title: Gdb gives no stack on a simple std::string uncaught exception
body: <p>im a little bit newbie on gdb so here goes:</p>
  
  <p>Im working on cpp unit testing operation right now. I try to construct string objects with invalid parameters like null_char but program expectedly gives exceptions :). When i try to debug the app using gdb, i type bt after the crash, but it gives me no stack message. 
  Any ideas to why that might happen? Thanks in advance.</p>