Merge branch 'upstream_master' into backend-grace

11 files changed, 332 insertions, 73 deletions

diff --git a/src/fpm.f90 b/src/fpm.f90
index 31b68ff..5854cfb 100644
--- a/src/fpm.f90
+++ b/src/fpm.f90
@@ -4,12 +4,12 @@ use fpm_backend, only: build_package
 use fpm_command_line, only: fpm_build_settings, fpm_new_settings, &
                       fpm_run_settings, fpm_install_settings, fpm_test_settings
 use fpm_dependency, only : new_dependency_tree
-use fpm_environment, only: run
+use fpm_environment, only: run, get_env, get_archiver
 use fpm_filesystem, only: is_dir, join_path, number_of_rows, list_files, exists, basename
 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: get_module_flags, is_unknown_compiler
+use fpm_compiler, only: get_module_flags, is_unknown_compiler, get_default_c_compiler
 
 
 use fpm_sources, only: add_executable_sources, add_sources_from_dir
@@ -51,6 +51,7 @@ subroutine build_model(model, settings, package, error)
 
     allocate(model%include_dirs(0))
     allocate(model%link_libraries(0))
+    allocate(model%external_modules(0))
 
     call new_dependency_tree(model%deps, cache=join_path("build", "cache.toml"))
     call model%deps%add(package, error)
@@ -62,6 +63,10 @@ subroutine build_model(model, settings, package, error)
         model%fortran_compiler = settings%compiler
     endif
 
+    model%archiver = get_archiver()
+    call get_default_c_compiler(model%fortran_compiler, model%c_compiler)
+    model%c_compiler = get_env('FPM_C_COMPILER',model%c_compiler)
+
     if (is_unknown_compiler(model%fortran_compiler)) then
         write(*, '(*(a:,1x))') &
             "<WARN>", "Unknown compiler", model%fortran_compiler, "requested!", &
@@ -147,7 +152,7 @@ subroutine build_model(model, settings, package, error)
             if (.not.allocated(model%packages(i)%sources)) allocate(model%packages(i)%sources(0))
 
             if (allocated(dependency%library)) then
-                
+
                 if (allocated(dependency%library%source_dir)) then
                     lib_dir = join_path(dep%proj_dir, dependency%library%source_dir)
                     if (is_dir(lib_dir)) then
@@ -165,12 +170,16 @@ subroutine build_model(model, settings, package, error)
                         end if
                     end do
                 end if
-                
+
             end if
 
             if (allocated(dependency%build%link)) then
                 model%link_libraries = [model%link_libraries, dependency%build%link]
             end if
+
+            if (allocated(dependency%build%external_modules)) then
+                model%external_modules = [model%external_modules, dependency%build%external_modules]
+            end if
         end associate
     end do
     if (allocated(error)) return
@@ -178,8 +187,9 @@ subroutine build_model(model, settings, package, error)
     if (settings%verbose) then
         write(*,*)'<INFO> BUILD_NAME: ',settings%build_name
         write(*,*)'<INFO> COMPILER:  ',settings%compiler
-        write(*,*)'<INFO> COMPILER OPTIONS:  ', model%fortran_compile_flags 
-        write(*,*)'<INFO> INCLUDE DIRECTORIES:  [', string_cat(model%include_dirs,','),']' 
+        write(*,*)'<INFO> C COMPILER:  ',model%c_compiler
+        write(*,*)'<INFO> COMPILER OPTIONS:  ', model%fortran_compile_flags
+        write(*,*)'<INFO> INCLUDE DIRECTORIES:  [', string_cat(model%include_dirs,','),']'
      end if
 
     ! Check for duplicate modules
@@ -190,7 +200,7 @@ subroutine build_model(model, settings, package, error)
 end subroutine build_model
 
 ! Check for duplicate modules
-subroutine check_modules_for_duplicates(model, duplicates_found) 
+subroutine check_modules_for_duplicates(model, duplicates_found)
     type(fpm_model_t), intent(in) :: model
     integer :: maxsize
     integer :: i,j,k,l,m,modi
@@ -370,7 +380,7 @@ subroutine cmd_run(settings,test)
 
     ! Check all names are valid
     ! or no name and found more than one file
-    toomany= size(settings%name).eq.0 .and. size(executables).gt.1 
+    toomany= size(settings%name).eq.0 .and. size(executables).gt.1
     if ( any(.not.found) &
     & .or. &
     & ( (toomany .and. .not.test) .or.  (toomany .and. settings%runner .ne. '') ) &
@@ -420,7 +430,7 @@ subroutine cmd_run(settings,test)
             end if
         end do
     endif
-    contains 
+    contains
     subroutine compact_list_all()
     integer, parameter :: LINE_WIDTH = 80
     integer :: i, j, nCol
diff --git a/src/fpm/cmd/new.f90 b/src/fpm/cmd/new.f90
index 5149bea..773d7a7 100644
--- a/src/fpm/cmd/new.f90
+++ b/src/fpm/cmd/new.f90
@@ -347,7 +347,7 @@ character(len=:,kind=tfc),allocatable :: littlefile(:)
         &'  # git repository.                                                             ',&
         &'  #                                                                             ',&
         &'  # You can be specific about which version of a dependency you would           ',&
-        &'  # like. By default the latest master master branch is used. You can           ',&
+        &'  # like. By default the latest default branch is used. You can           ',&
         &'  # optionally specify a branch, a tag or a commit value.                       ',&
         &'  #                                                                             ',&
         &'  # So here are several alternates for specifying a remote dependency (you      ',&
diff --git a/src/fpm/manifest/build.f90 b/src/fpm/manifest/build.f90
index d96974f..c9b3f44 100644
--- a/src/fpm/manifest/build.f90
+++ b/src/fpm/manifest/build.f90
@@ -34,6 +34,9 @@ module fpm_manifest_build
         !> Libraries to link against
         type(string_t), allocatable :: link(:)
 
+        !> External modules to use
+        type(string_t), allocatable :: external_modules(:)
+
     contains
 
         !> Print information on this instance
@@ -87,6 +90,9 @@ contains
         call get_value(table, "link", self%link, error)
         if (allocated(error)) return
 
+        call get_value(table, "external-modules", self%external_modules, error)
+        if (allocated(error)) return
+
     end subroutine new_build_config
 
 
@@ -110,7 +116,7 @@ contains
         do ikey = 1, size(list)
             select case(list(ikey)%key)
 
-            case("auto-executables", "auto-examples", "auto-tests", "link")
+            case("auto-executables", "auto-examples", "auto-tests", "link", "external-modules")
                 continue
 
             case default
@@ -135,7 +141,7 @@ contains
         !> Verbosity of the printout
         integer, intent(in), optional :: verbosity
 
-        integer :: pr, ilink
+        integer :: pr, ilink, imod
         character(len=*), parameter :: fmt = '("#", 1x, a, t30, a)'
 
         if (present(verbosity)) then
@@ -156,6 +162,12 @@ contains
                 write(unit, fmt) "   - " // self%link(ilink)%s
             end do
         end if
+        if (allocated(self%external_modules)) then
+            write(unit, fmt) " - external modules"
+            do imod = 1, size(self%external_modules)
+                write(unit, fmt) "   - " // self%external_modules(imod)%s
+            end do
+        end if
 
     end subroutine info
 
diff --git a/src/fpm_backend.f90 b/src/fpm_backend.f90
index 799b7a6..bdec3af 100644
--- a/src/fpm_backend.f90
+++ b/src/fpm_backend.f90
@@ -1,39 +1,38 @@
 !># Build backend
-!> Uses a list of `[[build_target_ptr]]` and a valid `[[fpm_model]]` instance 
+!> Uses a list of `[[build_target_ptr]]` and a valid `[[fpm_model]]` instance
 !> to schedule and execute the compilation and linking of package targets.
-!> 
+!>
 !> The package build process (`[[build_package]]`) comprises three steps:
 !>
 !> 1. __Target sorting:__ topological sort of the target dependency graph (`[[sort_target]]`)
 !> 2. __Target scheduling:__ group targets into schedule regions based on the sorting (`[[schedule_targets]]`)
 !> 3. __Target building:__ generate targets by compilation or linking
-!> 
+!>
 !> @note If compiled with OpenMP, targets will be build in parallel where possible.
 !>
 !>### Incremental compilation
-!> The backend process supports *incremental* compilation whereby targets are not 
+!> The backend process supports *incremental* compilation whereby targets are not
 !> re-compiled if their corresponding dependencies have not been modified.
-!> 
+!>
 !> - Source-based targets (*i.e.* objects) are not re-compiled if the corresponding source
 !>   file is unmodified AND all of the target dependencies are not marked for re-compilation
 !>
-!> - Link targets (*i.e.* executables and libraries) are not re-compiled if the 
+!> - Link targets (*i.e.* executables and libraries) are not re-compiled if the
 !>   target output file already exists AND all of the target dependencies are not marked for
 !>   re-compilation
 !>
 !> Source file modification is determined by a file digest (hash) which is calculated during
-!> the source parsing phase ([[fpm_source_parsing]]) and cached to disk after a target is 
+!> the source parsing phase ([[fpm_source_parsing]]) and cached to disk after a target is
 !> successfully generated.
 !>
 module fpm_backend
 
-use fpm_environment, only: run
-use fpm_filesystem, only: basename, dirname, join_path, exists, mkdir
+use fpm_environment, only: run, get_os_type, OS_WINDOWS
+use fpm_filesystem, only: basename, dirname, join_path, exists, mkdir, unix_path
 use fpm_model, only: fpm_model_t
-use fpm_targets, only: build_target_t, build_target_ptr, &
-                     FPM_TARGET_OBJECT, FPM_TARGET_ARCHIVE, FPM_TARGET_EXECUTABLE
-                     
-use fpm_strings, only: string_cat
+use fpm_targets, only: build_target_t, build_target_ptr, FPM_TARGET_OBJECT, &
+                       FPM_TARGET_C_OBJECT, FPM_TARGET_ARCHIVE, FPM_TARGET_EXECUTABLE
+use fpm_strings, only: string_cat, string_t
 
 implicit none
 
@@ -59,9 +58,9 @@ subroutine build_package(targets,model)
 
     ! Perform depth-first topological sort of targets
     do i=1,size(targets)
-        
+
         call sort_target(targets(i)%ptr)
-        
+
     end do
 
     ! Construct build schedule queue
@@ -106,20 +105,20 @@ subroutine build_package(targets,model)
         end if
 
     end do
-    
+
 end subroutine build_package
 
 
-!> Topologically sort a target for scheduling by 
+!> Topologically sort a target for scheduling by
 !>  recursing over its dependencies.
-!> 
+!>
 !> Checks disk-cached source hashes to determine if objects are
 !>  up-to-date. Up-to-date sources are tagged as skipped.
 !>
-!> On completion, `target` should either be marked as 
+!> On completion, `target` should either be marked as
 !> sorted (`target%sorted=.true.`) or skipped (`target%skip=.true.`)
 !>
-!> If `target` is marked as sorted, `target%schedule` should be an 
+!> If `target` is marked as sorted, `target%schedule` should be an
 !> integer greater than zero indicating the region for scheduling
 !>
 recursive subroutine sort_target(target)
@@ -190,7 +189,7 @@ recursive subroutine sort_target(target)
         end if
 
     end do
-    
+
     ! Mark flag as processed: either sorted or skipped
     target%sorted = .not.target%skip
 
@@ -270,14 +269,28 @@ subroutine build_target(model,target,stat)
         call run(model%fortran_compiler//" -c " // target%source%file_name // target%compile_flags &
               // " -o " // target%output_file, echo=.true., exitstat=stat)
 
+    case (FPM_TARGET_C_OBJECT)
+        call run(model%c_compiler//" -c " // target%source%file_name // target%compile_flags &
+                // " -o " // target%output_file)
+
     case (FPM_TARGET_EXECUTABLE)
-        
+
         call run(model%fortran_compiler// " " // target%compile_flags &
               //" "//target%link_flags// " -o " // target%output_file, echo=.true., exitstat=stat)
 
     case (FPM_TARGET_ARCHIVE)
-        call run("ar -rs " // target%output_file // " " // string_cat(target%link_objects," "), &
-                  echo=.true., exitstat=stat)
+
+        select case (get_os_type())
+        case (OS_WINDOWS)
+            call write_response_file(target%output_file//".resp" ,target%link_objects)
+            call run(model%archiver // target%output_file // " @" // target%output_file//".resp", &
+                     echo=.true., exitstat=stat)
+
+        case default
+            call run(model%archiver // target%output_file // " " // string_cat(target%link_objects," "), &
+                     echo=.true., exitstat=stat)
+
+        end select
 
     end select
 
@@ -289,4 +302,19 @@ subroutine build_target(model,target,stat)
 
 end subroutine build_target
 
+!> Response files allow to read command line options from files.
+!> Whitespace is used to separate the arguments, we will use newlines
+!> as separator to create readable response files which can be inspected
+!> in case of errors.
+subroutine write_response_file(name, argv)
+    character(len=*), intent(in) :: name
+    type(string_t), intent(in) :: argv(:)
+    integer :: iarg, io
+    open(file=name, newunit=io)
+    do iarg = 1, size(argv)
+        write(io, '(a)') unix_path(argv(iarg)%s)
+    end do
+    close(io)
+end subroutine write_response_file
+
 end module fpm_backend
diff --git a/src/fpm_command_line.f90 b/src/fpm_command_line.f90
index 9e9a572..f44bcd0 100644
--- a/src/fpm_command_line.f90
+++ b/src/fpm_command_line.f90
@@ -25,7 +25,7 @@
 module fpm_command_line
 use fpm_environment,  only : get_os_type, get_env, &
                              OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_WINDOWS, &
-                             OS_CYGWIN, OS_SOLARIS, OS_FREEBSD
+                             OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD
 use M_CLI2,           only : set_args, lget, sget, unnamed, remaining, specified
 use fpm_strings,      only : lower, split, fnv_1a
 use fpm_filesystem,   only : basename, canon_path, to_fortran_name
@@ -46,6 +46,7 @@ public :: fpm_cmd_settings, &
           get_command_line_settings
 
 type, abstract :: fpm_cmd_settings
+    character(len=:), allocatable :: working_dir
     logical                      :: verbose=.true.
 end type
 
@@ -119,6 +120,7 @@ contains
         integer                       :: i
         integer                       :: widest
         type(fpm_install_settings), allocatable :: install_settings
+        character(len=:), allocatable :: common_args, working_dir
 
         call set_help()
         ! text for --version switch,
@@ -129,6 +131,7 @@ contains
             case (OS_CYGWIN);  os_type =  "OS Type:     Cygwin"
             case (OS_SOLARIS); os_type =  "OS Type:     Solaris"
             case (OS_FREEBSD); os_type =  "OS Type:     FreeBSD"
+            case (OS_OPENBSD); os_type =  "OS Type:     OpenBSD"
             case (OS_UNKNOWN); os_type =  "OS Type:     Unknown"
             case default     ; os_type =  "OS Type:     UNKNOWN"
         end select
@@ -147,12 +150,14 @@ contains
            if(adjustl(cmdarg(1:1)) .ne. '-')exit
         enddo
 
+        common_args = '--directory:C " " '
+
         ! now set subcommand-specific help text and process commandline
         ! arguments. Then call subcommand routine
         select case(trim(cmdarg))
 
         case('run')
-            call set_args('&
+            call set_args(common_args //'&
             & --target " " &
             & --list F &
             & --all F &
@@ -205,7 +210,7 @@ contains
             & verbose=lget('verbose') )
 
         case('build')
-            call set_args( '&
+            call set_args(common_args // '&
             & --profile " " &
             & --list F &
             & --show-model F &
@@ -227,7 +232,7 @@ contains
             & verbose=lget('verbose') )
 
         case('new')
-            call set_args('&
+            call set_args(common_args // '&
             & --src F &
             & --lib F &
             & --app F &
@@ -297,7 +302,7 @@ contains
             endif
 
         case('help','manual')
-            call set_args('&
+            call set_args(common_args // '&
             & --verbose F &
             & ',help_help,version_text)
             if(size(unnamed).lt.2)then
@@ -345,7 +350,8 @@ contains
             call printhelp(help_text)
 
         case('install')
-            call set_args('--profile " " --no-rebuild F --verbose F --prefix " " &
+            call set_args(common_args // '&
+                & --profile " " --no-rebuild F --verbose F --prefix " " &
                 & --list F &
                 & --compiler "'//get_env('FPM_COMPILER','gfortran')//'" &
                 & --flag:: " "&
@@ -370,7 +376,7 @@ contains
             call move_alloc(install_settings, cmd_settings)
 
         case('list')
-            call set_args('&
+            call set_args(common_args // '&
             & --list F&
             & --verbose F&
             &', help_list, version_text)
@@ -379,7 +385,7 @@ contains
                call printhelp(help_list_dash)
             endif
         case('test')
-            call set_args('&
+            call set_args(common_args // '&
             & --target " " &
             & --list F&
             & --profile " "&
@@ -424,7 +430,7 @@ contains
             & verbose=lget('verbose') )
 
         case('update')
-            call set_args('--fetch-only F --verbose F --clean F', &
+            call set_args(common_args // ' --fetch-only F --verbose F --clean F', &
                 help_update, version_text)
 
             if( size(unnamed) .gt. 1 )then
@@ -440,7 +446,7 @@ contains
 
         case default
 
-            call set_args('&
+            call set_args(common_args // '&
             & --list F&
             & --verbose F&
             &', help_fpm, version_text)
@@ -461,6 +467,12 @@ contains
             call printhelp(help_text)
 
         end select
+
+        if (allocated(cmd_settings)) then
+            working_dir = sget("directory")
+            call move_alloc(working_dir, cmd_settings%working_dir)
+        end if
+
     contains
 
     subroutine check_build_vals()
@@ -673,6 +685,8 @@ contains
     '    install [--profile PROF] [--flag FFLAGS] [--no-rebuild] [--prefix PATH] [options]', &
     '                                                                       ', &
     'SUBCOMMAND OPTIONS                                                     ', &
+    ' -C, --directory PATH', &
+    '             Change working directory to PATH before running any command', &
     ' --profile PROF    selects the compilation profile for the build.',&
     '                   Currently available profiles are "release" for',&
     '                   high optimization and "debug" for full debug options.',&
diff --git a/src/fpm_compiler.f90 b/src/fpm_compiler.f90
index a499bb9..389ba94 100644
--- a/src/fpm_compiler.f90
+++ b/src/fpm_compiler.f90
@@ -35,7 +35,8 @@ use fpm_environment, only: &
         OS_WINDOWS, &
         OS_CYGWIN, &
         OS_SOLARIS, &
-        OS_FREEBSD
+        OS_FREEBSD, &
+        OS_OPENBSD
 implicit none
 public :: is_unknown_compiler
 public :: get_module_flags
@@ -239,7 +240,6 @@ subroutine get_debug_compile_flags(id, flags)
             & -g&
             & -assume byterecl&
             & -traceback&
-            & -coarray=single&
             &'
     case(id_intel_classic_mac)
         flags = '&
@@ -260,7 +260,6 @@ subroutine get_debug_compile_flags(id, flags)
             & /Z7&
             & /assume:byterecl&
             & /traceback&
-            & /Qcoarray:single&
             &'
     case(id_intel_llvm_nix, id_intel_llvm_unknown)
         flags = '&
@@ -271,7 +270,6 @@ subroutine get_debug_compile_flags(id, flags)
             & -g&
             & -assume byterecl&
             & -traceback&
-            & -coarray=single&
             &'
     case(id_intel_llvm_windows)
         flags = '&
@@ -281,7 +279,6 @@ subroutine get_debug_compile_flags(id, flags)
             & /Od&
             & /Z7&
             & /assume:byterecl&
-            & /Qcoarray:single&
             &'
     case(id_nag)
         flags = '&
@@ -332,6 +329,34 @@ subroutine get_module_flags(compiler, modpath, flags)
 
 end subroutine get_module_flags
 
+subroutine get_default_c_compiler(f_compiler, c_compiler)
+    character(len=*), intent(in) :: f_compiler
+    character(len=:), allocatable, intent(out) :: c_compiler
+    integer(compiler_enum) :: id
+
+    id = get_compiler_id(f_compiler)
+
+    select case(id)
+
+    case(id_intel_classic_nix, id_intel_classic_mac, id_intel_classic_windows, id_intel_classic_unknown)
+        c_compiler = 'icc'
+
+    case(id_intel_llvm_nix,id_intel_llvm_windows, id_intel_llvm_unknown)
+        c_compiler = 'icx'
+
+    case(id_flang)
+        c_compiler='clang'
+
+    case(id_ibmxl)
+        c_compiler='xlc'
+
+    case default
+        ! Fall-back to using Fortran compiler
+        c_compiler = f_compiler
+    end select
+
+end subroutine get_default_c_compiler
+
 function get_compiler_id(compiler) result(id)
     character(len=*), intent(in) :: compiler
     integer(kind=compiler_enum) :: id
diff --git a/src/fpm_environment.f90 b/src/fpm_environment.f90
index 982380d..107c977 100644
--- a/src/fpm_environment.f90
+++ b/src/fpm_environment.f90
@@ -1,5 +1,5 @@
 !> This module contains procedures that interact with the programming environment.
-!! 
+!!
 !! * [get_os_type] -- Determine the OS type
 !! * [get_env] -- return the value of an environment variable
 module fpm_environment
@@ -9,6 +9,7 @@ module fpm_environment
     public :: os_is_unix
     public :: run
     public :: get_env
+    public :: get_archiver
 
     integer, parameter, public :: OS_UNKNOWN = 0
     integer, parameter, public :: OS_LINUX   = 1
@@ -17,12 +18,13 @@ module fpm_environment
     integer, parameter, public :: OS_CYGWIN  = 4
     integer, parameter, public :: OS_SOLARIS = 5
     integer, parameter, public :: OS_FREEBSD = 6
+    integer, parameter, public :: OS_OPENBSD = 7
 contains
     !> Determine the OS type
     integer function get_os_type() result(r)
         !!
         !! Returns one of OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_WINDOWS, OS_CYGWIN,
-        !! OS_SOLARIS, OS_FREEBSD.
+        !! OS_SOLARIS, OS_FREEBSD, OS_OPENBSD.
         !!
         !! At first, the environment variable `OS` is checked, which is usually
         !! found on Windows. Then, `OSTYPE` is read in and compared with common
@@ -83,6 +85,12 @@ contains
                 r = OS_FREEBSD
                 return
             end if
+
+            ! OpenBSD
+            if (index(val, 'OpenBSD') > 0 .or. index(val, 'openbsd') > 0) then
+                r = OS_OPENBSD
+                return
+            end if
         end if
 
         ! Linux
@@ -110,7 +118,7 @@ contains
         end if
     end function get_os_type
 
-    !> Compare the output of [[get_os_type]] or the optional 
+    !> Compare the output of [[get_os_type]] or the optional
     !! passed INTEGER value to the value for OS_WINDOWS
     !! and return .TRUE. if they match and .FALSE. otherwise
     logical function os_is_unix(os) result(unix)
@@ -157,7 +165,7 @@ contains
     function get_env(NAME,DEFAULT) result(VALUE)
     implicit none
     !> name of environment variable to get the value of
-    character(len=*),intent(in)          :: NAME     
+    character(len=*),intent(in)          :: NAME
     !> default value to return if the requested value is undefined or blank
     character(len=*),intent(in),optional :: DEFAULT
     !> the returned value
@@ -189,4 +197,24 @@ contains
         if(VALUE.eq.''.and.present(DEFAULT))VALUE=DEFAULT
      end function get_env
 
+    function get_archiver() result(archiver)
+        character(:), allocatable :: archiver
+
+        associate(os_type => get_os_type())
+            if (os_type /= OS_WINDOWS .and. os_type /= OS_UNKNOWN) then
+                archiver = "ar -rs "
+            else
+                block
+                    integer :: estat
+
+                    call execute_command_line("ar --version", exitstat=estat)
+                    if (estat /= 0) then
+                        archiver = "lib /OUT:"
+                    else
+                        archiver = "ar -rs "
+                    end if
+                end block
+            end if
+        end associate
+    end function
 end module fpm_environment
diff --git a/src/fpm_filesystem.f90 b/src/fpm_filesystem.f90
index 6acd383..c9c97dd 100644
--- a/src/fpm_filesystem.f90
+++ b/src/fpm_filesystem.f90
@@ -4,13 +4,13 @@ module fpm_filesystem
 use,intrinsic :: iso_fortran_env, only : stdin=>input_unit, stdout=>output_unit, stderr=>error_unit
     use fpm_environment, only: get_os_type, &
                                OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_WINDOWS, &
-                               OS_CYGWIN, OS_SOLARIS, OS_FREEBSD
+                               OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD
     use fpm_strings, only: f_string, replace, string_t, split
     implicit none
     private
     public :: basename, canon_path, dirname, is_dir, join_path, number_of_rows, read_lines, list_files, env_variable, &
             mkdir, exists, get_temp_filename, windows_path, unix_path, getline, delete_file, to_fortran_name
-    public :: fileopen, fileclose, filewrite, warnwrite
+    public :: fileopen, fileclose, filewrite, warnwrite, parent_dir
 
     integer, parameter :: LINE_BUFFER_LEN = 1000
 
@@ -184,6 +184,15 @@ function dirname(path) result (dir)
 
 end function dirname
 
+!> Extract dirname from path
+function parent_dir(path) result (dir)
+    character(*), intent(in) :: path
+    character(:), allocatable :: dir
+
+    dir = path(1:scan(path,'/\',back=.true.)-1)
+
+end function parent_dir
+
 
 !> test if a name matches an existing directory path
 logical function is_dir(dir)
@@ -192,7 +201,7 @@ logical function is_dir(dir)
 
     select case (get_os_type())
 
-    case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD)
+    case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD)
         call execute_command_line("test -d " // dir , exitstat=stat)
 
     case (OS_WINDOWS)
@@ -214,7 +223,7 @@ function join_path(a1,a2,a3,a4,a5) result(path)
     character(len=1)                       :: filesep
 
     select case (get_os_type())
-        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD)
+        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD)
             filesep = '/'
         case (OS_WINDOWS)
             filesep = '\'
@@ -283,7 +292,7 @@ subroutine mkdir(dir)
     if (is_dir(dir)) return
 
     select case (get_os_type())
-        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD)
+        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD)
             call execute_command_line('mkdir -p ' // dir, exitstat=stat)
             write (*, '(" + ",2a)') 'mkdir -p ' // dir
 
@@ -322,7 +331,7 @@ recursive subroutine list_files(dir, files, recurse)
     allocate (temp_file, source=get_temp_filename())
 
     select case (get_os_type())
-        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD)
+        case (OS_UNKNOWN, OS_LINUX, OS_MACOS, OS_CYGWIN, OS_SOLARIS, OS_FREEBSD, OS_OPENBSD)
             call execute_command_line('ls -A ' // dir // ' > ' // temp_file, &
                                       exitstat=stat)
         case (OS_WINDOWS)
diff --git a/src/fpm_model.f90 b/src/fpm_model.f90
index bfb0115..9746e5f 100644
--- a/src/fpm_model.f90
+++ b/src/fpm_model.f90
@@ -1,6 +1,6 @@
 !># The fpm package model
 !>
-!> Defines the fpm model data types which encapsulate all information 
+!> Defines the fpm model data types which encapsulate all information
 !> required to correctly build a package and its dependencies.
 !>
 !> The process (see `[[build_model(subroutine)]]`) for generating a valid `[[fpm_model]]` involves
@@ -117,6 +117,12 @@ type :: fpm_model_t
     !> Command line name to invoke fortran compiler
     character(:), allocatable :: fortran_compiler
 
+    !> Command line to invoke for creating static library
+    character(:), allocatable :: archiver
+
+    !> Command line name to invoke c compiler
+    character(:), allocatable :: c_compiler
+
     !> Command line flags passed to fortran for compilation
     character(:), allocatable :: fortran_compile_flags
 
@@ -128,7 +134,10 @@ type :: fpm_model_t
 
     !> Native libraries to link against
     type(string_t), allocatable :: link_libraries(:)
-    
+
+    !> External modules used
+    type(string_t), allocatable :: external_modules(:)
+
     !> Project dependencies
     type(dependency_tree_t) :: deps
 
@@ -276,6 +285,13 @@ function info_model(model) result(s)
         if (i < size(model%link_libraries)) s = s // ", "
     end do
     s = s // "]"
+    !    type(string_t), allocatable :: external_modules(:)
+    s = s // ", external_modules=["
+    do i = 1, size(model%external_modules)
+        s = s // '"' // model%external_modules(i)%s // '"'
+        if (i < size(model%external_modules)) s = s // ", "
+    end do
+    s = s // "]"
     !    type(dependency_tree_t) :: deps
     ! TODO: print `dependency_tree_t` properly, which should become part of the
     !       model, not imported from another file
diff --git a/src/fpm_os.F90 b/src/fpm_os.F90
new file mode 100644
index 0000000..71663fe
--- /dev/null
+++ b/src/fpm_os.F90
@@ -0,0 +1,105 @@
+module fpm_os
+    use, intrinsic :: iso_c_binding, only : c_char, c_int, c_null_char, c_ptr, c_associated
+    use fpm_error, only : error_t, fatal_error
+    implicit none
+    private
+    public :: change_directory, get_current_directory
+
+#ifndef _WIN32
+    character(len=*), parameter :: pwd_env = "PWD"
+#else
+    character(len=*), parameter :: pwd_env = "CD"
+#endif
+
+    interface
+        function chdir(path) result(stat) &
+#ifndef _WIN32
+                bind(C, name="chdir")
+#else
+                bind(C, name="_chdir")
+#endif
+            import :: c_char, c_int
+            character(kind=c_char, len=1), intent(in) :: path(*)
+            integer(c_int) :: stat
+        end function chdir
+
+        function getcwd(buf, bufsize) result(path) &
+#ifndef _WIN32
+                bind(C, name="getcwd")
+#else
+                bind(C, name="_getcwd")
+#endif
+            import :: c_char, c_int, c_ptr
+            character(kind=c_char, len=1), intent(in) :: buf(*)
+            integer(c_int), value, intent(in) :: bufsize
+            type(c_ptr) :: path
+        end function getcwd
+    end interface
+
+contains
+
+    subroutine change_directory(path, error)
+        character(len=*), intent(in) :: path
+        type(error_t), allocatable, intent(out) :: error
+
+        character(kind=c_char, len=1), allocatable :: cpath(:)
+        integer :: stat
+
+        allocate(cpath(len(path)+1))
+        call f_c_character(path, cpath, len(path)+1)
+
+        stat = chdir(cpath)
+
+        if (stat /= 0) then
+            call fatal_error(error, "Failed to change directory to '"//path//"'")
+        end if
+    end subroutine change_directory
+
+    subroutine get_current_directory(path, error)
+        character(len=:), allocatable, intent(out) :: path
+        type(error_t), allocatable, intent(out) :: error
+
+        character(kind=c_char, len=1), allocatable :: cpath(:)
+        integer(c_int), parameter :: buffersize = 1000_c_int
+        type(c_ptr) :: tmp
+
+        allocate(cpath(buffersize))
+
+        tmp = getcwd(cpath, buffersize)
+        if (c_associated(tmp)) then
+            call c_f_character(cpath, path)
+        else
+            call fatal_error(error, "Failed to retrieve current directory")
+        end if
+
+    end subroutine get_current_directory
+
+    subroutine f_c_character(rhs, lhs, len)
+        character(kind=c_char), intent(out) :: lhs(*)
+        character(len=*), intent(in) :: rhs
+        integer, intent(in) :: len
+        integer :: length
+        length = min(len-1, len_trim(rhs))
+
+        lhs(1:length) = transfer(rhs(1:length), lhs(1:length))
+        lhs(length+1:length+1) = c_null_char
+
+    end subroutine f_c_character
+
+    subroutine c_f_character(rhs, lhs)
+        character(kind=c_char), intent(in) :: rhs(*)
+        character(len=:), allocatable, intent(out) :: lhs
+
+        integer :: ii
+
+        do ii = 1, huge(ii) - 1
+            if (rhs(ii) == c_null_char) then
+                exit
+            end if
+        end do
+        allocate(character(len=ii-1) :: lhs)
+        lhs = transfer(rhs(1:ii-1), lhs)
+
+    end subroutine c_f_character
+
+end module fpm_os
diff --git a/src/fpm_targets.f90 b/src/fpm_targets.f90
index 02bb600..c247232 100644
--- a/src/fpm_targets.f90
+++ b/src/fpm_targets.f90
@@ -35,7 +35,8 @@ implicit none
 private
 
 public FPM_TARGET_UNKNOWN, FPM_TARGET_EXECUTABLE, &
-       FPM_TARGET_ARCHIVE, FPM_TARGET_OBJECT
+       FPM_TARGET_ARCHIVE, FPM_TARGET_OBJECT, &
+       FPM_TARGET_C_OBJECT
 public build_target_t, build_target_ptr
 public targets_from_sources, resolve_module_dependencies
 public resolve_target_linking, add_target, add_dependency
@@ -50,7 +51,8 @@ integer, parameter :: FPM_TARGET_EXECUTABLE = 1
 integer, parameter :: FPM_TARGET_ARCHIVE = 2
 !> Target type is compiled object
 integer, parameter :: FPM_TARGET_OBJECT = 3
-
+!> Target type is c compiled object
+integer, parameter :: FPM_TARGET_C_OBJECT = 4
 
 !> Wrapper type for constructing arrays of `[[build_target_t]]` pointers
 type build_target_ptr
@@ -121,7 +123,7 @@ subroutine targets_from_sources(targets,model,error)
 
     call build_target_list(targets,model)
 
-    call resolve_module_dependencies(targets,error)
+    call resolve_module_dependencies(targets,model%external_modules,error)
     if (allocated(error)) return
 
     call resolve_target_linking(targets,model)
@@ -194,7 +196,8 @@ subroutine build_target_list(targets,model)
                 case (FPM_UNIT_MODULE,FPM_UNIT_SUBMODULE,FPM_UNIT_SUBPROGRAM,FPM_UNIT_CSOURCE)
 
                     call add_target(targets,source = sources(i), &
-                                type = FPM_TARGET_OBJECT,&
+                                type = merge(FPM_TARGET_C_OBJECT,FPM_TARGET_OBJECT,&
+                                               sources(i)%unit_type==FPM_UNIT_CSOURCE), &
                                 output_file = get_object_name(sources(i)))
 
                     if (with_lib .and. sources(i)%unit_scope == FPM_SCOPE_LIB) then
@@ -345,8 +348,9 @@ end subroutine add_dependency
 !> a source file in the package of the correct scope, then a __fatal error__
 !> is returned by the procedure and model construction fails.
 !>
-subroutine resolve_module_dependencies(targets,error)
+subroutine resolve_module_dependencies(targets,external_modules,error)
     type(build_target_ptr), intent(inout), target :: targets(:)
+    type(string_t), intent(in) :: external_modules(:)
     type(error_t), allocatable, intent(out) :: error
 
     type(build_target_ptr) :: dep
@@ -364,6 +368,11 @@ subroutine resolve_module_dependencies(targets,error)
                     cycle
                 end if
 
+                if (targets(i)%ptr%source%modules_used(j)%s .in. external_modules) then
+                    ! Dependency satisfied in system-installed module
+                    cycle
+                end if
+
                 if (any(targets(i)%ptr%source%unit_scope == &
                     [FPM_SCOPE_APP, FPM_SCOPE_EXAMPLE, FPM_SCOPE_TEST])) then
                     dep%ptr => &
@@ -442,7 +451,7 @@ subroutine resolve_target_linking(targets, model)
 
     integer :: i
     character(:), allocatable :: global_link_flags
-    character(:), allocatable :: global_compile_flags
+    character(:), allocatable :: global_include_flags
 
     if (size(targets) == 0) return
 
@@ -452,17 +461,16 @@ subroutine resolve_target_linking(targets, model)
         allocate(character(0) :: global_link_flags)
     end if
 
-    global_compile_flags = model%fortran_compile_flags
-
     if (allocated(model%link_libraries)) then
         if (size(model%link_libraries) > 0) then
             global_link_flags = global_link_flags // " -l" // string_cat(model%link_libraries," -l")
         end if
     end if
 
+    allocate(character(0) :: global_include_flags)
     if (allocated(model%include_dirs)) then
         if (size(model%include_dirs) > 0) then
-            global_compile_flags = global_compile_flags // &
+            global_include_flags = global_include_flags // &
             & " -I" // string_cat(model%include_dirs," -I")
         end if
     end if
@@ -471,7 +479,11 @@ subroutine resolve_target_linking(targets, model)
 
         associate(target => targets(i)%ptr)
 
-            target%compile_flags = global_compile_flags
+            if (target%target_type /= FPM_TARGET_C_OBJECT) then
+                target%compile_flags = model%fortran_compile_flags//" "//global_include_flags
+            else
+                target%compile_flags = global_include_flags
+            end if
 
             allocate(target%link_objects(0))