[Bug fortran/32957] New: C/Fortran interoperability and -fdefault-integer-8

[Bug fortran/32957] New: C/Fortran interoperability and -fdefault-integer-8

[dominiq at lps dot ens dot fr]

Many failures in the test suite with -fdefault-integer-8 come from tests mixing
C and Fortran. While definitively not an expert in this area, I find pretty
obvious that changing the default integer/real type on one side and not the
other is asking for troubles. Apparently gfortran, but not the test suite, is
finding some of them as in gfortran.dg/c_loc_tests_2.f03:

[karma] f90/bug% gfc -fdefault-integer-8
/opt/gcc/gcc-4.3-work/gcc/testsuite/gfortran.dg/c_loc_tests_2.f03
/opt/gcc/gcc-4.3-work/gcc/testsuite/gfortran.dg/c_loc_tests_2.f03:53.37:

    if(test_array_address(my_c_ptr_1, 100) .ne. 1) then
                                    1
Error: Type/rank mismatch in argument 'num_elements' at (1)
/opt/gcc/gcc-4.3-work/gcc/testsuite/gfortran.dg/c_loc_tests_2.f03:83.19:

  use c_loc_tests_2
                  1
Fatal Error: Can't open module file 'c_loc_tests_2.mod' for reading at (1): No
such file or directory

Using -fdefault-integer-8 with 'intrinsic :: iso_c_binding' should probably
trigger an error or at least a warning.


-- 
           Summary: C/Fortran interoperability and -fdefault-integer-8
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dominiq at lps dot ens dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

[Bug fortran/32957] C/Fortran interoperability and -fdefault-integer-8

[kargl at gcc dot gnu dot org]

------- Comment #1 from kargl at gcc dot gnu dot org  2007-08-01 15:04 -------
At this point, the easiest fix is probably going to be to document
that -fdefault-integer-8 should not be used with bind(c) code.  A
check of this option can be inserted at various locations during the
parsing.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

[Bug fortran/32957] C/Fortran interoperability and -fdefault-integer-8

[dominiq at lps dot ens dot fr]

------- Comment #2 from dominiq at lps dot ens dot fr  2007-08-02 17:08 -------
Subject: Re:  C/Fortran interoperability and
 -fdefault-integer-8

> A check of this option can be inserted at various locations during
> the parsing.

Certainly, but this will give a very interesting exercise to build test cases!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

[Bug fortran/32957] C/Fortran interoperability and -fdefault-integer-8

[fxcoudert at gcc dot gnu dot org]

-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |diagnostic
   Last reconfirmed|0000-00-00 00:00:00         |2007-10-05 12:44:03
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

[Bug fortran/32957] C/Fortran interoperability and -fdefault-integer-8

[dominiq at lps dot ens dot fr]

------- Comment #3 from dominiq at lps dot ens dot fr  2009-12-06 10:52 -------
If I apply the following patch:

--- c_loc_tests_2.f03   2009-11-25 18:17:45.000000000 +0100
+++ c_loc_tests_2_db_1.f03      2009-12-06 11:43:31.000000000 +0100
@@ -44,13 +44,13 @@ contains
   end subroutine test0

   subroutine test1() bind(c)
-    integer, target, dimension(100) :: int_array_tar
+    integer(c_int), target, dimension(100) :: int_array_tar
     type(c_ptr) :: my_c_ptr_1 = c_null_ptr
     type(c_ptr) :: my_c_ptr_2 = c_null_ptr

-    int_array_tar = 100
+    int_array_tar = 100_c_int
     my_c_ptr_1 = c_loc(int_array_tar)
-    if(test_array_address(my_c_ptr_1, 100) .ne. 1) then
+    if(test_array_address(my_c_ptr_1, 100_c_int) .ne. 1) then
        call abort()
     end if
   end subroutine test1

the test passes with -fdefault-integer-8. Note that

gfc -fdefault-integer-8 c_loc_tests_2_db_1.f03 c_loc_tests_2_funcs.c

gives a warning:

cc1: warning: command line option "-fdefault-integer-8" is valid for Fortran
but not for C

Although such warning can be trapped by adding in gcc/testsuite/lib/prune.exp
lines such that

     regsub -all "(^|\n)cc1: warning: command line option .-fwhole-file. is
valid for Fortran but not for C" $text "" text

it would be better to change the gfortran script to not pass gfortran options
to other languages.

If there is any interest in updating the interoperability tests to works with
-fdefault-*-8, I can comb the testsuite.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

[Bug fortran/32957] C/Fortran interoperability and -fdefault-integer-8

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32957

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2011-12-27 11:14:24 UTC ---
Created attachment 26187
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26187
patch to fix some failures with -fdefault-integer-8

I have this patch in my tree for a quite long time. It fixes some failures with
-fdefault-integer-8 by replacing some implicit kinds with explicit ones.