[PATCH] D17951: Implement is_always_lock_free

[Eric Fiselier via cfe-commits]

EricWF added a comment.

In http://reviews.llvm.org/D17951#376546, @bcraig wrote:

> Visual Studio has a flag, /Zc:wchar_t-, that turns wchar_t into a short.  This flag is for people that need to maintain ABI compatibility with ancient Visual Studios (MSVC6? MSVC5?).  It is definitely non-conformant, and many things support it poorly.
>
> I still have nightmares of supporting boost::filesystem users where boost::filesystem was built with real wchar_t, but clients tried to use it with wchar_t as short.  The linker generally disapproved of those shenanigans.
>
> I'm totally fine if libcxx doesn't try to support this situation... but if it did want to support it, it would need to selectively not define wchar_t.


+1 for libcxx not supporting that. I think there are plenty of places where this is already broken in libc++.


http://reviews.llvm.org/D17951