Nikolas Klauser 89c8a253d7
[libc++] Make optional::iterator experimental (#173470)
We haven't yet decided what we want the `optional::iterator` type to be
in the end, so let's make it experimental for now so that we don't
commit to an ABI yet.
2026-01-09 10:21:48 -05:00

83 lines
2.1 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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
// UNSUPPORTED: libcpp-has-no-experimental-optional-iterator
// <optional>
// constexpr iterator optional::end() noexcept;
// constexpr const_iterator optional::end() const noexcept;
#include <cassert>
#include <iterator>
#include <optional>
#include <ranges>
#include <type_traits>
#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::remove_reference_t<T> t = std::remove_reference_t<T>{};
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>());
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;
}