diff -Naur c:\blender-git\blender\extern\Eigen3/Eigen/src/Core/arch/SSE/PacketMath.h k:\BlenderGit\blender\extern\Eigen3/Eigen/src/Core/arch/SSE/PacketMath.h
--- c:\blender-git\blender\extern\Eigen3/Eigen/src/Core/arch/SSE/PacketMath.h	2018-05-25 13:29:14 -0600
+++ k:\BlenderGit\blender\extern\Eigen3/Eigen/src/Core/arch/SSE/PacketMath.h	2018-05-26 19:56:36 -0600
@@ -335,7 +335,7 @@
 template<> EIGEN_STRONG_INLINE void prefetch<double>(const double* addr) { _mm_prefetch((const char*)(addr), _MM_HINT_T0); }
 template<> EIGEN_STRONG_INLINE void prefetch<int>(const int*       addr) { _mm_prefetch((const char*)(addr), _MM_HINT_T0); }
 
-#if defined(_MSC_VER) && defined(_WIN64) && !defined(__INTEL_COMPILER)
+#if defined(_MSC_VER) && defined(_WIN64) && !defined(__INTEL_COMPILER) && !defined(__clang__)
 // The temporary variable fixes an internal compilation error in vs <= 2008 and a wrong-result bug in vs 2010
 // Direct of the struct members fixed bug #62.
 template<> EIGEN_STRONG_INLINE float  pfirst<Packet4f>(const Packet4f& a) { return a.m128_f32[0]; }