deprecated" on PHP >= 8.4

Author: JanJakes

tests/WP_SQLite_Driver_Tests.php

@@ -6276,6 +6276,33 @@ public function testUserVariables(): void {
 		$this->assertEquals( 3, $result[0]->{'@my_var'} );
 	}
 
+	public function testVariableBackupAndRestoreForDumps(): void {
+		// Set and backup variables.
+		$this->assertQuery( '/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;' );
+		$this->assertQuery( '/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;' );
+		$this->assertQuery( '/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;' );
+		$this->assertQuery( '/*!50503 SET NAMES utf8mb4 */;' );
+		$this->assertQuery( '/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;' );
+		$this->assertQuery( "/*!40103 SET TIME_ZONE='+00:00' */;" );
+		$this->assertQuery( '/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;' );
+		$this->assertQuery( '/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;' );
+		$this->assertQuery( "/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;" );
+		$this->assertQuery( '/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;' );
+		$this->assertQuery( '/*!40101 SET @saved_cs_client = @@character_set_client */; ' );
+		$this->assertQuery( '/*!50503 SET character_set_client = utf8mb4 */;' );
+
+		// Restore variables.
+		$this->assertQuery( '/*!40101 SET character_set_client = @saved_cs_client */;' );
+		$this->assertQuery( '/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;' );
+		$this->assertQuery( '/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;' );
+		$this->assertQuery( '/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;' );
+		$this->assertQuery( '/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;' );
+		$this->assertQuery( '/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;' );
+		$this->assertQuery( '/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;' );
+		$this->assertQuery( '/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;' );
+		$this->assertQuery( '/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;' );
+	}
+
 	public function testLockingStatements(): void {
 		$this->assertQuery( 'CREATE TABLE t (id INT)' );
 

wp-includes/sqlite-ast/class-wp-sqlite-driver.php

@@ -2925,7 +2925,7 @@ private function execute_set_system_variable_statement(
 		 *          SET updatable_views_with_limit = OFF;   ERROR 1231 (42000)
 		 *          SET updatable_views_with_limit = false; SELECT @@updatable_views_with_limit; -> NO
 		 */
-		$lowercase_value = strtolower( $value );
+		$lowercase_value = null === $value ? null : strtolower( $value );
 		if ( 'on' === $lowercase_value || 'off' === $lowercase_value ) {
 			$value = 'on' === $lowercase_value ? 1 : 0;
 		}