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Re: Handling of exception specification violations

Peter Schuller wrote:

In C++, I would like to take advantage of throw() clauses for their
documentative value (and possible future value if gcc implements
checked exceptions). At the same time however, I want to *usefully*
handle the throwing of unexpected exceptions (where "useful" includes
being able to inspect the exception in question).

Toward this end I have a couple of questions that my Googling has not

* gcc has an option -fno-enforce-eh-specs which has pretty much the effect
  I would want because it allows for generic top-level catch() statements
  that exit with a useful error message. The man-page says the compiler
  "will still optimize based on the exception specifications". Should I
  interpret this as saying it is *unsafe* to enable this option with
  code that *does* throw unexpected exceptions? If not, is it guaranteed
  to *be* safe?

the code will be unsafe. If an exception is thrown out of a throw () function, the effects will be undefined.

* providing user-defined behavior for std::unexpected() (as exemplified
  at [1]) would be an alternative aswell - *if* I can obtain a reference
  to the exception during runtime. Is there some way (standard or
  gcc-specific) to do this?

This is target specific. Note that the exception object might be foreign (a non C++ object). Look at unwind.h for details.


Nathan Sidwell    ::   ::     CodeSourcery LLC    ::

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