This deprecates passing null to non-nullable scale arguments of
internal functions, with the eventual goal of making the behavior
consistent with userland functions, where null is never accepted
for non-nullable arguments.
This change is expected to cause quite a lot of fallout. In most
cases, calling code should be adjusted to avoid passing null. In
some cases, PHP should be adjusted to make some function arguments
nullable. I have already fixed a number of functions before landing
this, but feel free to file a bug if you encounter a function that
doesn't accept null, but probably should. (The rule of thumb for
this to be applicable is that the function must have special behavior
for 0 or "", which is distinct from the natural behavior of the
parameter.)
RFC: https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg
Closes GH-6475.
SplDoublyLinkedList, SplObjectStorage and ArrayObject have empty
constructor (no arg), so it make sense to allow to unserialize empty
data.
This allow the hack (used in various place, including PHPUnit) to
instanciate class without call to constructor to work.
