Return const reference to local variable correctly

Question

Additionally to the answers 1, 2, 3 and GotW88, assume the following methods

QString createString()
{
    return QString("foobar");
}

const QString& getString()
{
    return createString();
}

This will yield the famous "warning C4172: returning address of local variable or temporary" with VS2013.

Now if i changed the second method to

const QString& getString()
{
    const QString& binder = createString();
    return binder;
}

Which does not report an error anymore. Is this a safe way to fix the warning without changing the signature of the API? Why does this work?

Answer 1

It doesn't work. That way you simply suppress the warning by making the situation harder to analyze. The behavior is still undefined.