[Bug fortran/45659] New: LTO / function pointers with iso_c_binding

[Joost dot VandeVondele at pci dot uzh dot ch]

Not quite sure if this CP2K derived testcase is really a bug, but for the
testcase below, I get the following warning and later an error (this might be
different issues?) :

> gfortran -flto test_c.c test.f90
test_c.c:3:8: warning: type of ‘build_eri’ does not match original declaration
[enabled by default]
test.f90:3:0: note: previously declared here

> cat test_c.c
#include<stdio.h>

void (*build_eri)();

void foo()
{
  printf("foo\n");
};

void init()
{
  build_eri=foo;
};

> cat test.f90
MODULE M1
  USE ISO_C_BINDING
  TYPE(C_FUNPTR), BIND(C) :: build_eri
  INTERFACE
     SUBROUTINE foo() BIND(C)
     END SUBROUTINE foo
  END INTERFACE
  INTERFACE
     SUBROUTINE init() BIND(C)
     END SUBROUTINE init
  END INTERFACE
CONTAINS
  SUBROUTINE test
   PROCEDURE(foo), POINTER :: foo_ptr
   CALL init()
   CALL C_F_PROCPOINTER(build_eri,foo_ptr)
   CALL foo_ptr()
  END SUBROUTINE
END MODULE

USE M1
CALL test
END

this can now be turned in an error using :

> gcc -c -flto test_c.c
> gfortran -c -flto test.f90
> ar -r all.a test_c.o test.o
> gfortran -fuse-linker-plugin -flto -O3 all.a
/data03/vondele/binutils-2.20.1/build/bin/ld: error: all.a: multiple definition
of 'build_eri'
/data03/vondele/binutils-2.20.1/build/bin/ld: all.a: previous definition here
test.f90:3:0: warning: type of ‘build_eri’ does not match original declaration
[enabled by default]
test_c.c:3:8: note: previously declared here
collect2: ld returned 1 exit status


-- 
           Summary: LTO / function pointers with iso_c_binding
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Joost dot VandeVondele at pci dot uzh dot ch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45659