I thought I've implemented all the sycl::vec specification changes under -fpreview-breaking-changes. Are you trying to fix things without preview?

The changes to align "preview" sycl::vec spanned several PRs and it was impossible to break everything into atomic independent patches, but I think #17722 was the one related to the std::byte the most.

And we enabled that (and other PRs') new implementation under -fpreview-breaking-changes in #18225.

On top of that, I believe we will be entering ABI breaking window for the next major release in a few weeks, when we'll "un-guard" those breaking changes and make them active by default without extra options.

Thanks for the pointers to the PRs! I might be missing something, but I don't see how these PRs enable the sycl::vec<std::byte> operators discussed in SYCL-Docs PR #674. The below code from the latest SYCL-CTS fails to compile, with and without -fpreview-breaking-changes when using release v6.2:

auto testVec1 = sycl::vec<std::byte, 1>(static_cast<std::byte>(1));
auto testVec2 = sycl::vec<std::byte, 1>(static_cast<std::byte>(2));
resVec = testVec1 == testVec2;

DPC++ release v6.2 used a version of SYCL-CTS (87f8677c), which did does test these sycl::vec<std::byte> operators. Again, I might be missing something, but I don't see support for these operators added in the commits since the v6.2 tag.

Using origin/sycl:

$ cat a.cpp                                                          
#include <sycl/sycl.hpp>                                             
                                                                     
int main() {                                                         
  auto testVec1 = sycl::vec<std::byte, 1>(static_cast<std::byte>(1));
  auto testVec2 = sycl::vec<std::byte, 1>(static_cast<std::byte>(2));
  auto resVec = testVec1 == testVec2;                                
}                                                                    

$ clang++ -fsycl a.cpp                                                                                           
a.cpp:6:26: error: use of overloaded operator '==' is ambiguous (with operand types 'sycl::vec<std::byte, 1>' and
      'sycl::vec<std::byte, 1>')                                                                                 
    6 |   auto resVec = testVec1 == testVec2;                                                                    
      |                 ~~~~~~~~ ^  ~~~~~~~~                                                                     
a.cpp:6:26: note: built-in candidate operator==(enum std::byte, enum std::byte)                                  
a.cpp:6:26: note: built-in candidate operator==(int, int)                                                        
...

$ clang++ -fsycl -fpreview-breaking-changes a.cpp
$

I've also checked that 6.2 release reports the same error in both default/preview modes indeed. I think 6.3 will include the fixes necessary though.

Okay, I haven't tried with commits beyond v6.2. Thanks for checking! Closing.