Hard error on Pytorch Cuda + Cuda toolkit version mismatch (#323)

setup.py

@@ -47,10 +47,9 @@ def check_cuda_torch_binary_vs_bare_metal(cuda_dir):
     print(raw_output + "from " + cuda_dir + "/bin\n")
 
     if (bare_metal_major != torch_binary_major) or (bare_metal_minor != torch_binary_minor):
-        # TODO:  make this a hard error?
-        print("\nWarning:  Cuda extensions are being compiled with a version of Cuda that does "
-              "not match the version used to compile Pytorch binaries.\n")
-    print("Pytorch binaries were compiled with Cuda {}\n".format(torch.version.cuda))
+        raise RuntimeError("Cuda extensions are being compiled with a version of Cuda that does "
+                           "not match the version used to compile Pytorch binaries.  "
+                           "Pytorch binaries were compiled with Cuda {}.\n".format(torch.version.cuda))
 
 if "--cuda_ext" in sys.argv:
     from torch.utils.cpp_extension import CUDAExtension