Re: Elaboration order handling (Was: Bug in 'gnatmake')

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Adam Beneschan <adam@irvine.com> writes:

> On Wednesday, June 19, 2013 5:57:35 PM UTC-7, Robert A Duff wrote:
>
>> And with standard Ada, it's even worse: the order can change for any
>> reason, or for no reason.  The implementation is allowed to roll dice
>> to determine the order!  Even running the exact same program without
>> recompiling could change order!
>
> You say that like it's a bad thing.

Yes, I do.  ;-)

> Actually, I can see a use for a compiler option to use a random number
> generator to determine the elaboration order (or other things that are
> implementation-dependent), because if the program relies on the order
> when it shouldn't, a random order will increase the chance that
> repeated testing will expose the problem.

Yes, I agree that would be useful.  But only as an option, and only
for testing.

It would be a useful option even if Ada were designed as I've been
saying it should (such that elaboration order is
deterministic/portable).  If the rule was "lexicographic order",
as I have suggested, I still don't think programmers should
depend on lexicographic order, and this option could help
prevent that.

- Bob