Re: boost::math::tools::promote_args not works with C++23 FP-types

From: John Maddock (jz.maddock_at_[hidden])
Date: 2023-02-19 17:04:37

On 19/02/2023 14:48, Gero Peterhoff via Boost wrote:
> Hi,
> promote_args from <boost/math/tools/promotion.hpp> not works with 
> new/extended C++23 FP-types
> https://godbolt.org/z/13fq8a3d7
>
> The problem might be the outdated "manual variadic" implementation for 
> C++03. Well, according to the documentation 
> (https://www.boost.org/doc/libs/1_81_0), boost::math requires C++11 
> anyway; with a switch to C++11 it also works (std::common_type).

I'm not surprised by this, and we will probably need to fix Config first 
and also have a working (ie released) C++23 compiler too.

The problem line is here: 
https://github.com/boostorg/math/blob/1c5194f3c36826db4e18ba52e7e601bae002c31d/include/boost/math/tools/promotion.hpp#L77 
where we assume that std::is_floating_point implies one of the 3 types 
we know about.

John.