Re: -isoC-2017 patch

[Ingo Schwarze <schwarze@usta.de>]

Hi Maya,

maya@netbsd.org wrote on Fri, Jul 27, 2018 at 03:02:04PM +0000:
> On Fri, Jul 27, 2018 at 04:23:26PM +0200, Ingo Schwarze wrote:

>>   https://www.iso.org/standard/74528.html
>> 
>> seems to indicate the existence of a brand new standard called
>> 
>>   ISO/IEC 9899:2018
>>   Information technology -- Programming languages -- C
>> 
>> but i failed to find any evidence that an official standard
>> called ISO/IEC 9899:2017 might exist.
>> 
>> Can you provide a reference to such a standard?

> I was reading
> http://www.open-std.org/jtc1/sc22/wg14/www/abq/c17_updated_proposed_fdis.pdf

Aha.  That appears to be outdated.

> which is a draft and unofficial, so yours is more correct.
> (looks like a lot of s/17/18/ will have to be done elsewhere...)

Possibly.

>> Even if it does exist (or if you suggest s/17/18/), note that mandoc
>> does not aim to provide macro arguments for all the standards under
>> the sun.  A new major revision of the C programming language is no
>> doubt an excellent candidate for addition, but i would still welcome
>> solid evidence that it will actually see substantial use in practice.
>> 
>> Does the NetBSD base system implement the C18 standard, and are you
>> going to update all the relevant NetBSD manual pages to refer to it,
>> where appropriate?  How many manual pages, approximately, do you
>> expect will reference it in NetBSD in the short term?

> There's not going to be many references to it

That sounds like a strong argument to *not* add it.
There is value in keeping programming languages small (including
mdoc(7)) and avoiding the introduction of low-utility syntax.

> like C11

After looking at the draft, it seems to me that there will likely
even be fewer references to C18 than to C11, given that C11 did
define a small number of new features, which at least in theory
might get implemented and documented.

> because it doesn't add new things, only makes changes to existing
> stuff.

I see.

> I made the first reference to newer-than-C11 to document some change.

I'm not sure i understand that sentence.

You mean, so far, you committed one single change to one single
NetBSD manual page (which one?) using the new macro argument,
to document a change you committed to the NetBSD source code
(which source code commit specifically?).

> It's not critical, it just felt like the right change to do.

Foc comparison, we decided to not add -p1003.1-2017 because it
is not a new version of the standard but merely incorporates
technical corrigenda into -p1003.1-2008.

For the case of the C standard, if differences between C11 and C18
matter for a specific feature, i would consider recommending a
wording like the following:

The
.Fn foobar
function conforms to
.St -isoC-2011  \" or -isoC-99 or -ansiC where appropriate
including the corrections with respect to BARFOO applied by
ISO/IEC 9899:2018
.Pq Dq ISO C18 .

I expect such cases to remain rare.  If it turns out they become
very numerous, *that* would establish a reason to add a new macro
argument.

Does that make sense to you?

Yours,
  Ingo
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