libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/ranges.copy.pass.cpp - llvm-project.git - Git at Google

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//

 // <algorithm>

 // UNSUPPORTED: c++03, c++11, c++14, c++17

 // template<input_iterator I, sentinel_for<I> S, weakly_incrementable O>
 //   requires indirectly_copyable<I, O>
 //   constexpr ranges::copy_result<I, O> ranges::copy(I first, S last, O result);
 // template<input_range R, weakly_incrementable O>
 //   requires indirectly_copyable<iterator_t<R>, O>
 //   constexpr ranges::copy_result<borrowed_iterator_t<R>, O> ranges::copy(R&& r, O result);

 #include <algorithm>
 #include <array>
 #include <cassert>
 #include <deque>
 #include <ranges>
 #include <vector>

 #include "almost_satisfies_types.h"
 #include "sized_allocator.h"
 #include "test_iterators.h"
 #include "test_macros.h"
 #include "type_algorithms.h"

 template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
 concept HasCopyIt = requires(In in, Sent sent, Out out) { std::ranges::copy(in, sent, out); };

 static_assert(HasCopyIt<int*>);
 static_assert(!HasCopyIt<InputIteratorNotDerivedFrom>);
 static_assert(!HasCopyIt<InputIteratorNotIndirectlyReadable>);
 static_assert(!HasCopyIt<InputIteratorNotInputOrOutputIterator>);
 static_assert(!HasCopyIt<int*, WeaklyIncrementableNotMovable>);
 struct NotIndirectlyCopyable {};
 static_assert(!HasCopyIt<int*, NotIndirectlyCopyable*>);
 static_assert(!HasCopyIt<int*, int*, SentinelForNotSemiregular>);
 static_assert(!HasCopyIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);

 template <class Range, class Out>
 concept HasCopyR = requires(Range range, Out out) { std::ranges::copy(range, out); };

 static_assert(HasCopyR<std::array<int, 10>, int*>);
 static_assert(!HasCopyR<InputRangeNotDerivedFrom, int*>);
 static_assert(!HasCopyR<InputRangeNotIndirectlyReadable, int*>);
 static_assert(!HasCopyR<InputRangeNotInputOrOutputIterator, int*>);
 static_assert(!HasCopyR<WeaklyIncrementableNotMovable, int*>);
 static_assert(!HasCopyR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
 static_assert(!HasCopyR<InputRangeNotSentinelSemiregular, int*>);
 static_assert(!HasCopyR<InputRangeNotSentinelEqualityComparableWith, int*>);

 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);

 // clang-format off
 template <class In, class Out, class Sent = In>
 constexpr void test_iterators() {
   { // simple test
     {
       std::array in{1, 2, 3, 4};
       std::array<int, 4> out;
       std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
           std::ranges::copy(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data()));
       assert(in == out);
       assert(base(ret.in) == in.data() + in.size());
       assert(base(ret.out) == out.data() + out.size());
     }
     {
       std::array in{1, 2, 3, 4};
       std::array<int, 4> out;
       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
       std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::copy(range, Out(out.data()));
       assert(in == out);
       assert(base(ret.in) == in.data() + in.size());
       assert(base(ret.out) == out.data() + out.size());
     }
   }

   { // check that an empty range works
     {
       std::array<int, 0> in;
       std::array<int, 0> out;
       auto ret = std::ranges::copy(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data()));
       assert(base(ret.in) == in.data());
       assert(base(ret.out) == out.data());
     }
     {
       std::array<int, 0> in;
       std::array<int, 0> out;
       auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
       auto ret   = std::ranges::copy(range, Out(out.data()));
       assert(base(ret.in) == in.data());
       assert(base(ret.out) == out.data());
     }
   }
 }
 // clang-format on

 #if TEST_STD_VER >= 23
 constexpr bool test_vector_bool(std::size_t N) {
   std::vector<bool> in(N, false);
   for (std::size_t i = 0; i < N; i += 2)
     in[i] = true;

   { // Test copy with aligned bytes
     std::vector<bool> out(N);
     std::ranges::copy(in, out.begin());
     assert(in == out);
   }
   { // Test copy with unaligned bytes
     std::vector<bool> out(N + 8);
     std::ranges::copy(in, out.begin() + 4);
     for (std::size_t i = 0; i < N; ++i)
       assert(out[i + 4] == in[i]);
   }

   return true;
 }
 #endif

 constexpr bool test() {
   types::for_each(types::forward_iterator_list<int*>{}, []<class Out>() {
     test_iterators<cpp20_input_iterator<int*>, Out, sentinel_wrapper<cpp20_input_iterator<int*>>>();
     test_iterators<ProxyIterator<cpp20_input_iterator<int*>>,
                    ProxyIterator<Out>,
                    sentinel_wrapper<ProxyIterator<cpp20_input_iterator<int*>>>>();

     types::for_each(types::forward_iterator_list<int*>{}, []<class In>() {
       test_iterators<In, Out>();
       test_iterators<In, Out, sized_sentinel<In>>();
       test_iterators<In, Out, sentinel_wrapper<In>>();

       test_iterators<ProxyIterator<In>, ProxyIterator<Out>>();
       test_iterators<ProxyIterator<In>, ProxyIterator<Out>, sized_sentinel<ProxyIterator<In>>>();
       test_iterators<ProxyIterator<In>, ProxyIterator<Out>, sentinel_wrapper<ProxyIterator<In>>>();
     });
   });

   { // check that ranges::dangling is returned
     std::array<int, 4> out;
     std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
         std::ranges::copy(std::array{1, 2, 3, 4}, out.data());
     assert(ret.out == out.data() + 4);
     assert((out == std::array{1, 2, 3, 4}));
   }

   { // check that an iterator is returned with a borrowing range
     std::array in{1, 2, 3, 4};
     std::array<int, 4> out;
     std::same_as<std::ranges::in_out_result<std::array<int, 4>::iterator, int*>> auto ret =
         std::ranges::copy(std::views::all(in), out.data());
     assert(ret.in == in.end());
     assert(ret.out == out.data() + 4);
     assert(in == out);
   }

   { // check that every element is copied exactly once
     struct CopyOnce {
       bool copied                               = false;
       constexpr CopyOnce()                      = default;
       constexpr CopyOnce(const CopyOnce& other) = delete;
       constexpr CopyOnce& operator=(const CopyOnce& other) {
         assert(!other.copied);
         copied = true;
         return *this;
       }
     };
     {
       std::array<CopyOnce, 4> in{};
       std::array<CopyOnce, 4> out{};
       auto ret = std::ranges::copy(in.begin(), in.end(), out.begin());
       assert(ret.in == in.end());
       assert(ret.out == out.end());
       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
     }
     {
       std::array<CopyOnce, 4> in{};
       std::array<CopyOnce, 4> out{};
       auto ret = std::ranges::copy(in, out.begin());
       assert(ret.in == in.end());
       assert(ret.out == out.end());
       assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
     }
   }

   { // check that the range is copied forwards
     struct OnlyForwardsCopyable {
       OnlyForwardsCopyable* next = nullptr;
       bool canCopy               = false;
       OnlyForwardsCopyable()     = default;
       constexpr OnlyForwardsCopyable& operator=(const OnlyForwardsCopyable&) {
         assert(canCopy);
         if (next != nullptr)
           next->canCopy = true;
         return *this;
       }
     };
     {
       std::array<OnlyForwardsCopyable, 3> in{};
       std::array<OnlyForwardsCopyable, 3> out{};
       out[0].next    = &out[1];
       out[1].next    = &out[2];
       out[0].canCopy = true;
       auto ret       = std::ranges::copy(in.begin(), in.end(), out.begin());
       assert(ret.in == in.end());
       assert(ret.out == out.end());
       assert(out[0].canCopy);
       assert(out[1].canCopy);
       assert(out[2].canCopy);
     }
     {
       std::array<OnlyForwardsCopyable, 3> in{};
       std::array<OnlyForwardsCopyable, 3> out{};
       out[0].next    = &out[1];
       out[1].next    = &out[2];
       out[0].canCopy = true;
       auto ret       = std::ranges::copy(in, out.begin());
       assert(ret.in == in.end());
       assert(ret.out == out.end());
       assert(out[0].canCopy);
       assert(out[1].canCopy);
       assert(out[2].canCopy);
     }
   }

 #if TEST_STD_VER >= 23
   { // Test vector<bool>::iterator optimization
     assert(test_vector_bool(8));
     assert(test_vector_bool(19));
     assert(test_vector_bool(32));
     assert(test_vector_bool(49));
     assert(test_vector_bool(64));
     assert(test_vector_bool(199));
     assert(test_vector_bool(256));
   }

   // Validate std::ranges::copy with std::vector<bool> iterators and custom storage types.
   // Ensure that assigned bits hold the intended values, while unassigned bits stay unchanged.
   // Related issue: https://llvm.org/PR131692.
   {
     //// Tests for std::ranges::copy with aligned bits

     { // Test the first (partial) word for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(8, false, Alloc(1));
       std::vector<bool, Alloc> out(8, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 1, in.begin() + 2), out.begin() + 1); // out[1] = false
       assert(out[1] == false);
       for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         if (i != 1)
           assert(out[i] == true);
     }
     { // Test the last (partial) word for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(8, false, Alloc(1));
       std::vector<bool, Alloc> out(8, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 1), out.begin()); // out[0] = false
       assert(out[0] == false);
       for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         assert(out[i] == true);
     }
     { // Test middle (whole) words for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(32, true, Alloc(1));
       for (std::size_t i = 0; i < in.size(); i += 2)
         in[i] = false;
       std::vector<bool, Alloc> out(32, false, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 4, in.end() - 4), out.begin() + 4);
       for (std::size_t i = 4; i < static_cast<std::size_t>(in.size() - 4); ++i)
         assert(in[i] == out[i]);
       for (std::size_t i = 0; i < 4; ++i)
         assert(out[i] == false);
       for (std::size_t i = 28; i < out.size(); ++i)
         assert(out[i] == false);
     }

     { // Test the first (partial) word for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(16, false, Alloc(1));
       std::vector<bool, Alloc> out(16, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 1, in.begin() + 3), out.begin() + 1); // out[1..2] = false
       assert(out[1] == false);
       assert(out[2] == false);
       for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         if (i != 1 && i != 2)
           assert(out[i] == true);
     }
     { // Test the last (partial) word for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(16, false, Alloc(1));
       std::vector<bool, Alloc> out(16, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 2), out.begin()); // out[0..1] = false
       assert(out[0] == false);
       assert(out[1] == false);
       for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         assert(out[i] == true);
     }
     { // Test middle (whole) words for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(64, true, Alloc(1));
       for (std::size_t i = 0; i < in.size(); i += 2)
         in[i] = false;
       std::vector<bool, Alloc> out(64, false, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 8, in.end() - 8), out.begin() + 8);
       for (std::size_t i = 8; i < static_cast<std::size_t>(in.size() - 8); ++i)
         assert(in[i] == out[i]);
       for (std::size_t i = 0; i < 8; ++i)
         assert(out[i] == false);
       for (std::size_t i = static_cast<std::size_t>(out.size() - 8); i < out.size(); ++i)
         assert(out[i] == false);
     }

     //// Tests for std::ranges::copy with unaligned bits

     { // Test the first (partial) word for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(8, false, Alloc(1));
       std::vector<bool, Alloc> out(8, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 7, in.end()), out.begin()); // out[0] = false
       assert(out[0] == false);
       for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         assert(out[i] == true);
     }
     { // Test the last (partial) word for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(8, false, Alloc(1));
       std::vector<bool, Alloc> out(8, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 1), out.begin() + 2); // out[2] = false
       assert(out[2] == false);
       for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         if (i != 2)
           assert(out[i] == true);
     }
     { // Test middle (whole) words for uint8_t
       using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
       std::vector<bool, Alloc> in(36, true, Alloc(1));
       for (std::size_t i = 0; i < in.size(); i += 2)
         in[i] = false;
       std::vector<bool, Alloc> out(40, false, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.end()), out.begin() + 4);
       for (std::size_t i = 0; i < in.size(); ++i)
         assert(in[i] == out[i + 4]);
       for (std::size_t i = 0; i < 4; ++i)
         assert(out[i] == false);
     }

     { // Test the first (partial) word for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(16, false, Alloc(1));
       std::vector<bool, Alloc> out(16, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin() + 14, in.end()), out.begin()); // out[0..1] = false
       assert(out[0] == false);
       assert(out[1] == false);
       for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         assert(out[i] == true);
     }
     { // Test the last (partial) word for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(16, false, Alloc(1));
       std::vector<bool, Alloc> out(16, true, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 2), out.begin() + 1); // out[1..2] = false
       assert(out[1] == false);
       assert(out[2] == false);
       for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
         if (i != 1 && i != 2)
           assert(out[i] == true);
     }
     { // Test middle (whole) words for uint16_t
       using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
       std::vector<bool, Alloc> in(72, true, Alloc(1));
       for (std::size_t i = 0; i < in.size(); i += 2)
         in[i] = false;
       std::vector<bool, Alloc> out(80, false, Alloc(1));
       std::ranges::copy(std::ranges::subrange(in.begin(), in.end()), out.begin() + 4);
       for (std::size_t i = 0; i < in.size(); ++i)
         assert(in[i] == out[i + 4]);
       for (std::size_t i = 0; i < 4; ++i)
         assert(out[i] == false);
       for (std::size_t i = in.size() + 4; i < out.size(); ++i)
         assert(out[i] == false);
     }
   }
 #endif

   return true;
 }

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

   return 0;
 }
	//===----------------------------------------------------------------------===//
	//
	// 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
	//
	//===----------------------------------------------------------------------===//

	// <algorithm>

	// UNSUPPORTED: c++03, c++11, c++14, c++17

	// template<input_iterator I, sentinel_for<I> S, weakly_incrementable O>
	// requires indirectly_copyable<I, O>
	// constexpr ranges::copy_result<I, O> ranges::copy(I first, S last, O result);
	// template<input_range R, weakly_incrementable O>
	// requires indirectly_copyable<iterator_t<R>, O>
	// constexpr ranges::copy_result<borrowed_iterator_t<R>, O> ranges::copy(R&& r, O result);

	#include <algorithm>
	#include <array>
	#include <cassert>
	#include <deque>
	#include <ranges>
	#include <vector>

	#include "almost_satisfies_types.h"
	#include "sized_allocator.h"
	#include "test_iterators.h"
	#include "test_macros.h"
	#include "type_algorithms.h"

	template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
	concept HasCopyIt = requires(In in, Sent sent, Out out) { std::ranges::copy(in, sent, out); };

	static_assert(HasCopyIt<int*>);
	static_assert(!HasCopyIt<InputIteratorNotDerivedFrom>);
	static_assert(!HasCopyIt<InputIteratorNotIndirectlyReadable>);
	static_assert(!HasCopyIt<InputIteratorNotInputOrOutputIterator>);
	static_assert(!HasCopyIt<int*, WeaklyIncrementableNotMovable>);
	struct NotIndirectlyCopyable {};
	static_assert(!HasCopyIt<int, NotIndirectlyCopyable>);
	static_assert(!HasCopyIt<int, int, SentinelForNotSemiregular>);
	static_assert(!HasCopyIt<int, int, SentinelForNotWeaklyEqualityComparableWith>);

	template <class Range, class Out>
	concept HasCopyR = requires(Range range, Out out) { std::ranges::copy(range, out); };

	static_assert(HasCopyR<std::array<int, 10>, int*>);
	static_assert(!HasCopyR<InputRangeNotDerivedFrom, int*>);
	static_assert(!HasCopyR<InputRangeNotIndirectlyReadable, int*>);
	static_assert(!HasCopyR<InputRangeNotInputOrOutputIterator, int*>);
	static_assert(!HasCopyR<WeaklyIncrementableNotMovable, int*>);
	static_assert(!HasCopyR<UncheckedRange<NotIndirectlyCopyable>, int>);
	static_assert(!HasCopyR<InputRangeNotSentinelSemiregular, int*>);
	static_assert(!HasCopyR<InputRangeNotSentinelEqualityComparableWith, int*>);

	static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);

	// clang-format off
	template <class In, class Out, class Sent = In>
	constexpr void test_iterators() {
	{ // simple test
	{
	std::array in{1, 2, 3, 4};
	std::array<int, 4> out;
	std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
	std::ranges::copy(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data()));
	assert(in == out);
	assert(base(ret.in) == in.data() + in.size());
	assert(base(ret.out) == out.data() + out.size());
	}
	{
	std::array in{1, 2, 3, 4};
	std::array<int, 4> out;
	auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
	std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::copy(range, Out(out.data()));
	assert(in == out);
	assert(base(ret.in) == in.data() + in.size());
	assert(base(ret.out) == out.data() + out.size());
	}
	}

	{ // check that an empty range works
	{
	std::array<int, 0> in;
	std::array<int, 0> out;
	auto ret = std::ranges::copy(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data()));
	assert(base(ret.in) == in.data());
	assert(base(ret.out) == out.data());
	}
	{
	std::array<int, 0> in;
	std::array<int, 0> out;
	auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
	auto ret = std::ranges::copy(range, Out(out.data()));
	assert(base(ret.in) == in.data());
	assert(base(ret.out) == out.data());
	}
	}
	}
	// clang-format on

	#if TEST_STD_VER >= 23
	constexpr bool test_vector_bool(std::size_t N) {
	std::vector<bool> in(N, false);
	for (std::size_t i = 0; i < N; i += 2)
	in[i] = true;

	{ // Test copy with aligned bytes
	std::vector<bool> out(N);
	std::ranges::copy(in, out.begin());
	assert(in == out);
	}
	{ // Test copy with unaligned bytes
	std::vector<bool> out(N + 8);
	std::ranges::copy(in, out.begin() + 4);
	for (std::size_t i = 0; i < N; ++i)
	assert(out[i + 4] == in[i]);
	}

	return true;
	}
	#endif

	constexpr bool test() {
	types::for_each(types::forward_iterator_list<int*>{}, []<class Out>() {
	test_iterators<cpp20_input_iterator<int>, Out, sentinel_wrapper<cpp20_input_iterator<int>>>();
	test_iterators<ProxyIterator<cpp20_input_iterator<int*>>,
	ProxyIterator<Out>,
	sentinel_wrapper<ProxyIterator<cpp20_input_iterator<int*>>>>();

	types::for_each(types::forward_iterator_list<int*>{}, []<class In>() {
	test_iterators<In, Out>();
	test_iterators<In, Out, sized_sentinel<In>>();
	test_iterators<In, Out, sentinel_wrapper<In>>();

	test_iterators<ProxyIterator<In>, ProxyIterator<Out>>();
	test_iterators<ProxyIterator<In>, ProxyIterator<Out>, sized_sentinel<ProxyIterator<In>>>();
	test_iterators<ProxyIterator<In>, ProxyIterator<Out>, sentinel_wrapper<ProxyIterator<In>>>();
	});
	});

	{ // check that ranges::dangling is returned
	std::array<int, 4> out;
	std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
	std::ranges::copy(std::array{1, 2, 3, 4}, out.data());
	assert(ret.out == out.data() + 4);
	assert((out == std::array{1, 2, 3, 4}));
	}

	{ // check that an iterator is returned with a borrowing range
	std::array in{1, 2, 3, 4};
	std::array<int, 4> out;
	std::same_as<std::ranges::in_out_result<std::array<int, 4>::iterator, int*>> auto ret =
	std::ranges::copy(std::views::all(in), out.data());
	assert(ret.in == in.end());
	assert(ret.out == out.data() + 4);
	assert(in == out);
	}

	{ // check that every element is copied exactly once
	struct CopyOnce {
	bool copied = false;
	constexpr CopyOnce() = default;
	constexpr CopyOnce(const CopyOnce& other) = delete;
	constexpr CopyOnce& operator=(const CopyOnce& other) {
	assert(!other.copied);
	copied = true;
	return *this;
	}
	};
	{
	std::array<CopyOnce, 4> in{};
	std::array<CopyOnce, 4> out{};
	auto ret = std::ranges::copy(in.begin(), in.end(), out.begin());
	assert(ret.in == in.end());
	assert(ret.out == out.end());
	assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
	}
	{
	std::array<CopyOnce, 4> in{};
	std::array<CopyOnce, 4> out{};
	auto ret = std::ranges::copy(in, out.begin());
	assert(ret.in == in.end());
	assert(ret.out == out.end());
	assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
	}
	}

	{ // check that the range is copied forwards
	struct OnlyForwardsCopyable {
	OnlyForwardsCopyable* next = nullptr;
	bool canCopy = false;
	OnlyForwardsCopyable() = default;
	constexpr OnlyForwardsCopyable& operator=(const OnlyForwardsCopyable&) {
	assert(canCopy);
	if (next != nullptr)
	next->canCopy = true;
	return *this;
	}
	};
	{
	std::array<OnlyForwardsCopyable, 3> in{};
	std::array<OnlyForwardsCopyable, 3> out{};
	out[0].next = &out[1];
	out[1].next = &out[2];
	out[0].canCopy = true;
	auto ret = std::ranges::copy(in.begin(), in.end(), out.begin());
	assert(ret.in == in.end());
	assert(ret.out == out.end());
	assert(out[0].canCopy);
	assert(out[1].canCopy);
	assert(out[2].canCopy);
	}
	{
	std::array<OnlyForwardsCopyable, 3> in{};
	std::array<OnlyForwardsCopyable, 3> out{};
	out[0].next = &out[1];
	out[1].next = &out[2];
	out[0].canCopy = true;
	auto ret = std::ranges::copy(in, out.begin());
	assert(ret.in == in.end());
	assert(ret.out == out.end());
	assert(out[0].canCopy);
	assert(out[1].canCopy);
	assert(out[2].canCopy);
	}
	}

	#if TEST_STD_VER >= 23
	{ // Test vector<bool>::iterator optimization
	assert(test_vector_bool(8));
	assert(test_vector_bool(19));
	assert(test_vector_bool(32));
	assert(test_vector_bool(49));
	assert(test_vector_bool(64));
	assert(test_vector_bool(199));
	assert(test_vector_bool(256));
	}

	// Validate std::ranges::copy with std::vector<bool> iterators and custom storage types.
	// Ensure that assigned bits hold the intended values, while unassigned bits stay unchanged.
	// Related issue: https://llvm.org/PR131692.
	{
	//// Tests for std::ranges::copy with aligned bits

	{ // Test the first (partial) word for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(8, false, Alloc(1));
	std::vector<bool, Alloc> out(8, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 1, in.begin() + 2), out.begin() + 1); // out[1] = false
	assert(out[1] == false);
	for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	if (i != 1)
	assert(out[i] == true);
	}
	{ // Test the last (partial) word for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(8, false, Alloc(1));
	std::vector<bool, Alloc> out(8, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 1), out.begin()); // out[0] = false
	assert(out[0] == false);
	for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	assert(out[i] == true);
	}
	{ // Test middle (whole) words for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(32, true, Alloc(1));
	for (std::size_t i = 0; i < in.size(); i += 2)
	in[i] = false;
	std::vector<bool, Alloc> out(32, false, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 4, in.end() - 4), out.begin() + 4);
	for (std::size_t i = 4; i < static_cast<std::size_t>(in.size() - 4); ++i)
	assert(in[i] == out[i]);
	for (std::size_t i = 0; i < 4; ++i)
	assert(out[i] == false);
	for (std::size_t i = 28; i < out.size(); ++i)
	assert(out[i] == false);
	}

	{ // Test the first (partial) word for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(16, false, Alloc(1));
	std::vector<bool, Alloc> out(16, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 1, in.begin() + 3), out.begin() + 1); // out[1..2] = false
	assert(out[1] == false);
	assert(out[2] == false);
	for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	if (i != 1 && i != 2)
	assert(out[i] == true);
	}
	{ // Test the last (partial) word for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(16, false, Alloc(1));
	std::vector<bool, Alloc> out(16, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 2), out.begin()); // out[0..1] = false
	assert(out[0] == false);
	assert(out[1] == false);
	for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	assert(out[i] == true);
	}
	{ // Test middle (whole) words for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(64, true, Alloc(1));
	for (std::size_t i = 0; i < in.size(); i += 2)
	in[i] = false;
	std::vector<bool, Alloc> out(64, false, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 8, in.end() - 8), out.begin() + 8);
	for (std::size_t i = 8; i < static_cast<std::size_t>(in.size() - 8); ++i)
	assert(in[i] == out[i]);
	for (std::size_t i = 0; i < 8; ++i)
	assert(out[i] == false);
	for (std::size_t i = static_cast<std::size_t>(out.size() - 8); i < out.size(); ++i)
	assert(out[i] == false);
	}

	//// Tests for std::ranges::copy with unaligned bits

	{ // Test the first (partial) word for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(8, false, Alloc(1));
	std::vector<bool, Alloc> out(8, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 7, in.end()), out.begin()); // out[0] = false
	assert(out[0] == false);
	for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	assert(out[i] == true);
	}
	{ // Test the last (partial) word for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(8, false, Alloc(1));
	std::vector<bool, Alloc> out(8, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 1), out.begin() + 2); // out[2] = false
	assert(out[2] == false);
	for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	if (i != 2)
	assert(out[i] == true);
	}
	{ // Test middle (whole) words for uint8_t
	using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
	std::vector<bool, Alloc> in(36, true, Alloc(1));
	for (std::size_t i = 0; i < in.size(); i += 2)
	in[i] = false;
	std::vector<bool, Alloc> out(40, false, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.end()), out.begin() + 4);
	for (std::size_t i = 0; i < in.size(); ++i)
	assert(in[i] == out[i + 4]);
	for (std::size_t i = 0; i < 4; ++i)
	assert(out[i] == false);
	}

	{ // Test the first (partial) word for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(16, false, Alloc(1));
	std::vector<bool, Alloc> out(16, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin() + 14, in.end()), out.begin()); // out[0..1] = false
	assert(out[0] == false);
	assert(out[1] == false);
	for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	assert(out[i] == true);
	}
	{ // Test the last (partial) word for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(16, false, Alloc(1));
	std::vector<bool, Alloc> out(16, true, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.begin() + 2), out.begin() + 1); // out[1..2] = false
	assert(out[1] == false);
	assert(out[2] == false);
	for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
	if (i != 1 && i != 2)
	assert(out[i] == true);
	}
	{ // Test middle (whole) words for uint16_t
	using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
	std::vector<bool, Alloc> in(72, true, Alloc(1));
	for (std::size_t i = 0; i < in.size(); i += 2)
	in[i] = false;
	std::vector<bool, Alloc> out(80, false, Alloc(1));
	std::ranges::copy(std::ranges::subrange(in.begin(), in.end()), out.begin() + 4);
	for (std::size_t i = 0; i < in.size(); ++i)
	assert(in[i] == out[i + 4]);
	for (std::size_t i = 0; i < 4; ++i)
	assert(out[i] == false);
	for (std::size_t i = in.size() + 4; i < out.size(); ++i)
	assert(out[i] == false);
	}
	}
	#endif

	return true;
	}

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

	return 0;
	}