changes necessary for compilation with llvm flang

cmake/OpenfastFortranOptions.cmake

@@ -31,6 +31,8 @@
 # - set_fast_intel_fortran
 # - set_fast_intel_fortran_posix
 # - set_fast_intel_fortran_windows
+# - set_fast_flang
+# - set_fast_llvm_flang
 #
 ################################################################################
 
@@ -40,10 +42,13 @@
 macro(set_fast_fortran)
   get_filename_component(FCNAME "${CMAKE_Fortran_COMPILER}" NAME)
 
-  # Abort if we do not have gfortran or Intel Fortran Compiler.
+  # Abort if we do not have gfortran, Intel Fortran, or a Flang compiler.
+  # Note: CMake reports Classic Flang (and Classic-based ROCm Flang) as "Flang",
+  # and the modern LLVM Flang (flang-new / flang) as "LLVMFlang" (CMake >= 3.24).
   if (NOT (${CMAKE_Fortran_COMPILER_ID} STREQUAL "GNU" OR
         ${CMAKE_Fortran_COMPILER_ID} MATCHES "^Intel" OR
-        ${CMAKE_Fortran_COMPILER_ID} STREQUAL "Flang"))
+        ${CMAKE_Fortran_COMPILER_ID} STREQUAL "Flang" OR
+        ${CMAKE_Fortran_COMPILER_ID} STREQUAL "LLVMFlang"))
     message(FATAL_ERROR "OpenFAST requires GFortran, Intel, or Flang Compiler. Compiler detected by CMake: ${FCNAME}.")
   endif()
 
@@ -52,13 +57,17 @@ macro(set_fast_fortran)
   if(${CMAKE_Fortran_COMPILER_ID} STREQUAL "GNU")
     if("${CMAKE_Fortran_COMPILER_VERSION}" STREQUAL "")
         message(WARNING "A version of GNU GFortran greater than 4.6.0 is required but CMake could not detect your GFortran version.")
-    elseif("${CMAKE_Fortran_COMPILER_VERSION}" VERSION_LESS "4.6.0")  
+    elseif("${CMAKE_Fortran_COMPILER_VERSION}" VERSION_LESS "4.6.0")
         message(FATAL_ERROR "A version of GNU GFortran greater than 4.6.0 is required. GFortran version detected by CMake: ${CMAKE_Fortran_COMPILER_VERSION}.")
     endif()
   elseif(${CMAKE_Fortran_COMPILER_ID} MATCHES "^Intel")
     if("${CMAKE_Fortran_COMPILER_VERSION}" VERSION_LESS "11")
       message(FATAL_ERROR "A version of Intel ifort greater than 11 is required. ifort version detected by CMake: ${CMAKE_Fortran_COMPILER_VERSION}.")
     endif()
+  elseif(${CMAKE_Fortran_COMPILER_ID} STREQUAL "LLVMFlang")
+    if("${CMAKE_Fortran_COMPILER_VERSION}" VERSION_LESS "20")
+      message(WARNING "LLVM Flang ${CMAKE_Fortran_COMPILER_VERSION} detected. OpenFAST has only been tested with LLVM Flang 23 and newer.")
+    endif()
   endif()
 
   # Force all .mod files to be stored in a single directory
@@ -73,6 +82,8 @@ macro(set_fast_fortran)
     set_fast_intel_fortran()
   elseif(${CMAKE_Fortran_COMPILER_ID} STREQUAL "Flang")
     set_fast_flang()
+  elseif(${CMAKE_Fortran_COMPILER_ID} STREQUAL "LLVMFlang")
+    set_fast_llvm_flang()
   endif()
 
   # If double precision option enabled, set preprocessor define to use
@@ -256,3 +267,40 @@ macro(set_fast_flang)
 
   check_f2008_features()
 endmacro(set_fast_flang)
+
+#
+# set_fast_llvm_flang - Customizations for the modern LLVM Flang compiler
+#
+macro(set_fast_llvm_flang)
+
+  set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} -fno-backslash -cpp -fPIC")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
+
+  # LLVM Flang fuses multiply-adds (FMA) by default on targets that support them (e.g. arm64).
+  # Several OpenFAST time-step consistency checks (e.g. Conv_Rdtn_UpdateDiscState in HydroDyn)
+  # compare `Time - n*DT` against EPSILON and fail when the product is not rounded separately;
+  # disabling contraction also keeps results consistent with the regression-test baselines.
+  set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} -ffp-contract=off")
+
+  # On macOS, CMake's Darwin platform module gives Fortran the clang-style shared library
+  # flags (-dynamiclib, -install_name), which the flang driver rejects. Use the equivalent
+  # driver/linker spellings instead.
+  if(APPLE)
+    set(CMAKE_SHARED_LIBRARY_CREATE_Fortran_FLAGS "-shared -Wl,-headerpad_max_install_names")
+    set(CMAKE_SHARED_MODULE_CREATE_Fortran_FLAGS "-Wl,-bundle -Wl,-headerpad_max_install_names")
+    set(CMAKE_SHARED_LIBRARY_SONAME_Fortran_FLAG "-Xlinker -install_name -Xlinker")
+  endif()
+
+  # If double precision, make default reals 8 bytes.  As with gfortran, LLVM Flang's
+  # -fdefault-real-8 on its own promotes DOUBLE PRECISION to REAL(16), which breaks the
+  # interfaces to the F77 NetLib routines (and REAL(16) is not available on all targets,
+  # e.g. arm64 macOS), so -fdefault-double-8 is required to keep DOUBLE PRECISION at 8 bytes.
+  # LLVM Flang has no -fno-default-real-8, so sources that must not be promoted (FFTPACK)
+  # are handled in modules/nwtc-library by stripping these flags in a separate directory scope.
+  if (DOUBLE_PRECISION)
+    set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} -fdefault-real-8 -fdefault-double-8")
+  endif()
+
+  check_f2008_features()
+endmacro(set_fast_llvm_flang)

glue-codes/labview/src/WaveTank.f90

@@ -151,7 +151,7 @@ subroutine WaveTank_Init(  &
 
    ! return rootname
    RootName_C = c_null_char
-   RootName_C = transfer(trim(SimSettings%Sim%OutRootName),RootName_C)
+   RootName_C = transfer(trim(SimSettings%Sim%OutRootName)//c_null_char, RootName_C, size(RootName_C))
 
    ! If SendScreenToFile - send to file <OutRootName>.screen.log if true
    if (SimSettings%Outs%SendScreenToFile) then
@@ -173,7 +173,7 @@ subroutine WaveTank_Init(  &
 
    ! VTK directory
    WrVTK_Dir_C = c_null_char
-   WrVTK_Dir_C = transfer( trim(SimSettings%Viz%WrVTK_Dir), WrVTK_Dir_C )
+   WrVTK_Dir_C = transfer( trim(SimSettings%Viz%WrVTK_Dir)//c_null_char, WrVTK_Dir_C, size(WrVTK_Dir_C) )
    ! return VTKdir
    VTKdir_C = c_null_char
    if (SimSettings%Viz%WrVTK > 0_c_int) VTKdir_C = WrVTK_Dir_C
@@ -224,8 +224,8 @@ subroutine WaveTank_Init(  &
    if (Failed_c('SeaSt_C_PreInit')) return
 
    SS_InputFile_C = c_null_char
-   SS_InputFile_C = transfer(trim(SimSettings%ModSettings%SS_InputFile ), SS_InputFile_C )
-   OutRootName_C  = transfer(trim(SimSettings%Sim%OutRootName)//'.SeaSt'//c_null_char, OutRootName_C)
+   SS_InputFile_C = transfer(trim(SimSettings%ModSettings%SS_InputFile )//c_null_char, SS_InputFile_C, size(SS_InputFile_C) )
+   OutRootName_C  = transfer(trim(SimSettings%Sim%OutRootName)//'.SeaSt'//c_null_char, OutRootName_C, size(OutRootName_C))
    call SeaSt_C_Init(            &
       SS_InputFile_C,            &
       OutRootName_C,             &
@@ -259,8 +259,8 @@ subroutine WaveTank_Init(  &
 !FIXME: this interface will change!!! -- Split with PreInit
 !FIXME: add WrVTK_Dir_C,  SimSettings%Viz%WrVTK, SimSettings%Viz%WrVTK_DT
    MD_InputFile_C = c_null_char
-   MD_InputFile_C = transfer(trim(SimSettings%ModSettings%MD_InputFile ), MD_InputFile_C )
-   OutRootName_C  = transfer(trim(SimSettings%Sim%OutRootName)//'.MD'//c_null_char, OutRootName_C)
+   MD_InputFile_C = transfer(trim(SimSettings%ModSettings%MD_InputFile )//c_null_char, MD_InputFile_C, size(MD_InputFile_C) )
+   OutRootName_C  = transfer(trim(SimSettings%Sim%OutRootName)//'.MD'//c_null_char, OutRootName_C, size(OutRootName_C))
    call MD_C_Init(                           &
       0_c_int,                               &   !< InputFilePassed: 0 for file, 1 for string
       c_loc(MD_InputFile_C(1)),              &
@@ -346,10 +346,10 @@ subroutine WaveTank_Init(  &
    if (Failed_c('ADI_C_SetupRotor')) return
 
    AD_InputFile_C  = c_null_char
-   AD_InputFile_C  = transfer(trim(SimSettings%ModSettings%AD_InputFile ), AD_InputFile_C )
+   AD_InputFile_C  = transfer(trim(SimSettings%ModSettings%AD_InputFile )//c_null_char, AD_InputFile_C, size(AD_InputFile_C) )
    IfW_InputFile_C = c_null_char
-   IfW_InputFile_C = transfer(trim(SimSettings%ModSettings%IfW_InputFile), IfW_InputFile_C)
-   OutRootName_C = transfer(trim(SimSettings%Sim%OutRootName)//'.ADI'//c_null_char, OutRootName_C)
+   IfW_InputFile_C = transfer(trim(SimSettings%ModSettings%IfW_InputFile)//c_null_char, IfW_InputFile_C, size(IfW_InputFile_C))
+   OutRootName_C = transfer(trim(SimSettings%Sim%OutRootName)//'.ADI'//c_null_char, OutRootName_C, size(OutRootName_C))
    call ADI_C_Init(                          &
       0,                                     &  ! ADinputFilePassed; 0 for file, 1 for string
       c_loc(AD_InputFile_C(1)),              &  ! ADinputFileString_C; Input file as a single string with lines delineated by C_NULL_CHAR

modules/aerodyn/src/AeroDyn.f90

@@ -7365,7 +7365,7 @@ subroutine AD_InitVars(iR, u, p, x, z, OtherState, y, m, InitOut, InputFileData,
                      Flags=VF_Linearize + VF_RotFrame, &
                      Num=p%NumBlNds, &
                      Perturb=Perturb, &
-                     LinNames=[('User property on blade '//trim(Num2LStr(j))//', node '//trim(Num2LStr(i))//', -', i = 1, p%NumBlNds)])
+                     LinNames=[(MV_LinName('User property on blade '//trim(Num2LStr(j))//', node '//trim(Num2LStr(i))//', -'), i = 1, p%NumBlNds)])
    end do
 
    ! Extended inputs

modules/aerodyn/src/FVW.f90

@@ -37,7 +37,9 @@ module FVW
 !! The parameters are set here and not changed during the simulation.
 !! The initial states and initial guess for the input are defined.
 subroutine FVW_Init(AFInfo, InitInp, u, p, x, xd, z, OtherState, y, m, Interval, InitOut, ErrStat, ErrMsg )
-   use OMP_LIB ! wrap with #ifdef _OPENMP if this causes an issue
+#ifdef _OPENMP
+   use OMP_LIB
+#endif
    type(AFI_ParameterType),         intent(in   )  :: AFInfo(:)      !< The airfoil parameter data, temporary, for UA..
    type(FVW_InitInputType),         intent(inout)  :: InitInp        !< Input data for initialization routine  (inout so we can use MOVE_ALLOC)
    type(FVW_InputType),             intent(  out)  :: u              !< An initial guess for the input; input mesh must be defined

modules/aerodyn/src/FVW_BiotSavart.f90

@@ -3,7 +3,9 @@
 module FVW_BiotSavart 
 
    use NWTC_Library, only: ReKi, IntKi, Pi, EqualRealNos
+#ifdef _OPENMP
    use OMP_LIB
+#endif
 
    implicit none
 

modules/awae/src/AWAE_IO.f90

@@ -125,7 +125,7 @@ subroutine ReadLowResWindVTK(n, p, Vamb_Low, errStat, errMsg)
    errStat = ErrID_None
    errMsg  = ""
 
-   FileName = transfer(trim(p%WindFilePath)//trim(PathSep)//"Low"//trim(PathSep)//"Amb.t"//trim(Num2LStr(n))//".vtk"//c_null_char, FileName)
+   FileName = transfer(trim(p%WindFilePath)//trim(PathSep)//"Low"//trim(PathSep)//"Amb.t"//trim(Num2LStr(n))//".vtk"//c_null_char, FileName, size(FileName))
    call ReadVTK_inflow_info(FileName, desc, dims, origin, gridSpacing, vecLabel, Vamb_Low, 1, ErrStat, ErrMsg)
    if (ErrStat /= ErrID_None) ErrMsg = "ReadLowResWindVTK:"//trim(ErrMsg)
 
@@ -152,7 +152,7 @@ subroutine ReadHighResWindVTK(nt, n, p, Vamb_high, errStat, errMsg)
    errStat = ErrID_None
    errMsg  = ""
 
-   FileName = transfer(trim(p%WindFilePath)//trim(PathSep)//"HighT"//trim(num2lstr(nt))//trim(PathSep)//"Amb.t"//trim(num2lstr(n))//".vtk"//c_null_char, FileName)
+   FileName = transfer(trim(p%WindFilePath)//trim(PathSep)//"HighT"//trim(num2lstr(nt))//trim(PathSep)//"Amb.t"//trim(num2lstr(n))//".vtk"//c_null_char, FileName, size(FileName))
    call ReadVTK_inflow_info(FileName, desc, dims, origin, gridSpacing, vecLabel, Vamb_high, 1, ErrStat, ErrMsg)
    if (ErrStat /= ErrID_None) ErrMsg = "ReadHighResWindVTK:"//trim(ErrMsg)
 

modules/elastodyn/src/ElastoDyn.f90

@@ -11263,14 +11263,14 @@ subroutine ED_InitVars(u, p, x, y, m, Vars, InputFileData, Linearize, ErrStat, E
                   Num=p%NumBl, &
                   Flags=VF_RotFrame + VF_Linearize + VF_2PI, &
                   Perturb=2.0_R8Ki * D2R_D, &
-                  LinNames=[('Blade '//trim(num2lstr(i))//' pitch command, rad', i=1,p%NumBl)])
+                  LinNames=[(MV_LinName('Blade '//trim(num2lstr(i))//' pitch command, rad'), i=1,p%NumBl)])
 
    call MV_AddVar(Vars%u, "BlPitchMom", FieldScalar, &
                   DL=DatLoc(ED_u_BlPitchMom), iAry=1, &
                   Num=p%NumBl, &
                   Flags=VF_RotFrame + VF_Linearize, &
                   Perturb=MaxTorque / 100.0_R8Ki, &
-                  LinNames=[('Blade '//trim(num2lstr(i))//' pitch moment, Nm', i=1,p%NumBl)])
+                  LinNames=[(MV_LinName('Blade '//trim(num2lstr(i))//' pitch moment, Nm'), i=1,p%NumBl)])
 
    call MV_AddVar(Vars%u, "YawMom", FieldScalar, &
                   DL=DatLoc(ED_u_YawMom), &
@@ -11334,12 +11334,12 @@ subroutine ED_InitVars(u, p, x, y, m, Vars, InputFileData, Linearize, ErrStat, E
    call MV_AddVar(Vars%y, 'BlPitch', FieldScalar, &
                   DatLoc(ED_y_BlPitch), &
                   Num=p%NumBl, &
-                  LinNames=[('Blade '//trim(num2lstr(i))//' pitch angle, rad', i=1,p%NumBl)])
+                  LinNames=[(MV_LinName('Blade '//trim(num2lstr(i))//' pitch angle, rad'), i=1,p%NumBl)])
 
    call MV_AddVar(Vars%y, 'BlPRate', FieldScalar, &
                   DatLoc(ED_y_BlPRate), &
                   Num=p%NumBl, &
-                  LinNames=[('Blade '//trim(num2lstr(i))//' pitch rate, rad/s', i=1,p%NumBl)])
+                  LinNames=[(MV_LinName('Blade '//trim(num2lstr(i))//' pitch rate, rad/s'), i=1,p%NumBl)])
 
    call MV_AddMeshVar(Vars%y, 'Nacelle', MotionFields, &
                       DatLoc(ED_y_NacelleMotion), &

modules/extptfm/src/ExtPtfm_MCKF.f90

@@ -321,7 +321,7 @@ subroutine ExtPtfm_InitVars(u, p, x, y, m, Vars, InputFileData, Linearize, ErrSt
                       Num=size(u%Fm), &
                       Flags = ior(VF_Linearize,VF_Solve), &
                       Perturb = 2.0_R8Ki*D2R_D, &  ! The inertias of Craig-Bampton modes are normalized to O(1)
-                      LinNames=[('Follower mode '//trim(num2lstr(i))//' forcing, -', i=1,size(u%Fm))])
+                      LinNames=[(MV_LinName('Follower mode '//trim(num2lstr(i))//' forcing, -'), i=1,size(u%Fm))])
     end if
 
     !---------------------------------------------------------------------------
@@ -346,19 +346,19 @@ subroutine ExtPtfm_InitVars(u, p, x, y, m, Vars, InputFileData, Linearize, ErrSt
                      DL=DatLoc(ExtPtfm_y_qm), &
                      Num=size(y%qm), &
                      Flags=VF_Solve, &
-                     LinNames=[('Follower mode '//trim(num2lstr(i))//' displacement, -', i=1,size(y%qm))])
+                     LinNames=[(MV_LinName('Follower mode '//trim(num2lstr(i))//' displacement, -'), i=1,size(y%qm))])
 
        call MV_AddVar(Vars%y, "qmdot", FieldScalar, &
                      DL=DatLoc(ExtPtfm_y_qmdot), &
                      Num=size(y%qmdot), &
                      Flags=VF_Solve, &
-                     LinNames=[('Follower mode '//trim(num2lstr(i))//' velocity, -/s', i=1,size(y%qmdot))])
+                     LinNames=[(MV_LinName('Follower mode '//trim(num2lstr(i))//' velocity, -/s'), i=1,size(y%qmdot))])
 
        call MV_AddVar(Vars%y, "qmdotdot", FieldScalar, &
                      DL=DatLoc(ExtPtfm_y_qmdotdot), &
                      Num=size(y%qmdotdot), &
                      Flags=VF_Solve, &
-                     LinNames=[('Follower mode '//trim(num2lstr(i))//' acceleration, -/s^2', i=1,size(y%qmdotdot))])
+                     LinNames=[(MV_LinName('Follower mode '//trim(num2lstr(i))//' acceleration, -/s^2'), i=1,size(y%qmdotdot))])
     end if
 
     if ( p%NumOuts > 0_IntKi ) then

modules/hydrodyn/src/HydroDyn.f90

@@ -1049,7 +1049,7 @@ subroutine HydroDyn_InitVars(Vars, u, p, x, y, m, InitOut, InputFileData, Linear
                      Flags=VF_DerivOrder1, &
                      Num=p%WAMIT(k)%SS_Exctn%numStates, &
                      Perturb=20000.0_R8Ki * D2R_D, &
-                     LinNames=[((trim(BodyDesc)//'Exctn'//trim(dofLabels(j))//Num2LStr(i), i = 1, p%WAMIT(k)%SS_Exctn%spDOF(j)), j = 1, 6)])
+                     LinNames=[((MV_LinName(trim(BodyDesc)//'Exctn'//trim(dofLabels(j))//Num2LStr(i)), i = 1, p%WAMIT(k)%SS_Exctn%spDOF(j)), j = 1, 6)])
    end do
 
    do k = 1, p%nWAMITObj
@@ -1060,7 +1060,7 @@ subroutine HydroDyn_InitVars(Vars, u, p, x, y, m, InitOut, InputFileData, Linear
                      Flags=VF_DerivOrder1, &
                      Num=p%WAMIT(k)%SS_Rdtn%numStates, &
                      Perturb=2.0_R8Ki * D2R_D , &
-                     LinNames=[((trim(BodyDesc)//'Rdtn'//trim(dofLabels(j))//Num2LStr(i), i = 1, p%WAMIT(k)%SS_Rdtn%spDOF(j)), j = 1, 6)])
+                     LinNames=[((MV_LinName(trim(BodyDesc)//'Rdtn'//trim(dofLabels(j))//Num2LStr(i)), i = 1, p%WAMIT(k)%SS_Rdtn%spDOF(j)), j = 1, 6)])
    end do
 
    !----------------------------------------------------------------------------
@@ -1094,21 +1094,21 @@ subroutine HydroDyn_InitVars(Vars, u, p, x, y, m, InitOut, InputFileData, Linear
                      Num=size(u%qAddDOF), &
                      Flags = ior(VF_Linearize,VF_Solve), &
                      Perturb = PerturbRot, &
-                     LinNames=[('Generalized DOF '//trim(num2lstr(i))//' displacement, -', i=1,size(u%qAddDOF))])
+                     LinNames=[(MV_LinName('Generalized DOF '//trim(num2lstr(i))//' displacement, -'), i=1,size(u%qAddDOF))])
 
       call MV_AddVar(Vars%u, "qAddDOFDot", FieldScalar, &
                      DL=DatLoc(HydroDyn_u_qAddDOFDot), &
                      Num=size(u%qAddDOFDot), &
                      Flags = ior(VF_Linearize,VF_Solve), &
                      Perturb = PerturbRot, &
-                     LinNames=[('Generalized DOF '//trim(num2lstr(i))//' velocity, -/s', i=1,size(u%qAddDOFDot))])
+                     LinNames=[(MV_LinName('Generalized DOF '//trim(num2lstr(i))//' velocity, -/s'), i=1,size(u%qAddDOFDot))])
 
       call MV_AddVar(Vars%u, "qAddDOFDotDot", FieldScalar, &
                      DL=DatLoc(HydroDyn_u_qAddDOFDotDot), &
                      Num=size(u%qAddDOFDotDot), &
                      Flags = ior(VF_Linearize,VF_Solve), &
                      Perturb = PerturbRot, &
-                     LinNames=[('Generalized DOF '//trim(num2lstr(i))//' acceleration, -/s^2', i=1,size(u%qAddDOFDotDot))])
+                     LinNames=[(MV_LinName('Generalized DOF '//trim(num2lstr(i))//' acceleration, -/s^2'), i=1,size(u%qAddDOFDotDot))])
    end if
 
    call MV_AddVar(Vars%u, "WaveElev0", FieldScalar, DatLoc(HydroDyn_u_WaveElev0), &
@@ -1140,7 +1140,7 @@ subroutine HydroDyn_InitVars(Vars, u, p, x, y, m, InitOut, InputFileData, Linear
                      DL=DatLoc(HydroDyn_y_FAddDOF), &
                      Num=size(y%FAddDOF), &
                      Flags=VF_Solve, &
-                     LinNames=[('Generalized DOF '//trim(num2lstr(i))//' force, -', i=1,size(y%FAddDOF))])
+                     LinNames=[(MV_LinName('Generalized DOF '//trim(num2lstr(i))//' force, -'), i=1,size(y%FAddDOF))])
    end if
 
    call MV_AddVar(Vars%y, "WriteOutput", FieldScalar, DatLoc(HydroDyn_y_WriteOutput), &

modules/hydrodyn/src/HydroDyn_C_Binding.f90

@@ -193,9 +193,9 @@ subroutine SetErr(ErrStat, ErrMsg, ErrStat_C, ErrMsg_C)
    integer                                :: i
    ErrStat_C = ErrStat     ! We will send back the same error status that is used in OpenFAST
    if (ErrMsgLen > ErrMsgLen_C-1) then   ! If ErrMsgLen is > the space in ErrMsg_C, do not copy everything over
-      ErrMsg_C = TRANSFER( trim(ErrMsg(1:ErrMsgLen_C-1))//C_NULL_CHAR, ErrMsg_C )
+      ErrMsg_C = TRANSFER( trim(ErrMsg(1:ErrMsgLen_C-1))//C_NULL_CHAR, ErrMsg_C, SIZE(ErrMsg_C) )
    else
-      ErrMsg_C = TRANSFER( trim(ErrMsg)//C_NULL_CHAR, ErrMsg_C )
+      ErrMsg_C = TRANSFER( trim(ErrMsg)//C_NULL_CHAR, ErrMsg_C, SIZE(ErrMsg_C) )
    endif
 end subroutine SetErr
 

modules/nwtc-library/CMakeLists.txt

@@ -51,6 +51,11 @@ elseif (${CMAKE_Fortran_COMPILER_ID} STREQUAL "Flang")
   if(APPLE OR UNIX)
     set(NWTC_SYS_FILE src/SysFlangLinux.f90)
   endif()
+elseif (${CMAKE_Fortran_COMPILER_ID} STREQUAL "LLVMFlang")
+  # SysGnuLinux.f90 can't be used: LLVM Flang does not provide the FSTAT extension
+  if(APPLE OR UNIX)
+    set(NWTC_SYS_FILE src/SysFlangLinux.f90)
+  endif()
 endif ()
 
 # System file
@@ -170,6 +175,13 @@ elseif (${CMAKE_Fortran_COMPILER_ID} MATCHES "^Intel")
 elseif (${CMAKE_Fortran_COMPILER_ID} STREQUAL "Flang")
    set_source_files_properties(${FFTPACK_SOURCES} PROPERTIES COMPILE_FLAGS
       "-fno-default-real-8")
+elseif (${CMAKE_Fortran_COMPILER_ID} STREQUAL "LLVMFlang")
+   # LLVM Flang has no -fno-default-real-8 (and per-source flags cannot remove a global
+   # flag), so FFTPACK is compiled as an object library in its own directory scope with
+   # -fdefault-real-8/-fdefault-double-8 stripped from CMAKE_Fortran_FLAGS.
+   add_subdirectory(src/NetLib/fftpack)
+   list(REMOVE_ITEM NWTCLIBS_SOURCES ${FFTPACK_SOURCES})
+   list(APPEND NWTCLIBS_SOURCES $<TARGET_OBJECTS:nwtc_fftpack_r4>)
 endif()
 
 # Recursive use of routine in qk61/dqk61 will trigger errors in debug