MinGW/G++/g95 link problem - libf95 undefined reference to `MAIN_'

Question

Hi folks,

Summing up, my problem consists on compiling g95 objects inside a C++ application. Actually, I'm constructing an interface for an old fortran program. For this task, I'm using the wxWidgets GUI library, and calling fortran subroutines when necessary. At the beginning, I was developing the entire project compiling my fortran files with gfortran (which comes with GCC) and linking them with my app by the g++ -o... command. Everything was working fine but some numbers values calculated by my fotran subroutines returned NAN values. Doing some research, I realized that compiling my fortran files with gfortran with the -m32 flag, generates this NAN values problem. Although compiling with -m64 flag, my code works properly well. The only trouble here is that my App should be 32bits and then I tryed another compiller. Here I found g95 Fortran compiler, which compiles my fortran code and gives the right output on a 32bits environment. But when I'm trying to link these g95 objects into my program I see this following error:

g++ -oCyclonTechTower.exe src\fortran\Modulo_Global.o src\fortran\Prop_Fisicas.o src\fortran\inversa.o src\fortran\tower.o src\fortran\PredadeCarga.o src\fortran\gota.o src\fortran\tadi.o src\view\SimulationORSATCustomDialog.o src\view\SimulationChildGUIFrame.o src\view\ParentGUIFrame.o src\view\ClientGUIFrame.o src\model\TowerData.o src\controller\SimulationController.o src\THEIACyclonTechTower.o ..\Resource\resource.o -Lc:\wxWidgets-2.6.4\lib -Lc:\MinGW\lib\gcc-lib\i686-pc-mingw32\4.1.2 -Bdynamic -Wl,--subsystem,windows -mwindows c:\wxWidgets-2.6.4\lib\libwx_mswu-2.6.a -lwxregexu-2.6 -lwxexpat-2.6 -lwxtiff-2.6 -lwxjpeg-2.6 -lwxpng-2.6 -lwxzlib-2.6 -lrpcrt4 -loleaut32 -lole32 -luuid -lwinspool -lwinmm -lshell32 -lcomctl32 -lcomdlg32 -lctl3d32 -ladvapi32 -lwsock32 -lgdi32 -lgcc -lf95 c:\MinGW\lib\gcc-lib\i686-pc-mingw32\4.1.2/libf95.a(main.o):(.text+0x32): undefined reference to `MAIN_' collect2: ld returned 1 exit status Build error occurred, build is stopped Time consumed: 1531 ms.

I have already read the g95 Manual for integration with C++ and I'm actually calling these functions bellow for controlling the fortran environment: void g95_runtime_start(int argc, char *argv[]); void g95_runtime_stop();

I also included the g95 Fortran Runtime Library libf95.a and the libgcc.a into my linker command. Finishing, I don't have a main method implemented because this is managed by wxWidgets, and my fortran subroutines can not have a main function because this is a C++ program calling fortran functions.

Can some of you guys help me with this problem? How can I fix this undefined reference to MAIN__ problem? Any idea will be much appreciated. Thanks in advance, George

Answer 1

Hi folks,

I'm answering my own question because I got the solution. The problem wasn't with my g95 intergration. I just overwirte the wxWidgets main macro for an int main function initialization as presented bellow:

// Give wxWidgets the means to create a MyApp object
//IMPLEMENT_APP(MyApp);

int main(int argc, char *argv[]) {

    //MyWxApp derives from wxApp
    MyApp *myapp = new MyApp();
    wxApp::SetInstance( myapp );
    wxEntryStart( argc, argv );
    myapp->OnInit();

    myapp->OnRun();
    myapp->OnExit();
    wxEntryCleanup();

}

By the way, the required main fucntion is now defined and my app is now working properly weel without NAN values.

I hope that this question can help others. Thanks, George