boost::optional::operator*() doesn't have "const &&" overload, allowing incorrect usage

[for.gcc.bugzilla@…]

#include <boost/optional.hpp>

const boost::optional<int> f()
{
    return {1};
}

int main()
{
    const int& ref = *f();
    // creates a boost::optional temporary
    // "*tmp" binds to "optional::operator*() const&"
    // "ref" starts pointing to internals of the returned temporary
    // temporary gets destroyed
    // we have a dangling reference
}

at the same time, std::optional in C++17 does have

constexpr const T&& operator*() const &&;

​overload, which lets the code above work correctly.

[boost bugs <for.gcc.bugzilla@…>]

the same lack of "() const&&" overload with boost::optional::value()

[boost bugs <for.gcc.bugzilla@…>]

Sorry, I just realised that even if boost::optional::operator*() had such an overload, it still wouldn't fix the problem in the bug description.