[cfp-interest 3411] Re: [SC22WG14.29686] WG14 2025/02 meeting action item: CFP to look at N3447's change 3.2, addition 50'

[Jim Thomas]

The addition for (informative) Annex J is intended to be an implication of what is already in 6.6.1 #5. It, per se, shouldn't have any effect on what users can safely do.

I think Joseph’s idea to change the “shall be” to “is” in 6.6.1 #5 (and not add anything to Annex J) is reasonable. This suggests a broader effort to eliminate all uses of “shall” and “shall not” that apply to implementations instead of users. Rajan, did you say that effort was in progress?

- Jim Thomas


> On Mar 12, 2025, at 9:49 AM, RAJAN BHAKTA <rbhakta at us.ibm.com> wrote:
> 
> In case people are not on the WG14 reflector.
>  
> Regards,
> 
> Rajan Bhakta
>  
>  
> From: owner-sc22wg14 at open-std.org <owner-sc22wg14 at open-std.org> on behalf of Joseph Myers <josmyers at redhat.com>
> Date: Wednesday, March 12, 2025 at 11:40 AM
> To: RAJAN BHAKTA <rbhakta at us.ibm.com>
> Cc: ISO C <sc22wg14 at open-std.org>
> Subject: [EXTERNAL] [SC22WG14.29686] WG14 2025/02 meeting action item: CFP to look at N3447's change 3.2, addition 50'
> 
> On Wed, 12 Mar 2025, RAJAN BHAKTA wrote:
> 
> > We suggest using the following wording instead:
> > 
> > (50’) A floating expression is evaluated in the translation environment 
> > with less arithmetic range or precision than if the expression were 
> > being evaluated in the execution environment.
> 
> The effect of that would seem to be that no program can safely use 
> floating-point expressions in constant expressions at all, in case the 
> implementation chooses to evaluate with less range or precision and so 
> give them undefined behavior.
> 
> I think we need a demons or ghosts paper to replace this "shall be" (in 
> 6.6.1) by "is" (or some similar change), since if there is UB here, there 
> should not be; the implementation should not be permitted to use less 
> range or precision in the translation environment.
> 
> -- 
> Joseph S. Myers
> josmyers at redhat.com
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