// *** before: ***
class Report {
    private ?array $rows = null;

    public function getRows(): array {
        // manual lazy-loading through a nullable backing field
        if ($this->rows === null) {
            $this->rows = $this->loadFromDatabase();
        }
        return $this->rows;
    }
}

// *** in version 8.4: ***
$reflector = new ReflectionClass(Report::class);
$report = $reflector->newLazyGhost(function (Report $report) {
    // runs only on the first access to a property or method of $report
    $report->__construct($this->loadFromDatabase());
});