[libcpp] Correctly define __cplusplus (PR libstdc++-v3/1773)

[Marc Glisse]

On Tue, 9 Aug 2011, Jason Merrill wrote:

> On 08/09/2011 09:14 AM, Marc Glisse wrote:
>> I don't think we should define the C++ 2011 value yet. In my opinion, we
>> should wait until:
>> 1) the standard is official
>> 2) gcc implements most of it: people will want to use __cplusplus as a
>> test to know if they can use C++0X features, not if the compiler does
>> some effort to implement half of them.
>
> I'm of two minds about this, but I see that clang and edg still use 199711L 
> in C++0x mode, so let's stick with that for now.

Note that at least clang now defines __cplusplus to its new C++11 value 
(in experimental C++0X mode only). Apparently they switched around last 
June and say they are not the only ones. So if you want to follow their 
lead...

-- 
Marc Glisse