[libcxx-commits] [libcxx] 9106047 - [libcxx][ranges] Add range.subrange.

via libcxx-commits libcxx-commits at lists.llvm.org
Fri Jun 11 09:34:48 PDT 2021


Author: zoecarver
Date: 2021-06-11T09:34:41-07:00
New Revision: 9106047ee3dd93a250deb1ef34b890f486dee710

URL: https://github.com/llvm/llvm-project/commit/9106047ee3dd93a250deb1ef34b890f486dee710
DIFF: https://github.com/llvm/llvm-project/commit/9106047ee3dd93a250deb1ef34b890f486dee710.diff

LOG: [libcxx][ranges] Add range.subrange.

Basically the title.

Differential Revision: https://reviews.llvm.org/D102006

Added: 
    libcxx/include/__ranges/subrange.h
    libcxx/test/std/ranges/range.utility/range.subrange/access/advance.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/access/get.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/access/primitives.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctad.compile.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end_size.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctor/pair_like_conv.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctor/range.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/ctor/range_size.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/general.compile.pass.cpp
    libcxx/test/std/ranges/range.utility/range.subrange/subrange_test_types.h

Modified: 
    libcxx/include/CMakeLists.txt
    libcxx/include/ranges

Removed: 
    


################################################################################
diff  --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index e83b289b13a2f..798c4d8915039 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -53,6 +53,7 @@ set(files
   __ranges/enable_view.h
   __ranges/view_interface.h
   __ranges/size.h
+  __ranges/subrange.h
   __split_buffer
   __std_stream
   __string

diff  --git a/libcxx/include/__ranges/subrange.h b/libcxx/include/__ranges/subrange.h
new file mode 100644
index 0000000000000..dcdb060330513
--- /dev/null
+++ b/libcxx/include/__ranges/subrange.h
@@ -0,0 +1,237 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef _LIBCPP___RANGES_SUBRANGE_H
+#define _LIBCPP___RANGES_SUBRANGE_H
+
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/advance.h>
+#include <__ranges/access.h>
+#include <__ranges/enable_borrowed_range.h>
+#include <__ranges/view_interface.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_HAS_NO_RANGES)
+
+// clang-format off
+namespace ranges {
+  template<class _From, class _To>
+  concept __convertible_to_non_slicing =
+    convertible_to<_From, _To> &&
+    // If they're both pointers, they must have the same element type.
+    !(is_pointer_v<decay_t<_From>> &&
+      is_pointer_v<decay_t<_To>> &&
+      __
diff erent_from<remove_pointer_t<decay_t<_From>>, remove_pointer_t<decay_t<_To>>>);
+
+  template<class _Tp>
+  concept __pair_like =
+    !is_reference_v<_Tp> && requires(_Tp __t) {
+      typename tuple_size<_Tp>::type; // Ensures `tuple_size<T>` is complete.
+      requires derived_from<tuple_size<_Tp>, integral_constant<size_t, 2>>;
+      typename tuple_element_t<0, remove_const_t<_Tp>>;
+      typename tuple_element_t<1, remove_const_t<_Tp>>;
+      { _VSTD::get<0>(__t) } -> convertible_to<const tuple_element_t<0, _Tp>&>;
+      { _VSTD::get<1>(__t) } -> convertible_to<const tuple_element_t<1, _Tp>&>;
+    };
+
+  template<class _Pair, class _Iter, class _Sent>
+  concept __pair_like_convertible_from =
+    !range<_Pair> && __pair_like<_Pair> &&
+    constructible_from<_Pair, _Iter, _Sent> &&
+    __convertible_to_non_slicing<_Iter, tuple_element_t<0, _Pair>> &&
+    convertible_to<_Sent, tuple_element_t<1, _Pair>>;
+
+  enum class _LIBCPP_ENUM_VIS subrange_kind : bool { unsized, sized };
+
+  template<class _Iter, class _Sent, bool>
+  struct __subrange_base {
+    static constexpr bool __store_size = false;
+    _Iter __begin_ = _Iter();
+    _Sent __end_ = _Sent();
+
+    constexpr __subrange_base() = default;
+    constexpr __subrange_base(_Iter __iter, _Sent __sent, make_unsigned_t<iter_
diff erence_t<_Iter>> = 0)
+      : __begin_(_VSTD::move(__iter)), __end_(__sent) { }
+  };
+
+  template<class _Iter, class _Sent>
+  struct __subrange_base<_Iter, _Sent, true> {
+    static constexpr bool __store_size = true;
+    _Iter __begin_ = _Iter();
+    _Sent __end_ = _Sent();
+    make_unsigned_t<iter_
diff erence_t<_Iter>> __size_ = 0;
+
+    constexpr __subrange_base() = default;
+    constexpr __subrange_base(_Iter __iter, _Sent __sent, decltype(__size_) __size)
+      : __begin_(_VSTD::move(__iter)), __end_(__sent), __size_(__size) { }
+  };
+
+  template<input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent = _Iter,
+           subrange_kind _Kind = sized_sentinel_for<_Sent, _Iter>
+             ? subrange_kind::sized
+             : subrange_kind::unsized>
+    requires (_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _Iter>)
+  struct _LIBCPP_TEMPLATE_VIS subrange
+    : public view_interface<subrange<_Iter, _Sent, _Kind>>,
+      private __subrange_base<_Iter, _Sent, _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _Iter>> {
+
+    using _Base = __subrange_base<_Iter, _Sent, _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _Iter>>;
+
+    subrange() requires default_initializable<_Iter> = default;
+
+    constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent)
+      requires (!_Base::__store_size)
+      : _Base(_VSTD::move(__iter), __sent) {}
+
+    constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent,
+                       make_unsigned_t<iter_
diff erence_t<_Iter>> __n)
+      requires (_Kind == subrange_kind::sized)
+      : _Base(_VSTD::move(__iter), __sent, __n) { }
+
+    template<__
diff erent_from<subrange> _Range>
+      requires borrowed_range<_Range> &&
+               __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
+               convertible_to<sentinel_t<_Range>, _Sent>
+    constexpr subrange(_Range&& __range)
+      requires (!_Base::__store_size)
+      : subrange(ranges::begin(__range), ranges::end(__range)) { }
+
+    template<__
diff erent_from<subrange> _Range>
+      requires borrowed_range<_Range> &&
+               __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
+               convertible_to<sentinel_t<_Range>, _Sent>
+    constexpr subrange(_Range&& __range)
+      requires _Base::__store_size && sized_range<_Range>
+      : subrange(__range, ranges::size(__range)) { }
+
+
+    template<borrowed_range _Range>
+      requires __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
+               convertible_to<sentinel_t<_Range>, _Sent>
+    constexpr subrange(_Range&& __range, make_unsigned_t<iter_
diff erence_t<_Iter>> __n)
+      requires (_Kind == subrange_kind::sized)
+      : subrange(ranges::begin(__range), ranges::end(__range), __n) { }
+
+    template<__
diff erent_from<subrange> _Pair>
+      requires __pair_like_convertible_from<_Pair, const _Iter&, const _Sent&>
+    constexpr operator _Pair() const { return _Pair(this->__begin_, this->__end_); }
+
+    constexpr _Iter begin() const requires copyable<_Iter> {
+      return this->__begin_;
+    }
+
+    [[nodiscard]] constexpr _Iter begin() requires (!copyable<_Iter>) {
+      return _VSTD::move(this->__begin_);
+    }
+
+    constexpr _Sent end() const { return this->__end_; }
+
+    [[nodiscard]] constexpr bool empty() const { return this->__begin_ == this->__end_; }
+
+    constexpr make_unsigned_t<iter_
diff erence_t<_Iter>> size() const
+      requires (_Kind == subrange_kind::sized)
+    {
+      if constexpr (_Base::__store_size)
+        return this->__size_;
+      else
+        return __to_unsigned_like(this->__end_ - this->__begin_);
+    }
+
+    [[nodiscard]] constexpr subrange next(iter_
diff erence_t<_Iter> __n = 1) const&
+      requires forward_iterator<_Iter> {
+      auto __tmp = *this;
+      __tmp.advance(__n);
+      return __tmp;
+    }
+
+    [[nodiscard]] constexpr subrange next(iter_
diff erence_t<_Iter> __n = 1) && {
+      advance(__n);
+      return _VSTD::move(*this);
+    }
+
+    [[nodiscard]] constexpr subrange prev(iter_
diff erence_t<_Iter> __n = 1) const
+      requires bidirectional_iterator<_Iter> {
+      auto __tmp = *this;
+      __tmp.advance(-__n);
+      return __tmp;
+    }
+
+    constexpr subrange& advance(iter_
diff erence_t<_Iter> __n) {
+      if constexpr (bidirectional_iterator<_Iter>) {
+        if (__n < 0) {
+          ranges::advance(this->__begin_, __n);
+          if constexpr (_Base::__store_size)
+            this->__size_ += _VSTD::__to_unsigned_like(-__n);
+          return *this;
+        }
+      }
+
+      auto __d = __n - ranges::advance(this->__begin_, __n, this->__end_);
+      if constexpr (_Base::__store_size)
+        this->__size_ -= _VSTD::__to_unsigned_like(__d);
+      return *this;
+    }
+  };
+
+  template<input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent>
+  subrange(_Iter, _Sent) -> subrange<_Iter, _Sent>;
+
+  template<input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent>
+  subrange(_Iter, _Sent, make_unsigned_t<iter_
diff erence_t<_Iter>>)
+    -> subrange<_Iter, _Sent, subrange_kind::sized>;
+
+  template<borrowed_range _Range>
+  subrange(_Range&&) -> subrange<iterator_t<_Range>, sentinel_t<_Range>,
+                                 (sized_range<_Range> || sized_sentinel_for<sentinel_t<_Range>, iterator_t<_Range>>)
+                                   ? subrange_kind::sized : subrange_kind::unsized>;
+
+  template<borrowed_range _Range>
+  subrange(_Range&&, make_unsigned_t<range_
diff erence_t<_Range>>)
+    -> subrange<iterator_t<_Range>, sentinel_t<_Range>, subrange_kind::sized>;
+
+  template<size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
+    requires (_Index < 2)
+  constexpr auto get(const subrange<_Iter, _Sent, _Kind>& __subrange) {
+    if constexpr (_Index == 0)
+      return __subrange.begin();
+    else
+      return __subrange.end();
+  }
+
+  template<size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
+    requires (_Index < 2)
+  constexpr auto get(subrange<_Iter, _Sent, _Kind>&& __subrange) {
+    if constexpr (_Index == 0)
+      return __subrange.begin();
+    else
+      return __subrange.end();
+  }
+} // namespace ranges
+
+using ranges::get;
+
+// clang-format off
+
+#endif // !defined(_LIBCPP_HAS_NO_RANGES)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_SUBRANGE_H

diff  --git a/libcxx/include/ranges b/libcxx/include/ranges
index 9e5b55e369e2e..edf74746c54c8 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -101,6 +101,7 @@ namespace std::ranges {
 #include <__ranges/enable_borrowed_range.h>
 #include <__ranges/enable_view.h>
 #include <__ranges/size.h>
+#include <__ranges/subrange.h>
 #include <__ranges/view_interface.h>
 #include <compare>          // Required by the standard.
 #include <initializer_list> // Required by the standard.

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/access/advance.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/access/advance.pass.cpp
new file mode 100644
index 0000000000000..2d1cd7edd2864
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/access/advance.pass.cpp
@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+#include "../subrange_test_types.h"
+
+constexpr bool test() {
+  std::ranges::subrange<int*> a(globalBuff, globalBuff + 8, 8);
+  auto a1 = a.next();
+  assert(a1.begin() == globalBuff + 1);
+  assert(a1.size() == 7);
+  auto a5 = a.next(5);
+  assert(a5.begin() == globalBuff + 5);
+  assert(a5.size() == 3);
+  auto a4 = a5.prev();
+  assert(a4.begin() == globalBuff + 4);
+  assert(a4.size() == 4);
+
+  std::ranges::subrange<InputIter> b(InputIter(globalBuff), InputIter(globalBuff + 8));
+  auto b1 = std::move(b).next();
+  assert(b1.begin().base() == globalBuff + 1);
+
+  std::ranges::subrange<BidirIter> c(BidirIter(globalBuff + 4), BidirIter(globalBuff + 8));
+  auto c1 = c.prev();
+  assert(c1.begin().base() == globalBuff + 3);
+  auto c2 = c.prev(4);
+  assert(c2.begin().base() == globalBuff);
+
+  std::ranges::subrange<BidirIter> d(BidirIter(globalBuff + 4), BidirIter(globalBuff + 8));
+  auto d1 = d.advance(4);
+  assert(d1.begin().base() == globalBuff + 8);
+  assert(d1.empty());
+  auto d2 = d1.advance(-4);
+  assert(d2.begin().base() == globalBuff + 4);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/access/get.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/access/get.pass.cpp
new file mode 100644
index 0000000000000..8c1a027096c57
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/access/get.pass.cpp
@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+#include "../subrange_test_types.h"
+
+template<size_t I, class S>
+concept GetInvocable = requires {
+  std::get<I>(std::declval<S>());
+};
+
+static_assert( GetInvocable<0, std::ranges::subrange<int*>>);
+static_assert( GetInvocable<1, std::ranges::subrange<int*>>);
+static_assert(!GetInvocable<2, std::ranges::subrange<int*>>);
+static_assert(!GetInvocable<3, std::ranges::subrange<int*>>);
+
+constexpr bool test() {
+  std::ranges::subrange<int*> a(globalBuff, globalBuff + 8, 8);
+  assert(std::get<0>(a) == a.begin());
+  assert(std::get<1>(a) == a.end());
+
+  assert(a.begin() == std::get<0>(std::move(a)));
+  std::ranges::subrange<int*> b(globalBuff, globalBuff + 8, 8);
+  assert(b.end() == std::get<1>(std::move(b)));
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/access/primitives.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/access/primitives.pass.cpp
new file mode 100644
index 0000000000000..fe31471cb06eb
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/access/primitives.pass.cpp
@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+#include "../subrange_test_types.h"
+
+// Note: begin and end tested in range.subrange.ctor.pass.cpp.
+
+constexpr bool test() {
+  std::ranges::subrange<MoveOnlyForwardIter, int*> a(MoveOnlyForwardIter(globalBuff), globalBuff + 8, 8);
+  assert(a.begin().base == globalBuff);
+  assert(!a.empty());
+  assert(a.size() == 8);
+
+  std::ranges::subrange<ForwardIter> b(ForwardIter(nullptr), ForwardIter(nullptr));
+  assert(b.empty());
+
+  std::ranges::subrange<ForwardIter> c{ForwardIter(globalBuff), ForwardIter(globalBuff)};
+  assert(c.empty());
+
+  std::ranges::subrange<ForwardIter> d(ForwardIter(globalBuff), ForwardIter(globalBuff + 1));
+  assert(!d.empty());
+
+  std::ranges::subrange<SizedSentinelForwardIter> e(SizedSentinelForwardIter(globalBuff),
+                                                    SizedSentinelForwardIter(globalBuff + 8), 8);
+  assert(!e.empty());
+  assert(e.size() == 8);
+
+  // Make sure that operator- is used to calculate size when possible.
+  if (!std::is_constant_evaluated())
+    assert(SizedSentinelForwardIter::minusCount == 1);
+
+  return true;
+}
+
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctad.compile.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctad.compile.pass.cpp
new file mode 100644
index 0000000000000..e34b519fd9328
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctad.compile.pass.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+
+using FI = forward_iterator<int*>;
+FI fi{nullptr};
+int *ptr = nullptr;
+
+static_assert(std::same_as<decltype(std::ranges::subrange(fi, fi)),
+                           std::ranges::subrange<FI, FI, std::ranges::subrange_kind::unsized>>);
+static_assert(std::same_as<decltype(std::ranges::subrange(ptr, ptr, 0)),
+                           std::ranges::subrange<int*, int*, std::ranges::subrange_kind::sized>>);
+static_assert(std::same_as<decltype(std::ranges::subrange(ptr, nullptr, 0)),
+                           std::ranges::subrange<int*, nullptr_t, std::ranges::subrange_kind::sized>>);
+
+struct ForwardRange {
+  forward_iterator<int*> begin() const;
+  forward_iterator<int*> end() const;
+};
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<ForwardRange> = true;
+
+struct SizedRange {
+  int *begin();
+  int *end();
+};
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<SizedRange> = true;
+
+static_assert(std::same_as<decltype(std::ranges::subrange(ForwardRange())),
+                           std::ranges::subrange<FI, FI, std::ranges::subrange_kind::unsized>>);
+static_assert(std::same_as<decltype(std::ranges::subrange(SizedRange())),
+                           std::ranges::subrange<int*, int*, std::ranges::subrange_kind::sized>>);
+static_assert(std::same_as<decltype(std::ranges::subrange(SizedRange(), 8)),
+                           std::ranges::subrange<int*, int*, std::ranges::subrange_kind::sized>>);

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end.pass.cpp
new file mode 100644
index 0000000000000..5a6364f5368f7
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end.pass.cpp
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include "../subrange_test_types.h"
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+
+// convertible-to-non-slicing cases:
+//   1. Not convertible (fail)
+//   2. Only one is a pointer (succeed)
+//   3. Both are not pointers (succeed)
+//   4. Pointer elements are 
diff erent types (fail)
+//   5. Pointer elements are same type (succeed)
+
+// !StoreSize ctor.
+static_assert( std::is_constructible_v<ForwardSubrange, ForwardIter, ForwardIter>); // Default case.
+static_assert(!std::is_constructible_v<ForwardSubrange, Empty, ForwardIter>); // 1.
+static_assert( std::is_constructible_v<ConvertibleForwardSubrange, ConvertibleForwardIter, int*>); // 2.
+static_assert( std::is_constructible_v<ForwardSubrange, ForwardIter, ForwardIter>); // 3. (Same as default case.)
+// 4. and 5. must be sized.
+
+constexpr bool test() {
+  ForwardSubrange a(ForwardIter(globalBuff), ForwardIter(globalBuff + 8));
+  assert(a.begin().base() == globalBuff);
+  assert(a.end().base() == globalBuff + 8);
+
+  ConvertibleForwardSubrange b(ConvertibleForwardIter(globalBuff), globalBuff + 8);
+  assert(b.begin() == globalBuff);
+  assert(b.end() == globalBuff + 8);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end_size.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end_size.pass.cpp
new file mode 100644
index 0000000000000..e8ae605379f61
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/begin_end_size.pass.cpp
@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include "../subrange_test_types.h"
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+
+// convertible-to-non-slicing cases:
+//   1. Not convertible (fail)
+//   2. Only one is a pointer (succeed)
+//   3. Both are not pointers (succeed)
+//   4. Pointer elements are 
diff erent types (fail)
+//   5. Pointer elements are same type (succeed)
+
+static_assert( std::is_constructible_v<SizedSentinelForwardSubrange, ConditionallyConvertibleIter, ConditionallyConvertibleIter, ConditionallyConvertibleIter::u
diff erence_type>); // Default case.
+static_assert(!std::is_constructible_v<SizedSentinelForwardSubrange, Empty, ConditionallyConvertibleIter, ConditionallyConvertibleIter::u
diff erence_type>); // 1.
+static_assert( std::is_constructible_v<ConvertibleSizedSentinelForwardSubrange, ConvertibleSizedSentinelForwardIter, int*, ConvertibleSizedSentinelForwardIter::u
diff erence_type>); // 2.
+static_assert( std::is_constructible_v<SizedSentinelForwardSubrange, ConditionallyConvertibleIter, ConditionallyConvertibleIter, ConditionallyConvertibleIter::u
diff erence_type>); // 3. (Same as default case.)
+static_assert(!std::is_constructible_v<SizedIntPtrSubrange, long*, int*, size_t>); // 4.
+static_assert( std::is_constructible_v<SizedIntPtrSubrange, int*, int*, size_t>); // 5.
+
+constexpr bool test() {
+  SizedSentinelForwardSubrange a(ConditionallyConvertibleIter(globalBuff), ConditionallyConvertibleIter(globalBuff + 8), 8);
+  assert(a.begin().base() == globalBuff);
+  assert(a.end().base() == globalBuff + 8);
+  assert(a.size() == 8);
+
+  ConvertibleSizedSentinelForwardSubrange b(ConvertibleSizedSentinelForwardIter(globalBuff), ConvertibleSizedSentinelForwardIter(globalBuff + 8), 8);
+  assert(b.begin() == globalBuff);
+  assert(b.end() == globalBuff + 8);
+  assert(b.size() == 8);
+
+  SizedIntPtrSubrange c(globalBuff, globalBuff + 8, 8);
+  assert(c.begin() == globalBuff);
+  assert(c.end() == globalBuff + 8);
+  assert(c.size() == 8);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctor/pair_like_conv.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/pair_like_conv.pass.cpp
new file mode 100644
index 0000000000000..1b749831ec8fd
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/pair_like_conv.pass.cpp
@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include "../subrange_test_types.h"
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+#include <tuple>
+#include <utility>
+
+static_assert( std::is_convertible_v<ForwardSubrange, std::pair<ForwardIter, ForwardIter>>);
+static_assert( std::is_convertible_v<ForwardSubrange, std::tuple<ForwardIter, ForwardIter>>);
+static_assert(!std::is_convertible_v<ForwardSubrange, std::tuple<ForwardIter, ForwardIter>&>);
+static_assert(!std::is_convertible_v<ForwardSubrange, std::tuple<ForwardIter, ForwardIter, ForwardIter>>);
+static_assert( std::is_convertible_v<ConvertibleForwardSubrange, std::tuple<ConvertibleForwardIter, int*>>);
+static_assert(!std::is_convertible_v<SizedIntPtrSubrange, std::tuple<long*, int*>>);
+static_assert( std::is_convertible_v<SizedIntPtrSubrange, std::tuple<int*, int*>>);
+
+constexpr bool test() {
+  ForwardSubrange a(ForwardIter(globalBuff), ForwardIter(globalBuff + 8));
+  std::pair<ForwardIter, ForwardIter> aPair = a;
+  assert(aPair.first.base() == globalBuff);
+  assert(aPair.second.base() == globalBuff + 8);
+  std::tuple<ForwardIter, ForwardIter> aTuple = a;
+  assert(get<0>(aTuple).base() == globalBuff);
+  assert(get<1>(aTuple).base() == globalBuff + 8);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range.pass.cpp
new file mode 100644
index 0000000000000..a6e03001cc860
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range.pass.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include "../subrange_test_types.h"
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+
+static_assert( std::is_constructible_v<ForwardSubrange, ForwardBorrowedRange>); // Default case.
+static_assert(!std::is_constructible_v<ForwardSubrange, ForwardRange>); // Not borrowed.
+// Iter convertible to sentinel (pointer) type.
+static_assert( std::is_constructible_v<ConvertibleForwardSubrange, ConvertibleForwardBorrowedRange>);
+// Where neither iter or sentinel are pointers, but they are 
diff erent.
+static_assert( std::is_constructible_v<DifferentSentinelSubrange, ForwardBorrowedRangeDifferentSentinel>);
+static_assert( std::is_constructible_v<DifferentSentinelWithSizeMemberSubrange, DifferentSentinelWithSizeMember>);
+
+constexpr bool test() {
+  ForwardSubrange a{ForwardBorrowedRange()};
+  assert(a.begin().base() == globalBuff);
+  assert(a.end().base() == globalBuff + 8);
+
+  ConvertibleForwardSubrange b{ConvertibleForwardBorrowedRange()};
+  assert(b.begin() == globalBuff);
+  assert(b.end() == globalBuff + 8);
+
+  DifferentSentinelSubrange c{ForwardBorrowedRangeDifferentSentinel()};
+  assert(c.begin().base() == globalBuff);
+  assert(c.end().value == globalBuff + 8);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range_size.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range_size.pass.cpp
new file mode 100644
index 0000000000000..fe71fee4f7ca2
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/ctor/range_size.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+// Tested in pair_like_conv.pass.cpp.
+
+int main(int, char**) {
+  return 0;
+}

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/general.compile.pass.cpp b/libcxx/test/std/ranges/range.utility/range.subrange/general.compile.pass.cpp
new file mode 100644
index 0000000000000..a7a944bc3374a
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/general.compile.pass.cpp
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// class std::ranges::subrange;
+
+#include <ranges>
+
+#include <cassert>
+#include "test_macros.h"
+#include "test_iterators.h"
+
+template<std::ranges::subrange_kind K, class... Args>
+concept ValidSubrangeKind = requires { typename std::ranges::subrange<Args..., K>; };
+
+template<class... Args>
+concept ValidSubrange = requires { typename std::ranges::subrange<Args...>; };
+
+static_assert( ValidSubrange<forward_iterator<int*>>);
+static_assert( ValidSubrange<forward_iterator<int*>, forward_iterator<int*>>);
+static_assert( ValidSubrangeKind<std::ranges::subrange_kind::unsized, forward_iterator<int*>, forward_iterator<int*>>);
+static_assert( ValidSubrangeKind<std::ranges::subrange_kind::sized, forward_iterator<int*>, forward_iterator<int*>>);
+// Wrong sentinel type.
+static_assert(!ValidSubrange<forward_iterator<int*>, int*>);
+static_assert( ValidSubrange<int*>);
+static_assert( ValidSubrange<int*, int*>);
+// Must be sized.
+static_assert(!ValidSubrangeKind<std::ranges::subrange_kind::unsized, int*, int*>);
+static_assert( ValidSubrangeKind<std::ranges::subrange_kind::sized, int*, int*>);
+// Wrong sentinel type.
+static_assert(!ValidSubrange<int*, forward_iterator<int*>>);
+// Not an iterator.
+static_assert(!ValidSubrange<int>);

diff  --git a/libcxx/test/std/ranges/range.utility/range.subrange/subrange_test_types.h b/libcxx/test/std/ranges/range.utility/range.subrange/subrange_test_types.h
new file mode 100644
index 0000000000000..95326dbaacd1b
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.subrange/subrange_test_types.h
@@ -0,0 +1,215 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 SUBRANGE_TEST_TYPES_H
+#define SUBRANGE_TEST_TYPES_H
+
+#include "test_macros.h"
+#include "test_iterators.h"
+
+int globalBuff[8];
+
+struct Empty {};
+
+using InputIter = cpp17_input_iterator<int*>;
+using ForwardIter = forward_iterator<int*>;
+using BidirIter = bidirectional_iterator<int*>;
+
+using ForwardSubrange = std::ranges::subrange<ForwardIter, ForwardIter, std::ranges::subrange_kind::unsized>;
+using SizedIntPtrSubrange = std::ranges::subrange<int*, int*, std::ranges::subrange_kind::sized>;
+
+struct MoveOnlyForwardIter {
+    typedef std::forward_iterator_tag       iterator_category;
+    typedef int                             value_type;
+    typedef std::ptr
diff _t                  
diff erence_type;
+    typedef int*                            pointer;
+    typedef int&                            reference;
+    typedef MoveOnlyForwardIter             self;
+
+    int *base = nullptr;
+
+    MoveOnlyForwardIter() = default;
+    MoveOnlyForwardIter(MoveOnlyForwardIter &&) = default;
+    MoveOnlyForwardIter &operator=(MoveOnlyForwardIter&&) = default;
+    MoveOnlyForwardIter(MoveOnlyForwardIter const&) = delete;
+    constexpr MoveOnlyForwardIter(int *ptr) : base(ptr) { }
+
+    friend bool operator==(const self&, const self&);
+    friend constexpr bool operator==(const self& lhs, int* rhs) { return lhs.base == rhs; }
+
+    reference operator*() const;
+    pointer operator->() const;
+    self& operator++();
+    self operator++(int);
+    self& operator--();
+    self operator--(int);
+
+    constexpr operator pointer() const { return base; }
+};
+
+struct SizedSentinelForwardIter {
+    typedef std::forward_iterator_tag            iterator_category;
+    typedef int                                  value_type;
+    typedef std::ptr
diff _t                       
diff erence_type;
+    typedef int*                                 pointer;
+    typedef int&                                 reference;
+    typedef std::make_unsigned_t<std::ptr
diff _t> u
diff erence_type;
+    typedef SizedSentinelForwardIter             self;
+
+    int *base;
+
+    SizedSentinelForwardIter() = default;
+    constexpr SizedSentinelForwardIter(int *ptr) : base(ptr) { }
+
+    friend constexpr bool operator==(const self& lhs, const self& rhs) { return lhs.base == rhs.base; }
+
+    reference operator*() const;
+    pointer operator->() const;
+    self& operator++();
+    self operator++(int);
+    self& operator--();
+    self operator--(int);
+
+    static int minusCount;
+    friend constexpr 
diff erence_type operator-(SizedSentinelForwardIter const&a,
+                                               SizedSentinelForwardIter const&b) {
+      if (!std::is_constant_evaluated())
+        minusCount++;
+      return a.base - b.base;
+    }
+};
+
+int SizedSentinelForwardIter::minusCount = 0;
+
+struct ConvertibleForwardIter {
+    typedef std::forward_iterator_tag       iterator_category;
+    typedef int                             value_type;
+    typedef std::ptr
diff _t                  
diff erence_type;
+    typedef int*                            pointer;
+    typedef int&                            reference;
+    typedef ConvertibleForwardIter          self;
+
+    int *base_ = nullptr;
+
+    constexpr ConvertibleForwardIter() = default;
+    constexpr explicit ConvertibleForwardIter(int *ptr) : base_(ptr) { }
+
+    friend bool operator==(const self&, const self&);
+
+    reference operator*() const;
+    pointer operator->() const;
+    self& operator++();
+    self operator++(int);
+    self& operator--();
+    self operator--(int);
+
+    constexpr operator pointer() const { return base_; }
+
+    // Explicitly deleted so this doesn't model sized_sentinel_for.
+    friend constexpr 
diff erence_type operator-(int *, self const&) = delete;
+    friend constexpr 
diff erence_type operator-(self const&, int*) = delete;
+};
+using ConvertibleForwardSubrange = std::ranges::subrange<ConvertibleForwardIter, int*,
+                                                         std::ranges::subrange_kind::unsized>;
+static_assert(std::is_convertible_v<ConvertibleForwardIter, int*>);
+
+template<bool EnableConvertible>
+struct ConditionallyConvertibleBase {
+    typedef std::forward_iterator_tag            iterator_category;
+    typedef int                                  value_type;
+    typedef std::ptr
diff _t                       
diff erence_type;
+    typedef int*                                 pointer;
+    typedef int&                                 reference;
+    typedef std::make_unsigned_t<std::ptr
diff _t> u
diff erence_type;
+    typedef ConditionallyConvertibleBase         self;
+
+    int *base_ = nullptr;
+
+    constexpr ConditionallyConvertibleBase() = default;
+    constexpr explicit ConditionallyConvertibleBase(int *ptr) : base_(ptr) {}
+
+    constexpr int *base() const { return base_; }
+
+    friend bool operator==(const self&, const self&);
+
+    reference operator*() const;
+    pointer operator->() const;
+    self& operator++();
+    self operator++(int);
+    self& operator--();
+    self operator--(int);
+
+    template<bool E = EnableConvertible>
+      requires E
+    constexpr operator pointer() const { return base_; }
+};
+using ConditionallyConvertibleIter = ConditionallyConvertibleBase<false>;
+using SizedSentinelForwardSubrange = std::ranges::subrange<ConditionallyConvertibleIter,
+                                                           ConditionallyConvertibleIter,
+                                                           std::ranges::subrange_kind::sized>;
+using ConvertibleSizedSentinelForwardIter = ConditionallyConvertibleBase<true>;
+using ConvertibleSizedSentinelForwardSubrange = std::ranges::subrange<ConvertibleSizedSentinelForwardIter, int*,
+                                                                      std::ranges::subrange_kind::sized>;
+
+struct ForwardBorrowedRange {
+  constexpr ForwardIter begin() const { return ForwardIter(globalBuff); }
+  constexpr ForwardIter end() const { return ForwardIter(globalBuff + 8); }
+};
+
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<ForwardBorrowedRange> = true;
+
+struct ForwardRange {
+  ForwardIter begin() const;
+  ForwardIter end() const;
+};
+
+struct ConvertibleForwardBorrowedRange {
+  constexpr ConvertibleForwardIter begin() const { return ConvertibleForwardIter(globalBuff); }
+  constexpr int *end() const { return globalBuff + 8; }
+};
+
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<ConvertibleForwardBorrowedRange> = true;
+
+struct ForwardBorrowedRangeDifferentSentinel {
+  struct sentinel {
+    int *value;
+    friend bool operator==(sentinel s, ForwardIter i) { return s.value == i.base(); }
+  };
+
+  constexpr ForwardIter begin() const { return ForwardIter(globalBuff); }
+  constexpr sentinel end() const { return sentinel{globalBuff + 8}; }
+};
+
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<ForwardBorrowedRangeDifferentSentinel> = true;
+
+using DifferentSentinelSubrange = std::ranges::subrange<ForwardIter,
+                                                        ForwardBorrowedRangeDifferentSentinel::sentinel,
+                                                        std::ranges::subrange_kind::unsized>;
+
+struct DifferentSentinelWithSizeMember {
+  struct sentinel {
+    int *value;
+    friend bool operator==(sentinel s, ForwardIter i) { return s.value == i.base(); }
+  };
+
+  constexpr ForwardIter begin() const { return ForwardIter(globalBuff); }
+  constexpr sentinel end() const { return sentinel{globalBuff + 8}; }
+  constexpr size_t size() const { return 8; }
+};
+
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<DifferentSentinelWithSizeMember> = true;
+
+using DifferentSentinelWithSizeMemberSubrange = std::ranges::subrange<ForwardIter,
+                                                                      DifferentSentinelWithSizeMember::sentinel,
+                                                                      std::ranges::subrange_kind::unsized>;
+
+#endif // SUBRANGE_TEST_TYPES_H


        


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