wp-includes/PHPMailer/PHPMailer.php:3992Check if an attachment (non-inline) is present.
bool public function attachmentExists() { foreach ($this->attachment as $attachment) { if ('attachment' === $attachment[6]) { return true; } } return false; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/PHPMailer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.