From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,ecc38b3271b36b88
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!nx02.iad01.newshosting.com!newshosting.com!newsfeed.neostrada.pl!unt-exc-01.news.neostrada.pl!newsfeed01.sul.t-online.de!t-online.de!news.belwue.de!LF.net!news.enyo.de!not-for-mail
From: Florian Weimer <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
Subject: Re: What is the warning about builtin-function on gcc-4.6.0 ?
Date: Sat, 26 Mar 2011 18:02:01 +0100
Message-ID: <8762r5hl2u.fsf@mid.deneb.enyo.de>
References: <b7736fb9-8593-47cc-9ac5-58a95ff6be5f@34g2000pru.googlegroups.com>
	<87aagiclte.fsf@mid.deneb.enyo.de>
	<475d10ca-5d4e-490c-9b88-e12cd3cd3faa@b13g2000prf.googlegroups.com>
	<87d3lejjyv.fsf@mid.deneb.enyo.de>
	<6c748f70-7e75-49b4-a467-d1d2d6b24323@w9g2000prg.googlegroups.com>
	<m2d3leey0k.fsf@pushface.org> <87k4flhoeg.fsf@mid.deneb.enyo.de>
	<m28vw1g7wf.fsf@pushface.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: ruchba.enyo.de 1301158921 20273 172.17.135.6 (26 Mar 2011 17:02:01
 GMT)
X-Complaints-To: news@enyo.de
Cancel-Lock: sha1:mHBL1CbvKiCUQdEyvNgARyjwc1g=
Xref: g2news2.google.com comp.lang.ada:19444
Date: 2011-03-26T18:02:01+01:00
List-Id: <comp.lang.ada>

* Simon Wright:

> Florian Weimer <fw@deneb.enyo.de> writes:
>
>> * Simon Wright:
>>
>>> ytomino <aghia05@gmail.com> writes:
>>>
>>>> nn...then, there are no function to take infinity and NaN...
>>>
>>> 'Valid should do the trick.
>>>
>>>    FP_Value := 1.0 / 0.0;
>>>    if FP_Value'Valid then
>>>       --  it won't be
>>
>> This is a compiler bug.
>
> I don't understand what you mean.

The standard requires that FP_Value'Valid is true.

> If the compiler doesn't raise an exception on division by zero (it's
> allowed not to, and GNAT doesn't) it will (in this case) set the result
> to +Inf, and 'Valid will return False.

My understanding is that an implementation must either raise
Constraint_Error, or the evaluation of an expression must result in a
valid value.