`<vector>`: `vector<bool>::iterator` fails to meet Cpp17InputIterator requirements

Describe the bug

The following program doesn't compile.

#include <vector>

int main()
{
    std::vector<bool> vb{true};
    vb.begin()->flip();
    (*vb.begin()).flip();
}

It's probably intended that (*vb.begin()).flip() works and is equivalent to vb[0].flip(). As per [tab:inputiterator], it seems that vb.begin()->flip() also needs to be supported.

Command-line test case

Godbolt link

Expected behavior

vb.begin()->flip() works and is equivalent to vb[0].flip().

STL version

Microsoft Visual Studio Community 2022
Version 17.12.0 Preview 2.1

(Probably in all existing versions.)

Additional context

We may need to correspondingly change member type pointer to conform to [iterator.traits]/1.

Also, it's even not very clear to me that vector<bool>::iterator is required to meet the Cpp17InputIterator named requirements. Given vector<bool> is not a real container, it's unclear which requirements on iterators of containers are applied to iterators of vector<bool>. LWG-1422 is related.

Start with the implementation of vector::iterator and reproduce the provided program using the Godbolt link. Check the Cpp17InputIterator and iterator_traits requirements cited in the issue; done means both flip() expressions compile and behave equivalently to vb[0].flip().