[flang-commits] [flang] [llvm] [libcxx] [clang-tools-extra] [libcxxabi] [lld] [compiler-rt] [mlir] [libclc] [clang] [lldb] [libunwind] [libc] [libc++][ranges] Implement ranges::contains_subrange (PR #66963)

via flang-commits flang-commits at lists.llvm.org
Tue Jan 9 10:48:54 PST 2024


https://github.com/ZijunZhaoCCK updated https://github.com/llvm/llvm-project/pull/66963

>From 647f5fe641b30c874bab770fced9fcec9b601161 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Wed, 13 Sep 2023 14:26:01 -0700
Subject: [PATCH 01/10] [libc++] Implement ranges::contains_subrange

---
 libcxx/include/CMakeLists.txt                 |   1 +
 .../__algorithm/ranges_contains_subrange.h    | 145 +++++++++
 libcxx/include/algorithm                      |  14 +
 ...obust_against_copying_projections.pass.cpp |   2 +
 .../ranges.contains_subrange.pass.cpp         | 293 ++++++++++++++++++
 .../niebloid.compile.pass.cpp                 |   1 +
 6 files changed, 456 insertions(+)
 create mode 100644 libcxx/include/__algorithm/ranges_contains_subrange.h
 create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 0fe3ab44d2466e..dd3ff541fbc7ba 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -110,6 +110,7 @@ set(files
   __algorithm/ranges_binary_search.h
   __algorithm/ranges_clamp.h
   __algorithm/ranges_contains.h
+  __algorithm/ranges_contains_subrange.h
   __algorithm/ranges_copy.h
   __algorithm/ranges_copy_backward.h
   __algorithm/ranges_copy_if.h
diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
new file mode 100644
index 00000000000000..16de6c29cb2a1a
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -0,0 +1,145 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
+#define _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
+
+#include <__algorithm/ranges_starts_with.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/ranges_operations.h>
+#include <__functional/reference_wrapper.h>
+#include <__iterator/concepts.h>
+#include <__iterator/distance.h>
+#include <__iterator/indirectly_comparable.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 23
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __contains_subrange {
+struct __fn {
+  template <input_iterator _Iter1,
+            sentinel_for<_Iter1> _Sent1,
+            input_iterator _Iter2,
+            sentinel_for<_Iter2> _Sent2,
+            class _Pred,
+            class _Proj1,
+            class _Proj2,
+            class _Offset>
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __contains_subrange_fn_impl(
+      _Iter1 __first1,
+      _Sent1 __last1,
+      _Iter2 __first2,
+      _Sent2 __last2,
+      _Pred& __pred,
+      _Proj1& __proj1,
+      _Proj2& __proj2,
+      _Offset __offset) {
+    if (__offset < 0)
+      return false;
+    else {
+      for (; __offset >= 0; __offset--, __first1++) {
+        auto result = ranges::starts_with(
+            std::move(__first1),
+            std::move(__last1),
+            std::move(__first2),
+            std::move(__last2),
+            std::ref(__pred),
+            std::ref(__proj1),
+            std::ref(__proj2));
+        if (result)
+          return true;
+      }
+      return false;
+    }
+  }
+
+  template <input_iterator _Iter1,
+            sentinel_for<_Iter1> _Sent1,
+            input_iterator _Iter2,
+            sentinel_for<_Iter2> _Sent2,
+            class _Pred  = ranges::equal_to,
+            class _Proj1 = identity,
+            class _Proj2 = identity>
+    requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
+      _Iter1 __first1,
+      _Sent1 __last1,
+      _Iter2 __first2,
+      _Sent2 __last2,
+      _Pred __pred   = {},
+      _Proj1 __proj1 = {},
+      _Proj2 __proj2 = {}) const {
+    auto __n1     = ranges::distance(__first1, __last1);
+    auto __n2     = ranges::distance(__first2, __last2);
+    auto __offset = __n1 - __n2;
+
+    return __contains_subrange_fn_impl(
+        std::move(__first1),
+        std::move(__last1),
+        std::move(__first2),
+        std::move(__last2),
+        __pred,
+        __proj1,
+        __proj2,
+        std::move(__offset));
+  }
+
+  template <input_range _Range1,
+            input_range _Range2,
+            class _Pred  = ranges::equal_to,
+            class _Proj1 = identity,
+            class _Proj2 = identity>
+    requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
+      _Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const {
+    auto __n1 = 0;
+    auto __n2 = 0;
+
+    if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
+      __n1 = ranges::size(__range1);
+      __n2 = ranges::size(__range2);
+    } else {
+      __n1 = ranges::distance(ranges::begin(__range1), ranges::end(__range1));
+      __n2 = ranges::distance(ranges::begin(__range2), ranges::end(__range2));
+    }
+
+    auto __offset = __n1 - __n2;
+    return __contains_subrange_fn_impl(
+        ranges::begin(__range1),
+        ranges::end(__range1),
+        ranges::begin(__range2),
+        ranges::end(__range2),
+        __pred,
+        __proj1,
+        __proj2,
+        __offset);
+    }
+};
+} // namespace __contains_subrange
+
+inline namespace __cpo {
+inline constexpr auto contains_subrange = __contains_subrange::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 23
+
+#endif // _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
\ No newline at end of file
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 1176602a2b6951..7c490ef40ac5f8 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -217,6 +217,19 @@ namespace ranges {
     constexpr ranges::minmax_element_result<borrowed_iterator_t<R>>
       minmax_element(R&& r, Comp comp = {}, Proj proj = {});                                              // since C++20
 
+  template<forward_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
+    sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = identity,
+    class Proj2 = identity>
+    requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
+    constexpr bool ranges::contains_subrange(I1 first1, S1 last1, I2 first2,
+      S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});                        // since C++23
+
+  template<forward_range R1, forward_range R2,
+    class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
+    requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
+    constexpr bool ranges::contains_subrange(R1&& r1, R2&& r2, Pred pred = {},
+      Proj1 proj1 = {}, Proj2 proj2 = {});                                                  // since C++23
+
   template<class I, class O>
     using copy_result = in_out_result<I, O>;                                                // since C++20
 
@@ -1875,6 +1888,7 @@ template <class BidirectionalIterator, class Compare>
 #include <__algorithm/ranges_binary_search.h>
 #include <__algorithm/ranges_clamp.h>
 #include <__algorithm/ranges_contains.h>
+#include <__algorithm/ranges_contains_subrange.h>
 #include <__algorithm/ranges_copy.h>
 #include <__algorithm/ranges_copy_backward.h>
 #include <__algorithm/ranges_copy_if.h>
diff --git a/libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.pass.cpp b/libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.pass.cpp
index e96a57f4005e04..cc031867b908a3 100644
--- a/libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.pass.cpp
+++ b/libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.pass.cpp
@@ -86,6 +86,8 @@ constexpr bool all_the_algorithms()
     assert(copies == 0);
     (void)std::ranges::contains(a, value, Proj(&copies));
     assert(copies == 0);
+    (void)std::ranges::contains_subrange(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::contains_subrange(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
 #endif
     (void)std::ranges::count(first, last, value, Proj(&copies)); assert(copies == 0);
     (void)std::ranges::count(a, value, Proj(&copies)); assert(copies == 0);
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
new file mode 100644
index 00000000000000..fd4d858b255db7
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
@@ -0,0 +1,293 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++20
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=2000000
+
+// template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
+//     requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
+//     constexpr bool ranges::contains(I first, S last, const T& value, Proj proj = {});       // since C++23
+
+// template<input_range R, class T, class Proj = identity>
+//     requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+//     constexpr bool ranges::contains(R&& r, const T& value, Proj proj = {});                 // since C++23
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <ranges>
+#include <vector>
+
+#include "almost_satisfies_types.h"
+#include "boolean_testable.h"
+#include "test_iterators.h"
+
+struct NotEqualityComparable {};
+
+template <class Iter1, class Sent1 = Iter1, class Iter2 = int*, class Sent2 = Iter2>
+concept HasContainsSubrangeSubrangeIt = requires(Iter1 first1, Sent1 last1, Iter2 first2, Sent2 last2) {
+  std::ranges::contains_subrange(first1, last1, first2, last2);
+};
+
+static_assert(HasContainsSubrangeSubrangeIt<int*>);
+static_assert(!HasContainsSubrangeSubrangeIt<NotEqualityComparable*>);
+static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotDerivedFrom>);
+static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotIndirectlyReadable>);
+static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotInputOrOutputIterator>);
+static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
+static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
+static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>);
+
+static_assert(!HasContainsSubrangeSubrangeIt<int*, int>);
+static_assert(!HasContainsSubrangeSubrangeIt<int, int*>);
+static_assert(HasContainsSubrangeSubrangeIt<int*, int*>);
+
+template <class Range1, class Range2 = UncheckedRange<int*>>
+concept HasContainsSubrangeR = requires(Range1&& range1, Range2&& range2) {
+    std::ranges::contains_subrange(std::forward<Range1>(range1), std::forward<Range2>(range2)); };
+
+static_assert(HasContainsSubrangeR<UncheckedRange<int*>>);
+static_assert(HasContainsSubrangeR<ForwardRangeNotDerivedFrom>);
+static_assert(!HasContainsSubrangeR<ForwardIteratorNotIncrementable>);
+static_assert(!HasContainsSubrangeR<ForwardRangeNotSentinelSemiregular>);
+static_assert(!HasContainsSubrangeR<ForwardRangeNotSentinelEqualityComparableWith>);
+static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, UncheckedRange<int**>>); // not indirectly comparable
+static_assert(HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotDerivedFrom>);
+static_assert(HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotIncrementable>);
+static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotSentinelSemiregular>);
+static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotSentinelEqualityComparableWith>);
+
+static std::vector<int> comparable_data;
+
+template <class Iter1, class Sent1 = Iter1, class Iter2, class Sent2 = Iter2>
+constexpr void test_iterators() {
+  {  // simple tests
+    int a[] = {1, 2, 3, 4, 5, 6};
+    int p[] = {3, 4, 5};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      [[maybe_unused]] std::same_as<bool> decltype(auto) ret =
+        std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      [[maybe_unused]] std::same_as<bool> decltype(auto) ret =
+        std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // no match
+    int a[] = {1, 2, 3, 4, 5, 6};
+    int p[] = {3, 4, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(!ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(!ret);
+    }
+  }
+
+  { // range consists of just one element
+    int a[] = {3};
+    int p[] = {3, 4, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 1)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(!ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(!ret);
+    }
+  }
+
+  { // subrange consists of just one element
+    int a[] = {23, 1, 20, 3, 54, 2};
+    int p[] = {3};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 1)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // range has zero length
+    int a[] = {};
+    int p[] = {3, 4, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(!ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(!ret);
+    }
+  }
+
+  { // subrange has zero length
+    int a[] = {3, 4, 2};
+    int p[] = {};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // range and subrange are identical
+    int a[] = {3, 4, 11, 32, 54, 2};
+    int p[] = {3, 4, 11, 32, 54, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 6)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // subrange is longer than range
+    int a[] = {3, 4, 2};
+    int p[] = {23, 3, 4, 2, 11, 32, 54, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 8)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(!ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(!ret);
+    }
+  }
+
+  { // subrange is subsequence
+    int a[] = {23, 1, 0, 54, 2};
+    int p[] = {1, 0, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(!ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(!ret);
+    }
+  }
+
+  { // repeated subrange
+    int a[] = {23, 1, 0, 2, 54, 1, 0, 2, 23, 33};
+    int p[] = {1, 0, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 10)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // check that the predicate is used
+    int a[] = {23, 81, 61, 0, 42, 25, 1, 2, 1, 29, 2};
+    int p[] = {-1, -2, -1};
+    auto pred = [](int l, int r) { return l * -1 == r; };
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 11)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end(), pred);
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange, pred);
+      assert(ret);
+    }
+  }
+
+  { // check that the projections are used
+    int a[] = {1, 3, 15, 1, 2, 1, 8};
+    int p[] = {2, 1, 2};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 7)));
+    auto subrange  = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end(), {},
+         [](int i) { return i - 3; },
+         [](int i) { return i * -1; });
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange, {},
+         [](int i) { return i - 3; },
+         [](int i) { return i * -1; });
+      assert(ret);
+    }
+  }
+
+  { // check the nodiscard extension
+    // use #pragma around to suppress error: ignoring return value of function
+    // declared with 'nodiscard' attribute [-Werror,-Wunused-result]
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wunused-result"
+    int a[] = {1, 9, 0, 13, 25};
+    int p[] = {1, 9, 0};
+    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    std::ranges::contains_subrange(whole, subrange);
+    #pragma clang diagnostic pop
+  }
+}
+
+constexpr bool test() {
+    types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter2>() {
+    types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter1>() {
+      if constexpr (std::forward_iterator<Iter1> && std::forward_iterator<Iter2>)
+        test_iterators<Iter1, Iter1, Iter2, Iter2>();
+      if constexpr (std::forward_iterator<Iter2>)
+        test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, Iter2>();
+      if constexpr (std::forward_iterator<Iter1>)
+        test_iterators<Iter1, Iter1, Iter2, sized_sentinel<Iter2>>();
+      test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, sized_sentinel<Iter2>>();
+    });
+  });
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
\ No newline at end of file
diff --git a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
index 494e9fd19c3545..9506ca1c768bd7 100644
--- a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
+++ b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
@@ -67,6 +67,7 @@ static_assert(test(std::ranges::binary_search, a, 42));
 static_assert(test(std::ranges::clamp, 42, 42, 42));
 #if TEST_STD_VER >= 23
 static_assert(test(std::ranges::contains, a, 42));
+static_assert(test(std::ranges::contains_subrange, a, a));
 #endif
 static_assert(test(std::ranges::copy, a, a));
 static_assert(test(std::ranges::copy_backward, a, a));

>From 5a1d555e0cdf070ee415e9c1b1e8c928d79e4d71 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Wed, 20 Sep 2023 18:41:04 -0700
Subject: [PATCH 02/10] format

---
 libcxx/include/__algorithm/ranges_contains_subrange.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index 16de6c29cb2a1a..f8e885d3259be6 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -129,7 +129,7 @@ struct __fn {
         __proj1,
         __proj2,
         __offset);
-    }
+  }
 };
 } // namespace __contains_subrange
 

>From 7cb4d06f6c801a52e239f5f2a780001f73c25e30 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Thu, 21 Sep 2023 11:06:02 -0700
Subject: [PATCH 03/10] Add a newline

---
 libcxx/include/__algorithm/ranges_contains_subrange.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index f8e885d3259be6..8fdd460c8d6f34 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -142,4 +142,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_STD_VER >= 23
 
-#endif // _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
\ No newline at end of file
+#endif // _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H

>From aee12dd713093aad9f8b1e7b8281f50235047982 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Tue, 26 Sep 2023 16:56:38 -0700
Subject: [PATCH 04/10] 1. call distance(r) directly 2. replace auto with int
 to avoid potential errors

---
 .../__algorithm/ranges_contains_subrange.h     | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index 8fdd460c8d6f34..6dd8324c5dfa69 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -40,7 +40,7 @@ struct __fn {
             class _Pred,
             class _Proj1,
             class _Proj2,
-            class _Offset>
+            class _Offset = int>
   static _LIBCPP_HIDE_FROM_ABI constexpr bool __contains_subrange_fn_impl(
       _Iter1 __first1,
       _Sent1 __last1,
@@ -85,9 +85,9 @@ struct __fn {
       _Pred __pred   = {},
       _Proj1 __proj1 = {},
       _Proj2 __proj2 = {}) const {
-    auto __n1     = ranges::distance(__first1, __last1);
-    auto __n2     = ranges::distance(__first2, __last2);
-    auto __offset = __n1 - __n2;
+    int __n1     = ranges::distance(__first1, __last1);
+    int __n2     = ranges::distance(__first2, __last2);
+    int __offset = __n1 - __n2;
 
     return __contains_subrange_fn_impl(
         std::move(__first1),
@@ -108,18 +108,18 @@ struct __fn {
     requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
       _Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const {
-    auto __n1 = 0;
-    auto __n2 = 0;
+    int __n1 = 0;
+    int __n2 = 0;
 
     if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
       __n1 = ranges::size(__range1);
       __n2 = ranges::size(__range2);
     } else {
-      __n1 = ranges::distance(ranges::begin(__range1), ranges::end(__range1));
-      __n2 = ranges::distance(ranges::begin(__range2), ranges::end(__range2));
+      __n1 = ranges::distance(__range1);
+      __n2 = ranges::distance(__range2);
     }
 
-    auto __offset = __n1 - __n2;
+    int __offset = __n1 - __n2;
     return __contains_subrange_fn_impl(
         ranges::begin(__range1),
         ranges::end(__range1),

>From b2c57a20557fd7d7af15eafc0a11ba6bd4c3a333 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Sun, 1 Oct 2023 22:41:08 -0700
Subject: [PATCH 05/10] Reformat

---
 .../ranges.contains_subrange.pass.cpp         | 115 +++++++++---------
 1 file changed, 59 insertions(+), 56 deletions(-)

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
index fd4d858b255db7..172c30ad8b979c 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
@@ -51,7 +51,7 @@ static_assert(HasContainsSubrangeSubrangeIt<int*, int*>);
 
 template <class Range1, class Range2 = UncheckedRange<int*>>
 concept HasContainsSubrangeR = requires(Range1&& range1, Range2&& range2) {
-    std::ranges::contains_subrange(std::forward<Range1>(range1), std::forward<Range2>(range2)); };
+  std::ranges::contains_subrange(std::forward<Range1>(range1), std::forward<Range2>(range2)); };
 
 static_assert(HasContainsSubrangeR<UncheckedRange<int*>>);
 static_assert(HasContainsSubrangeR<ForwardRangeNotDerivedFrom>);
@@ -69,26 +69,25 @@ static std::vector<int> comparable_data;
 template <class Iter1, class Sent1 = Iter1, class Iter2, class Sent2 = Iter2>
 constexpr void test_iterators() {
   {  // simple tests
-    int a[] = {1, 2, 3, 4, 5, 6};
-    int p[] = {3, 4, 5};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    int a[]       = {1, 2, 3, 4, 5, 6};
+    int p[]       = {3, 4, 5};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       [[maybe_unused]] std::same_as<bool> decltype(auto) ret =
-        std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+          std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(ret);
     }
     {
-      [[maybe_unused]] std::same_as<bool> decltype(auto) ret =
-        std::ranges::contains_subrange(whole, subrange);
+      [[maybe_unused]] std::same_as<bool> decltype(auto) ret = std::ranges::contains_subrange(whole, subrange);
       assert(ret);
     }
   }
 
   { // no match
-    int a[] = {1, 2, 3, 4, 5, 6};
-    int p[] = {3, 4, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    int a[]       = {1, 2, 3, 4, 5, 6};
+    int p[]       = {3, 4, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -101,9 +100,9 @@ constexpr void test_iterators() {
   }
 
   { // range consists of just one element
-    int a[] = {3};
-    int p[] = {3, 4, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 1)));
+    int a[]       = {3};
+    int p[]       = {3, 4, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 1)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -116,9 +115,9 @@ constexpr void test_iterators() {
   }
 
   { // subrange consists of just one element
-    int a[] = {23, 1, 20, 3, 54, 2};
-    int p[] = {3};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    int a[]       = {23, 1, 20, 3, 54, 2};
+    int p[]       = {3};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 1)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -131,9 +130,9 @@ constexpr void test_iterators() {
   }
 
   { // range has zero length
-    int a[] = {};
-    int p[] = {3, 4, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a)));
+    int a[]       = {};
+    int p[]       = {3, 4, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -146,9 +145,9 @@ constexpr void test_iterators() {
   }
 
   { // subrange has zero length
-    int a[] = {3, 4, 2};
-    int p[] = {};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
+    int a[]       = {3, 4, 2};
+    int p[]       = {};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -161,9 +160,9 @@ constexpr void test_iterators() {
   }
 
   { // range and subrange are identical
-    int a[] = {3, 4, 11, 32, 54, 2};
-    int p[] = {3, 4, 11, 32, 54, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
+    int a[]       = {3, 4, 11, 32, 54, 2};
+    int p[]       = {3, 4, 11, 32, 54, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 6)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -176,9 +175,9 @@ constexpr void test_iterators() {
   }
 
   { // subrange is longer than range
-    int a[] = {3, 4, 2};
-    int p[] = {23, 3, 4, 2, 11, 32, 54, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
+    int a[]       = {3, 4, 2};
+    int p[]       = {23, 3, 4, 2, 11, 32, 54, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 8)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -191,9 +190,9 @@ constexpr void test_iterators() {
   }
 
   { // subrange is subsequence
-    int a[] = {23, 1, 0, 54, 2};
-    int p[] = {1, 0, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
+    int a[]       = {23, 1, 0, 54, 2};
+    int p[]       = {1, 0, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -206,9 +205,9 @@ constexpr void test_iterators() {
   }
 
   { // repeated subrange
-    int a[] = {23, 1, 0, 2, 54, 1, 0, 2, 23, 33};
-    int p[] = {1, 0, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 10)));
+    int a[]       = {23, 1, 0, 2, 54, 1, 0, 2, 23, 33};
+    int p[]       = {1, 0, 2};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 10)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -221,10 +220,10 @@ constexpr void test_iterators() {
   }
 
   { // check that the predicate is used
-    int a[] = {23, 81, 61, 0, 42, 25, 1, 2, 1, 29, 2};
-    int p[] = {-1, -2, -1};
-    auto pred = [](int l, int r) { return l * -1 == r; };
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 11)));
+    int a[]       = {23, 81, 61, 0, 42, 25, 1, 2, 1, 29, 2};
+    int p[]       = {-1, -2, -1};
+    auto pred     = [](int l, int r) { return l * -1 == r; };
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 11)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end(), pred);
@@ -237,40 +236,44 @@ constexpr void test_iterators() {
   }
 
   { // check that the projections are used
-    int a[] = {1, 3, 15, 1, 2, 1, 8};
-    int p[] = {2, 1, 2};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 7)));
+    int a[]        = {1, 3, 15, 1, 2, 1, 8};
+    int p[]        = {2, 1, 2};
+    auto whole     = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 7)));
     auto subrange  = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     {
-      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end(), {},
-         [](int i) { return i - 3; },
-         [](int i) { return i * -1; });
+      bool ret = std::ranges::contains_subrange(
+          whole.begin(),
+          whole.end(),
+          subrange.begin(),
+          subrange.end(),
+          {},
+          [](int i) { return i - 3; },
+          [](int i) { return i * -1; });
       assert(ret);
     }
     {
-      bool ret = std::ranges::contains_subrange(whole, subrange, {},
-         [](int i) { return i - 3; },
-         [](int i) { return i * -1; });
+      bool ret = std::ranges::contains_subrange(
+          whole, subrange, {}, [](int i) { return i - 3; }, [](int i) { return i * -1; });
       assert(ret);
     }
   }
 
   { // check the nodiscard extension
-    // use #pragma around to suppress error: ignoring return value of function
-    // declared with 'nodiscard' attribute [-Werror,-Wunused-result]
-    #pragma clang diagnostic push
-    #pragma clang diagnostic ignored "-Wunused-result"
-    int a[] = {1, 9, 0, 13, 25};
-    int p[] = {1, 9, 0};
-    auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
+// use #pragma around to suppress error: ignoring return value of function
+// declared with 'nodiscard' attribute [-Werror,-Wunused-result]
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-result"
+    int a[]       = {1, 9, 0, 13, 25};
+    int p[]       = {1, 9, 0};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
     std::ranges::contains_subrange(whole, subrange);
-    #pragma clang diagnostic pop
+#pragma clang diagnostic pop
   }
 }
 
 constexpr bool test() {
-    types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter2>() {
+  types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter2>() {
     types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter1>() {
       if constexpr (std::forward_iterator<Iter1> && std::forward_iterator<Iter2>)
         test_iterators<Iter1, Iter1, Iter2, Iter2>();

>From ae96c2f72baaddc9dd121cd645b15b45a44c23a6 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Mon, 2 Oct 2023 17:45:39 -0700
Subject: [PATCH 06/10] Correct input type and call ranges::search()

---
 .../__algorithm/ranges_contains_subrange.h    | 40 ++++++------
 .../ranges.contains_subrange.pass.cpp         | 65 ++++++++++---------
 2 files changed, 56 insertions(+), 49 deletions(-)

diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index 6dd8324c5dfa69..d4fcb8c08a24aa 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -9,7 +9,7 @@
 #ifndef _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
 #define _LIBCPP___ALGORITHM_RANGES_CONTAINS_SUBRANGE_H
 
-#include <__algorithm/ranges_starts_with.h>
+#include <__algorithm/ranges_search.h>
 #include <__config>
 #include <__functional/identity.h>
 #include <__functional/ranges_operations.h>
@@ -33,9 +33,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 namespace ranges {
 namespace __contains_subrange {
 struct __fn {
-  template <input_iterator _Iter1,
+  template <forward_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
-            input_iterator _Iter2,
+            forward_iterator _Iter2,
             sentinel_for<_Iter2> _Sent2,
             class _Pred,
             class _Proj1,
@@ -53,25 +53,21 @@ struct __fn {
     if (__offset < 0)
       return false;
     else {
-      for (; __offset >= 0; __offset--, __first1++) {
-        auto result = ranges::starts_with(
-            std::move(__first1),
-            std::move(__last1),
-            std::move(__first2),
-            std::move(__last2),
-            std::ref(__pred),
-            std::ref(__proj1),
-            std::ref(__proj2));
-        if (result)
-          return true;
-      }
-      return false;
+      auto result = ranges::search(
+          std::move(__first1),
+          std::move(__last1),
+          std::move(__first2),
+          std::move(__last2),
+          std::ref(__pred),
+          std::ref(__proj1),
+          std::ref(__proj2));
+      return result.empty() == false;
     }
   }
 
-  template <input_iterator _Iter1,
+  template <forward_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
-            input_iterator _Iter2,
+            forward_iterator _Iter2,
             sentinel_for<_Iter2> _Sent2,
             class _Pred  = ranges::equal_to,
             class _Proj1 = identity,
@@ -87,6 +83,8 @@ struct __fn {
       _Proj2 __proj2 = {}) const {
     int __n1     = ranges::distance(__first1, __last1);
     int __n2     = ranges::distance(__first2, __last2);
+    if (__n2 == 0)
+      return true;
     int __offset = __n1 - __n2;
 
     return __contains_subrange_fn_impl(
@@ -100,8 +98,8 @@ struct __fn {
         std::move(__offset));
   }
 
-  template <input_range _Range1,
-            input_range _Range2,
+  template <forward_range _Range1,
+            forward_range _Range2,
             class _Pred  = ranges::equal_to,
             class _Proj1 = identity,
             class _Proj2 = identity>
@@ -119,6 +117,8 @@ struct __fn {
       __n2 = ranges::distance(__range2);
     }
 
+    if (__n2 == 0)
+      return true;
     int __offset = __n1 - __n2;
     return __contains_subrange_fn_impl(
         ranges::begin(__range1),
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
index 172c30ad8b979c..0b7a2359b2b666 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
@@ -32,40 +32,36 @@
 struct NotEqualityComparable {};
 
 template <class Iter1, class Sent1 = Iter1, class Iter2 = int*, class Sent2 = Iter2>
-concept HasContainsSubrangeSubrangeIt = requires(Iter1 first1, Sent1 last1, Iter2 first2, Sent2 last2) {
+concept HasContainsSubrangeIt = requires(Iter1 first1, Sent1 last1, Iter2 first2, Sent2 last2) {
   std::ranges::contains_subrange(first1, last1, first2, last2);
 };
 
-static_assert(HasContainsSubrangeSubrangeIt<int*>);
-static_assert(!HasContainsSubrangeSubrangeIt<NotEqualityComparable*>);
-static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotDerivedFrom>);
-static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotIndirectlyReadable>);
-static_assert(!HasContainsSubrangeSubrangeIt<InputIteratorNotInputOrOutputIterator>);
-static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
-static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
-static_assert(!HasContainsSubrangeSubrangeIt<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>);
-
-static_assert(!HasContainsSubrangeSubrangeIt<int*, int>);
-static_assert(!HasContainsSubrangeSubrangeIt<int, int*>);
-static_assert(HasContainsSubrangeSubrangeIt<int*, int*>);
+static_assert(HasContainsSubrangeIt<int*>);
+static_assert(!HasContainsSubrangeIt<ForwardIteratorNotDerivedFrom>);
+static_assert(!HasContainsSubrangeIt<ForwardIteratorNotIncrementable>);
+static_assert(!HasContainsSubrangeIt<int*, SentinelForNotSemiregular>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int**>); // not indirectly comparable
+static_assert(!HasContainsSubrangeIt<int*, SentinelForNotWeaklyEqualityComparableWith>);
+static_assert(!HasContainsSubrangeIt<int*, int*, ForwardIteratorNotDerivedFrom>);
+static_assert(!HasContainsSubrangeIt<int*, int*, ForwardIteratorNotIncrementable>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int*, SentinelForNotSemiregular>);
+static_assert(!HasContainsSubrangeIt<int*, int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
 
 template <class Range1, class Range2 = UncheckedRange<int*>>
 concept HasContainsSubrangeR = requires(Range1&& range1, Range2&& range2) {
   std::ranges::contains_subrange(std::forward<Range1>(range1), std::forward<Range2>(range2)); };
 
 static_assert(HasContainsSubrangeR<UncheckedRange<int*>>);
-static_assert(HasContainsSubrangeR<ForwardRangeNotDerivedFrom>);
+static_assert(!HasContainsSubrangeR<ForwardRangeNotDerivedFrom>);
 static_assert(!HasContainsSubrangeR<ForwardIteratorNotIncrementable>);
 static_assert(!HasContainsSubrangeR<ForwardRangeNotSentinelSemiregular>);
 static_assert(!HasContainsSubrangeR<ForwardRangeNotSentinelEqualityComparableWith>);
 static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, UncheckedRange<int**>>); // not indirectly comparable
-static_assert(HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotDerivedFrom>);
-static_assert(HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotIncrementable>);
+static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotDerivedFrom>);
+static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotIncrementable>);
 static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotSentinelSemiregular>);
 static_assert(!HasContainsSubrangeR<UncheckedRange<int*>, ForwardRangeNotSentinelEqualityComparableWith>);
 
-static std::vector<int> comparable_data;
-
 template <class Iter1, class Sent1 = Iter1, class Iter2, class Sent2 = Iter2>
 constexpr void test_iterators() {
   {  // simple tests
@@ -272,18 +268,29 @@ constexpr void test_iterators() {
   }
 }
 
+template <class Iter1, class Sent1 = Iter1>
+constexpr void test_iterators2() {
+  test_iterators<Iter1, Sent1, forward_iterator<int*>>();
+  test_iterators<Iter1, Sent1, forward_iterator<int*>, sized_sentinel<forward_iterator<int*>>>();
+  test_iterators<Iter1, Sent1, bidirectional_iterator<int*>>();
+  test_iterators<Iter1, Sent1, bidirectional_iterator<int*>, sized_sentinel<bidirectional_iterator<int*>>>();
+  test_iterators<Iter1, Sent1, random_access_iterator<int*>>();
+  test_iterators<Iter1, Sent1, random_access_iterator<int*>, sized_sentinel<random_access_iterator<int*>>>();
+  test_iterators<Iter1, Sent1, contiguous_iterator<int*>>();
+  test_iterators<Iter1, Sent1, contiguous_iterator<int*>, sized_sentinel<contiguous_iterator<int*>>>();
+  test_iterators<Iter1, Sent1, int*>();
+}
+
 constexpr bool test() {
-  types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter2>() {
-    types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter1>() {
-      if constexpr (std::forward_iterator<Iter1> && std::forward_iterator<Iter2>)
-        test_iterators<Iter1, Iter1, Iter2, Iter2>();
-      if constexpr (std::forward_iterator<Iter2>)
-        test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, Iter2>();
-      if constexpr (std::forward_iterator<Iter1>)
-        test_iterators<Iter1, Iter1, Iter2, sized_sentinel<Iter2>>();
-      test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, sized_sentinel<Iter2>>();
-    });
-  });
+  test_iterators2<forward_iterator<int*>>();
+  test_iterators2<forward_iterator<int*>, sized_sentinel<forward_iterator<int*>>>();
+  test_iterators2<bidirectional_iterator<int*>>();
+  test_iterators2<bidirectional_iterator<int*>, sized_sentinel<bidirectional_iterator<int*>>>();
+  test_iterators2<random_access_iterator<int*>>();
+  test_iterators2<random_access_iterator<int*>, sized_sentinel<random_access_iterator<int*>>>();
+  test_iterators2<contiguous_iterator<int*>>();
+  test_iterators2<contiguous_iterator<int*>, sized_sentinel<contiguous_iterator<int*>>>();
+  test_iterators2<int*>();
 
   return true;
 }

>From 11384e6c94e5e297050dd1b4beace6e628caebb2 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Wed, 3 Jan 2024 19:00:40 -0800
Subject: [PATCH 07/10] 1. update function 2. add nondiscard tests

---
 libcxx/include/__algorithm/ranges_contains_subrange.h         | 2 +-
 .../diagnostics/ranges.nodiscard_extensions.compile.pass.cpp  | 2 ++
 .../libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp | 4 ++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index d4fcb8c08a24aa..23c5ea767de114 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -61,7 +61,7 @@ struct __fn {
           std::ref(__pred),
           std::ref(__proj1),
           std::ref(__proj2));
-      return result.empty() == false;
+      return !result.empty();
     }
   }
 
diff --git a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.compile.pass.cpp b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.compile.pass.cpp
index 7e2d64b8c9b618..790260d209a95d 100644
--- a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.compile.pass.cpp
+++ b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.compile.pass.cpp
@@ -28,6 +28,8 @@ void test() {
   std::ranges::binary_search(range, 1);
   std::ranges::binary_search(iter, iter, 1);
   std::ranges::clamp(1, 2, 3);
+  std::ranges::contains_subrange(range, range);
+  std::ranges::contains_subrange(iter, iter, iter, iter);
   std::ranges::count_if(range, pred);
   std::ranges::count_if(iter, iter, pred);
   std::ranges::count(range, 1);
diff --git a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
index f0a0e4889a7603..c41461fff516fa 100644
--- a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
@@ -91,6 +91,10 @@ void test() {
   std::ranges::upper_bound(iter, iter, 1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 
 #if TEST_STD_VER >= 23
+  std::ranges::contains_subrange(range, range);
+  // expected-warning at -1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+  std::ranges::contains_subrange(iter, iter, iter, iter);
+  // expected-warning at -1 {{ignoring return value of function declared with 'nodiscard' attribute}}
   std::ranges::fold_left(range, 0, std::plus());
   // expected-warning at -1{{ignoring return value of function declared with 'nodiscard' attribute}}
   std::ranges::fold_left(iter, iter, 0, std::plus());

>From 2973c85802f8d265a943f024bfca16d64dc8f240 Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Thu, 4 Jan 2024 18:39:42 -0800
Subject: [PATCH 08/10] update code

---
 libcxx/include/algorithm                      |  16 +--
 .../ranges.contains_subrange.pass.cpp         | 105 ++++++++----------
 2 files changed, 55 insertions(+), 66 deletions(-)

diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 7c490ef40ac5f8..70e30bc87e8128 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -217,18 +217,18 @@ namespace ranges {
     constexpr ranges::minmax_element_result<borrowed_iterator_t<R>>
       minmax_element(R&& r, Comp comp = {}, Proj proj = {});                                              // since C++20
 
-  template<forward_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
-    sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = identity,
-    class Proj2 = identity>
+  template<forward_iterator I1, sentinel_for<I1> S1,
+           forward_iterator I2, sentinel_for<I2> S2,
+           class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
     requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
-    constexpr bool ranges::contains_subrange(I1 first1, S1 last1, I2 first2,
-      S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});                        // since C++23
+    constexpr bool contains_subrange(I1 first1, S1 last1, I2 first2, S2 last2,
+                                     Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});                // since C++23
 
   template<forward_range R1, forward_range R2,
-    class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
+           class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
     requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
-    constexpr bool ranges::contains_subrange(R1&& r1, R2&& r2, Pred pred = {},
-      Proj1 proj1 = {}, Proj2 proj2 = {});                                                  // since C++23
+    constexpr bool contains_subrange(R1&& r1, R2&& r2, Pred pred = {},
+                                     Proj1 proj1 = {}, Proj2 proj2 = {});                                // since C++23
 
   template<class I, class O>
     using copy_result = in_out_result<I, O>;                                                // since C++20
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
index 0b7a2359b2b666..89701c1c2487dd 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
@@ -11,22 +11,25 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=2000000
 
-// template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
-//     requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
-//     constexpr bool ranges::contains(I first, S last, const T& value, Proj proj = {});       // since C++23
+// template<forward_iterator I1, sentinel_for<I1> S1,
+//          forward_iterator I2, sentinel_for<I2> S2, class Proj = identity>
+//     requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
+//     constexpr bool ranges::contains_subrange(I1 first1, S1 last1, I2 first2, S2 last2,
+//                                     Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});       // since C++23
 
-// template<input_range R, class T, class Proj = identity>
-//     requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
-//     constexpr bool ranges::contains(R&& r, const T& value, Proj proj = {});                 // since C++23
+// template<forward_range R1, forward_range R2,
+//          class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
+//     requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
+//     constexpr bool ranges::contains_subrange(R1&& r1, R2&& r2, Pred pred = {},
+//                                              Proj1 proj1 = {}, Proj2 proj2 = {});                 // since C++23
 
 #include <algorithm>
-#include <array>
 #include <cassert>
+#include <concepts>
 #include <ranges>
-#include <vector>
+#include <utility>
 
 #include "almost_satisfies_types.h"
-#include "boolean_testable.h"
 #include "test_iterators.h"
 
 struct NotEqualityComparable {};
@@ -67,15 +70,15 @@ constexpr void test_iterators() {
   {  // simple tests
     int a[]       = {1, 2, 3, 4, 5, 6};
     int p[]       = {3, 4, 5};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
-      [[maybe_unused]] std::same_as<bool> decltype(auto) ret =
+      std::same_as<bool> decltype(auto) ret =
           std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(ret);
     }
     {
-      [[maybe_unused]] std::same_as<bool> decltype(auto) ret = std::ranges::contains_subrange(whole, subrange);
+      std::same_as<bool> decltype(auto) ret = std::ranges::contains_subrange(whole, subrange);
       assert(ret);
     }
   }
@@ -83,8 +86,8 @@ constexpr void test_iterators() {
   { // no match
     int a[]       = {1, 2, 3, 4, 5, 6};
     int p[]       = {3, 4, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(!ret);
@@ -98,8 +101,8 @@ constexpr void test_iterators() {
   { // range consists of just one element
     int a[]       = {3};
     int p[]       = {3, 4, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 1)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(!ret);
@@ -113,8 +116,8 @@ constexpr void test_iterators() {
   { // subrange consists of just one element
     int a[]       = {23, 1, 20, 3, 54, 2};
     int p[]       = {3};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 1)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(ret);
@@ -129,7 +132,7 @@ constexpr void test_iterators() {
     int a[]       = {};
     int p[]       = {3, 4, 2};
     auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(!ret);
@@ -143,7 +146,7 @@ constexpr void test_iterators() {
   { // subrange has zero length
     int a[]       = {3, 4, 2};
     int p[]       = {};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
     auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p)));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
@@ -158,8 +161,8 @@ constexpr void test_iterators() {
   { // range and subrange are identical
     int a[]       = {3, 4, 11, 32, 54, 2};
     int p[]       = {3, 4, 11, 32, 54, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 6)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(ret);
@@ -173,8 +176,8 @@ constexpr void test_iterators() {
   { // subrange is longer than range
     int a[]       = {3, 4, 2};
     int p[]       = {23, 3, 4, 2, 11, 32, 54, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 3)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 8)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(!ret);
@@ -188,8 +191,8 @@ constexpr void test_iterators() {
   { // subrange is subsequence
     int a[]       = {23, 1, 0, 54, 2};
     int p[]       = {1, 0, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(!ret);
@@ -203,8 +206,8 @@ constexpr void test_iterators() {
   { // repeated subrange
     int a[]       = {23, 1, 0, 2, 54, 1, 0, 2, 23, 33};
     int p[]       = {1, 0, 2};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 10)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
       assert(ret);
@@ -219,8 +222,8 @@ constexpr void test_iterators() {
     int a[]       = {23, 81, 61, 0, 42, 25, 1, 2, 1, 29, 2};
     int p[]       = {-1, -2, -1};
     auto pred     = [](int l, int r) { return l * -1 == r; };
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 11)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end(), pred);
       assert(ret);
@@ -234,8 +237,8 @@ constexpr void test_iterators() {
   { // check that the projections are used
     int a[]        = {1, 3, 15, 1, 2, 1, 8};
     int p[]        = {2, 1, 2};
-    auto whole     = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 7)));
-    auto subrange  = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole     = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange  = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     {
       bool ret = std::ranges::contains_subrange(
           whole.begin(),
@@ -261,36 +264,22 @@ constexpr void test_iterators() {
 #pragma clang diagnostic ignored "-Wunused-result"
     int a[]       = {1, 9, 0, 13, 25};
     int p[]       = {1, 9, 0};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 5)));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
     std::ranges::contains_subrange(whole, subrange);
 #pragma clang diagnostic pop
   }
 }
 
-template <class Iter1, class Sent1 = Iter1>
-constexpr void test_iterators2() {
-  test_iterators<Iter1, Sent1, forward_iterator<int*>>();
-  test_iterators<Iter1, Sent1, forward_iterator<int*>, sized_sentinel<forward_iterator<int*>>>();
-  test_iterators<Iter1, Sent1, bidirectional_iterator<int*>>();
-  test_iterators<Iter1, Sent1, bidirectional_iterator<int*>, sized_sentinel<bidirectional_iterator<int*>>>();
-  test_iterators<Iter1, Sent1, random_access_iterator<int*>>();
-  test_iterators<Iter1, Sent1, random_access_iterator<int*>, sized_sentinel<random_access_iterator<int*>>>();
-  test_iterators<Iter1, Sent1, contiguous_iterator<int*>>();
-  test_iterators<Iter1, Sent1, contiguous_iterator<int*>, sized_sentinel<contiguous_iterator<int*>>>();
-  test_iterators<Iter1, Sent1, int*>();
-}
-
 constexpr bool test() {
-  test_iterators2<forward_iterator<int*>>();
-  test_iterators2<forward_iterator<int*>, sized_sentinel<forward_iterator<int*>>>();
-  test_iterators2<bidirectional_iterator<int*>>();
-  test_iterators2<bidirectional_iterator<int*>, sized_sentinel<bidirectional_iterator<int*>>>();
-  test_iterators2<random_access_iterator<int*>>();
-  test_iterators2<random_access_iterator<int*>, sized_sentinel<random_access_iterator<int*>>>();
-  test_iterators2<contiguous_iterator<int*>>();
-  test_iterators2<contiguous_iterator<int*>, sized_sentinel<contiguous_iterator<int*>>>();
-  test_iterators2<int*>();
+  types::for_each(types::forward_iterator_list<int*>{}, []<class Iter1> {
+    types::for_each(types::forward_iterator_list<int*>{}, []<class Iter2> {
+      test_iterators<Iter1, Iter1, Iter2, Iter2>();
+      test_iterators<Iter1, Iter1, Iter2, sized_sentinel<Iter2>>();
+      test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, Iter2>();
+      test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, sized_sentinel<Iter2>>();
+    });
+  });
 
   return true;
 }
@@ -300,4 +289,4 @@ int main(int, char**) {
   static_assert(test());
 
   return 0;
-}
\ No newline at end of file
+}

>From b0f9bac17a5a200c77aa7d5207b4c0b252c92bdf Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Thu, 4 Jan 2024 18:39:42 -0800
Subject: [PATCH 09/10] update code

---
 libcxx/docs/Status/RangesAlgorithms.csv       |  6 +-
 .../__algorithm/ranges_contains_subrange.h    | 83 ++++---------------
 libcxx/modules/std/algorithm.inc              |  2 -
 3 files changed, 17 insertions(+), 74 deletions(-)

diff --git a/libcxx/docs/Status/RangesAlgorithms.csv b/libcxx/docs/Status/RangesAlgorithms.csv
index 2fe530bf75fd94..419bf58d683217 100644
--- a/libcxx/docs/Status/RangesAlgorithms.csv
+++ b/libcxx/docs/Status/RangesAlgorithms.csv
@@ -3,13 +3,13 @@ C++20,all C++20 algorithms,N/A,N/A,✅
 C++23,`find_last <https://wg21.link/P1223R5>`_,Unassigned,No patch yet,Not started
 C++23,`find_last_if <https://wg21.link/P1223R5>`_,Unassigned,No patch yet,Not started
 C++23,`find_last_if_not <https://wg21.link/P1223R5>`_,Unassigned,No patch yet,Not started
-C++23,`starts_with <https://wg21.link/P1659R3>`_,Zijun Zhao,`D150735 <https://llvm.org/D150735>`_,✅
-C++23,`ends_with <https://wg21.link/P1659R3>`_,Zijun Zhao,No patch yet,In Progress
+C++23,`starts_with <https://wg21.link/P1659R3>`_,Zijun Zhao,`D150735 <https://llvm.org/D150735>`_,Complete
+C++23,`ends_with <https://wg21.link/P1659R3>`_,Zijun Zhao,N/A,Complete
 C++23,`shift_left <https://wg21.link/p2440r1>`_,Unassigned,No patch yet,Not started
 C++23,`shift_right <https://wg21.link/p2440r1>`_,Unassigned,No patch yet,Not started
 C++23,`iota (algorithm) <https://wg21.link/p2440r1>`_,Unassigned,No patch yet,Not started
 C++23,`fold <https://wg21.link/p2322r5>`_,Unassigned,No patch yet,Not started
-C++23,`contains <https://wg21.link/p2302r2>`_,Zijun Zhao,No patch yet,In Progress
+C++23,`contains <https://wg21.link/p2302r2>`_,Zijun Zhao,N/A,Complete
 C++23,`fold_left_with_iter <https://wg21.link/p2322r6>`_,Christopher Di Bella,N/A,Complete
 C++23,`fold_left <https://wg21.link/p2322r6>`_,Christopher Di Bella,N/A,Complete
 C++23,`fold_left_first_with_iter <https://wg21.link/p2322r6>`_,Christopher Di Bella,N/A,In progress
diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index 23c5ea767de114..beb4d84f232bab 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -33,38 +33,6 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 namespace ranges {
 namespace __contains_subrange {
 struct __fn {
-  template <forward_iterator _Iter1,
-            sentinel_for<_Iter1> _Sent1,
-            forward_iterator _Iter2,
-            sentinel_for<_Iter2> _Sent2,
-            class _Pred,
-            class _Proj1,
-            class _Proj2,
-            class _Offset = int>
-  static _LIBCPP_HIDE_FROM_ABI constexpr bool __contains_subrange_fn_impl(
-      _Iter1 __first1,
-      _Sent1 __last1,
-      _Iter2 __first2,
-      _Sent2 __last2,
-      _Pred& __pred,
-      _Proj1& __proj1,
-      _Proj2& __proj2,
-      _Offset __offset) {
-    if (__offset < 0)
-      return false;
-    else {
-      auto result = ranges::search(
-          std::move(__first1),
-          std::move(__last1),
-          std::move(__first2),
-          std::move(__last2),
-          std::ref(__pred),
-          std::ref(__proj1),
-          std::ref(__proj2));
-      return !result.empty();
-    }
-  }
-
   template <forward_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             forward_iterator _Iter2,
@@ -73,29 +41,19 @@ struct __fn {
             class _Proj1 = identity,
             class _Proj2 = identity>
     requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool static operator()(
       _Iter1 __first1,
       _Sent1 __last1,
       _Iter2 __first2,
       _Sent2 __last2,
       _Pred __pred   = {},
       _Proj1 __proj1 = {},
-      _Proj2 __proj2 = {}) const {
-    int __n1     = ranges::distance(__first1, __last1);
-    int __n2     = ranges::distance(__first2, __last2);
-    if (__n2 == 0)
-      return true;
-    int __offset = __n1 - __n2;
+      _Proj2 __proj2 = {}) {
+    auto __n2 = ranges::distance(__first2, __last2);
+    if (__n2  == 0) return true;
 
-    return __contains_subrange_fn_impl(
-        std::move(__first1),
-        std::move(__last1),
-        std::move(__first2),
-        std::move(__last2),
-        __pred,
-        __proj1,
-        __proj2,
-        std::move(__offset));
+    auto ret = ranges::search(std::move(__first1), __last1, std::move(__first2), __last2, __pred, std::ref(__proj1), std::ref(__proj2));
+    return ret.empty() == false;
   }
 
   template <forward_range _Range1,
@@ -104,31 +62,18 @@ struct __fn {
             class _Proj1 = identity,
             class _Proj2 = identity>
     requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
-  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
-      _Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const {
-    int __n1 = 0;
-    int __n2 = 0;
-
-    if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
-      __n1 = ranges::size(__range1);
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool static operator()(
+      _Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) {
+    auto __n2 = 0;
+    if constexpr (sized_range<_Range2>) {
       __n2 = ranges::size(__range2);
     } else {
-      __n1 = ranges::distance(__range1);
-      __n2 = ranges::distance(__range2);
+      __n2 = std::distance(cbegin(__range2), cend(__range2));
     }
+    if (__n2  == 0) return true;
 
-    if (__n2 == 0)
-      return true;
-    int __offset = __n1 - __n2;
-    return __contains_subrange_fn_impl(
-        ranges::begin(__range1),
-        ranges::end(__range1),
-        ranges::begin(__range2),
-        ranges::end(__range2),
-        __pred,
-        __proj1,
-        __proj2,
-        __offset);
+    auto ret = ranges::search(__range1, __range2, __pred, std::ref(__proj1), std::ref(__proj2));
+    return ret.empty() == false;
   }
 };
 } // namespace __contains_subrange
diff --git a/libcxx/modules/std/algorithm.inc b/libcxx/modules/std/algorithm.inc
index 75e8a3af78dea2..e7796bfa26af81 100644
--- a/libcxx/modules/std/algorithm.inc
+++ b/libcxx/modules/std/algorithm.inc
@@ -46,9 +46,7 @@ export namespace std {
   // [alg.contains], contains
   namespace ranges {
     using std::ranges::contains;
-#if 0
     using std::ranges::contains_subrange;
-#endif
   } // namespace ranges
 #endif // _LIBCPP_STD_VER >= 23
 

>From 72d92de43d24b8b32bc50267fd2b473cc2340c2f Mon Sep 17 00:00:00 2001
From: Zijun Zhao <zijunzhao at google.com>
Date: Thu, 4 Jan 2024 18:39:42 -0800
Subject: [PATCH 10/10] update code

---
 .../ranges.contains_subrange.pass.cpp         | 43 +++++++++++++------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
index 89701c1c2487dd..98527901bfe800 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp
@@ -188,6 +188,36 @@ constexpr void test_iterators() {
     }
   }
 
+  { // subrange is the prefix
+    int a[]       = {3, 43, 5, 100, 433, 278, 6457, 900};
+    int p[]       = {3, 43, 5};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
+  { // subrange is the suffix
+    int a[]       = {3, 43, 5, 7, 68, 100, 433, 900};
+    int p[]       = {100, 433, 900};
+    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
+    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
+    {
+      bool ret = std::ranges::contains_subrange(whole.begin(), whole.end(), subrange.begin(), subrange.end());
+      assert(ret);
+    }
+    {
+      bool ret = std::ranges::contains_subrange(whole, subrange);
+      assert(ret);
+    }
+  }
+
   { // subrange is subsequence
     int a[]       = {23, 1, 0, 54, 2};
     int p[]       = {1, 0, 2};
@@ -256,19 +286,6 @@ constexpr void test_iterators() {
       assert(ret);
     }
   }
-
-  { // check the nodiscard extension
-// use #pragma around to suppress error: ignoring return value of function
-// declared with 'nodiscard' attribute [-Werror,-Wunused-result]
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wunused-result"
-    int a[]       = {1, 9, 0, 13, 25};
-    int p[]       = {1, 9, 0};
-    auto whole    = std::ranges::subrange(Iter1(a), Sent1(Iter1(std::end(a))));
-    auto subrange = std::ranges::subrange(Iter2(p), Sent2(Iter2(std::end(p))));
-    std::ranges::contains_subrange(whole, subrange);
-#pragma clang diagnostic pop
-  }
 }
 
 constexpr bool test() {



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