Update: tree-shaking to handle submodules correctly

Author: LKedward

src/fpm_model.f90

@@ -95,6 +95,9 @@ module fpm_model
     !> Type of source unit
     integer :: unit_type = FPM_UNIT_UNKNOWN
 
+    !> Parent modules (submodules only)
+    type(string_t), allocatable :: parent_modules(:)
+
     !>  Modules USEd by this source file (lowerstring)
     type(string_t), allocatable :: modules_used(:)
 
@@ -224,6 +227,12 @@ function info_srcfile(source) result(s)
         if (i < size(source%modules_provided)) s = s // ", "
     end do
     s = s // "]"
+    s = s // ", parent_modules=["
+    do i = 1, size(source%parent_modules)
+        s = s // '"' // source%parent_modules(i)%s // '"'
+        if (i < size(source%parent_modules)) s = s // ", "
+    end do
+    s = s // "]"
     !    integer :: unit_type = FPM_UNIT_UNKNOWN
     s = s // ", unit_type="
     select case(source%unit_type)

src/fpm_source_parsing.f90

@@ -78,7 +78,7 @@ function parse_f_source(f_filename,error) result(f_source)
 
     logical :: inside_module
     integer :: stat
-    integer :: fh, n_use, n_include, n_mod, i, j, ic, pass
+    integer :: fh, n_use, n_include, n_mod, n_parent, i, j, ic, pass
     type(string_t), allocatable :: file_lines(:), file_lines_lower(:)
     character(:), allocatable :: temp_string, mod_name, string_parts(:)
 
@@ -104,11 +104,13 @@ function parse_f_source(f_filename,error) result(f_source)
         n_use = 0
         n_include = 0
         n_mod = 0
+        n_parent = 0
         inside_module = .false.
         file_loop: do i=1,size(file_lines_lower)
 
             ! Skip comment lines
-            if (index(file_lines_lower(i)%s,'!') == 1) then
+            if (index(file_lines_lower(i)%s,'!') == 1 .or. &
+                len_trim(file_lines_lower(i)%s) < 1) then
                 cycle
             end if
 
@@ -296,6 +298,8 @@ function parse_f_source(f_filename,error) result(f_source)
 
                 inside_module = .true.
 
+                n_parent = n_parent + 1
+
                 if (pass == 2) then
 
                     if (index(temp_string,':') > 0) then
@@ -312,7 +316,7 @@ function parse_f_source(f_filename,error) result(f_source)
                     end if
 
                     f_source%modules_used(n_use)%s = temp_string
-
+                    f_source%parent_modules(n_parent)%s = temp_string
                     f_source%modules_provided(n_mod)%s = mod_name
 
                 end if
@@ -379,6 +383,7 @@ function parse_f_source(f_filename,error) result(f_source)
             allocate(f_source%modules_used(n_use))
             allocate(f_source%include_dependencies(n_include))
             allocate(f_source%modules_provided(n_mod))
+            allocate(f_source%parent_modules(n_parent))
         end if
 
     end do

src/fpm_targets.f90

@@ -508,6 +508,22 @@ subroutine prune_build_targets(targets)
 
                     end do
 
+                elseif (target%source%unit_type == FPM_UNIT_SUBMODULE) then
+                    ! Remove submodules if their parents are not used
+
+                    exclude_target(i) = .true.
+                    target%skip = .true.
+                    do j=1,size(target%source%parent_modules)
+
+                        if (target%source%parent_modules(j)%s .in. modules_used) then
+                            
+                            exclude_target(i) = .false.
+                            target%skip = .false.
+
+                        end if 
+
+                    end do
+
                 end if
             end if
 
@@ -543,7 +559,7 @@ subroutine prune_build_targets(targets)
     recursive subroutine collect_used_modules(target)
         type(build_target_t), intent(in) :: target
 
-        integer :: j
+        integer :: j, k
 
         if (allocated(target%source)) then
             do j=1,size(target%source%modules_used)
@@ -552,14 +568,28 @@ recursive subroutine collect_used_modules(target)
 
                     modules_used = [modules_used, target%source%modules_used(j)]
 
+                    ! Recurse into child submodules
+                    do k=1,size(targets)
+                        if (allocated(targets(k)%ptr%source)) then
+                            if (targets(k)%ptr%source%unit_type == FPM_UNIT_SUBMODULE) then
+                                if (target%source%modules_used(j)%s .in. targets(k)%ptr%source%parent_modules) then
+                                    call collect_used_modules(targets(k)%ptr)
+                                end if
+                            end if
+                        end if
+                    end do
+
                 end if
 
             end do
         end if
 
+        ! Recurse into dependencies
         do j=1,size(target%dependencies)
 
-            call collect_used_modules(target%dependencies(j)%ptr)
+            if (target%dependencies(j)%ptr%target_type /= FPM_TARGET_ARCHIVE) then
+                call collect_used_modules(target%dependencies(j)%ptr)
+            end if
 
         end do