[Bug c++/83400] New: g++ -O1 doesn't execute any code in destructors with a throw statement if it sees another throw

[redbeard0531 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83400

            Bug ID: 83400
           Summary: g++ -O1 doesn't execute any code in destructors with a
                    throw statement if it sees another throw
           Product: gcc
           Version: 7.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redbeard0531 at gmail dot com
  Target Milestone: ---

Repro code below doesn't print the "in dtor" line when compiled with -O1 or
higher. It does with g++ -O0 and with clang++ at any optimization level. Note
that even with the raise() call enabled, which would prevent the second
exception from firing, it still won't print "in dtor".

I've reproed with g++ 4.8.2, 5.4.0, 7.2.0, and 7.2.1, all on linux. No warnings
are output even with -Wall -Wextra.


#include <exception>
#include <string>
#include <iostream>
#include <signal.h>

struct ThrowInDtor{
    ~ThrowInDtor() noexcept(false) {
        std::cout << "in dtor"  << std::endl; // Doesn't print.
        // raise(SIGINT); // Still repros with this commented in.
        throw std::exception();
    }
};

int main() {
    try {
        ThrowInDtor throws;
        throw std::exception();
    } catch (std::exception&) {
        // unreachable
    }
}