- previously had a single pointer/value zeros (8 bytes), this meant
that the reinterpret cast to a List would yield a reference that
could be unsafe under certain conditions.
Eg,
const labelList& myList = labelList::null();
Info<< myList.size() << nl; // OK since size is the first parameter
SubList<label>(myList, 0); // Unsafe
The SubList usage is unsafe since it passes in pointer and size into
the underlying UList. However, the pointer from the labelList::null()
will be whatever happens to be around in memory immediately after the
NullObject singleton. This is mostly not a problem if the List size
is always checked, but does mean that the data pointer is rather
dubious.
- Increase the size of the nullObject singleton to 32 bytes of zeros
to ensure that most reinterpret casting will not result in objects
that reference arbitrary memory.
The 32-byte data size is rather arbitrary, but covers most basic
containers.
