What comes first - stack unwinding or copying of return values

Question

Is the mutex used in method GetValues() released before or after copy constructing the dummy instance?

Answer 1

Here is a small complete test programm (in addition to James Kanzes good explanation), which will show if the unlock is done before or after stack unwinding:

#include 

class PseudoLockGuard
{
public:
    enum LockState { IsStillLocked, IsUnlocked};

    PseudoLockGuard(LockState& value) : m_value(value) {};
    ~PseudoLockGuard() { m_value = IsUnlocked; };

private:
    LockState& m_value;
};

PseudoLockGuard::LockState Test()
{
    PseudoLockGuard::LockState indicator = PseudoLockGuard::IsStillLocked;

    PseudoLockGuard lock(indicator);

    return indicator;// Will return IsStillLocked or IsUnlocked?
}

int main(int , char** )
{
   PseudoLockGuard::LockState result = Test();

   std::cout << (result == PseudoLockGuard::IsStillLocked 
                 ? "Return Value before Unlock" 
                 : "Return Value after Unlock"); 

   // Outputs "Return Value before Unlock"

   return 0;
}