Build errors with LLVM 19.1.4 (clang/clang++/flang-new)

[climbfuji]

Efforts are underway to build spack-stack and the models that use spack-stack with LLVM, latest version 19.1.4. The latest LLVM flang compiler (flang-new in the installation) supposedly is the most robust Fortran compiler in terms of Fortran 2018 and 2023 standard implementations. For ip@5.1.0, I get a number of build errors.

First, related to OpenMP (this may not be an ip problem, but a problem with the LLVM setup in spack / the spack-stack compiler config, but I want to mention it here). See below for the more important issue.

-- The C compiler identification is Clang 19.1.4
-- The Fortran compiler identification is LLVMFlang 19.1.4
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /home/dom/prod/spack-stack-20241208/spack/lib/spack/env/clang/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting Fortran compiler ABI info
-- Detecting Fortran compiler ABI info - done
-- Check for working Fortran compiler: /home/dom/prod/spack-stack-20241208/spack/lib/spack/env/clang/flang - skipped
-- Library kinds that will be build: 4;d;8
CMake Error at /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find OpenMP_Fortran (missing: OpenMP_Fortran_FLAGS
  OpenMP_Fortran_LIB_NAMES)
Call Stack (most recent call first):
  /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake/Modules/FindOpenMP.cmake:577 (find_package_handle_standard_args)
  CMakeLists.txt:49 (find_package)


-- Configuring incomplete, errors occurred!
==> Error: ProcessError: Command exited with status 1:
    '/usr/bin/cmake' '-G' 'Unix Makefiles' '-DCMAKE_INSTALL_PREFIX:STRING=/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/ip-5.1.0-tjxba2z' '-DCMAKE_INSTALL_RPATH_USE_LINK_PATH:BOOL=ON' '-DCMAKE_INSTALL_RPATH:STRING=/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/ip-5.1.0-tjxba2z/lib;/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/ip-5.1.0-tjxba2z/lib64' '-DCMAKE_PREFIX_PATH:STRING=/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/openblas-0.3.28-xyxhfho;/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/gmake-4.2.1-biq3xx4' '-DCMAKE_BUILD_TYPE:STRING=Release' '-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON' '-DCMAKE_INTERPROCEDURAL_OPTIMIZATION:BOOL=OFF' '-DCMAKE_POLICY_DEFAULT_CMP0090:STRING=NEW' '-DCMAKE_FIND_USE_PACKAGE_REGISTRY:BOOL=OFF' '-DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=ON' '-DOPENMP:BOOL=ON' '-DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON' '-DBUILD_TESTING:BOOL=OFF' '-DBUILD_SHARED_LIBS:BOOL=OFF' '-DBUILD_4:BOOL=ON' '-DBUILD_D:BOOL=ON' '-DBUILD_8:BOOL=ON' '-DBUILD_DEPRECATED:BOOL=OFF' '-DBLA_VENDOR:STRING=OpenBLAS' '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-tjxba2zroualxeksqgradgrqneogfpju/spack-src'

2. After turning off the openmp variant for ip, I get this error during the build phase.

[ 83%] Linking Fortran static library libip_4.a
cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /usr/bin/cmake -P CMakeFiles/ip_4.dir/cmake_clean_target.cmake
cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /usr/bin/cmake -E cmake_link_script CMakeFiles/ip_4.dir/link.txt --verbose=1
/home/dom/prod/llvm-19.1.4/bin/llvm-ar qc libip_4.a CMakeFiles/ip_4.dir/gdswzd_c.F90.o CMakeFiles/ip_4.dir/gdswzd_mod.F90.o CMakeFiles/ip_4.dir/ipolates.F90.o CMakeFiles/ip_4.dir/ipolatev.F90.o CMakeFiles/ip_4.dir/ipxwafs.F90.o CMakeFiles/ip_4.dir/ipxwafs2.F90.o CMakeFiles/ip_4.dir/ipxwafs3.F90.o CMakeFiles/ip_4.dir/movect.F90.o CMakeFiles/ip_4.dir/bilinear_interp_mod.F90.o CMakeFiles/ip_4.dir/bicubic_interp_mod.F90.o CMakeFiles/ip_4.dir/neighbor_interp_mod.F90.o CMakeFiles/ip_4.dir/budget_interp_mod.F90.o CMakeFiles/ip_4.dir/spectral_interp_mod.F90.o CMakeFiles/ip_4.dir/neighbor_budget_interp_mod.F90.o CMakeFiles/ip_4.dir/ip_mod.F90.o CMakeFiles/ip_4.dir/ip_grid_descriptor_mod.F90.o CMakeFiles/ip_4.dir/ip_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_station_points_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_gaussian_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_equid_cylind_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_lambert_conf_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_mercator_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_polar_stereo_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_rot_equid_cylind_egrid_mod.F90.o CMakeFiles/ip_4.dir/ip_rot_equid_cylind_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_constants_mod.F90.o CMakeFiles/ip_4.dir/ip_grids_mod.F90.o CMakeFiles/ip_4.dir/ip_grid_factory_mod.F90.o CMakeFiles/ip_4.dir/ip_interpolators_mod.F90.o CMakeFiles/ip_4.dir/earth_radius_mod.F90.o CMakeFiles/ip_4.dir/polfix_mod.F90.o CMakeFiles/ip_4.dir/sp_mod.F.o
/home/dom/prod/llvm-19.1.4/bin/llvm-ranlib libip_4.a
make[2]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
[ 83%] Built target ip_4
make[1]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
make: *** [Makefile:139: all] Error 2
==> Error: ProcessError: Command exited with status 2:
    '/home/dom/prod/spack-stack-20241208/envs/ne-clang-19.1.4/install/clang/19.1.4/gmake-4.2.1-biq3xx4/bin/make' '-j4'

12 errors found in build log:
     664    cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /home/dom/prod/spack-stack-20241208/spack/lib/spack/env/clang/flang -DLSIZE=8 -I/home/dom/p
            rod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src/include_8 -module-dirinclude_8 -fPIC -c /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip
            -5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90 -o CMakeFiles/ip_8.dir/gdswzd_c.F90.o
     665    [ 77%] Building Fortran object src/CMakeFiles/ip_4.dir/neighbor_interp_mod.F90.o
     666    cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /home/dom/prod/spack-stack-20241208/spack/lib/spack/env/clang/flang -DLSIZE=4 -I/home/dom/p
            rod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src/include_4 -module-dirinclude_4 -fPIC -c /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip
            -5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/neighbor_interp_mod.F90 -o CMakeFiles/ip_4.dir/neighbor_interp_mod.F90.o
     667    /usr/bin/cmake -E touch src/CMakeFiles/ip_8.dir/gdswzd_mod.F90.o.provides.build
     668    [ 78%] Building Fortran object src/CMakeFiles/ip_4.dir/spectral_interp_mod.F90.o
     669    cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /home/dom/prod/spack-stack-20241208/spack/lib/spack/env/clang/flang -DLSIZE=4 -I/home/dom/p
            rod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src/include_4 -module-dirinclude_4 -fPIC -c /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip
            -5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/spectral_interp_mod.F90 -o CMakeFiles/ip_4.dir/spectral_interp_mod.F90.o
  >> 670    error: Semantic errors in /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90
  >> 671    /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90:206:5: error: No specific subroutine of generic 'gdswzd' matches the actual arguments
     672          CALL GDSWZD(IGDTNUM,IGDTMPL,IGDTLEN,IOPT,NPTS,FILL, &
     673          ^
  >> 674    /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90:291:5: error: No specific subroutine of generic 'gdswzd' matches the actual arguments
     675          CALL GDSWZD(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, &
     676          ^
  >> 677    error: Semantic errors in /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90
  >> 678    /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90:184:58: error: The type of 'igdtlen' has already been implicitly declared
     679          INTEGER(KIND=C_LONG), VALUE, INTENT(IN)  :: IGDTNUM, IGDTLEN
     680                                                               ^^^^^^^
  >> 681    /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90:173:39: Implicit declaration of 'igdtlen'
     682        SUBROUTINE GDSWZD_C(IGDTNUM,IGDTMPL,IGDTLEN,IOPT,NPTS,FILL, &
     683                                            ^^^^^^^
  >> 684    /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-src/src/gdswzd_c.F90:291:5: error: No specific subroutine of generic 'gdswzd' matches the actual arguments
     685          CALL GDSWZD(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, &
     686          ^
  >> 687    make[2]: *** [src/CMakeFiles/ip_8.dir/build.make:78: src/CMakeFiles/ip_8.dir/gdswzd_c.F90.o] Error 1
     688    make[2]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
  >> 689    make[1]: *** [CMakeFiles/Makefile2:157: src/CMakeFiles/ip_8.dir/all] Error 2
     690    make[1]: *** Waiting for unfinished jobs....
     691    /usr/bin/cmake -E touch src/CMakeFiles/ip_d.dir/gdswzd_mod.F90.o.provides.build
  >> 692    make[2]: *** [src/CMakeFiles/ip_d.dir/build.make:78: src/CMakeFiles/ip_d.dir/gdswzd_c.F90.o] Error 1
     693    make[2]: *** Waiting for unfinished jobs....
     694    make[2]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
  >> 695    make[1]: *** [CMakeFiles/Makefile2:131: src/CMakeFiles/ip_d.dir/all] Error 2
     696    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/bicubic_interp_mod.mod src/CMakeFiles/ip_4.dir/bicubic_interp_mod.mod.stamp LLVMFlang
     697    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/bilinear_interp_mod.mod src/CMakeFiles/ip_4.dir/bilinear_interp_mod.mod.stamp LLVMFlang
     698    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/budget_interp_mod.mod src/CMakeFiles/ip_4.dir/budget_interp_mod.mod.stamp LLVMFlang
     699    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/gdswzd_c_mod.mod src/CMakeFiles/ip_4.dir/gdswzd_c_mod.mod.stamp LLVMFlang
     700    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/neighbor_budget_interp_mod.mod src/CMakeFiles/ip_4.dir/neighbor_budget_interp_mod.mod.stamp LLVMFlang
     701    /usr/bin/cmake -E cmake_copy_f90_mod src/include_4/neighbor_interp_mod.mod src/CMakeFiles/ip_4.dir/neighbor_interp_mod.mod.stamp LLVMFlang

     ...

     728    cd /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet/src && /usr/bin/cmake -E cmake_link_script CMakeFiles/ip_4.dir/link.txt --verbose=1
     729    /home/dom/prod/llvm-19.1.4/bin/llvm-ar qc libip_4.a CMakeFiles/ip_4.dir/gdswzd_c.F90.o CMakeFiles/ip_4.dir/gdswzd_mod.F90.o CMakeFiles/ip_4.dir/ipolates.F90.o CMakeFiles/ip_4.dir/ipolatev.F90.o CMakeFiles/ip_4.dir/ipxwafs.F90.o C
            MakeFiles/ip_4.dir/ipxwafs2.F90.o CMakeFiles/ip_4.dir/ipxwafs3.F90.o CMakeFiles/ip_4.dir/movect.F90.o CMakeFiles/ip_4.dir/bilinear_interp_mod.F90.o CMakeFiles/ip_4.dir/bicubic_interp_mod.F90.o CMakeFiles/ip_4.dir/neighbor_interp_
            mod.F90.o CMakeFiles/ip_4.dir/budget_interp_mod.F90.o CMakeFiles/ip_4.dir/spectral_interp_mod.F90.o CMakeFiles/ip_4.dir/neighbor_budget_interp_mod.F90.o CMakeFiles/ip_4.dir/ip_mod.F90.o CMakeFiles/ip_4.dir/ip_grid_descriptor_mod.
            F90.o CMakeFiles/ip_4.dir/ip_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_station_points_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_gaussian_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_equid_cylind_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_lambert_con
            f_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_mercator_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_polar_stereo_grid_mod.F90.o CMakeFiles/ip_4.dir/ip_rot_equid_cylind_egrid_mod.F90.o CMakeFiles/ip_4.dir/ip_rot_equid_cylind_grid_mod.F90.o CMa
            keFiles/ip_4.dir/ip_constants_mod.F90.o CMakeFiles/ip_4.dir/ip_grids_mod.F90.o CMakeFiles/ip_4.dir/ip_grid_factory_mod.F90.o CMakeFiles/ip_4.dir/ip_interpolators_mod.F90.o CMakeFiles/ip_4.dir/earth_radius_mod.F90.o CMakeFiles/ip_
            4.dir/polfix_mod.F90.o CMakeFiles/ip_4.dir/sp_mod.F.o
     730    /home/dom/prod/llvm-19.1.4/bin/llvm-ranlib libip_4.a
     731    make[2]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
     732    [ 83%] Built target ip_4
     733    make[1]: Leaving directory '/home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-xu6qmet'
  >> 734    make: *** [Makefile:139: all] Error 2

See build log for details:
  /home/dom/prod/spack-stack-20241208/cache/build_stage/spack-stage-ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm/spack-build-out.txt

==> Warning: Skipping build of neptune-env-1.5.0-brzkxflfd47igcfri5irwb354fsfzdkf since ip-5.1.0-xu6qmettya3gcg3pbojfefjrmw7tplfm failed

Worth noting: good old sp@2.5.0 builds fine with flang-new@19.1.4.

[edwardhartnett]

Can we get this compiler working on GitHub CI?

[climbfuji]

I checked the GitHub runners, at the moment the closest is LLVM clang 18.1.3 in the Ubuntu 24.04 image: https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Readme.md

Maybe it's possible to apt-install 19.1.4?

[AlexanderRichert-NOAA]

FWIW, this is what I get when I try clang+flang 19.1.4 on my personal machine:

If I get time this week I can try to look into further and see how big of a lift it would be to add clang/flang support. I'm not too surprised that the sp library worked with them, I think it's all the modern fortran magic Kyle added to ip that makes things tricky :)