[LLVMdev] C++14 support for shared_mutex

[Nathan Wilson]

On Jun 8, 2015 10:53 PM, "Edward Diener" <eldlistmailingz at tropicsoft.com>
wrote:
>
> On 6/8/2015 10:10 PM, Tim Northover wrote:
>>
>> On 8 June 2015 at 17:53, Edward Diener <eldlistmailingz at tropicsoft.com>
wrote:
>>>
>>> How can I tell at compile time through predefined macros whether libc++
>>> includes/supports the C++14 header file shared_mutex ?
>>
>>
>> I doubt it's even theoretically possible. Clang can be used with
>> multiple standard libraries, and there's no real way for it to know
>> just what you're compiling against (even if it knows in general terms
>> that it's libc++).
>
>
> I am not talking about clang, I am talking about libc++. Is this the
correct mailing list to ask a question about libc++ or is there a better
one ? I did not see a separate llvm mailing list for libc++.

I see Marshall's commits and review requests directed toward the cfe-dev
list with libcxx in the subject. So, you loop them in or try that mailing
list.

>
>
>>
>> On a tightly controlled platform like OS X you might find a mostly
>> reliable proxy like the clang version (though people trying to use an
>> updated libc++ may curse you for it).
>
>
> I can tell "in general terms that it's libc++". The Boost.config headers
can know that from the macro _LIBCPP_VERSION. Once I can tell, you are
saying that there is no reliable way to tell whether libc++ supports
shared_mutex, which is currently a completely valid C++14 header file and
implementation ? That seems pretty poor of libc++. I don't mean to be
critical but I think that a good standard library creates predefined values
so that what can tell what is being offered in that library for any given
release. You can't wait until run-time to include a header which may not be
there.
>
> I don't want to check anything in clang because, as I understand it,
libc++ can be and is being used by compilers other than clang. So I would
assume that either _LIBCPP_VERSION or some other macro connected with
libc++ should tell me at compile time if shared_mutex is supported.
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150608/c3cf951e/attachment.html>