bit_size_type - a data type?

[Richard Kenner]

> bitsizetype is a type that can hold any values of sizetype *
> BITS_PER_UNIT so we can safely do bit-size calculations without overflow.
> This type shouldn't end up used in code though.

Unfortunately, it does, though not in C.  Ada's 'Size attribute returns
the size in bits, so the proper type for that computations is bitsizetype,
though many computations end up being constant-folded.