Re: is_constant_evaluated

From: Robert Ramey (ramey_at_[hidden])
Date: 2021-08-05 19:42:52

On 8/5/21 12:52 AM, John Maddock via Boost wrote:
> On 05/08/2021 01:53, Andrey Semashev via Boost wrote:
>> On 8/5/21 2:14 AM, Gavin Lambert via Boost wrote:
>>> On 5/08/2021 7:03 am, Andrey Semashev wrote:
>>>> I might add that including <type_traits> just to test got a feature 
>>>> macro is not good.
> 
> No need for that - we already include <version> (which is lightweight) 
> and all that's needed in this case.  Both <version> and 
> is_constant_evaluated are C++20, so you're very unlikely to have the 
> latter without the former.
> 

OK - it's all crystal clear now ... NOT.  I don't see a consensus here.

I'm liking the idea of implementing boost::is_constant_evaluated() back 
to C++11 which a default value of false if there is not compiler 
support. Along with a boost config style feature macro so we'd have a 
unified model.

Personally, I've never found compile times to be a big problem. I'm not 
saying that there is no compile time cost - just that it doesn't seem so 
much that it's been worth worrying about.

Robert Ramey