Remove ENV_VARIABLE() as it duplicates the functionality of GET_ENV()

The ENV_VARIABLE() procedure is performing functions already available
in the GET_ENV() procedure. This changes the ENV_VARIABLE() calls to
GET_ENV() calls to eliminate the duplication functionality.

Author: urbanjost

src/fpm_compiler.F90

@@ -28,7 +28,6 @@
 module fpm_compiler
 use,intrinsic :: iso_fortran_env, only: stderr=>error_unit
 use fpm_environment, only: &
-        get_env, &
         get_os_type, &
         OS_LINUX, &
         OS_MACOS, &

src/fpm_filesystem.F90

@@ -14,7 +14,7 @@ module fpm_filesystem
     public :: basename, canon_path, dirname, is_dir, join_path, number_of_rows, list_files, get_local_prefix, &
             mkdir, exists, get_temp_filename, windows_path, unix_path, getline, delete_file, fileopen, fileclose, &
             filewrite, warnwrite, parent_dir, is_hidden_file, read_lines, read_lines_expanded, which, run, &
-            LINE_BUFFER_LEN, os_delete_dir, is_absolute_path, env_variable, get_home, execute_and_read_output, &
+            LINE_BUFFER_LEN, os_delete_dir, is_absolute_path, get_home, execute_and_read_output, &
             get_dos_path
     integer, parameter :: LINE_BUFFER_LEN = 32768
 
@@ -54,29 +54,6 @@ end function c_is_dir
 
 contains
 
-
-!> return value of environment variable
-subroutine env_variable(var, name)
-   character(len=:), allocatable, intent(out) :: var
-   character(len=*), intent(in) :: name
-   integer :: length, stat
-
-   call get_environment_variable(name, length=length, status=stat)
-   if (stat /= 0) return
-
-   allocate(character(len=length) :: var)
-
-   if (length > 0) then
-      call get_environment_variable(name, var, status=stat)
-      if (stat /= 0) then
-         deallocate(var)
-         return
-      end if
-   end if
-
-end subroutine env_variable
-
-
 !> Extract filename from path with/without suffix
 function basename(path,suffix) result (base)
 
@@ -1017,15 +994,15 @@ function get_local_prefix(os) result(prefix)
         character(len=:), allocatable :: home
 
         if (os_is_unix(os)) then
-            call env_variable(home, "HOME")
-            if (allocated(home)) then
+            home=get_env('HOME','')
+            if (home /= '' ) then
                 prefix = join_path(home, ".local")
             else
                 prefix = default_prefix_unix
             end if
         else
-            call env_variable(home, "APPDATA")
-            if (allocated(home)) then
+            home=get_env('APPDATA','')
+            if (home /= '' ) then
                 prefix = join_path(home, "local")
             else
                 prefix = default_prefix_win
@@ -1068,14 +1045,14 @@ subroutine get_home(home, error)
         type(error_t), allocatable, intent(out) :: error
 
         if (os_is_unix()) then
-            call env_variable(home, 'HOME')
-            if (.not. allocated(home)) then
+            home=get_env('HOME','')
+            if ( home == '' ) then
                 call fatal_error(error, "Couldn't retrieve 'HOME' variable")
                 return
             end if
         else
-            call env_variable(home, 'USERPROFILE')
-            if (.not. allocated(home)) then
+            home=get_env('USERPROFILE','')
+            if ( home == '' ) then
                 call fatal_error(error, "Couldn't retrieve '%USERPROFILE%' variable")
                 return
             end if