I know that the C and C++ standards leave many aspects of the language implementation-defined just because if there is an architecture with other characteristics, it would be very difficult or impossible to write a standard conforming compiler for it.
I know that 40 years ago any computer had its own unique specification. However, I don't know of any architectures used today where:
CHAR_BIT != 8
Take a look at this one
offering backward compatibility for people who have not yet migrated all their Univac software.
CHAR_BIT == 9
sizeof(char*) != sizeof(int*)
Don't know if they offer a C++ compiler though, but they could.