message: fix bug in promote cast policy: use bfloat16 instead of fp16
diff: @@ -118,7 +118,7 @@ struct CPU_WrapFunction_<DtypeCastPolicy::promote, Redispatch, F, Ret,
  guts::typelist::typelist<Args...>> {
  static Ret call(Args... args) {
  c10::impl::ExcludeDispatchKeyGuard no_autocastCPU(DispatchKey::AutocastCPU);
  - auto to_type = promote_type(at::kHalf, args...);
  + auto to_type = promote_type(at::kBFloat16, args...);
  return (*F)(cpu_cached_cast(to_type, args)...);
  }
  };
  