VTKM_ASSERT should be defined at configure
The assert macro is installed with the same macro logic as used to build vtk-m. The result of this is that it is possible to install vtk-m in release mode, where the the assert definition is not used. In a downstream library, its possible that I build it in Debug. Now we are compiling the same function twice, one in vtkm and one in the downstream library, that contains different code.
I think the vtk-m assert macro should be defined by cmake, so that this is not possible.