[Boost-users] Re: Guidelines for effective exception usage

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2004-08-26 17:47:21

On Aug 26, 2004, at 5:05 PM, David Abrahams wrote:

> In question was whether an exception can be thrown from within the
> run_time_error's copy ctor during unwinding, and whether that would
> cause termination.  It's no longer clear to me that such an
> implementation would be legal.

18.6.1 makes it clear that std::exception and all classes derived from 
it can not let an exception escape from their copy constructor.  So if 
std::runtime_error's copy ctor throws, unexpected must be called, which 
will lead to termination.

I suspect what was meant by the standard was that std::exception's copy 
ctor can't fail, and ditto for all classes derived from std::exception. 
  And thus the need for a statically checked nothrow (or can't fail) 
spec.

-Howard