Add support for toggling Fortran features (#864)

- implicit-typing: toggle default implicit typing rules
  - option to disable in GFortran
  - option to enable in LFortran
- implicit-external: toggle implicit external interfaces
  - option to disable in GFortran
  - option to enable in LFortran
- source-form: select source form ("free", "fixed", or "default")
  - option to set free/fixed form in GFortran
  - option to set fixed form in LFortran

ci/run_tests.sh

@@ -158,6 +158,14 @@ pushd cpp_files
 "$fpm" test
 popd
 
+# Test Fortran features
+for feature in free-form fixed-form implicit-typing implicit-external
+do
+  pushd $feature
+  "$fpm" run
+  popd
+done
+
 # Test app exit codes
 pushd fpm_test_exit_code
 "$fpm" build

example_packages/fixed-form/app/main.f90

@@ -0,0 +1,4 @@
+      program test
+      use lib
+      call hello
+      end

example_packages/fixed-form/fpm.toml

@@ -0,0 +1,2 @@
+name = "fixed-form"
+fortran.source-form = "fixed"

example_packages/fixed-form/src/lib.f90

@@ -0,0 +1,7 @@
+      module lib
+      contains
+      subroutine h e l l o
+      print '(a)',
+     +"Hello, fixed world!"
+      end subroutine
+      end module

example_packages/free-form/app/main.f

@@ -0,0 +1,4 @@
+program test
+use lib
+call hello
+end

example_packages/free-form/fpm.toml

@@ -0,0 +1,3 @@
+name = "free-form"
+fortran.source-form = "free"
+executable = [{main="main.f", name="free-form"}]

example_packages/free-form/src/lib.f

@@ -0,0 +1,6 @@
+module lib
+contains
+subroutine hello
+print '(a)', "Hello, free world!"
+end subroutine
+end module

example_packages/implicit-external/app/main.f90

@@ -0,0 +1,5 @@
+program test
+  integer :: ijk
+  call impl(ijk)
+  if (ijk /= 1) error stop
+end program test

example_packages/implicit-external/fpm.toml

@@ -0,0 +1,2 @@
+name = "implicit-external"
+fortran.implicit-external = true

example_packages/implicit-external/src/impl.f90

@@ -0,0 +1,4 @@
+subroutine impl(ijk)
+  integer :: ijk
+  ijk = 1
+end subroutine impl

example_packages/implicit-typing/app/main.f90

@@ -0,0 +1,4 @@
+program test
+  use impl
+  if (ijk /= 1) error stop
+end program

example_packages/implicit-typing/fpm.toml

@@ -0,0 +1,2 @@
+name = "implicit-typing"
+fortran.implicit-typing = true

example_packages/implicit-typing/src/impl.f90

@@ -0,0 +1,3 @@
+module impl
+  parameter(ijk = 1)
+end module

src/fpm.f90

@@ -10,7 +10,7 @@ module fpm
 use fpm_environment, only: get_env
 use fpm_filesystem, only: is_dir, join_path, list_files, exists, &
                    basename, filewrite, mkdir, run, os_delete_dir
-use fpm_model, only: fpm_model_t, srcfile_t, show_model, &
+use fpm_model, only: fpm_model_t, srcfile_t, show_model, fortran_features_t, &
                     FPM_SCOPE_UNKNOWN, FPM_SCOPE_LIB, FPM_SCOPE_DEP, &
                     FPM_SCOPE_APP, FPM_SCOPE_EXAMPLE, FPM_SCOPE_TEST
 use fpm_compiler, only: new_compiler, new_archiver, set_cpp_preprocessor_flags
@@ -112,6 +112,11 @@ subroutine build_model(model, settings, package, error)
             if (allocated(error)) exit
 
             model%packages(i)%name = dependency%name
+            associate(features => model%packages(i)%features)
+                features%implicit_typing = dependency%fortran%implicit_typing
+                features%implicit_external = dependency%fortran%implicit_external
+                features%source_form = dependency%fortran%source_form
+            end associate
             call package%version%to_string(version)
             model%packages(i)%version = version
 

src/fpm/manifest/fortran.f90

@@ -0,0 +1,105 @@
+module fpm_manifest_fortran
+    use fpm_error, only : error_t, syntax_error, fatal_error
+    use fpm_toml, only : toml_table, toml_key, toml_stat, get_value
+    implicit none
+    private
+
+    public :: fortran_config_t, new_fortran_config
+
+    !> Configuration data for Fortran
+    type :: fortran_config_t
+
+        !> Enable default implicit typing
+        logical :: implicit_typing
+
+        !> Enable implicit external interfaces
+        logical :: implicit_external
+
+        !> Form to use for all Fortran sources
+        character(:), allocatable :: source_form
+
+    end type fortran_config_t
+
+contains
+
+    !> Construct a new build configuration from a TOML data structure
+    subroutine new_fortran_config(self, table, error)
+
+        !> Instance of the fortran configuration
+        type(fortran_config_t), intent(out) :: self
+
+        !> Instance of the TOML data structure
+        type(toml_table), intent(inout) :: table
+
+        !> Error handling
+        type(error_t), allocatable, intent(out) :: error
+
+        integer :: stat
+        character(:), allocatable :: source_form
+
+        call check(table, error)
+        if (allocated(error)) return
+
+        call get_value(table, "implicit-typing", self%implicit_typing, .false., stat=stat)
+
+        if (stat /= toml_stat%success) then
+            call fatal_error(error,"Error while reading value for 'implicit-typing' in fpm.toml, expecting logical")
+            return
+        end if
+
+        call get_value(table, "implicit-external", self%implicit_external, .false., stat=stat)
+
+        if (stat /= toml_stat%success) then
+            call fatal_error(error,"Error while reading value for 'implicit-external' in fpm.toml, expecting logical")
+            return
+        end if
+
+        call get_value(table, "source-form", source_form, "free", stat=stat)
+
+        if (stat /= toml_stat%success) then
+            call fatal_error(error,"Error while reading value for 'source-form' in fpm.toml, expecting logical")
+            return
+        end if
+        select case(source_form)
+        case default
+            call fatal_error(error,"Value of source-form cannot be '"//source_form//"'")
+            return
+        case("free", "fixed", "default")
+            self%source_form = source_form
+        end select
+
+    end subroutine new_fortran_config
+
+    !> Check local schema for allowed entries
+    subroutine check(table, error)
+
+        !> Instance of the TOML data structure
+        type(toml_table), intent(inout) :: table
+
+        !> Error handling
+        type(error_t), allocatable, intent(out) :: error
+
+        type(toml_key), allocatable :: list(:)
+        integer :: ikey
+
+        call table%get_keys(list)
+
+        ! table can be empty
+        if (size(list) < 1) return
+
+        do ikey = 1, size(list)
+            select case(list(ikey)%key)
+
+            case("implicit-typing", "implicit-external", "source-form")
+                continue
+
+            case default
+                call syntax_error(error, "Key "//list(ikey)%key//" is not allowed in fortran")
+                exit
+
+            end select
+        end do
+
+    end subroutine check
+
+end module fpm_manifest_fortran

src/fpm/manifest/package.f90

@@ -27,6 +27,7 @@
 !>[profiles]
 !>[build]
 !>[install]
+!>[fortran]
 !>[[ executable ]]
 !>[[ example ]]
 !>[[ test ]]
@@ -38,6 +39,7 @@ module fpm_manifest_package
     use fpm_manifest_profile, only : profile_config_t, new_profiles, get_default_profiles
     use fpm_manifest_example, only : example_config_t, new_example
     use fpm_manifest_executable, only : executable_config_t, new_executable
+    use fpm_manifest_fortran, only : fortran_config_t, new_fortran_config
     use fpm_manifest_library, only : library_config_t, new_library
     use fpm_manifest_install, only: install_config_t, new_install_config
     use fpm_manifest_test, only : test_config_t, new_test
@@ -75,6 +77,9 @@ module fpm_manifest_package
         !> Installation configuration data
         type(install_config_t) :: install
 
+        !> Fortran meta data
+        type(fortran_config_t) :: fortran
+
         !> Library meta data
         type(library_config_t), allocatable :: library
 
@@ -173,6 +178,14 @@ subroutine new_package(self, table, root, error)
         call new_install_config(self%install, child, error)
         if (allocated(error)) return
 
+        call get_value(table, "fortran", child, requested=.true., stat=stat)
+        if (stat /= toml_stat%success) then
+            call fatal_error(error, "Type mismatch for fortran entry, must be a table")
+            return
+        end if
+        call new_fortran_config(self%fortran, child, error)
+        if (allocated(error)) return
+
         call get_value(table, "version", version, "0")
         call new_version(self%version, version, error)
         if (allocated(error) .and. present(root)) then
@@ -328,7 +341,7 @@ subroutine check(table, error)
             case("version", "license", "author", "maintainer", "copyright", &
                     & "description", "keywords", "categories", "homepage", "build", &
                     & "dependencies", "dev-dependencies", "profiles", "test", "executable", &
-                    & "example", "library", "install", "extra", "preprocess")
+                    & "example", "library", "install", "extra", "preprocess", "fortran")
                 continue
 
             end select