Notes about __cxa_end_catch

[Coleen Phillimore]

/*
Regarding the discussion of __cxa_end_catch:

If you need to clean up more than one live exception from a
catch handler, don't you need a 'count' parameter to
__cxa_end_catch?  In this case, you destroy both X and
Y objects (whether or not they're both on the stack,
or just X is).

Our equivalent of end_catch has a count parameter which
is set to the number of live exception objects to
delete and is used for branching out of the nested catch
clause (not by rethrow).
*/
struct X { X(); ~X(); };
struct Y { Y(); ~Y(); };
extern "C" int printf(const char *,...);
main()
{
  try {
    throw X();
  } catch (X x) {
    try {
        throw Y();
    } catch(...) {
        //generates __cxa_end_catch(/*levels=*/2)
        return 1;
    }
  }
}

-- 
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Coleen Phillimore                  | mailto:coleen at zko.dec.com
Compaq Computer Corp.   Nashua, NH | COMPAQ C++ Compiler Development
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