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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
//
//===----------------------------------------------------------------------===//
// REQUIRES: std-at-least-c++26
// <optional>
// constexpr iterator optional::end() noexcept;
// constexpr const_iterator optional::end() const noexcept;
#include <cassert>
#include <iterator>
#include <optional>
#include <ranges>
#include <utility>
template <typename T>
constexpr bool test() {
std::optional<T> disengaged{std::nullopt};
{ // end() is marked noexcept
static_assert(noexcept(disengaged.end()));
static_assert(noexcept(std::as_const(disengaged).end()));
}
{ // end() == begin() and end() == end() if the optional is disengaged
auto it = disengaged.end();
auto it2 = std::as_const(disengaged).end();
assert(it == disengaged.begin());
assert(disengaged.begin() == it);
assert(it == disengaged.end());
assert(it2 == std::as_const(disengaged).begin());
assert(std::as_const(disengaged).begin() == it2);
assert(it2 == std::as_const(disengaged).end());
}
std::optional<T> engaged{T{}};
{ // end() != begin() if the optional is engaged
auto it = engaged.end();
auto it2 = std::as_const(engaged).end();
assert(it != engaged.begin());
assert(engaged.begin() != it);
assert(it2 != std::as_const(engaged).begin());
assert(std::as_const(engaged).begin() != it2);
}
return true;
}
constexpr bool tests() {
assert(test<int>());
assert(test<char>());
assert(test<const int>());
assert(test<const char>());
return true;
}
int main(int, char**) {
assert(tests());
static_assert(tests());
return 0;
}
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