Forgetting an exception vtable gives runtime crash

[mlbrooks]

#if defined WITH_USER_FIX
#define UFIX(...) __VA_ARGS__ // user adds this code, after understanding what the problem is
#else
#define UFIX(...)
#endif

exception E {};
UFIX( vtable(E) E_vt; )
int main() {
	try {
		throw (E){ UFIX( & E_vt ) };
	} catch ( E * ) {
	}
	printf( "done\n" );
	return 0;
}

Actual: Runtime error, segment fault at memory location near zero

Expected: Compile warning or error, indicating cannot throw (E){}

-DWITH_USER_FIX, actual and expected: print "done"

Note that a user learning CFA exceptions is likely to forget either a manual vtable declaration or to use Exception.hfa. Such a user is not well equipped to understand that the segment fault means the vtable is missing.

Mike would be satisfied by handling the problem case as: Error, no default ctor for E. Others may disagree.