False-positive from -Wsource-uses-openmp with SYCL

[al42and]

Describe the bug

Building a program with -Wsource-uses-openmp -fopenmp -fsycl produces warnings about OpenMP pragmas. Building the same program without -fsycl does not produce any warnings. The source indeed uses OpenMP, but the warning should not be issued as long as we have -fopenmp flag.

To reproduce

#include <iostream>

int main() {
#pragma omp parallel for
  for (int i = 0; i < 8; i++) {
    std::cout << i << std::endl;
  }
  return 0;
}

$ clang++ simple-sycl-omp.cpp -Wsource-uses-openmp -fopenmp && echo ok
ok
$ clang++ simple-sycl-omp.cpp -Wsource-uses-openmp -fopenmp -fsycl
simple-sycl-omp.cpp:4:9: warning: unexpected '#pragma omp ...' in program [-Wsource-uses-openmp]
    4 | #pragma omp parallel for
      |         ^

Environment

• Ubuntu 22.04
• DPC++ version: 2172d9e

Additional context

The warning comes from the device pass:

$ clang++ simple-sycl-omp.cpp -Wsource-uses-openmp -fopenmp -fsycl -c -v
clang version 20.0.0git (https://github.com/intel/llvm 2172d9ee91d5ff70fc3e995c3dfd64c84c3738a7)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/aland/intel-sycl/llvm/build/install/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
Found CUDA installation: /usr/local/cuda-12.3, version 12.3
Found HIP installation: /opt/rocm, version 6.1.40092
 "/home/aland/intel-sycl/llvm/build/install/bin/clang-20" -cc1 -triple spir64-unknown-unknown -aux-triple x86_64-unknown-linux-gnu -fsycl-is-device -fdeclare-spirv-builtins -mllvm -sycl-opt -fenable-sycl-dae -fsycl-instrument-device-code -Wno-sycl-strict -O2 -fsycl-int-header=/tmp/simple-sycl-omp-header-83cbd0.h -fsycl-int-footer=/tmp/simple-sycl-omp-footer-95cb5a.h -sycl-std=2020 -ffine-grained-bitfield-accesses -fsycl-unique-prefix=uid9031853f69f4f78a -D__SYCL_ANY_DEVICE_HAS_ANY_ASPECT__=1 -Wspir-compat -emit-llvm-bc -emit-llvm-uselists -disable-free -clear-ast-before-backend -main-file-name simple-sycl-omp.cpp -mrelocation-model static -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -aux-target-cpu x86-64 -debugger-tuning=gdb -fdebug-compilation-dir=/home/aland/sycl_tests -v -fcoverage-compilation-dir=/home/aland/sycl_tests -resource-dir /home/aland/intel-sycl/llvm/build/install/lib/clang/20 -internal-isystem /home/aland/intel-sycl/llvm/build/install/bin/../include/sycl/stl_wrappers -internal-isystem /home/aland/intel-sycl/llvm/build/install/bin/../include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward -internal-isystem /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wsource-uses-openmp -std=c++17 -fdeprecated-macro -ferror-limit 19 -fgpu-rdc -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/simple-sycl-omp-bc25c5.bc -x c++ simple-sycl-omp.cpp
clang -cc1 version 20.0.0git based upon LLVM 20.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward"
ignoring duplicate directory "/home/aland/intel-sycl/llvm/build/install/lib/clang/20/include"
ignoring duplicate directory "/usr/local/include"
ignoring duplicate directory "/usr/include/x86_64-linux-gnu"
ignoring duplicate directory "/usr/include"
ignoring duplicate directory "/usr/local/include"
ignoring duplicate directory "/home/aland/intel-sycl/llvm/build/install/lib/clang/20/include"
ignoring duplicate directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/aland/intel-sycl/llvm/build/install/bin/../include/sycl/stl_wrappers
 /home/aland/intel-sycl/llvm/build/install/bin/../include
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward
 /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
simple-sycl-omp.cpp:4:9: warning: unexpected '#pragma omp ...' in program [-Wsource-uses-openmp]
    4 | #pragma omp parallel for
      |         ^
1 warning generated.
 "/home/aland/intel-sycl/llvm/build/install/bin/clang-20" -cc1 -triple x86_64-unknown-linux-gnu -sycl-std=2020 -fsycl-unique-prefix=uid9031853f69f4f78a -include-internal-header /tmp/simple-sycl-omp-header-83cbd0.h -dependency-filter /tmp/simple-sycl-omp-header-83cbd0.h -fsycl-enable-int-header-diags -include-internal-footer /tmp/simple-sycl-omp-footer-95cb5a.h -dependency-filter /tmp/simple-sycl-omp-footer-95cb5a.h -fsycl-is-host -D__SYCL_ANY_DEVICE_HAS_ANY_ASPECT__=1 -emit-obj -disable-free -clear-ast-before-backend -main-file-name simple-sycl-omp.cpp -mrelocation-model static -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic --dependent-lib=sycl-devicelib-host -debugger-tuning=gdb -fdebug-compilation-dir=/home/aland/sycl_tests -v -fcoverage-compilation-dir=/home/aland/sycl_tests -resource-dir /home/aland/intel-sycl/llvm/build/install/lib/clang/20 -internal-isystem /home/aland/intel-sycl/llvm/build/install/bin/../include/sycl/stl_wrappers -internal-isystem /home/aland/intel-sycl/llvm/build/install/bin/../include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward -internal-isystem /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wsource-uses-openmp -std=c++17 -fdeprecated-macro -ferror-limit 19 -fopenmp -fgpu-rdc -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/simple-sycl-omp-65a940.o -x c++ simple-sycl-omp.cpp
clang -cc1 version 20.0.0git based upon LLVM 20.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12"
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward"
ignoring duplicate directory "/home/aland/intel-sycl/llvm/build/install/lib/clang/20/include"
ignoring duplicate directory "/usr/local/include"
ignoring duplicate directory "/usr/include/x86_64-linux-gnu"
ignoring duplicate directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/aland/intel-sycl/llvm/build/install/bin/../include/sycl/stl_wrappers
 /home/aland/intel-sycl/llvm/build/install/bin/../include
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/x86_64-linux-gnu/c++/12
 /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/backward
 /home/aland/intel-sycl/llvm/build/install/lib/clang/20/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
 "/home/aland/intel-sycl/llvm/build/install/bin/clang-offload-bundler" -type=o -targets=sycl-spir64-unknown-unknown,host-x86_64-unknown-linux-gnu -output=simple-sycl-omp.o -input=/tmp/simple-sycl-omp-bc25c5.bc -input=/tmp/simple-sycl-omp-65a940.o -verbose