Fortran shared lib .so shows undefined symbol error

[csH2]

Hi everyone I need help about a compilation issue.

I'm compiling a Fortran code to obtain shared library .so. In the code it uses a module. The compiling has no problem while it reports undefined symbol error when opening the .so library.

Code mesh_map.F are as follows:

#include "cfx5ext.h"

    dllexport(mesh_map)
          SUBROUTINE mesh_map (CZ, DZ, IZ, LZ, RZ)
          USE EXTRA_FLUID2
          USE ISO_C_BINDING
          USE IFPORT
          IMPLICIT NONE
          CHARACTER*(1) CZ(*)
          DOUBLE PRECISION DZ(*)
          INTEGER IZ(*)
          LOGICAL LZ(*)
          REAL RZ(*)

          MAP_STATUS = 1

          END

extra_fluid2.f90:

    Module EXTRA_FLUID2
    INTEGER :: map_status = 0
    end module EXTRA_FLUID2

Compiling command:

 ifort -c extra_fluid2.f90

/home/xxx/intel/oneapi/compiler/2021.4.0/linux/bin/intel64/ifort -fpic -assume 2underscore -check uninit -warn declarations -diag-error 6717 -ftz -O2 -fp-speculation=safe -fp-model=precise -fp-model=source -fimf-arch-consistency=true -qno-opt-dynamic-align -fpe0 -fomit-frame-pointer -real-size 32 -integer-size 32 -I/usr/ansys_inc/v192/CFX/include -o linux-amd64/ifort/mesh_map.o -c mesh_map.F 
-lrt/xxx/intel/oneapi/compiler/2021.4.0/linux/bin/intel64/ifort -shared -o ./linux-amd64/ifort/libmesh_map.so linux-amd64/ifort/mesh_map.o extra_fluid2.o

When I check the .so library using:

ldd -r libmesh_map.so

The result shows as:

undefined symbol: extra_fluid2_mp_map_status__        (./libmesh_map.so)

How can I fix this? Thanks in advance.

I've tried compilation in Windows and no problem was found for the dll file. While in Linux it reports above error.

[Steve_Lionel · Accepted solution]

When you compiled  mesh_map.F, you specified -assume 2underscore, but didn't specify that when compiling extra_fluid2.f90. This causes the global symbols to be inconsistent. Take that off.

I'm also puzzled by the "dllexport(meshmap)" in mesh_map.F. I have to assume that's a macro defined in the #include.

[csH2]

Thank you Steve! Yes, I think dllexport should be removed.

[Barbara_P_Intel]

dllexport is not required for Linux.  Here's more info.

[csH2]

Yes. Thank you for your reply!