Re: What is the warning about builtin-function on gcc-4.6.0 ?

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

"Randy Brukardt" <randy@rrsoftware.com> writes:

> "Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
> news:wccsju8fptr.fsf@shell01.TheWorld.com...
>> But "EQUAL (ABS I, I)" can return False.  The test calls FAILED
>> (twice) if it does, so the test is wrong.
>
> Doesn't that depend on the implementation of EQUAL? It's just a function 
> call, it doesn't necessarily have the same semantics as "=". (I think the 
> intent is that the result is the same as "=" for valid values, but I doubt 
> anything is guaranteed about invalid values.)
>
> The actual implementation of EQUAL is full of recursion (it's intended to be 
> an optimization blocker), and it's hard to tell whether or not one of the 
> inner calls would cause some other results for invalid values (such as 
> raising Constraint_Error).
>
> And if it didn't do that, the implementor could change the function to 
> include 'Valid on the operands to ensure that they're not invalid.

Sure, EQUAL can raise C_E on invalid values.
But I don't think it can return True for invalid values
that are not mathematically equal.  (If it can, I think it's
a mistake in the REPORT package.)  I'm too lazy to inspect it
right now.

Has EQUAL changed since Ada 83 days?  Just curious.

> I suspect that there are lot of tests that might fail if the rules for valid 
> values are taken to the limit -- any test that intentionally raises an 
> exception is always at risk for optimization problems (and that is what 
> 13.9.1 is ultimately about).

Yes, and I'll bet an agressive implementation of 11.6 would find some
wrong ACATS tests.

- Bob