wp-includes/pomo/po.php:76Same as export, but writes the result to a file
$filenamestring$include_headersbooloptionaltruebool public function export_to_file( $filename, $include_headers = true ) { $fh = fopen( $filename, 'w' ); if ( false === $fh ) { return false; } $export = $this->export( $include_headers ); $res = fwrite( $fh, $export ); if ( false === $res ) { return false; } return fclose( $fh ); }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/pomo/po.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.