[Cfp-interest 2139] Re: (SC22WG14.18377) Comments on N2561 (TS 18661-3 as Annex update)

[Joseph Myers]

On Sat, 26 Sep 2020, Jim Thomas wrote:

> Here is a link to an N2561 update which is awaiting an N-number. Changes 
> are in response to Joseph Myers’s comments below. The link is into the 
> CFP wiki. Contact me if you need login information.

> >> On Sep 10, 2020, at 4:30 PM, Joseph Myers <joseph at codesourcery.com> wrote:
> >> 
> >> Some comments on N2561 (TS 18661-3 as Annex update - note that 
> >> http://www.open-std.org/jtc1/sc22/wg14/www/wg14_document_log.htm has the 
> >> descriptions for N2558 and N2561 swapped), where it deviates from the 
> >> original TS and subsequent CR resolutions:
> >> 
> >> * This version introduces changes to default argument promotions for 
> >> _Float16, _Float32 and _Float64.  This is a bad idea.  To quote again the 
> >> response to DR#206: "real float promotion to double is in Standard C 
> >> purely for compatibility with K&R. Since complex is new, that 
> >> compatibility is not an issue, and having it behave like real float would 
> >> introduce undesired overhead".  Exactly the same reasoning as for _Complex 
> >> float applies for these new types: they didn't exist in K&R C, so there is 
> >> no need for promotion when passed in variable arguments, and it's more 
> >> efficient not to promote them (as well as allowing for the possibility of 
> >> a signaling NaN being passed as-is by a copy operation, which cannot 
> >> happen when promoted).

I'd like to check on the status of the fix for this.  A discussion on the 
liaison list drew my attention to the fact that N2601, the most recent 
version of TS 18661-3 as Annex, still included those promotions, and I'm 
not aware of any subsequent paper removing them from the Annex.

The September 2020 CFP minutes 
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2584.pdf and the October 
2020 CFP minutes http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2615.pdf 
included an action item to remove those promotions.  As far as I can see, 
while the slide deck 
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2578.pdf has those 
promotions struck out on the last slide, the actual proposed Annex text 
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2579.pdf and the 
subsequent version 
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2601.pdf don't reflect 
that.  Did CFP change their mind (I don't see anything relevant in 
subsequent minutes), or should this be handled through a subsequent paper?

-- 
Joseph S. Myers
joseph at codesourcery.com