[Ada] Expansion of Ada2012 predicate checks for type conversions

[Robert Dewar]

On 8/18/2011 5:33 AM, Arnaud Charlet wrote:
>>> 2011-08-05  Ed Schonberg<schonberg@adacore.com>
>>>
>>> 	* exp_ch4.adb (Expand_N_Type_Conversion): When expanding a
>>> 	predicate
>>> 	check, indicate that the copy of the original node does not come from
>>> 	source, to prevent an infinite recursion of the expansion.
>>
>> For ChangeLog entries we usually, and per the GNU Coding Conventions,
>> do not provide the "Why?", just the "What?".
>
> Yes we know about this and we'll have unfortunately to disagree on this one: we
> very strongly believe at AdaCore and for GNAT development that mentioning the
> why is much more useful than just the what and insist on doing so in our
> changelogs, rather than having to refer to separate emails for understanding
> a change.
>
> Having such detailled changelogs is very useful in practice to maintain code
> and modify it, at least that's our experience.
>
> So in other words, we find this GNU Coding Conventions a bad practice, and
> insist on not following it, intentionally.

to add to this a bit. We do agree that having the "why" only in the 
changelog and not in the code is a bad idea. Indeed, it is critical
that the code contain full comments (often for instance, critical
comments are what you are NOT doing and why, this is one respect in
which code can never be self documenting).

I fully understand the concern about people using revision histories
as a substitute for proper code comments. We never let that happen in
the GNAT case, part of our review process ensures that any missing
comments in the source get fixed before an FSF checkin.
>
> Arno