(gdb) bt
#0  0x44fb73f8 in QSqlDatabase::close (this=<optimized out>)
    at kernel/qsqldatabase.cpp:875
#1  0x44fba128 in ~QSqlDatabase (this=0x2a2edad4, __in_chrg=<optimized out>)
    at kernel/qsqldatabase.cpp:803
#2  QSqlDatabase::~QSqlDatabase (this=0x2a2edad4, __in_chrg=<optimized out>)
    at kernel/qsqldatabase.cpp:800
#3  0x44fbaf40 in ~QHashNode (this=0x2a2edac8, __in_chrg=<optimized out>)
    at ../../src/corelib/tools/qhash.h:206
#4  QHash<QString, QSqlDatabase>::deleteNode2 (node=0x2a2edac8)
    at ../../src/corelib/tools/qhash.h:542
#5  0x40a3ce4c in QHashData::free_helper (this=0x2a2e7d30,
    node_delete=0x44fbaf30 <QHash<QString, QSqlDatabase>::deleteNode2(QHashData::Node*)>) at tools/qhash.cpp:423
#6  0x44fb708c in (anonymous namespace)::Q_QGS_dbDict::innerFunction()::Holder::~Holder() () at ../../src/corelib/tools/qhash.h:589
#7  0x40ef83c0 in __run_exit_handlers (status=0,
    listp=0x410074a4 <__exit_funcs>, run_list_atexit=<optimized out>)
    at exit.c:78
#8  0x40ef8440 in __GI_exit (status=<optimized out>) at exit.c:100
#9  0x40edbed8 in __libc_start_main (main=0xbefff974, argc=1090547712,
    ubp_av=0x40edbed8 <__libc_start_main+280>, init=<optimized out>,
    fini=0x2a007c20 <__libc_csu_fini>, rtld_fini=0x400111b8 <_dl_fini>,
    stack_end=0xbefff974) at libc-start.c:258
---Type <return> to continue, or q <return> to quit---
#10 0x2a00354c in _start ()