[SYCL] Bug in SYCL header path

[AidanBeltonS]

Describe the bug
A truncated version of the sycl.hpp path works when it should not. It should only be able to find the header with sycl/sycl.hpp.
Bug found when adding test to #6769.

To Reproduce
Compile the below cpp file with the -fsycl option. This should not compile as the include path should be sycl/sycl.hpp, however it does successfully find the file path.

Build llvm as normal.
Set environment paths

export PATH=$PATH_TO_LLVM/build/bin:$PATH
export LD_LIBRARY_PATH=$PATH_TO_LLVM/build/lib:$LD_LIBRARY_PATH

Create source file test_file.cpp

#include <sycl.hpp>

int main () {
  sycl::queue Q;

  return 0;
}

Compile file, this will compile when it should not be able to find the sycl.hpp path.

clang++ -fsycl test_file.cpp

Environment (please complete the following information):

• OS: Linux, Ubuntu
• Target device and vendor: Intel CPU/GPU
• DPC++ version: commit c7289d0

[bader]

@intel/dpcpp-clang-driver-reviewers, I suppose clang driver adds additional include paths or system paths, where SYCL headers is found w/o additional directory prefix. Could you take a look, please?

[mdtoguchi]

By default, the driver will add bin/../include/sycl as a search directory. This has basically always been in place. Should this no longer be the case?

[bader]

I see following:
"-internal-isystem" "bin/../include/sycl"
"-internal-isystem" "bin/../include"

I think we added "bin/../include/sycl" to enable #include <CL/sycl.hpp>, but it has a side effect, which described in this issue. To fix we probably should deploy CL directory to include rather than include/sycl and after that we can remove "-internal-isystem" "bin/../include/sycl".

[keryell]

It would be interesting to have a test checking that if we have a user-provided sycl.hpp #include <sycl.hpp> or `#include "sycl.hpp" can include this file.

[bader]

It would be interesting to have a test checking that if we have a user-provided sycl.hpp #include <sycl.hpp> or `#include "sycl.hpp" can include this file.

This sounds like a basic functionality and I'm 100% sure it's already covered by existing tests. I think it user-provided sycl.hpp is located in system paths or user also provided -I <path-to-user-provided-sycl.hpp>, then there will be no issues.

My point is that only include directory should be added by default and adding include/sycl might cause unexpected side effect like including a wrong header.

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be automatically closed in 30 days.

[AidanBeltonS]

AFAIK this issue has not yet been address, so I have removed the Stale label.