Re: [boost] [config] Using SD-6 macros

Subject: Re: [boost] [config] Using SD-6 macros
From: Stephen Kelly (hello_at_[hidden])
Date: 2015-06-12 18:54:04

Edward Diener wrote:

> On 6/12/2015 12:06 PM, John Maddock wrote:
> Some of it, although very clever, seems like educated "guesswork". Isn't
> it better if the compiler tells us what is omplemented ?

For come compiler versions/cxx features the answer is no: For some Clang 
releases which support SD-6 macros, they didn't implement the SD-6 macro 
for 
features which they documented as available. 

In some cases, they implemented the __has_feature macro for a feature but 
not the SD-6, and in other cases vice-versa. 

> About what std lib features are you speaking ? Most of the things I see
> at
> https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
> are predefined. Are you saying that because the compiler implementations
> of SD-6 most likely have to include standard library headers in order to
> implement SD-6 correctly that we should avoid using SD-6 ?

The reason for this is literally that the chair of SG-10 didn't want to 
require the stdlib implementor to have to open another file in their editor 
to add the macro there.

 http://thread.gmane.org/gmane.comp.lang.c++.isocpp.features/17/focus=22

I get headaches thinking of all the reasons that that's absurd.

Thanks,

Steve.