What is wrong with this way to move temporary variable out of function? [duplicate]

This question already has an answer here:

• Is it possible to std::move objects out of functions? (C++11) 2 answers

I'm trying to understand what is wrong with following code where Result is a class with a move constructor:

Result&& GetResult(unsigned char* ptr)
{
    Result res = Result(ptr);
    return std::move(res);
}

Result ret = GetResult(ptr);

I know that the recommended way is to have return type Result and return res; and let compiler to call move constructor itself. But I want to understand what is going on in the case above with the lifetime of local variable res, because it seems to be "dead" at the time it is passed to move constructor in Result ret = GetResult(ptr);. On the other hand Result&& res = GetResult(ptr); keeps it alive.