Merge branch 'master' into different-archiver-on-windows

9 files changed, 129 insertions, 18 deletions

diff --git a/README.md b/README.md
index d4e9002..290b586 100644
--- a/README.md
+++ b/README.md
@@ -101,7 +101,7 @@ This guide explains the process of building *fpm* on a platform for the first ti
 To build *fpm* without a prior *fpm* version a single source file version is available
 at each release.
 
-To build manually using the single source distribution use
+To build manually using the single source distribution, run the following code (from within the current directory)
 
 ```
 mkdir _tmp
diff --git a/manifest-reference.md b/manifest-reference.md
index 1a33dc1..77ee2eb 100644
--- a/manifest-reference.md
+++ b/manifest-reference.md
@@ -33,6 +33,8 @@ Every manifest file consists of the following sections:
     Toggle automatic discovery of executables
   - [*link*](#link-external-libraries):
     Link with external dependencies
+  - [*external-modules*](#use-system-installed-modules):
+    Specify modules used that are not within your fpm package
 - Target sections:
   - [*library*](#library-configuration)
     Configuration of the library target
@@ -353,6 +355,30 @@ In this case the order of the libraries matters:
 link = ["blas", "lapack"]
 ```
 
+## Use system-installed modules
+
+To use modules that are not defined within your fpm package or its dependencies,
+specify the module name using the *external-modules* key in the *build* table.
+
+> __Important:__ *fpm* cannot automatically locate external module files; it is the responsibility
+> of the user to specify the necessary include directories using compiler flags such that
+> the compiler can locate external module files during compilation.
+
+*Example:*
+
+```toml
+[build]
+external-modules = "netcdf"
+```
+
+Multiple external modules can be specified as a list.
+
+*Example:*
+
+```toml
+[build]
+external-modules = ["netcdf", "h5lt"]
+```
 
 ## Automatic target discovery
 
diff --git a/src/fpm.f90 b/src/fpm.f90
index fa2087d..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: get_archiver, 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)
@@ -63,6 +64,8 @@ subroutine build_model(model, settings, package, error)
     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))') &
@@ -173,6 +176,10 @@ subroutine build_model(model, settings, package, error)
             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
@@ -180,6 +187,7 @@ 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> C COMPILER:  ',model%c_compiler
         write(*,*)'<INFO> COMPILER OPTIONS:  ', model%fortran_compile_flags
         write(*,*)'<INFO> INCLUDE DIRECTORIES:  [', string_cat(model%include_dirs,','),']'
      end if
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 f84d2ea..51861b4 100644
--- a/src/fpm_backend.f90
+++ b/src/fpm_backend.f90
@@ -30,9 +30,8 @@ module fpm_backend
 use fpm_environment, only: run
 use fpm_filesystem, only: dirname, join_path, exists, mkdir
 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_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
 
 implicit none
@@ -241,6 +240,10 @@ subroutine build_target(model,target)
         call run(model%fortran_compiler//" -c " // target%source%file_name // target%compile_flags &
               // " -o " // target%output_file)
 
+    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 &
diff --git a/src/fpm_compiler.f90 b/src/fpm_compiler.f90
index a499bb9..ca0f4d7 100644
--- a/src/fpm_compiler.f90
+++ b/src/fpm_compiler.f90
@@ -332,6 +332,34 @@ 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_model.f90 b/src/fpm_model.f90
index 84f70d4..9746e5f 100644
--- a/src/fpm_model.f90
+++ b/src/fpm_model.f90
@@ -120,6 +120,9 @@ type :: fpm_model_t
     !> 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
 
@@ -132,6 +135,9 @@ 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
 
@@ -279,6 +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_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))
 
diff --git a/test/fpm_test/test_module_dependencies.f90 b/test/fpm_test/test_module_dependencies.f90
index f193646..992f227 100644
--- a/test/fpm_test/test_module_dependencies.f90
+++ b/test/fpm_test/test_module_dependencies.f90
@@ -67,6 +67,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -137,6 +138,7 @@ contains
         character(:), allocatable :: scope_str
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -196,6 +198,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(1))
 
@@ -249,6 +252,7 @@ contains
         character(:), allocatable :: scope_str
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(3))
 
@@ -308,6 +312,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -335,6 +340,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -361,6 +367,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -388,6 +395,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))
 
@@ -507,6 +515,7 @@ contains
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))