PtrVectorBase member data could undergo narrowing conversion when reading a linux-produced data file on a Mac.
art::PtrVectorBase has a member datum
indicies_ of type
indices_t, which is a typedef to
key_type being itself a typedef to
unsigned long. ROOT 5+ always stores this as 64 bits, but upon reading on OS X, it is narrowed to 32 bits.
In order to avoid the possibility of undesired narrowing, we should change the typedef of
unsigned long long. This will not increase IO storage requirements, and will increase in-memory storage requirements only on OS X.
We should also survey art suite code for other examples of the same phenomenon.