No friction when compiling with Clang on Mac OSX.

[erwincoumans]

Create project files using cmake on Mac OSX using clang, and friction appears to be broken.

See also discussion here:
http://bulletphysics.org/Bullet/phpBB3/posting.php?mode=reply&f=9&t=9851

[erwincoumans]

Jens wrote:

"Just look like i solved this problem in Blender.
Problem is inlining in btSolverBody.h

#ifdef USE_SIMD

struct  btSimdScalar
{
    SIMD_FORCE_INLINE   btSimdScalar()
    {

    }
/* workaround for clang 3.4 ( == apple clang 5.1 ) issue, friction would fail with forced inlining */
#if (defined(__clang__) && defined(__apple_build_version__) &&  (__clang_major__ == 5) && (__clang_minor__ == 1)) \
|| (defined(__clang__) && !defined(__apple_build_version__) && (__clang_major__ == 3) && (__clang_minor__ == 4))
    inline __attribute__ ((noinline)) btSimdScalar(float    fl)
#else
    SIMD_FORCE_INLINE   btSimdScalar(float  fl)
#endif

Perhaps not the root problem ( compiler bug or strictness ? )

Cheers ... Jens"

[erwincoumans]

This commit seems to be a work-around for the Clang
907ac49
If I have time, I will create a repro case for Clang/LLVM developers (unless they already fixed it)