[libc++] bitset has non-conforming member typedef-names iterator and const_iterator

[frederick-vs-ja]

Currently, the following program doesn't compile with libc++ because libc++'s bitset has non-conforming iterator and const_iterator members (despite being private). Godbolt link.

#include <bitset>

struct R {
    using iterator = int*;
    using const_iterator = const int*;
};

struct Derived : R, std::bitset<42> {};

int main()
{
    Derived::iterator i [[maybe_unused]]{};
    Derived::const_iterator j [[maybe_unused]]{};
}

llvm-project/libcxx/include/bitset

Lines 190 to 191 in ef8d506

	typedef __bit_iterator<__bitset, false> iterator;
	typedef __bit_iterator<__bitset, true> const_iterator;

llvm-project/libcxx/include/bitset

Lines 452 to 453 in ef8d506

	typedef __bit_iterator<__bitset, false> iterator;
	typedef __bit_iterator<__bitset, true> const_iterator;

llvm-project/libcxx/include/bitset

Lines 567 to 568 in ef8d506

	typedef __bit_iterator<__bitset, false> iterator;
	typedef __bit_iterator<__bitset, true> const_iterator;

These iterator types are themselves useful, so I think we should just __uglify these typedef-names.