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

[Adam Beneschan <adam@irvine.com>]

On Mar 29, 11:35 am, Robert A Duff <bobd...@shell01.TheWorld.com>
wrote:

> > 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.

The version of Report's body I'm looking at is from 3/29/01, but the
comments don't indicate any changes to EQUAL since the first version.
EQUAL can't propagate C_E because it has an exception handler for it:
it just reverts to "return X = Y" if any exception is raised.  If the
compiler's behavior is incorrect and doesn't raise C_E for
abs(Integer'First) when it's supposed to, then presumably
abs(Integer'First) will still be Integer'First (on a normal 2's
complement machine), and EQUAL will return TRUE.  [If the compiler did
something interesting like reserving a bit pattern like 16#8000# or
16#80000000# to be an invalid integer, then Integer'Last would be -
Integer'First and the interesting part of C45632A would never be
executed due to the first IF.]

                                     -- Adam