What are the potential issues when upgrading from PHP 7.4 to PHP 8.0?

One potential issue when upgrading from PHP 7.4 to PHP 8.0 is the deprecation of the "real" type declaration for return types. To solve this, you should replace "real" with "float" in your return type declarations.

// Before PHP 8.0
function calculateTotal(float $price, int $quantity): real {
    return $price * $quantity;
}

// After PHP 8.0
function calculateTotal(float $price, int $quantity): float {
    return $price * $quantity;
}