[cfe-dev] [libcxx] RFC: C++14 and beyond

[Richard Smith]

On Tue, May 7, 2013 at 11:37 AM, Howard Hinnant <hhinnant at apple.com> wrote:

> So I'm thinking along these lines in <__config>, below where platforms
> customize things:
>
> #ifndef _LIBCPP_STD_VER
> #  if  1 // -std=c++98/03/11
> #    define _LIBCPP_STD_VER 11
> #  elif 0 // -std=c++1y/14
> #    define _LIBCPP_STD_VER 13  // current year, or date of std
> ratification
> #  elif 0 // -std=c++17
>    // ...
> #  endif
> #endif  // _LIBCPP_STD_VER
>
> I can't make this work today because I can't tell the difference between
> -std=c++98/03/11 and -std=c++1y/14.
>
> If the client (or platform) desires, they can #define _LIBCPP_STD_VER and
> to whatever they want and <__config> will respect their definition.
>
> libcxx implementors can:
>
> #if _LIBCPP_STD_VER > 11
>
> // implement a post C++11 feature
>
> #endif
>
> The clang driver could be taught how to set _LIBCPP_STD_VER.
>
> Thoughts?  Help on telling the difference between -std=c++98/03/11 and
> -std=c++1y/14?


There's been some discussion on the -admin reflector about what value we
should use for __cplusplus, but it didn't reach anything that looked like
consensus. How about we use 201305L (ie, now) as the value for __cplusplus
for our c++1y mode for the 3.3 release, and you key off __cplusplus >
201103L ?
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