[Mingw-users] DLL with stdcall won't link

[Paul H. <cfu...@ea...>]

I'm learning how to compile Fortran into a DLL and call it from C++. My
test DLL is just a tiny Fortran subroutine. File hello.for:

         SUBROUTINE hello
         PRINT *,"Hello"
         END


File hello.DEF:

LIBRARY hello
DESCRIPTION "Fortran DLL to say hello"
EXPORTS
	hello_


I build hello.dll from those files like this:

g77 -c hello.for
dlltool hello.o -d hello.DEF -D hello -e hello.exp -l hello.lib
g77 hello.o hello.exp -shared -o hello.dll


The main C++ routine in file main.cpp calls the DLL like this:

extern "C" void hello_(void);
int main()
{
     hello_();
     return 0;
}

I compile it and link it to the DLL with this line:

g++ main.cpp hello.lib


All the above works ok. But I also want to try building the DLL to use
the stdcall convention. So I compile the Fortran with -mrtd and use this
declaration in the C++ source:

extern "C" void hello_(void) __attribute__((stdcall));

Now when attempting to link the executable, there's an error message
about an undefined reference to hello_@0. Could someone please explain
where I'm going wrong?