Implement --flag option for Fortran fpm

3 files changed, 350 insertions, 246 deletions

diff --git a/fpm/src/fpm.f90 b/fpm/src/fpm.f90
index 68385cd..c66abf2 100644
--- a/fpm/src/fpm.f90
+++ b/fpm/src/fpm.f90
@@ -9,7 +9,7 @@ use fpm_filesystem, only: is_dir, join_path, number_of_rows, list_files, exists,
 use fpm_model, only: fpm_model_t, srcfile_t, show_model, &
                     FPM_SCOPE_UNKNOWN, FPM_SCOPE_LIB, FPM_SCOPE_DEP, &
                     FPM_SCOPE_APP, FPM_SCOPE_EXAMPLE, FPM_SCOPE_TEST
-use fpm_compiler, only: add_compile_flag_defaults
+use fpm_compiler, only: get_module_flags
 
 
 use fpm_sources, only: add_executable_sources, add_sources_from_dir
@@ -64,7 +64,10 @@ subroutine build_model(model, settings, package, error)
 
     model%output_directory = join_path('build',basename(model%fortran_compiler)//'_'//settings%build_name)
 
-    call add_compile_flag_defaults(settings%build_name, basename(model%fortran_compiler), model)
+    call get_module_flags(model%fortran_compiler, &
+        & join_path(model%output_directory,model%package_name), &
+        & model%fortran_compile_flags)
+    model%fortran_compile_flags = settings%flag // model%fortran_compile_flags
     if(settings%verbose)then
        write(*,*)'<INFO>COMPILER OPTIONS:  ', model%fortran_compile_flags 
     endif
diff --git a/fpm/src/fpm_command_line.f90 b/fpm/src/fpm_command_line.f90
index 72a4000..65812b8 100644
--- a/fpm/src/fpm_command_line.f90
+++ b/fpm/src/fpm_command_line.f90
@@ -27,8 +27,9 @@ use fpm_environment,  only : get_os_type, get_env, &
                              OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_WINDOWS, &
                              OS_CYGWIN, OS_SOLARIS, OS_FREEBSD
 use M_CLI2,           only : set_args, lget, sget, unnamed, remaining, specified
-use fpm_strings,      only : lower, split
+use fpm_strings,      only : lower, split, fnv_1a
 use fpm_filesystem,   only : basename, canon_path, to_fortran_name
+use fpm_compiler, only : get_default_compile_flags
 use,intrinsic :: iso_fortran_env, only : stdin=>input_unit, &
                                        & stdout=>output_unit, &
                                        & stderr=>error_unit
@@ -65,6 +66,7 @@ type, extends(fpm_cmd_settings)  :: fpm_build_settings
     logical                      :: show_model=.false.
     character(len=:),allocatable :: compiler
     character(len=:),allocatable :: build_name
+    character(len=:),allocatable :: flag
 end type
 
 type, extends(fpm_build_settings)  :: fpm_run_settings
@@ -106,7 +108,7 @@ character(len=20),parameter :: manual(*)=[ character(len=20) ::&
 &  ' ',     'fpm',     'new',   'build',  'run',     &
 &  'test',  'runner', 'install', 'update', 'list',   'help',   'version'  ]
 
-character(len=:), allocatable :: val_runner, val_build, val_compiler
+character(len=:), allocatable :: val_runner, val_build, val_compiler, val_flag
 
 contains
     subroutine get_command_line_settings(cmd_settings)
@@ -157,6 +159,7 @@ contains
             & --example F&
             & --runner " " &
             & --compiler "'//get_env('FPM_COMPILER','gfortran')//'" &
+            & --flag:: " "&
             & --verbose F&
             & --',help_run,version_text)
 
@@ -192,6 +195,7 @@ contains
             & args=remaining,&
             & build_name=val_build,&
             & compiler=val_compiler, &
+            & flag=val_flag, &
             & example=lget('example'), &
             & list=lget('list'),&
             & name=names,&
@@ -204,6 +208,7 @@ contains
             & --list F &
             & --show-model F &
             & --compiler "'//get_env('FPM_COMPILER','gfortran')//'" &
+            & --flag:: " "&
             & --verbose F&
             & --',help_build,version_text)
 
@@ -213,6 +218,7 @@ contains
             cmd_settings=fpm_build_settings(  &
             & build_name=val_build,&
             & compiler=val_compiler, &
+            & flag=val_flag, &
             & list=lget('list'),&
             & show_model=lget('show-model'),&
             & verbose=lget('verbose') )
@@ -339,6 +345,7 @@ contains
             call set_args('--release F --no-rebuild F --verbose F --prefix " " &
                 & --list F &
                 & --compiler "'//get_env('FPM_COMPILER','gfortran')//'" &
+                & --flag:: " "&
                 & --libdir "lib" --bindir "bin" --includedir "include"', &
                 help_install, version_text)
 
@@ -349,6 +356,7 @@ contains
                 list=lget('list'), &
                 build_name=val_build, &
                 compiler=val_compiler, &
+                flag=val_flag, &
                 no_rebuild=lget('no-rebuild'), &
                 verbose=lget('verbose'))
             call get_char_arg(install_settings%prefix, 'prefix')
@@ -373,6 +381,7 @@ contains
             & --release F&
             & --runner " " &
             & --compiler "'//get_env('FPM_COMPILER','gfortran')//'" &
+            & --flag:: " "&
             & --verbose F&
             & --',help_test,version_text)
 
@@ -402,6 +411,7 @@ contains
             & args=remaining, &
             & build_name=val_build, &
             & compiler=val_compiler, &
+            & flag=val_flag, &
             & example=.false., &
             & list=lget('list'), &
             & name=names, &
@@ -455,7 +465,17 @@ contains
             val_compiler='gfortran'
         endif
 
-        val_build=trim(merge('release','debug  ',lget('release')))
+        val_flag = sget('flag')
+        if (val_flag == '') then
+            call get_default_compile_flags(val_compiler, lget('release'), val_flag)
+        else
+            if (lget('release')) then
+                write(stdout,'(a)') &
+                    '<WARNING> --release ignored since explicit --flag argument provided'
+            end if
+        end if
+        allocate(character(len=16) :: val_build)
+        write(val_build, '(z16.16)') fnv_1a(val_flag)
 
     end subroutine check_build_vals
 
@@ -516,17 +536,17 @@ contains
    ' ']
    help_list_dash = [character(len=80) :: &
    '                                                                                ', &
-   ' build [--compiler COMPILER_NAME] [--release] [--list]                          ', &
+   ' build [--compiler COMPILER_NAME] [--release] [--flag FFLAGS] [--list]          ', &
    ' help [NAME(s)]                                                                 ', &
    ' new NAME [[--lib|--src] [--app] [--test] [--example]]|                         ', &
    '          [--full|--bare][--backfill]                                           ', &
    ' update [NAME(s)] [--fetch-only] [--clean] [--verbose]                          ', &
    ' list [--list]                                                                  ', &
-   ' run  [[--target] NAME(s) [--example] [--release] [--all] [--runner "CMD"]      ', &
-   '      [--compiler COMPILER_NAME] [--list] [-- ARGS]                             ', &
-   ' test [[--target] NAME(s)] [--release] [--runner "CMD"] [--list]                ', &
+   ' run  [[--target] NAME(s) [--example] [--release] [--flag FFLAGS] [--all]       ', &
+   '      [--runner "CMD"] [--compiler COMPILER_NAME] [--list] [-- ARGS]            ', &
+   ' test [[--target] NAME(s)] [--release] [--flag FFLAGS] [--runner "CMD"] [--list]', &
    '      [--compiler COMPILER_NAME] [-- ARGS]                                      ', &
-   ' install [--release] [--no-rebuild] [--prefix PATH] [options]                   ', &
+   ' install [--release] [--flag FFLAGS] [--no-rebuild] [--prefix PATH] [options]   ', &
    ' ']
     help_usage=[character(len=80) :: &
     '' ]
@@ -632,24 +652,26 @@ contains
     '                                                                       ', &
     '  Their syntax is                                                      ', &
     '                                                                       ', &
-    '    build [--release] [--list] [--compiler COMPILER_NAME]              ', &
+    '    build [--release] [--flag FFLAGS] [--list] [--compiler COMPILER_NAME]', &
     '    new NAME [[--lib|--src] [--app] [--test] [--example]]|             ', &
-   '              [--full|--bare][--backfill]                               ', &
+    '             [--full|--bare][--backfill]                               ', &
     '    update [NAME(s)] [--fetch-only] [--clean]                          ', &
-    '    run [[--target] NAME(s)] [--release] [--list] [--example] [--all]  ', &
-    '        [--runner "CMD"] [--compiler COMPILER_NAME] [-- ARGS]          ', &
-    '    test [[--target] NAME(s)] [--release] [--list]                     ', &
+    '    run [[--target] NAME(s)] [--release] [--flag FFLAGS] [--list] [--example]', &
+    '        [--all] [--runner "CMD"] [--compiler COMPILER_NAME] [-- ARGS]  ', &
+    '    test [[--target] NAME(s)] [--release] [--flag FFLAGS] [--list]     ', &
     '         [--runner "CMD"] [--compiler COMPILER_NAME] [-- ARGS]         ', &
     '    help [NAME(s)]                                                     ', &
     '    list [--list]                                                      ', &
-    '    install [--release] [--no-rebuild] [--prefix PATH] [options]       ', &
+    '    install [--release] [--flag FFLAGS] [--no-rebuild] [--prefix PATH] [options]', &
     '                                                                       ', &
     'SUBCOMMAND OPTIONS                                                     ', &
     '  --release  Builds or runs in release mode (versus debug mode). fpm(1)', &
-    '             Defaults to using common compiler debug flags and building', &
-    '             in "build/*_debug/". When this flag is present build      ', &
-    '             output goes into "build/*_release/" and common compiler   ', &
-    '             optimization flags are used.                              ', &
+    '             Defaults to using common compiler debug flags.            ', &
+    '             When this flag is present common compiler optimization flags', &
+    '             are used.', &
+    '  --flag FFLAGS  Use compile arguments provided in FFLAGS rather than', &
+    '                 defaults from debug or release mode, module flags are', &
+    '                 provided by fpm(1) and must not be present in FFLAGS', &
     '  --list     List candidates instead of building or running them. On   ', &
     '             the fpm(1) command this shows a brief list of subcommands.', &
     '  --runner CMD   Provides a command to prefix program execution paths. ', &
@@ -708,8 +730,9 @@ contains
     ' run(1) - the fpm(1) subcommand to run project applications            ', &
     '                                                                       ', &
     'SYNOPSIS                                                               ', &
-    ' fpm run [[--target] NAME(s)[--release][--compiler COMPILER_NAME]      ', &
-    '         [--runner "CMD"] [--example] [--list] [--all] [-- ARGS]       ', &
+    ' fpm run [[--target] NAME(s) [--release] [--flag FFLAGS]', &
+    '         [--compiler COMPILER_NAME] [--runner "CMD"] [--example]', &
+    '         [--list] [--all] [-- ARGS]', &
     '                                                                       ', &
     ' fpm run --help|--version                                              ', &
     '                                                                       ', &
@@ -734,6 +757,7 @@ contains
     ' --all   Run all examples or applications. An alias for --target ''*''.  ', &
     ' --example  Run example programs instead of applications.              ', &
     ' --release  selects the optimized build instead of the debug build.    ', &
+    ' --flags FFLAGS    selects compile arguments for the build', &
     ' --compiler COMPILER_NAME  Specify a compiler name. The default is     ', &
     '                           "gfortran" unless set by the environment    ', &
     '                           variable FPM_COMPILER.                      ', &
@@ -774,7 +798,7 @@ contains
     ' build(1) - the fpm(1) subcommand to build a project                   ', &
     '                                                                       ', &
     'SYNOPSIS                                                               ', &
-    ' fpm build [--release][--compiler COMPILER_NAME] [-list]               ', &
+    ' fpm build [--release] [--flags FFLAGS] [--compiler COMPILER_NAME] [-list]', &
     '                                                                       ', &
     ' fpm build --help|--version                                            ', &
     '                                                                       ', &
@@ -798,6 +822,7 @@ contains
     'OPTIONS                                                                ', &
     ' --release    build in build/*_release instead of build/*_debug with   ', &
     '              high optimization instead of full debug options.         ', &
+    ' --flags FFLAGS  selects compile arguments for the build', &
     ' --compiler   COMPILER_NAME  Specify a compiler name. The default is   ', &
     '                           "gfortran" unless set by the environment    ', &
     '                           variable FPM_COMPILER.                      ', &
@@ -954,8 +979,8 @@ contains
     ' test(1) - the fpm(1) subcommand to run project tests                  ', &
     '                                                                       ', &
     'SYNOPSIS                                                               ', &
-    ' fpm test [[--target] NAME(s)][--release][--compiler COMPILER_NAME ]   ', &
-    '          [--runner "CMD"] [--list][-- ARGS]                           ', &
+    ' fpm test [[--target] NAME(s)] [--release] [--flag FFLAGS]', &
+    '          [--compiler COMPILER_NAME ] [--runner "CMD"] [--list][-- ARGS]', &
     '                                                                       ', &
     ' fpm test --help|--version                                             ', &
     '                                                                       ', &
@@ -971,8 +996,8 @@ contains
     '                   any single character and "*" represents any string. ', &
     '                   Note The glob string normally needs quoted to       ', &
     '                   protect the special characters from shell expansion.', &
-    ' --release  selects the optimized build instead of the debug           ', &
-    '            build.                                                     ', &
+    ' --release  selects the optimized build instead of the debug build.    ', &
+    ' --flags FFLAGS  selects compile arguments for the build', &
     ' --compiler COMPILER_NAME  Specify a compiler name. The default is     ', &
     '                           "gfortran" unless set by the environment    ', &
     '                           variable FPM_COMPILER.                      ', &
@@ -1021,7 +1046,7 @@ contains
     ' install(1) - install fpm projects', &
     '', &
     'SYNOPSIS', &
-    ' fpm install [--release] [--list] [--no-rebuild] [--prefix DIR]', &
+    ' fpm install [--release] [--flag FFLAGS] [--list] [--no-rebuild] [--prefix DIR]', &
     '             [--bindir DIR] [--libdir DIR] [--includedir DIR]', &
     '             [--verbose]', &
     '', &
@@ -1036,6 +1061,7 @@ contains
     ' --list            list all installable targets for this project,', &
     '                   but do not install any of them', &
     ' --release         selects the optimized build instead of the debug build', &
+    ' --flags FFLAGS    selects compile arguments for the build', &
     ' --no-rebuild      do not rebuild project before installation', &
     ' --prefix DIR      path to installation directory (requires write access),', &
     '                   the default prefix on Unix systems is $HOME/.local', &
diff --git a/fpm/src/fpm_compiler.f90 b/fpm/src/fpm_compiler.f90
index 3335b11..955f00a 100644
--- a/fpm/src/fpm_compiler.f90
+++ b/fpm/src/fpm_compiler.f90
@@ -1,27 +1,6 @@
 !># Define compiler command options
 !!
 !! This module defines compiler options to use for the debug and release builds.
-module fpm_compiler
-use fpm_model, only: fpm_model_t
-use fpm_filesystem, only: join_path
-public  add_compile_flag_defaults
-
-contains
-!> Choose compile flags based on cli settings & manifest inputs
-subroutine add_compile_flag_defaults(build_name,compiler,model)
-character(len=*),intent(in) :: build_name   !! select build from {release,debug}
-character(len=*),intent(in) :: compiler     !! compiler name
-type(fpm_model_t), intent(inout) :: model   !! model to add compiler options to
-
-! could just be a function to return a string instead of passing model
-! but likely to change other components like matching C compiler
-
-character(len=:),allocatable :: fflags    ! optional flags that might be overridden by user
-character(len=:),allocatable :: modpath 
-character(len=:),allocatable :: mandatory ! flags required for fpm to function properly;
-                                          ! ie. add module path and module include directory as appropriate
-
-! special reserved names "debug" and "release" are for supported compilers with no user-specified compile or load flags
 
 ! vendor            Fortran   C         Module output   Module include OpenMP    Free for OSS
 !                   compiler  compiler  directory       directory
@@ -46,206 +25,302 @@ character(len=:),allocatable :: mandatory ! flags required for fpm to function p
 ! G95               ?          ?       -fmod=          -I            -fopenmp   discontinued
 ! Open64            ?          ?       -module         -I            -mp        discontinued
 ! Unisys            ?          ?       ?               ?             ?          discontinued
-character(len=*),parameter :: names(*)=[ character(len=10) :: &
-& 'caf', &
-& 'gfortran', &
-& 'f95', &
-& 'nvfortran', &
-& 'ifort', &
-& 'ifx', &
-& 'pgfortran', &
-& 'pgf90', &
-& 'pgf95', &
-& 'flang', &
-& 'lfc', &
-& 'nagfor', &
-& 'crayftn', &
-& 'xlf90', &
-& 'unknown']
-integer :: i
-
-    modpath=join_path(model%output_directory,model%package_name)
-    fflags=''
-    mandatory=''
-
-    select case(build_name//'_'//compiler)
-
-    case('release_caf')
-       fflags='&
-       & -O3&
-       & -Wimplicit-interface&
-       & -fPIC&
-       & -fmax-errors=1&
-       & -funroll-loops&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-    case('debug_caf')
-       fflags = '&
-       & -Wall&
-       & -Wextra&
-       & -Wimplicit-interface&
-       & -fPIC -fmax-errors=1&
-       & -g&
-       & -fbounds-check&
-       & -fcheck-array-temporaries&
-       & -fbacktrace&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-    case('release_gfortran')
-       fflags='&
-       & -O3&
-       & -Wimplicit-interface&
-       & -fPIC&
-       & -fmax-errors=1&
-       & -funroll-loops&
-       & -fcoarray=single&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-    case('debug_gfortran')
-       fflags = '&
-       & -Wall&
-       & -Wextra&
-       & -Wimplicit-interface&
-       & -fPIC -fmax-errors=1&
-       & -g&
-       & -fcheck=bounds&
-       & -fcheck=array-temps&
-       & -fbacktrace&
-       & -fcoarray=single&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-
-    case('release_f95')
-       fflags='&
-       & -O3&
-       & -Wimplicit-interface&
-       & -fPIC&
-       & -fmax-errors=1&
-       & -ffast-math&
-       & -funroll-loops&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-    case('debug_f95')
-       fflags = '&
-       & -Wall&
-       & -Wextra&
-       & -Wimplicit-interface&
-       & -fPIC -fmax-errors=1&
-       & -g&
-       & -fbounds-check&
-       & -fcheck-array-temporaries&
-       & -Wno-maybe-uninitialized -Wno-uninitialized&
-       & -fbacktrace&
-       &'
-       mandatory=' -J '//modpath//' -I '//modpath 
-
-    case('release_nvfortran')
-       fflags = '&
-       & -Mbackslash&
-       &'
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('debug_nvfortran')
-       fflags = '&
-       & -Minform=inform&
-       & -Mbackslash&
-       & -g&
-       & -Mbounds&
-       & -Mchkptr&
-       & -Mchkstk&
-       & -traceback&
-       &'
-       mandatory=' -module '//modpath//' -I '//modpath 
-
-    case('release_ifort')
-       fflags = '&
-       & -fp-model precise&
-       & -pc 64&
-       & -align all&
-       & -error-limit 1&
-       & -reentrancy threaded&
-       & -nogen-interfaces&
-       & -assume byterecl&
-       &'
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('debug_ifort')
-       fflags = '&
-       & -warn all&
-       & -check:all:noarg_temp_created&
-       & -error-limit 1&
-       & -O0&
-       & -g&
-       & -assume byterecl&
-       & -traceback&
-       &'
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('release_ifx')
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('debug_ifx')
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-
-    case('release_pgfortran','release_pgf90','release_pgf95')  ! Portland Group F90/F95 compilers
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('debug_pgfortran','debug_pgf90','debug_pgf95')  ! Portland Group F90/F95 compilers
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-
-    case('release_flang')
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-    case('debug_flang')
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-
-    case('release_lfc')
-       fflags = ' '
-       mandatory=' -M '//modpath//' -I '//modpath 
-    case('debug_lfc')
-       fflags = ' '
-       mandatory=' -M '//modpath//' -I '//modpath 
-
-    case('release_nagfor')
-       fflags = ' &
-       & -O4&
-       & -coarray=single&
-       & -PIC&
-       &'
-       mandatory=' -mdir '//modpath//' -I '//modpath !
-    case('debug_nagfor')
-       fflags = '&
-       & -g&
-       & -C=all&
-       & -O0&
-       & -gline&
-       & -coarray=single&
-       & -PIC&
-       &'
-       mandatory=' -mdir '//modpath//' -I '//modpath !
-    case('release_crayftn')
-       fflags = ' '
-       mandatory=' -J '//modpath//' -I '//modpath 
-    case('debug_crayftn')
-       fflags = ' '
-       mandatory=' -J '//modpath//' -I '//modpath 
-
-    case('release_xlf90')
-       fflags = ' '
-       mandatory=' -qmoddir '//modpath//' -I '//modpath 
-    case('debug_xlf90')
-       fflags = ' '
-       mandatory=' -qmoddir '//modpath//' -I '//modpath 
+module fpm_compiler
+use fpm_model, only: fpm_model_t
+use fpm_filesystem, only: join_path, basename
+implicit none
+public :: get_module_flags
+public :: get_default_compile_flags
+public :: get_debug_compile_flags
+public :: get_release_compile_flags
+
+enum, bind(C)
+    enumerator :: &
+        id_unknown, &
+        id_gcc, &
+        id_f95, &
+        id_caf, &
+        id_intel_classic, &
+        id_intel_llvm, &
+        id_pgi, &
+        id_nvhpc, &
+        id_nag, &
+        id_flang, &
+        id_ibmxl, &
+        id_cray, &
+        id_lahey, &
+        id_lfortran
+end enum
+integer, parameter :: compiler_enum = kind(id_unknown)
+
+contains
+
+subroutine get_default_compile_flags(compiler, release, flags)
+    character(len=*), intent(in) :: compiler
+    logical, intent(in) :: release
+    character(len=:), allocatable, intent(out) :: flags
+    integer :: id
+
+    id = get_compiler_id(compiler)
+    if (release) then
+        call get_release_compile_flags(id, flags)
+    else
+        call get_debug_compile_flags(id, flags)
+    end if
 
+end subroutine get_default_compile_flags
+
+subroutine get_release_compile_flags(id, flags)
+    integer(compiler_enum), intent(in) :: id
+    character(len=:), allocatable, intent(out) :: flags
+
+    select case(id)
+    case default
+        flags = ""
+
+    case(id_caf)
+        flags='&
+            & -O3&
+            & -Wimplicit-interface&
+            & -fPIC&
+            & -fmax-errors=1&
+            & -funroll-loops&
+            &'
+    case(id_gcc)
+        flags='&
+            & -O3&
+            & -Wimplicit-interface&
+            & -fPIC&
+            & -fmax-errors=1&
+            & -funroll-loops&
+            & -fcoarray=single&
+            &'
+    case(id_f95)
+        flags='&
+            & -O3&
+            & -Wimplicit-interface&
+            & -fPIC&
+            & -fmax-errors=1&
+            & -ffast-math&
+            & -funroll-loops&
+            &'
+    case(id_nvhpc)
+        flags = '&
+            & -Mbackslash&
+            &'
+    case(id_intel_classic)
+        flags = '&
+            & -fp-model precise&
+            & -pc 64&
+            & -align all&
+            & -error-limit 1&
+            & -reentrancy threaded&
+            & -nogen-interfaces&
+            & -assume byterecl&
+            &'
+    case(id_nag)
+        flags = ' &
+            & -O4&
+            & -coarray=single&
+            & -PIC&
+            &'
+    end select
+end subroutine get_release_compile_flags
+
+subroutine get_debug_compile_flags(id, flags)
+    integer(compiler_enum), intent(in) :: id
+    character(len=:), allocatable, intent(out) :: flags
+
+    select case(id)
     case default
-       fflags = ' '
-       mandatory=' -module '//modpath//' -I '//modpath 
-       write(*,'(*(a))')'<WARNING> unknown compiler (',compiler,') and build name (',build_name,') combination.'
-       write(*,'(a,*(T31,6(a:,", "),/))')'          known compilers are ',(trim(names(i)),i=1,size(names)-1)
+        flags = ""
+
+    case(id_caf)
+        flags = '&
+            & -Wall&
+            & -Wextra&
+            & -Wimplicit-interface&
+            & -fPIC -fmax-errors=1&
+            & -g&
+            & -fbounds-check&
+            & -fcheck-array-temporaries&
+            & -fbacktrace&
+            &'
+
+    case(id_gcc)
+        flags = '&
+            & -Wall&
+            & -Wextra&
+            & -Wimplicit-interface&
+            & -fPIC -fmax-errors=1&
+            & -g&
+            & -fbounds-check&
+            & -fcheck-array-temporaries&
+            & -fbacktrace&
+            & -fcoarray=single&
+            &'
+
+    case(id_f95)
+        flags = '&
+            & -Wall&
+            & -Wextra&
+            & -Wimplicit-interface&
+            & -fPIC -fmax-errors=1&
+            & -g&
+            & -fbounds-check&
+            & -fcheck-array-temporaries&
+            & -Wno-maybe-uninitialized -Wno-uninitialized&
+            & -fbacktrace&
+            &'
+
+    case(id_nvhpc)
+        flags = '&
+            & -Minform=inform&
+            & -Mbackslash&
+            & -g&
+            & -Mbounds&
+            & -Mchkptr&
+            & -Mchkstk&
+            & -traceback&
+            &'
+
+    case(id_intel_classic)
+        flags = '&
+            & -warn all&
+            & -check:all:noarg_temp_created&
+            & -error-limit 1&
+            & -O0&
+            & -g&
+            & -assume byterecl&
+            & -traceback&
+            &'
+
+    case(id_nag)
+        flags = '&
+            & -g&
+            & -C=all&
+            & -O0&
+            & -gline&
+            & -coarray=single&
+            & -PIC&
+            &'
     end select
+end subroutine get_debug_compile_flags
+
+subroutine get_module_flags(compiler, modpath, flags)
+    character(len=*), intent(in) :: compiler
+    character(len=*), intent(in) :: modpath
+    character(len=:), allocatable, intent(out) :: flags
+    integer(compiler_enum) :: id
+
+    id = get_compiler_id(compiler)
+
+    select case(id)
+    case default
+        flags=' -module '//modpath//' -I '//modpath
+
+    case(id_caf, id_gcc, id_f95, id_cray)
+        flags=' -J '//modpath//' -I '//modpath
+
+    case(id_intel_classic, id_intel_llvm, id_nvhpc, id_pgi, id_flang)
+        flags=' -module '//modpath//' -I '//modpath
+
+    case(id_lahey)
+        flags=' -M '//modpath//' -I '//modpath
+
+    case(id_nag)
+        flags=' -mdir '//modpath//' -I '//modpath !
+
+    case(id_ibmxl)
+        flags=' -qmoddir '//modpath//' -I '//modpath
+
+    end select
+
+end subroutine get_module_flags
+
+function get_compiler_id(compiler) result(id)
+    character(len=*), intent(in) :: compiler
+    integer(kind=compiler_enum) :: id
+
+    if (check_compiler(compiler, "gfortran")) then
+        id = id_gcc
+        return
+    end if
+
+    if (check_compiler(compiler, "f95")) then
+        id = id_f95
+        return
+    end if
+
+    if (check_compiler(compiler, "caf")) then
+        id = id_caf
+        return
+    end if
+
+    if (check_compiler(compiler, "ifort")) then
+        id = id_intel_classic
+        return
+    end if
+
+    if (check_compiler(compiler, "ifx")) then
+        id = id_intel_llvm
+        return
+    end if
+
+    if (check_compiler(compiler, "nvfortran")) then
+        id = id_nvhpc
+        return
+    end if
+
+    if (check_compiler(compiler, "pgfortran") &
+        & .or. check_compiler(compiler, "pgf90") &
+        & .or. check_compiler(compiler, "pgf95")) then
+        id = id_pgi
+        return
+    end if
+
+    if (check_compiler(compiler, "nagfor")) then
+        id = id_nag
+        return
+    end if
+
+    if (check_compiler(compiler, "flang")) then
+        id = id_flang
+        return
+    end if
+
+    if (check_compiler(compiler, "xlf90")) then
+        id = id_ibmxl
+        return
+    end if
+
+    if (check_compiler(compiler, "crayftn")) then
+        id = id_cray
+        return
+    end if
+
+    if (check_compiler(compiler, "lfc")) then
+        id = id_lahey
+        return
+    end if
+
+    if (check_compiler(compiler, "lfort")) then
+        id = id_lfortran
+        return
+    end if
+
+    id = id_unknown
+
+end function get_compiler_id
 
-    model%fortran_compile_flags = fflags//' '//mandatory
-     
-end subroutine add_compile_flag_defaults
+function check_compiler(compiler, expected) result(match)
+    character(len=*), intent(in) :: compiler
+    character(len=*), intent(in) :: expected
+    logical :: match
+    match = compiler == expected
+    if (.not. match) then
+        match = index(basename(compiler), expected) > 0
+    end if
+end function check_compiler
 
 end module fpm_compiler