More on type sizes

[Richard Kenner]

    P.S.: Chill uses bit arrays. For these, the elements have a TYPE_SIZE
    (of one), but no TYPE_SIZE_UNIT.  

What code handles these?  Other languages (such as Ada) could benefit from
that, and I'd like to support it fully sometime, but what code handles it?

    Incidentally, the TYPE_SIZE of these elements is integer_size_node,
    which is still wrong, since it has integer_type_node as type - this
    should be converted to bitsizetype.

Yes, that's certainly wrong.  How did it happen?  Does the front end set
TYPE_SIZE?  That almost always sounds wrong to me: only layout_type
should be setting it.