[Cfp-interest] Fwd: (SC22WG14.14921) Floating-point DR#13 and integer arguments to type-generic macros

[Jim Thomas]

We’ll add this issue to the agenda for the Feb 20 teleconference.

- Jim Thomas

> Begin forwarded message:
> 
> From: Joseph Myers <joseph at codesourcery.com>
> Subject: (SC22WG14.14921) Floating-point DR#13 and integer arguments to type-generic macros
> Date: February 12, 2018 at 9:46:11 AM PST
> To: <sc22wg14 at open-std.org>
> 
> I believe these comments all still apply to the version of the DR 
> resolution in N2202: it still determines a type, but says nothing about 
> what function is determined from that type (needed to cover dadd(f, f) 
> which needs to call daddl to stay compatible with TS 18661-1, for example 
> - the type determined is float, but what function is determined from it?).
> 
> -- 
> Joseph S. Myers
> joseph at codesourcery.com
> 
> On Thu, 23 Nov 2017, Joseph Myers wrote:
> 
>> Looking at the latest proposed DR resolution 
>> <http://wiki.edg.com/pub/CFP/WebHome/tgmath_for_narrowing_functions-20171117.pdf>:
>> 
>> This resolution changes text that partially determines a function called 
>> by type-generic macros such as dadd, to text that determines a type.  Does 
>> it then result in a call to a function whose parameters have that type?  I 
>> don't see anything saying so, but it's possible I've missed some text in 
>> the complicated sequence of (C11 amended by 18661-1 amended by 18661-2 
>> amended by 18661-3 amended by DR#9 amended by DR#13 as modified by this 
>> proposed change to the resolution of DR#13).
>> 
>> In any case, there needs to be *something* about choosing a function whose 
>> arguments have a wider type than the one determined from the types of the 
>> arguments (subject to whatever's needed to keep things well-defined in the 
>> case of integer arguments, if desired), because of the dadd(f, f) case, 
>> which is clearly specified in TS 18661-1 to call the function daddl, and 
>> is included as an example there - as there isn't any dadd function with 
>> float or double arguments.  A correction to TS 18661-3 should not have the 
>> effect of invalidating something that was valid with TS 18661-1.
>> 
>> -- 
>> Joseph S. Myers
>> joseph at codesourcery.com

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