[llvm] [openmp] [OpenMP] Fix runtimes default build (PR #149871)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

> `omp.h` is moved from `lib/clang/22/include/omp.h` to `include/omp.h`.

I assume `lib/clang/22/include/omp.h` is in the Clang build tree and `include/omp.h` is in the OpenMP build tree.

The openmp build must not write outside its own build tree. Doing so causes countless problems such as conflicting versions of `omp.h` when building multiple openmp builds in different directories (such as Release/Debug), or the Clang build directory being read-only.

>  "/local/home/work/llvm-project/build-3-stage/build_Release_LTO-PGO-BOLT_main/bin/clang-22" ...

This looks like you are invoking clang from the build directory. Either switch to a bootstrapping-build of openmp, or install both Clang and openmp into the same CMAKE_INSTALL_PREFIX it launch Clang from there.



https://github.com/llvm/llvm-project/pull/149871