Fix: work around lfortran issue 12521

src/julienne/julienne_file_s.F90

@@ -26,16 +26,24 @@
 
   module procedure write_to_character_file_name
     integer file_unit, l
-    logical file_open
+    logical file_open, i_opened
 
     call_assert(allocated(self%lines_))
 
     inquire(file=file_name, opened=file_open, number=file_unit)
-    if (.not. file_open) open(newunit=file_unit, file=file_name, form='formatted', status='unknown', action='write')
+
+    if (.not. file_open) then
+       open(newunit=file_unit, file=file_name, form='formatted', status='unknown', action='write')
+       i_opened = .true.
+    else
+       i_opened = .false.
+    end if
 
     do l = 1, size(self%lines_)
       write(file_unit, '(a)') self%lines_(l)%string()
     end do
+
+    if (i_opened) close(file_unit)
   end procedure
 
   module procedure write_to_string_file_name
@@ -70,12 +78,22 @@
 
       allocate(file_object%lines_(num_lines))
 
+      read_and_store_lines: &
       do line_num = 1, num_lines
+#ifdef __LFORTRAN__
+        if (lengths(line_num)==0) then
+          file_object%lines_(line_num) = string_t("")
+          if (allocated(line)) deallocate(line)
+          allocate(character(len=1) :: line)
+          read(file_unit, '(a)') line
+          cycle read_and_store_lines
+        end if
+#endif
+        if (allocated(line)) deallocate(line)
         allocate(character(len=lengths(line_num)) :: line)
         read(file_unit, '(a)') line
         file_object%lines_(line_num) = string_t(line)
-        deallocate(line)
-      end do
+      end do read_and_store_lines
 
     end associate
 

test/driver.F90

@@ -16,6 +16,7 @@ program test_suite_driver
   use character_stop_code_test_m       ,only :      character_stop_code_test_t
 #endif
   use command_line_test_m              ,only :             command_line_test_t
+  use file_test_m                      ,only :                     file_test_t
   use formats_test_m                   ,only :                  formats_test_t
   use multi_image_test_m               ,only :              multi_image_test_t, multi_image_setup
   use string_test_m                    ,only :                   string_test_t
@@ -40,6 +41,7 @@ program test_suite_driver
     ,test_fixture_t(        test_description_test_t()) &
     ,test_fixture_t(          test_diagnosis_test_t()) &
     ,test_fixture_t(             test_result_test_t()) &
+    ,test_fixture_t(                    file_test_t()) &
     ,test_fixture_t(            command_line_test_t()) &
   ]))
     call test_harness%report_results

test/modules/file_test_m.F90

@@ -0,0 +1,68 @@
+! Copyright (c) 2024-2025, The Regents of the University of California and Sourcery Institute
+! Terms of use are as specified in LICENSE.txt
+
+#include "language-support.F90"
+
+module file_test_m
+  !! Check data partitioning across files
+  use julienne_m, only : &
+     file_t &
+    ,operator(.all.) &
+    ,operator(.also.) &
+    ,operator(.equalsExpected.) &
+    ,passing_test &
+    ,string_t &
+    ,test_description_t &
+    ,test_diagnosis_t &
+    ,test_result_t &
+    ,test_t &
+    ,usher
+  use assert_m, only : assert
+  implicit none
+
+  private
+  public :: file_test_t
+
+  type, extends(test_t) :: file_test_t
+  contains
+    procedure, nopass :: subject
+    procedure, nopass :: results
+  end type
+
+contains
+
+  pure function subject() result(specimen)
+    character(len=:), allocatable :: specimen
+    specimen = "A file_t object"
+  end function
+
+  function results() result(test_results)
+    type(test_result_t), allocatable :: test_results(:)
+    type(test_description_t), allocatable :: test_descriptions(:)
+    type(file_test_t) file_test
+
+    test_descriptions = [ &
+      test_description_t(string_t("reading a written file"), usher(check_write_then_read)) &
+    ]
+    test_results = file_test%run(test_descriptions)
+  end function
+
+  function check_write_then_read() result(test_diagnosis)
+    !! Check that a written file can be read correctly
+    type(test_diagnosis_t) test_diagnosis
+    character(len=*), parameter :: file_name = "build/file_t-unit-test-data.txt"
+
+    test_diagnosis = passing_test()
+
+    associate(output_lines => [string_t("foo"), string_t(""), string_t("bar ")])
+      associate(output_file => file_t(output_lines))
+        call output_file%write_lines(file_name)
+        associate(input_file => file_t(file_name))
+          test_diagnosis = test_diagnosis .also. (.all. (input_file%lines() .equalsExpected. output_lines))
+        end associate
+      end associate
+    end associate
+
+  end function
+
+end module file_test_m