PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE (Ada RFC)

[Florian Weimer]

* Richard Kenner:

>      This is wrong (as discussed before) and is likely the cause of PR21573
>      (not VRP-related, the expanders for SWITCH_EXPR look at these
>      attributes, too).  I'm not sure if it is safe to delete these
>      assignment statmeents because TYPE_MIN_VALUE/TYPE_MAX_VALUE are used
>      quite extensively throught GIGI.
>
> Well, what *should* they be set to?  That is indeed setting them to the
> minimum and maximum values as defined by the language.

No, the language (or, more precisely, GNAT) defines them as 0 and
2**size - 1.  Otherwise the 'Valid attribute doesn't work.  Necessary
range checks will be optimized away, too.