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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// constexpr iterator(iterator<!Const> i)
// requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>;
#include <cassert>
#include <ranges>
#include <tuple>
#include "../types.h"
template <bool Const>
struct ConvertibleIter : IterBase<ConvertibleIter<Const>> {
using iterator_category = std::random_access_iterator_tag;
using value_type = std::tuple<int>;
using difference_type = intptr_t;
bool movedFromOtherConst = false;
int i = 0;
constexpr ConvertibleIter() = default;
constexpr ConvertibleIter(int ii) : i(ii) {}
template <bool otherConst>
requires(Const != otherConst)
constexpr ConvertibleIter(ConvertibleIter<otherConst> it) : movedFromOtherConst(true), i(it.i) {}
};
template <class Iter, class ConstIter>
struct BasicView : std::ranges::view_base {
Iter begin();
Iter end();
ConstIter begin() const;
ConstIter end() const;
};
template <class View>
using ElemIter = std::ranges::iterator_t<std::ranges::elements_view<View, 0>>;
template <class View>
using ConstElemIter = std::ranges::iterator_t<const std::ranges::elements_view<View, 0>>;
using ConvertibleView = BasicView<ConvertibleIter<false>, ConvertibleIter<true>>;
using NonConvertibleView = BasicView<forward_iterator<std::tuple<int>*>, bidirectional_iterator<std::tuple<int>*>>;
static_assert(std::is_constructible_v<ConstElemIter<ConvertibleView>, ElemIter<ConvertibleView>>);
static_assert(!std::is_constructible_v<ElemIter<ConvertibleView>, ConstElemIter<ConvertibleView>>);
static_assert(!std::is_constructible_v<ConstElemIter<NonConvertibleView>, ElemIter<NonConvertibleView>>);
static_assert(!std::is_constructible_v<ElemIter<NonConvertibleView>, ConstElemIter<NonConvertibleView>>);
constexpr bool test() {
ElemIter<ConvertibleView> iter{ConvertibleIter<false>{5}};
ConstElemIter<ConvertibleView> constIter = iter; // implicit
assert(constIter.base().movedFromOtherConst);
assert(constIter.base().i == 5);
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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