Re: [boost] C++17 detection

Subject: Re: [boost] C++17 detection
From: Robert Ramey (ramey_at_[hidden])
Date: 2017-09-14 14:36:42

On 9/14/17 2:27 AM, John Maddock via Boost wrote:
> 
>>>> Boost.Config actually uses the feature testing macros when available
>>>> and when applicable (in combination with other things, i.e. an
>>>> understanding of what the C++ implementation in question actually is
>>>> known to support, regardless of what it advertises). Using the feature
>>>> testing macros alone may not be what you want.
>>> I'd be happy to used Boost.Config - that's where I looked first.  But I
>>> don't see what I need in there.
>>>
>> Pull requests are welcome.
> 
> Indeed, or file a feature request.

Hmmm - the problem is i'm already two interrupt levels below where I 
really want to be.  So I was hoping for an existing fix that I didn't 
really have to think about.  If something that starts out seeming 
trivial often end up sucking up a bunch of unanticipated time.

> Note that historically Boost.Config has never added new macros unless 
> there is demand from within Boost.
> 
> And while it's true that we have been laggardly in adding C++17 feature 
> macros, so far no one has ever asked for them either... not once till now.
> 
> BTW, what I'm missing from this discussion, is exactly what C++17 
> features you are actually interested in?

BOOST_NO_CXX17_STD_IS_DETECTED

According to http://en.cppreference.com/w/cpp/experimental/is_detected

it's currently in <experimental/type_traits> as part of library 
fundamentals v2.  I had mistakenly thought it was slated for C++17.  So 
maybe it's not appropriate to include in Boost.Config yet.

Robert Ramey