Flang19

[TimothyCera-NOAA]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[h-vetinari]

Thanks for opening the PR! Responding to your comment from #7:

The new recipe is not working on Windows. "cmake" doesn't find OpenMP.

Yeah, I think this is a CMake issue (which is unfortunately still somewhat expected as flang is pretty new). What I did in conda-forge/openblas-feedstock#115 was:

• bump CMake minimum to 3.12 to pick up handling of OpenMP_ROOT (or equivalently, opt into the respective policy)
• add find_package(OpenMP REQUIRED) in CMakeLists.txt
• use the following additional build arguments:

REM https://discourse.cmake.org/t/how-to-find-openmp-with-clang-on-macos/8860
set "CMAKE_EXTRA=-DOpenMP_ROOT=%LIBRARY_LIB%"
REM not picked up by `find_package(OpenMP)` for some reason
set "CMAKE_EXTRA=-DOpenMP_Fortran_FLAGS=-fopenmp -DOpenMP_Fortran_LIB_NAMES=libomp"

[h-vetinari]

You're already getting the newest CMake anyway, however, newer policies (in CMake terminology) will still not take effect, unless the CMake minimal version as defined in CMakeLists.txt is raised. This would need a patch of the sources (or a new upstream release with that change).