Subject: Re: [boost] [config] Configuring for C++14 and later library features.
From: John Maddock (jz.maddock_at_[hidden])
Date: 2015-04-24 13:40:13
>> This doesn't look acceptable to me, but what to do? The only solution I
>> can see is to simply not support these features in Boost.Config, but
>> rather rely on users needing these features checking the std detection
>> macros directly. Which will work up until someone implements a feature
>> without defining the appropriate macro :(
> You could just define the macro based on compiler version. That could be
> backed by a test which not only checks for __cpp_lib_integer_sequence but for
> std::integer_sequence itself.
Compiler version is irrelevant, it's the std lib that matters. I think
for most std lib's, yes we could use existing machinery to check this,
I'm not sure about clang/libc++ though - _LIBCPP_VERSION appears to be
stuck at 1101 and the clang version number is notoriously unreliable.
Any clang experts confirm this?
> PS: I thought it was enough to include any STL header (e.g. cstddef) to get
> all these macros defined. Isn't it the case? How would one test for a feature
> that is implemented in a new header?
Please see the paper linked to, but basically it suggests using
__has_include(<name>). Of course technically, none of this is in the
standard, rather it's contained in an ever changing "standing document".
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk