In an earlier commit, we took out the "-w" flag for CUDA builds, which
disables all compiler warnings. The original reason for disabling
warnings was an errant warning about unused functions. It was taken out
because the visual studio compiler complains when this flag overrides
another warning flag (such as /W3).
Although the visual studio compiler was not complaining about unused
functions, we were getting lots of other warnings. These warnings did
not seem to actually come from the visual studio compiler. They probably
come from whatever CUDA uses for a device compiler. But it is unclear
how to specifically target these warnings.
So, the easiest solution is to add the "-w" flag back. To get around the
other warning, we now (hopefully temporarily) remove warning flags from
CMAKE_CXX_FLAGS to prevent the conflicting flags.
c5e849981f