Implementing swap for class with std::mutex

Question

Suppose we have a class with a std::mutex:

class Foo
{
    std::mutex mutex_;
    std::string str_;
    // other members etc
public:
           


        

Answer 1

I don't think your swap implementation is safe. If another algorithm tries to lock rhs.mutex_ first and then lhs.mutex_, you may end up with a deadlock. Try std::lock() instead.