https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55918
--- Comment #6 from James Y Knight <foom at fuhm dot net> --- I realize that my suggestion above could only solve _most_ of the problem -- e.g. the original example, where the noexcept function doesn't have a try/catch in it. In that original example, there's no entry for the IP of the call in the LSDA table. The personality fn already knows during phase1 that this indicates termination -- but it simply fails to actually trigger the terminate in phase1, even though it easily could (& should!). However, in the example from comment #4, there _WILL_ be an entry in the callsite table covering the throw (necessarily, in order to to catch type "float"), so the "missing callsite => terminate" mechanism isn't applicable in that case. As the comment mentioned, to handle that, we'd need some alternative indication for termination which can be put in the action list. ISTM this could be done most straightforwardly by using an action record with a ttype pointing to a new ABI-defined special-purpose symbol (e.g. "__cxxabiv1::__eh_noexcept"). In libsupc++'s impl, that symbol can be an object whose type is a new std::type_info subclass, whose __do_catch overload calls terminate. Thus, when the personality fn falls through all the _actual_ catch action records, and comes to this, last one, it will query whether it can catch an exception by calling its __do_catch, and immediately trigger termination. GCC, then, can emit that as the last "catch" action in the chain for a try/catch in a noexcept function (instead of the cleanup action with code that calls std::terminate explicitly in the cleanup, that it does now).
