94461822c7
`subrange` is also a `tuple-like`. To avoid the add entire `subrange` dependencies to `tuple-like`, we need forward declaration of `subrange`. However, the class template constraints of `subrange` currently requires `__iterator/concepts.h`, which requires `<concepts>`. The problem is that currently `tuple-like` is used in several different places, including libc++ extension for pair constructors. we don't want to add `<concepts>` to pair and other stuff. So this change also created several small headers that `subrange`'s declaration needed inside `__iterator/concepts/` Differential Revision: https://reviews.llvm.org/D136268
48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17
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// elements_view() requires default_initializable<V> = default;
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#include <cassert>
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#include <ranges>
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#include <tuple>
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#include <type_traits>
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template <bool DefaultInitializable>
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struct View : std::ranges::view_base {
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int i = 42;
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constexpr explicit View()
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requires DefaultInitializable
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= default;
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std::tuple<int>* begin() const;
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std::tuple<int>* end() const;
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};
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// clang-format off
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static_assert( std::is_default_constructible_v<std::ranges::elements_view<View<true >, 0>>);
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static_assert(!std::is_default_constructible_v<std::ranges::elements_view<View<false>, 0>>);
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// clang-format on
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constexpr bool test() {
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{
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std::ranges::elements_view<View<true>, 0> ev = {};
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assert(ev.base().i == 42);
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}
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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