Mingw-w64 C dynamic linking with circular calls (without two way linkage)

build.bat

gcc -Wl,--export-all-symbols main.c -o prog.exe
gcc -shared -fPIC lib.c -o lib.o
gcc -c -DBUILDING_LIB lib.c
gcc -shared -o lib.dll lib.o -Wl,--out-implib,lib.a

lib.c

#include <stdio.h>
#include "main.h"

#ifdef BUILDING_LIB
#define LIB __declspec(dllexport)
#else
#define LIB __declspec(dllimport)
#endif

int LIB library_function(void (*f)())
{
    printf("Hello from library!\n");
    f();
    /* unexported_callback(); */ /*< This one will not be exported in the second case */
    return 0;
}

main.c

#include <stdio.h>
#include <windows.h>

void exported_callback() /*< Function we want to export */
{
    printf("Hello from callback!\n");
}

void unexported_callback() /*< Function we don't want to export */
{
    printf("Hello from unexported callback!\n");
}

typedef long long int (*lib_func)();

int call_library()
{
   void     *handle  = NULL;
   lib_func  func    = NULL;
   handle = LoadLibraryW(L"./lib.dll");

   func = GetProcAddress(handle, "library_function");

   if (func == NULL) {
       fprintf(stderr, "Unable to get symbol\n");
      return -1;
   }

   func(exported_callback);
   return 0;
}

int main(int argc, const char *argv[])
{
    printf("Hello from main!\n");
    call_library();
    return 0;
}