Capture and move a unique_ptr in a c++14 lambda expression

Question

I am capturing a unique_ptr in a lambda expression this way:

auto str = make_unique(\"my string\");
auto lambda = [ capturedStr = std::move(str)          


        

Answer 1

auto lambda = [ capturedStr = std::move(str) ] {
   cout << *capturedStr.get() << endl;
   auto str2 = std::move(capturedStr); // <--- Not working, why?
};

To give more detail the compiler is effectively making this transformation:

class NameUpToCompiler
{
    unique_ptr capturedStr;  // initialized from move assignment in lambda capture expression

    void operator()() const
    {
        cout << *capturedStr.get() << endl;
        auto str2 = std::move(capturedStr);  // move will alter member 'captureStr' but can't because of const member function.
    }
}

The use of mutable on the lambda will remove the const from the operator() member function therefore allowing the members to be altered.