[cfp-interest 3836] Re: Annex H.13#4

[Jim Thomas]

> On Mar 24, 2026, at 2:06 PM, Damian McGuckin <damianm at esi.com.au> wrote:
> 
> 
> 	Use of the macros carg, cimag, conj, cproj, or creal with any
> 	argument of standard floating type, binary floating type, or
> 	complex type invokes a complex function. Use of the macro with an
> 	argument of a decimal floating type results in undefined behavior
> 
> Why does the C standard mandate a function be called?

Annex H extends the specification in the main standard where all the tgmath macros invoke functions. 

> It seems overly
> restrictive.

How?
> 
> Also, I would prefer the second sentence say
> 
> 	The use of a macro with a decimal floating type argument is
> 	undefined behavior,
> OR
> 	The use of a macro with an argument of decimal floating type is
> 	undefined behavior,
> 
> because the currently might be confused with the concept of "decimal floating
> type result".

The standard has no instances of “is undefined behavior”. It says “results in undefined behavior” in various contexts. Use of the macro is not undefined behavior per se.

- Jim Thomas

> 
> Thanks - Damian
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