Re: ACATS c460008 and VRP (was: Bootstrap failure on trunk: x86_64-linux-gnu)

[Laurent GUERBY <laurent at guerby dot net>]

On Wed, 2006-03-01 at 18:48 -0500, Richard Kenner wrote:
>     It looks like this one needs overflow checking to pass (-gnato):
> 
> ACATS should aways be run with -gnato since that's the only way to
> get the behavior mandated by RM.  Why are we running it without it?  Is
> this new?  Certainly -gnato was used during validations.

On GCC we use -gnato on tests known to need it
(/gcc/testsuite/ada/acats/overflow.lst) since we want to test
flags the typical GCC/Ada user does use and not what official validation
requires (which is -gnato -gnatE IIRC).

VRP might now force us to update the overflow list but I'm not sure
about switching to a full -gnato everywhere.

>     Richard, Arnaud, could you check amongst GNAT experts if for such
>     types (non power of two modulus), it's not worth enabling overflow
>     checks by default now that we have VRP doing non trivial
>     optimisations? People using non power of two modulus are not caring
>     for performance anyway, so having a compliant implementation by
>     default won't harm.
> 
> Hardly worth writing the code to bother with that given how rare
> such things are ...

True.

Laurent