wp-includes/pomo/mo.php:61$filenamestringbool public function export_to_file( $filename ) { $fh = fopen( $filename, 'wb' ); if ( ! $fh ) { return false; } $res = $this->export_to_file_handle( $fh ); fclose( $fh ); return $res; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/pomo/mo.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.