Why does debugging "pure virtual method called" have to be so hard?

[Mark Mitchell]

>>>>> "Joe" == Joe Buck <jbuck@Synopsys.COM> writes:

    Joe> What if we have something like virtual void f () throw (Foo,
    Joe> Bar) = 0;

    Joe> There are always two possibilities: the specification allows
    Joe> __pure_virtual_exception to pass, or it does not.  So the
    Joe> ideal compiler would generate one of the two calls.  If we
    Joe> can't tell or we are lazy, it would be better to make
    Joe> mistakes in favor of not throwing (so the optimizer won't
    Joe> make bad code), so a simple thing would be to generate the
    Joe> _nothrow version if there is any throw specification at all.

But, this yields somewhat odd semantics.  The whole point of throwing
an exception from a call to a pure virtual function would be to allow
the program to catch it, and do something sensible!  IMO, this is
getting over-complicated.

    Joe> The _exit(-1) could be easily changed to abort(), and people
    Joe> debugging the problem could still set a breakpoint on
    Joe> __pure_virtual.  Maybe that one-line change is the one we
    Joe> should really make.

This sounds right to me.

-- 
Mark Mitchell 			mark@markmitchell.com
Mark Mitchell Consulting	http://www.markmitchell.com