Minimal main program for bug 24945

main.cpp

#include <dlfcn.h>
#include <cstdio>
#include <cstring> // strerror
#include <errno.h>   // errno

typedef void(*test_func)(bool);

int main() {
  printf("Qt BUG related to dlclose\n=========================\n1. Program starting.\n");
  printf("2. Loading dynamic library 'mod.so' linked to Qt.\n");
  void *handle = dlopen("./mod.so", RTLD_NOW); 
  if (handle == NULL) {
    printf("Library 'mod.so' not found (%s).\n", strerror(errno));
    return -1;
  }

  printf("3. Getting 'run_test' function.\n");
  test_func run_test = (test_func)dlsym(handle, "run_test");
  if (run_test == NULL) {
    printf("Symbol not found.\n");
    return -1;
  }
  printf("4. Passing control to Qt.\n");

  /** The bug only happens if a QApplication is effectively started.
   */
  run_test(false);

  printf("5. 'mod' returned.\n");
  printf("6. Calling dlclose.\n");

  /** This is where the bug appears.
   */
  dlclose(handle);
  printf("7. Program end.\n");
  return 0;
}