Function build_cpp_float_struct_di_node 

fn build_cpp_float_struct_di_node<'ll, 'tcx>(
    cx: &GenericCx<'ll, FullCx<'ll, 'tcx>>,
    float_ty: Ty<'tcx>,
    bits_ty: Ty<'tcx>,
    bits_names: &[&str],
) -> DINodeCreationResult<'ll>

float_ty must be a ty::Float and bits_ty must be a ty::Uint. cx.size_of(bits_ty) * bits_names.len() must equal cx.size_of(float_ty).