proxy_iterator_interface<T, std::random_access_iterator_tag> is not a RandomAccessIterator #81
Description
The zip_iterator from the documentation does not pass the RandomAccessIterator concept check from Boost.ConceptCheck. That is:
function_requires<boost::RandomAccessIterator<zip_iterator>(); gives:
./boost/concept_check.hpp:209:13: error: conversion from 'std::input_iterator_tag' to non-scalar type 'std::bidirectional_iterator_tag' requested Maybe that is to be expected because the old RandomAccessIterator is not inline with the c++20 concepts one?
Here is the full snippet:
#include <boost/concept_check.hpp> #include <boost/stl_interfaces/iterator_interface.hpp> #include <algorithm> #include <array> #include <tuple> #include <cassert> struct zip_iterator : boost::stl_interfaces::proxy_iterator_interface< zip_iterator, std::random_access_iterator_tag, std::tuple<int, int>, std::tuple<int &, int &>> { constexpr zip_iterator() noexcept : it1_(), it2_() {} constexpr zip_iterator(int * it1, int * it2) noexcept : it1_(it1), it2_(it2) {} constexpr std::tuple<int &, int &> operator*() const noexcept { return std::tuple<int &, int &>{*it1_, *it2_}; } constexpr zip_iterator & operator += (std::ptrdiff_t i) noexcept { it1_ += i; it2_ += i; return *this; } constexpr auto operator-(zip_iterator other) const noexcept { return it1_ - other.it1_; } private: int * it1_; int * it2_; }; int main() { function_requires<boost::RandomAccessIterator<zip_iterator>(); return 0; }Context: boostorg/gil#669