I'm not sure if this issue is specific to kernel attributes or has wider applicability, but it can be difficult to understand whether host or device compilation is producing a given warning or error.

I'm most concerned about cases when only one of the compilers produces a warning, as below:

#include <CL/sycl.hpp>
using namespace sycl;

int main(int argc, char* argv[])
{
    queue q;
    q.submit([&](handler& cgh)
    {
        cgh.single_task<class test>([]() [[cl::intel_reqd_sub_group_size(8)]]
        {
        });
    });
}

reqd_sub_group_size.cpp:9:44: warning: 'intel_reqd_sub_group_size' attribute ignored [-Wignored-attributes]
        cgh.single_task<class test>([]() [[cl::intel_reqd_sub_group_size(8)]]
                                           ^
1 warning generated.

It is not clear from this message that the attribute was ignored on the host but respected on the device (or that this is expected behavior). Is there any way we could make this more obvious, like inserting the words "host" and "device" into the compilation output somewhere?