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

Subject: Re: [boost] [config] Using SD-6 macros
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2015-06-13 17:59:18

On 13.06.2015 21:44, Edward Diener wrote:
> On 6/13/2015 1:28 PM, John Maddock wrote:
>>
>> Unfortunately that's not quite true - sometimes you can't reliably
>> include a std lib header even when __has_include reports true as noted
>> above.
>
> You chided me for not being specific so now I will chide you. Please
> point out to me one case or more where the SD-6 implementation is buggy
> in this respect. I don't mean that the header is buggy, because that's
> something that config rightly deals with, but that __has_include tells
> you that a header exists where it does not.

One example is the <regex> header which existed in libstdc++ bundled 
with gcc 4.8 (not sure if it was added to earlier gcc versions) but was 
unusable until 4.9. Although gcc didn't support SD-6 in those versions, 
one could use clang with libstdc++.