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

[Richard Smith]

On Tue, May 7, 2013 at 11:56 AM, Howard Hinnant <hhinnant at apple.com> wrote:

> On May 7, 2013, at 2:52 PM, Richard Smith <richard at metafoo.co.uk> wrote:
>
> > 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 ?
>
> That sounds fine with me.  If there's any political problems with that,
> using a "throw away" macro (e.g. __experimental_1y, _MAKE_HOWARD_HAPPY) or
> whatever would be fine too.  :-)  libcxx can adapt to changing clangs.


Done.
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