`const auto&` vs `const auto`

auto-ref.cc

#include <iostream>
#include <string>
#include <type_traits>

struct Foo
{
    std::string content;

    const std::string& get() const
    {
        return content;
    }
};

int main()
{
    Foo foo { "foo" };

    {
        /*
         * str is a value
         */
        const auto str = foo.get();

        static_assert(std::is_same_v<decltype(str), std::remove_reference_t<decltype(str)>>);
    }

    {
        /*
         * str is a reference
         */
        const auto& str = foo.get();

        static_assert(
            not std::is_same_v<decltype(str), std::remove_reference_t<decltype(str)>>);
    }

    {
        /*
         * str is a reference
         */
        auto&& str = foo.get();

        static_assert(
            not std::is_same_v<decltype(str), std::remove_reference_t<decltype(str)>>);
    }
}