Pure Virtual Method Called Error Google Protocol Buffer

Question

Right now I have a QList of protobuf Messages. Inside of a while loop, I create messages and add them to the QList . I try to use the DebugString Method to print them out and in the while loop it works fine with no errors. When I try to call the exact same ->DebugString() method outside of the while loop I get:

Abort (Core dumped).

pure virtual method called terminate called without an active exception

QList<const ::google::protobuf::Message*> allMessages;

while() {
    msgs::sensor::Plot nextMsg;
    ....
    allMessages.append(&nextMsg);
    std::cout << allMessages.at(0)->DebugString();
}
std::cout << allMessages.at(0)->DebugString();

Answer 1

nextMsg is a local variable inside the while loop, it will be destroyed when get out of the loop, and then address saved in allMessages becomes dangled. Any dereference on it is just UB.

If you want to use the pointers outside of the loop, you need to new them inside the loop (and delete them at last), or use smart pointers to avoid manual memory management.