[Cfp-interest 3031] Re: <math.h> macros and exceptions

[Jim Thomas]

Do we intend for the evaluation of any object-like macros defined in Clause 7 or Annexes F, G, H or K to raise a floating-point exception at execution time? If not, we might add that as a requirement in 7.1.2. See 7.1.2 #7 (in n3219).

> On Feb 11, 2024, at 9:58 AM, Fred J. Tydeman <tydeman at tybor.com> wrote:
> 
> On Wed, 7 Feb 2024 19:37:46 +0000 Rajan Bhakta wrote:
>> 
>>       Jim:  Are there any <math.h> macros with this issue?  Should words be added to an introduction section in <float.h>?
>>       ^Fred: Look into.
> 
> <math.h> macros that should not raise exceptions when evaluated:
> 
> HUGE_VAL, HUGE_VALF, HUGE_VALL, HUGE_VAL_D*
> INFINITY, DEC_INFINITY
> NAN, DEC_NAN
> 
> 
> Aside:  Should 7.12.1#5 (overflow) mention HUGE_VAL_D*?

Right. Perhaps change 

returns the value of the macro HUGE_VAL, HUGE_VALF, or HUGE_VALL according to the return type

to

returns the value of the macro HUGE_VAL suffixed according to the return type

which would cover the macros in Annex H too.

> 
> SNAN macro "requirement" is in a Recommended practice in F.2.1.

I think it's F.2.2 in n3219. It doesn't use “shall” or a form of “require”. Are you interpreting “raises” (in recommended practice) as a requirement?

> 
> FLTn_SNAN, DECn_SNAN, FLTnx_SNAN, DECnx_SNAN in H.3#6
> HUGE_VAL_Fn, HUGE_VAL_Dn, HUGE_VAL_Fnx, HUGE_VAL_Dnx in H.11.1
> 
> Aside:  5.2.4.2.2#22 mentions SNAN for translation time initializer,
> while H.3#6 mentions static or thread storage duration.

Good catch. I think it’s 5.2.5.3.2#28 in n3219. Is there any reason not to use the words in H.3#6 in both places? 

- Jim Thomas

> 
> 
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> Fred J. Tydeman        Tydeman Consulting
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