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

[Robert Dewar]

Richard Kenner wrote:
>     If this still doesn't convince you, here's an example which doesn't
>     use Ada.Unchecked_Conversion at all.
> 
> Well sure, reading an uninitialized value is erroneous except for the use
> of 'Valid.

That is wrong, it is a bounded error. and of course validit checks must
work as described in the ghnat rm.
> 
> I'm not saying that things aren't broken, just being very careful in the
> definition of what a "valid" value in an object is.  The point is that these
> values are not "valid" (which is why 'Valid returns FALSE) and that the
> compiler (specifically VRP) is *correct* in deducing that the values are
> in the valid range of the type *except* for 'Valid and range checks.

right, but range ckecks for validity checking arr crucial
> 
> Those checks need to be done another way, such as by using the "base type".
> The issues with that have to do with debug output, representation within
> Gigi, and whether the NOP_EXPRs that would have to be used to implement
> that will be maintained.

the are done with the base type now!