Allow external link dependencies with scope limited to targets

- move reader for string list to toml-f proxy
- allow link entry in executable and test tables
- bump toml-f version to v0.2.1
- add example package linking a single executable against gomp

16 files changed, 137 insertions, 42 deletions

diff --git a/ci/run_tests.bat b/ci/run_tests.bat
index 0c0339c..44f6e5c 100755
--- a/ci/run_tests.bat
+++ b/ci/run_tests.bat
@@ -132,3 +132,13 @@ if errorlevel 1 exit 1
 
 .\build\gfortran_debug\app\Program_with_module
 if errorlevel 1 exit 1
+
+
+cd ..\link_executable
+if errorlevel 1 exit 1
+
+%fpm_path% build
+if errorlevel 1 exit 1
+
+.\build\gfortran_debug\app\gomp_test
+if errorlevel 1 exit 1
diff --git a/ci/run_tests.sh b/ci/run_tests.sh
index d5d3045..894b1f0 100755
--- a/ci/run_tests.sh
+++ b/ci/run_tests.sh
@@ -73,3 +73,7 @@ cd ../program_with_module
 cd ../link_external
 "${f_fpm_path}" build
 ./build/gfortran_debug/app/link_external
+
+cd ../link_executable
+"${f_fpm_path}" build
+./build/gfortran_debug/app/gomp_test
diff --git a/example_packages/README.md b/example_packages/README.md
index 95f28d7..0eb0653 100644
--- a/example_packages/README.md
+++ b/example_packages/README.md
@@ -17,5 +17,6 @@ the features demonstrated in each package and which versions of fpm are supporte
 | program_with_module | App-only; module+program in single source file                |            Y            |  Y  |
 | submodules          | Lib-only; submodules (3 levels)                               |            N            |  Y  |
 | link_external       | Link external library                                         |            N            |  Y  |
+| link_executable     | Link external library to a single executable                  |            N            |  Y  |
 | with_c              | Compile with `c` source files                                 |            N            |  Y  |
 | with_makefile       | External build command (makefile)                             |            Y            |  N  |
diff --git a/example_packages/link_executable/.gitignore b/example_packages/link_executable/.gitignore
new file mode 100644
index 0000000..a007fea
--- /dev/null
+++ b/example_packages/link_executable/.gitignore
@@ -0,0 +1 @@
+build/*
diff --git a/example_packages/link_executable/app/main.f90 b/example_packages/link_executable/app/main.f90
new file mode 100644
index 0000000..b1df402
--- /dev/null
+++ b/example_packages/link_executable/app/main.f90
@@ -0,0 +1,11 @@
+program gomp_example
+  implicit none
+
+  interface
+    integer function omp_get_num_procs()
+    end function
+  end interface
+
+  print *, omp_get_num_procs()
+
+end program gomp_example
diff --git a/example_packages/link_executable/fpm.toml b/example_packages/link_executable/fpm.toml
new file mode 100644
index 0000000..f3545ca
--- /dev/null
+++ b/example_packages/link_executable/fpm.toml
@@ -0,0 +1,8 @@
+name = "link_executable"
+build.auto-executables = false
+
+[[executable]]
+name = "gomp_test"
+source-dir = "app"
+main = "main.f90"
+link = ["gomp"]
diff --git a/fpm/fpm.toml b/fpm/fpm.toml
index fc3a381..404e65c 100644
--- a/fpm/fpm.toml
+++ b/fpm/fpm.toml
@@ -8,7 +8,7 @@ copyright = "2020 fpm contributors"
 [dependencies]
 [dependencies.toml-f]
 git = "https://github.com/toml-f/toml-f"
-tag = "v0.2"
+tag = "v0.2.1"
 
 [dependencies.M_CLI2]
 git = "https://github.com/urbanjost/M_CLI2.git"
diff --git a/fpm/src/fpm/manifest/build_config.f90 b/fpm/src/fpm/manifest/build_config.f90
index a88fd58..612c051 100644
--- a/fpm/src/fpm/manifest/build_config.f90
+++ b/fpm/src/fpm/manifest/build_config.f90
@@ -11,8 +11,7 @@
 module fpm_manifest_build_config
     use fpm_error, only : error_t, syntax_error, fatal_error
     use fpm_strings, only : string_t
-    use fpm_toml, only : toml_table, toml_array, toml_key, toml_stat, get_value, &
-        & len
+    use fpm_toml, only : toml_table, toml_key, toml_stat, get_value
     implicit none
     private
 
@@ -54,9 +53,7 @@ contains
         !> Error handling
         type(error_t), allocatable, intent(out) :: error
 
-        integer :: stat, ilink, nlink
-        type(toml_array), pointer :: children
-        character(len=:), allocatable :: link
+        integer :: stat
 
         call check(table, error)
         if (allocated(error)) return
@@ -75,30 +72,8 @@ contains
             return
         end if
 
-        call get_value(table, "link", children, requested=.false.)
-        if (associated(children)) then
-            nlink = len(children)
-            allocate(self%link(nlink))
-            do ilink = 1, nlink
-                call get_value(children, ilink, link, stat=stat)
-                if (stat /= toml_stat%success) then
-                    call fatal_error(error, "Entry in link field cannot be read")
-                    exit
-                end if
-                call move_alloc(link, self%link(ilink)%s)
-            end do
-            if (allocated(error)) return
-        else
-            call get_value(table, "link", link, stat=stat)
-            if (stat /= toml_stat%success) then
-                call fatal_error(error, "Entry in link field cannot be read")
-                return
-            end if
-            if (allocated(link)) then
-                allocate(self%link(1))
-                call move_alloc(link, self%link(1)%s)
-            end if
-        end if
+        call get_value(table, "link", self%link, error)
+        if (allocated(error)) return
 
     end subroutine new_build_config
 
diff --git a/fpm/src/fpm/manifest/executable.f90 b/fpm/src/fpm/manifest/executable.f90
index 87d9a8d..b34c409 100644
--- a/fpm/src/fpm/manifest/executable.f90
+++ b/fpm/src/fpm/manifest/executable.f90
@@ -7,11 +7,13 @@
 !>name = "string"
 !>source-dir = "path"
 !>main = "file"
+!>link = ["lib"]
 !>[executable.dependencies]
 !>```
 module fpm_manifest_executable
     use fpm_manifest_dependency, only : dependency_t, new_dependencies
     use fpm_error, only : error_t, syntax_error
+    use fpm_strings, only : string_t
     use fpm_toml, only : toml_table, toml_key, toml_stat, get_value
     implicit none
     private
@@ -34,6 +36,9 @@ module fpm_manifest_executable
         !> Dependency meta data for this executable
         type(dependency_t), allocatable :: dependency(:)
 
+        !> Libraries to link against
+        type(string_t), allocatable :: link(:)
+
     contains
 
         !> Print information on this instance
@@ -76,6 +81,9 @@ contains
             if (allocated(error)) return
         end if
 
+        call get_value(table, "link", self%link, error)
+        if (allocated(error)) return
+
     end subroutine new_executable
 
 
@@ -110,7 +118,7 @@ contains
             case("name")
                 name_present = .true.
 
-            case("source-dir", "main", "dependencies")
+            case("source-dir", "main", "dependencies", "link")
                 continue
 
             end select
diff --git a/fpm/src/fpm/manifest/test.f90 b/fpm/src/fpm/manifest/test.f90
index c01d51d..cb7f666 100644
--- a/fpm/src/fpm/manifest/test.f90
+++ b/fpm/src/fpm/manifest/test.f90
@@ -11,6 +11,7 @@
 !>name = "string"
 !>source-dir = "path"
 !>main = "file"
+!>link = ["lib"]
 !>[test.dependencies]
 !>```
 module fpm_manifest_test
@@ -69,6 +70,9 @@ contains
             if (allocated(error)) return
         end if
 
+        call get_value(table, "link", self%link, error)
+        if (allocated(error)) return
+
     end subroutine new_test
 
 
@@ -103,7 +107,7 @@ contains
             case("name")
                 name_present = .true.
 
-            case("source-dir", "main", "dependencies")
+            case("source-dir", "main", "dependencies", "link")
                 continue
 
             end select
diff --git a/fpm/src/fpm/toml.f90 b/fpm/src/fpm/toml.f90
index ecefdd8..34f7c58 100644
--- a/fpm/src/fpm/toml.f90
+++ b/fpm/src/fpm/toml.f90
@@ -13,6 +13,7 @@
 !> For more details on the library used see: https://toml-f.github.io/toml-f
 module fpm_toml
     use fpm_error, only : error_t, fatal_error, file_not_found_error
+    use fpm_strings, only : string_t
     use tomlf, only : toml_table, toml_array, toml_key, toml_stat, get_value, &
         & set_value, toml_parse, toml_error, new_table, add_table, add_array, len
     implicit none
@@ -23,6 +24,11 @@ module fpm_toml
     public :: new_table, add_table, add_array, len
 
 
+    interface get_value
+        module procedure :: get_child_value_string_list
+    end interface get_value
+
+
 contains
 
 
@@ -62,4 +68,50 @@ contains
     end subroutine read_package_file
 
 
+    subroutine get_child_value_string_list(table, key, list, error)
+
+        !> Instance of the TOML data structure
+        type(toml_table), intent(inout) :: table
+
+        !> Key to read from
+        character(len=*), intent(in) :: key
+
+        !> List of strings to read
+        type(string_t), allocatable, intent(out) :: list(:)
+
+        !> Error handling
+        type(error_t), allocatable, intent(out) :: error
+
+        integer :: stat, ilist, nlist
+        type(toml_array), pointer :: children
+        character(len=:), allocatable :: str
+
+        call get_value(table, key, children, requested=.false.)
+        if (associated(children)) then
+            nlist = len(children)
+            allocate(list(nlist))
+            do ilist = 1, nlist
+                call get_value(children, ilist, str, stat=stat)
+                if (stat /= toml_stat%success) then
+                    call fatal_error(error, "Entry in "//key//" field cannot be read")
+                    exit
+                end if
+                call move_alloc(str, list(ilist)%s)
+            end do
+            if (allocated(error)) return
+        else
+            call get_value(table, key, str, stat=stat)
+            if (stat /= toml_stat%success) then
+                call fatal_error(error, "Entry in "//key//" field cannot be read")
+                return
+            end if
+            if (allocated(str)) then
+                allocate(list(1))
+                call move_alloc(str, list(1)%s)
+            end if
+        end if
+
+    end subroutine get_child_value_string_list
+
+
 end module fpm_toml
diff --git a/fpm/src/fpm_backend.f90 b/fpm/src/fpm_backend.f90
index d705ec2..3cb95d7 100644
--- a/fpm/src/fpm_backend.f90
+++ b/fpm/src/fpm_backend.f90
@@ -22,8 +22,8 @@ contains
 subroutine build_package(model)
     type(fpm_model_t), intent(inout) :: model
 
-    integer :: i
-    character(:), allocatable :: base, linking, subdir
+    integer :: i, ilib
+    character(:), allocatable :: base, linking, subdir, link_flags
 
     if (.not.exists(model%output_directory)) then
         call mkdir(model%output_directory)
@@ -57,9 +57,9 @@ recursive subroutine build_target(model,target,linking)
     type(build_target_t), intent(inout) :: target
     character(:), allocatable, intent(in) :: linking
 
-    integer :: i, j
+    integer :: i, j, ilib
     type(build_target_t), pointer :: exe_obj
-    character(:), allocatable :: objs
+    character(:), allocatable :: objs, link_flags
 
     if (target%built) then
         return
@@ -119,8 +119,15 @@ recursive subroutine build_target(model,target,linking)
               // " -o " // target%output_file)
 
     case (FPM_TARGET_EXECUTABLE)
+        link_flags = linking
+        if (allocated(target%link_libraries)) then
+            do ilib = 1, size(target%link_libraries)
+                link_flags = link_flags // " -l" // target%link_libraries(ilib)%s
+            end do
+        end if
+
         call run("gfortran " // objs // model%fortran_compile_flags &
-              //linking// " -o " // target%output_file)
+              //link_flags// " -o " // target%output_file)
 
     case (FPM_TARGET_ARCHIVE)
         call run("ar -rs " // target%output_file // objs)
diff --git a/fpm/src/fpm_model.f90 b/fpm/src/fpm_model.f90
index 7643416..20f174b 100644
--- a/fpm/src/fpm_model.f90
+++ b/fpm/src/fpm_model.f90
@@ -51,6 +51,8 @@ type srcfile_t
         ! Modules USEd by this source file (lowerstring)
     type(string_t), allocatable :: include_dependencies(:)
         ! Files INCLUDEd by this source file
+    type(string_t), allocatable :: link_libraries(:)
+        ! Native libraries to link against
 end type srcfile_t
 
 type build_target_ptr
@@ -66,6 +68,8 @@ type build_target_t
     type(build_target_ptr), allocatable :: dependencies(:)
         ! Resolved build dependencies
     integer :: target_type = FPM_TARGET_UNKNOWN
+    type(string_t), allocatable :: link_libraries(:)
+        ! Native libraries to link against
 
     logical :: built = .false.
     logical :: touched = .false.
diff --git a/fpm/src/fpm_sources.f90 b/fpm/src/fpm_sources.f90
index 2932b52..fa5c6e7 100644
--- a/fpm/src/fpm_sources.f90
+++ b/fpm/src/fpm_sources.f90
@@ -155,6 +155,9 @@ subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
                  canon_path(executables(i)%source_dir) ) then
                 
                 sources(j)%exe_name = executables(i)%name
+                if (allocated(executables(i)%link)) then
+                    exe_source%link_libraries = executables(i)%link
+                end if
                 cycle exe_loop
 
             end if
@@ -164,6 +167,9 @@ subroutine add_executable_sources(sources,executables,scope,auto_discover,error)
         ! Add if not already discovered (auto_discovery off)
         exe_source = parse_source(join_path(executables(i)%source_dir,executables(i)%main),error)
         exe_source%exe_name = executables(i)%name
+        if (allocated(executables(i)%link)) then
+            exe_source%link_libraries = executables(i)%link
+        end if
         exe_source%unit_scope = scope
         
         if (allocated(error)) return
diff --git a/fpm/src/fpm_targets.f90 b/fpm/src/fpm_targets.f90
index 2cd4418..c3a59fd 100644
--- a/fpm/src/fpm_targets.f90
+++ b/fpm/src/fpm_targets.f90
@@ -3,7 +3,7 @@ use fpm_error, only: error_t, fatal_error
 use fpm_model
 use fpm_environment, only: get_os_type, OS_WINDOWS
 use fpm_filesystem, only: dirname, join_path, canon_path
-use fpm_strings, only: operator(.in.)
+use fpm_strings, only: string_t, operator(.in.)
 implicit none
 
 contains
@@ -45,9 +45,11 @@ subroutine targets_from_sources(model,sources)
             
             if (sources(i)%unit_scope == FPM_SCOPE_APP) then
                 call add_target(model%targets,type = FPM_TARGET_EXECUTABLE,&
+                            link_libraries = sources(i)%link_libraries, &
                             output_file = join_path(model%output_directory,'app',sources(i)%exe_name))
             else
                 call add_target(model%targets,type = FPM_TARGET_EXECUTABLE,&
+                            link_libraries = sources(i)%link_libraries, &
                             output_file = join_path(model%output_directory,'test',sources(i)%exe_name))
             
             end if
@@ -108,11 +110,12 @@ end subroutine targets_from_sources
 
 
 !> Add new target to target list
-subroutine add_target(targets,type,output_file,source)
+subroutine add_target(targets,type,output_file,source,link_libraries)
     type(build_target_ptr), allocatable, intent(inout) :: targets(:)
     integer, intent(in) :: type
     character(*), intent(in) :: output_file
     type(srcfile_t), intent(in), optional :: source
+    type(string_t), intent(in), optional :: link_libraries(:)
 
     integer :: i
     type(build_target_ptr), allocatable :: temp(:)
@@ -138,6 +141,7 @@ subroutine add_target(targets,type,output_file,source)
     new_target%target_type = type
     new_target%output_file = output_file
     if (present(source)) new_target%source = source
+    if (present(link_libraries)) new_target%link_libraries = link_libraries
     allocate(new_target%dependencies(0))
     
     targets = [targets, build_target_ptr(new_target)]
@@ -245,4 +249,4 @@ function find_module_dependency(targets,module_name,include_dir) result(target_p
 
 end function find_module_dependency
 
-end module fpm_targets
\ No newline at end of file
+end module fpm_targets
diff --git a/manifest-reference.md b/manifest-reference.md
index 5002881..63a533f 100644
--- a/manifest-reference.md
+++ b/manifest-reference.md
@@ -233,7 +233,7 @@ See [specifying dependencies](#specifying-dependencies) for more details.
 Executables can also specify their own external library dependencies.
 See [external libraries](#link-external-libraries) for more details.
 
-> Currently not supported in any version
+> Linking against libraries is supported in Fortran fpm only
 
 *Example:*
 
@@ -278,7 +278,7 @@ See [specifying dependencies](#specifying-dependencies) for more details.
 Tests can also specify their own external library dependencies.
 See [external libraries](#link-external-libraries) for more details.
 
-> Currently not supported in any version
+> Linking against libraries is supported in Fortran fpm only
 
 *Example:*