This function doesn't appear to work at all. You have to create a new BCMath\Number object to use it, at which point it attempts to overwrite the value of said object - and of course that won't work because BCMath\Number::$value is readonly.
(PHP 8 >= 8.4.0)
BcMath\Number::__unserialize — Désérialise un paramètre de données en un objet BcMath\Number
Désérialise un paramètre de données en un objet BcMath\Number.
dataCette méthode lève une ValueError si des données sérialisées invalides sont passées.
This function doesn't appear to work at all. You have to create a new BCMath\Number object to use it, at which point it attempts to overwrite the value of said object - and of course that won't work because BCMath\Number::$value is readonly.