Add: external-modules key to build table for non-fpm modules

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
 

src/fpm.f90

@@ -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)
@@ -171,6 +172,10 @@ 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

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 @@ subroutine new_build_config(self, table, error)
         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 @@ subroutine check(table, error)
         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 @@ subroutine info(self, unit, verbosity)
         !> 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 @@ subroutine info(self, unit, verbosity)
                 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
 

src/fpm_model.f90

@@ -129,6 +129,9 @@ module fpm_model
     !> 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 +279,13 @@ 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

src/fpm_targets.f90

@@ -121,7 +121,7 @@ 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)
@@ -345,8 +345,9 @@ 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 +365,11 @@ 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 => &

test/fpm_test/test_module_dependencies.f90

@@ -67,6 +67,7 @@ subroutine test_library_module_use(error)
         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 @@ subroutine test_scope(exe_scope,error)
         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 @@ subroutine test_program_with_module(error)
         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 @@ subroutine test_scope(exe_scope,error)
         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 @@ subroutine test_missing_library_use(error)
         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 @@ subroutine test_missing_program_use(error)
         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 @@ subroutine test_invalid_library_use(error)
         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 @@ subroutine test_subdirectory_module_use(error)
         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 @@ subroutine test_invalid_subdirectory_module_use(error)
         type(build_target_ptr), allocatable :: targets(:)
 
         model%output_directory = ''
+        allocate(model%external_modules(0))
         allocate(model%packages(1))
         allocate(model%packages(1)%sources(2))