Destructor Exceptions Considered Harmful
  ----------------------------------------               26-Jan-95
  by Nathan Myers  <myersn@roguewave.com>               X3J16/95-0023
     Rogue Wave Software                                 WG21/0623
 
  This is a very short proposal:
 
  I know of no way to handle cleanly the effect of an exception
  thrown from a destructor, particularly while destroying a
  vector of objects of unknown (e.g. parameterized) type.  In
  particular, I know of no way to implement a standard library
  which can recover from such an event.
 
  Therefore, I recommend that we add to the front matter for the
  library the following text:
 
  "The effect of throwing an exception from the destructor of
  an object destroyed by any standard library function is
  undefined, except as documented for any particular function."
 
  Example of the problem:
  -----------------------
 
    class E; class T { ~T() throw E; }   // user types
 
    vector<T> v;
 
  Imagine implementing vector<T>.  When an element is appended to the
  end, and storage must be reallocated, and the elements copied, what
  does one do if one has copied all the elements, and then begins to
  destroy the old elements, and a destructor throws?  One then has two
  vectors, one containing a mix of raw storage, a partially destroyed
  element, and undestroyed elements.  The storage cannot be reclaimed
  until all the destructors are called, the destructors must not be called
  out of order, and the destructor that threw cannot be called again.