title: "Caffe2 building failed"
body: <p>When I execute the instructions "build_windows.bat" for building Caffe2, there is a huge problem.</p>
  
  <pre><code>"D:\caffe2\caffe2\build\ALL_BUILD.vcxproj" (default target) (1) -&gt;
  "D:\caffe2\caffe2\build\caffe2\caffe2.vcxproj" (default target) (5) -&gt;
  (ClCompile target) -&gt;
    D:\caffe2\caffe2\caffe2\operators\mod_op.cc(38): error C2668: "signbit": ??????????? [D:\caffe2\caffe
  2\build\caffe2\caffe2.vcxproj]
  
  
  "D:\caffe2\caffe2\build\ALL_BUILD.vcxproj" (default target) (1) -&gt;
  "D:\caffe2\caffe2\build\modules\detectron\caffe2_detectron_ops_gpu.vcxproj" (default target) (7) -&gt;
  (CustomBuild target) -&gt;
    D:/caffe2/caffe2/modules/detectron/softmax_focal_loss_op.cu(80): error : calling a __host__ function(
  "pow&lt;double, float&gt; ") from a __global__ function("caffe2::_NV_ANON_NAMESPACE::SoftmaxFocalLossKernel")
   is not allowed [D:\caffe2\caffe2\build\modules\detectron\caffe2_detectron_ops_gpu.vcxproj]
    D:/caffe2/caffe2/modules/detectron/softmax_focal_loss_op.cu(80): error : identifier "pow&lt;double, floa
  t&gt; " is undefined in device code [D:\caffe2\caffe2\build\modules\detectron\caffe2_detectron_ops_gpu.vcx
  proj]
  4310 Warning(s)
  3 Error(s)
  </code></pre>
  
  <p>Time Elapsed 01:02:49.30
  "Caffe2 building failed"</p>
  
  <p>It seems that there are lots of errors and I hope u guys could help me!
  Thanks a lot!</p>