Cannot use custom type in kernel

Hello,

I am unable to use a custom type in my OpenCL kernel, passing it by value (error: unsupported kernel argument type. This problem arises in compilation time). I found a solution in this question https://forums.intel.com/s/question/0D50P00004Nr1jn/emulation-fails-with-userdefined-data-type-for-a-kernel-argument, which tackles the problem passing a pointer and setting the address qualifier __global. I would rather stay with the passing by value version, due to some application constraints. I am using Intel FPGA SDK for OpenCL 16.1. Is there other way to overcome this issue instead of this ugly trick?

Just in case it helps you, I reproduced the problem with a minimal kernel:

typedef struct {
     char a;
     char b;
 } error_type;
  
__kernel void min_kernel(error_type err_data) {
     err_data.a = 'a';
     err_data.b = 'b';
}

Thank you.