[PATCH] D14180: enable -fms-extensions by default on the mingw-w64 target

[Reid Kleckner via cfe-commits]

rnk added a comment.

> ! In http://reviews.llvm.org/D14180#280193, @martell wrote:

> 

> > You can then change the mingw headers to use `__has_builtin(_InterlockedCompareExchange)` to provide compatibility with either mode.

> 

> 

> Yes I could do this but this still won't work with the the existing mingw toolchains that don't have this in their headers right?

>  I can update head to support both though yes


I'm suggesting that we can make the builtins available in an MSVC environment, rather than making them available in an MS extensions environment. This should be compatible with old mingw headers, and then we can flip this default.


http://reviews.llvm.org/D14180