third_party/llvm-project/libcxx/test/std/ranges/range.adaptors/range.join.view/ctor.default.pass.cpp

//===----------------------------------------------------------------------===//
//
// 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
// UNSUPPORTED: !c++experimental

// join_view() requires default_initializable<V> = default;

#include <cassert>
#include <ranges>

#include "types.h"

struct DefaultView : std::ranges::view_base {
  int i; // deliberately uninitialised

  ChildView* begin() const;
  ChildView* end() const;
};

constexpr bool test() {
  {
    std::ranges::join_view<ParentView<ChildView>> jv;
    assert(std::move(jv).base().ptr_ == globalChildren);
  }

  // Default constructor should value initialise underlying view
  {
    std::ranges::join_view<DefaultView> jv;
    assert(jv.base().i == 0);
  }

  static_assert( std::default_initializable<std::ranges::join_view<ParentView<ChildView>>>);
  static_assert(!std::default_initializable<std::ranges::join_view<CopyableParent>>);

  return true;
}

int main(int, char**) {
  test();
  static_assert(test());

  return 0;
}