Re: Ada.Calendar.Formatting.Image (or Time_Of) changing the time

["Randy Brukardt" <randy@rrsoftware.com>]

"Optikos" <ZUERCHER_Andreas@outlook.com> wrote in message 
news:f94395b7-f2de-4c49-8edd-b24bfa64cc37@googlegroups.com...
>On Tuesday, March 3, 2020 at 5:49:35 PM UTC-6, Randy Brukardt wrote:
>> "Simon Wright" wrote in message
>> news:lyv9nl8p6w.fsf@pushface.org...
>> ...
>> > There was a conversation on Ada-Comment in June last year, in which it
>> > turned out that compiler implementers may have have been 
>> > misinterpreting
>> > the ARM. It was quite confusing.
>>
>> Not just a conversation, but also a Binding Interpretation AI (which
>> therefore applies to Ada 2012 compilers), AI12-0336-1.
>
>Shouldn't these Binding AIs that take effect from a past edition of the ISO
>standard onward (and not merely incorporated into Ada 2020 or Ada
>202X post-2020) ..be an ISO/IEC corrigendum..?  Allowing errata be
>permanently published semi-officially in any forum other than
>cummulatively in an official ISO/IEC corrigendum seems to be against the
>ISO/IEC rules.

Not necessarily. ISO has very strict limits on the number of Corrigenda that 
can be issued for a particular standard; after that the only choice is to 
update the Standard.

Remember that from ISO's perspective older standards don't actually exist; 
only the latest version is relevant to ISO. So the difference between 
non-Corrigendum Binding Interpretations and Amendments is non-existent to 
ISO.

But as a practical matter, people continue to use older standards and they 
need corrections (not allowing implementers to fix language bugs would be 
worse; why would anyone want to implement nonsense?). Such users need 
guidance as well, as do the implementers.

For ACATS purposes (which maintains testing all of the older standards 
except Ada 83), generally non-Corrigendum binding interpretations are 
optional for older standards, which means that either the original wording 
or the new wording is allowed. (We prefer the new wording, of course, but 
there's no mechanism to require it.) OTOH, Amendments are ignored for the 
purposes of testing older standards -- that's why we classify them 
differently.

                                                 Randy.