[libcxx-commits] [libcxx] WIP [libc++][ranges] P3137R3: `views::to_input` (PR #151449)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Jul 31 07:37:41 PDT 2025
https://github.com/H-G-Hristov updated https://github.com/llvm/llvm-project/pull/151449
>From 3715bf4274952b1a1ac536182feda8736c0161df Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 9 Jul 2025 19:25:52 +0300
Subject: [PATCH] [libc++][ranges] P3137R3: `views::to_input`
Implements: https://wg21.link/P3137R3
Closes #127873
https://wg21.link/range.to.input
---
libcxx/docs/FeatureTestMacroTable.rst | 2 +
libcxx/docs/ReleaseNotes/22.rst | 1 +
libcxx/docs/Status/Cxx2cPapers.csv | 2 +-
libcxx/include/CMakeLists.txt | 1 +
libcxx/include/__ranges/to_input_view.h | 221 +++++++++++++++
libcxx/include/module.modulemap.in | 3 +
libcxx/include/ranges | 15 +
libcxx/include/version | 2 +
libcxx/modules/std/ranges.inc | 10 +
.../ranges.version.compile.pass.cpp | 27 ++
.../version.version.compile.pass.cpp | 27 ++
.../cpo.compile.pass.cpp | 2 +-
.../range.to_input/adaptor.pass.cpp | 257 ++++++++++++++++++
.../range.to_input/base.pass.cpp | 85 ++++++
.../range.to_input/begin.pass.cpp | 25 ++
.../range.to_input/ctad.compile.pass.cpp | 30 ++
.../range.to_input/ctor.default.pass.cpp | 81 ++++++
.../range.to_input/ctor.view.pass.cpp | 24 ++
.../enable_borrowed_range.compile.pass.cpp | 37 +++
.../range.to_input/end.pass.cpp | 25 ++
.../range.to_input/general.pass.cpp | 67 +++++
.../iterator/ctor.default.pass.cpp | 80 ++++++
.../range.to_input/size.pass.cpp | 109 ++++++++
.../generate_feature_test_macro_components.py | 5 +
24 files changed, 1136 insertions(+), 2 deletions(-)
create mode 100644 libcxx/include/__ranges/to_input_view.h
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/adaptor.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/base.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/begin.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/ctad.compile.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.default.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.view.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/enable_borrowed_range.compile.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/end.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/general.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/iterator/ctor.default.pass.cpp
create mode 100644 libcxx/test/std/ranges/range.adaptors/range.to_input/size.pass.cpp
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 61805726a4ff0..4a54d6c2a5679 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -488,6 +488,8 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_ranges_concat`` *unimplemented*
---------------------------------------------------------- -----------------
+ ``__cpp_lib_ranges_to_input`` ``202502L``
+ ---------------------------------------------------------- -----------------
``__cpp_lib_ratio`` ``202306L``
---------------------------------------------------------- -----------------
``__cpp_lib_rcu`` *unimplemented*
diff --git a/libcxx/docs/ReleaseNotes/22.rst b/libcxx/docs/ReleaseNotes/22.rst
index 15bf46d44b07f..e468277fa76ad 100644
--- a/libcxx/docs/ReleaseNotes/22.rst
+++ b/libcxx/docs/ReleaseNotes/22.rst
@@ -39,6 +39,7 @@ Implemented Papers
------------------
- P2321R2: ``zip`` (`Github <https://github.com/llvm/llvm-project/issues/105169>`__) (The paper is partially implemented. ``zip_transform_view`` is implemented in this release)
+- P3137R3: ``views::to_input`` (`Github <https://github.com/llvm/llvm-project/issues/127873>`__)
Improvements and New Features
-----------------------------
diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index febb0c176f9c4..9a3b30d99c5e1 100644
--- a/libcxx/docs/Status/Cxx2cPapers.csv
+++ b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -101,7 +101,7 @@
"`P2900R14 <https://wg21.link/P2900R14>`__","Contracts for C++","2025-02 (Hagenberg)","","",""
"`P3475R2 <https://wg21.link/P3475R2>`__","Defang and deprecate ``memory_order::consume``","2025-02 (Hagenberg)","","",""
"`P2786R13 <https://wg21.link/P2786R13>`__","Trivial Relocatability For C++26","2025-02 (Hagenberg)","","",""
-"`P3137R3 <https://wg21.link/P3137R3>`__","``views::to_input``","2025-02 (Hagenberg)","","",""
+"`P3137R3 <https://wg21.link/P3137R3>`__","``views::to_input``","2025-02 (Hagenberg)","|Complete|","22",""
"`P0472R3 <https://wg21.link/P0472R3>`__","Put ``std::monostate`` in ``<utility>``","2025-02 (Hagenberg)","|Complete|","21",""
"`P3349R1 <https://wg21.link/P3349R1>`__","Converting contiguous iterators to pointers","2025-02 (Hagenberg)","","",""
"`P3372R3 <https://wg21.link/P3372R3>`__","constexpr containers and adaptors","2025-02 (Hagenberg)","|In Progress|","",""
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index ed5475141b50a..4bfc0d81f65bf 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -735,6 +735,7 @@ set(files
__ranges/take_view.h
__ranges/take_while_view.h
__ranges/to.h
+ __ranges/to_input_view.h
__ranges/transform_view.h
__ranges/view_interface.h
__ranges/views.h
diff --git a/libcxx/include/__ranges/to_input_view.h b/libcxx/include/__ranges/to_input_view.h
new file mode 100644
index 0000000000000..433bc9ad8cc0f
--- /dev/null
+++ b/libcxx/include/__ranges/to_input_view.h
@@ -0,0 +1,221 @@
+// -*- 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_TO_INPUT_VIEW_H
+#define _LIBCPP___RANGES_TO_INPUT_VIEW_H
+
+#include <__concepts/constructible.h>
+#include <__concepts/convertible_to.h>
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/iter_move.h>
+#include <__iterator/iter_swap.h>
+#include <__iterator/iterator_traits.h>
+#include <__ranges/access.h>
+#include <__ranges/all.h>
+#include <__ranges/concepts.h>
+#include <__ranges/size.h>
+#include <__ranges/view_interface.h>
+#include <__type_traits/maybe_const.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 26
+
+namespace ranges {
+
+// [range.to.input.view
+
+template <input_range _View>
+ requires view<_View>
+class to_input_view : public view_interface<to_input_view<_View>> {
+ _View __base_ = _View(); // exposition only
+
+ // [range.to.input.iterator], class template to_input_view::iterator
+ template <bool _Const>
+ class iterator; // exposition only
+
+public:
+ _LIBCPP_HIDE_FROM_ABI to_input_view()
+ requires default_initializable<_View>
+ = default;
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit to_input_view(_View __base) : __base_(std::move(__base)) {}
+
+ _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
+ requires copy_constructible<_View>
+ {
+ return __base_;
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
+ requires(!__simple_view<_View>)
+ {
+ return iterator<false>{ranges::begin(__base_)};
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
+ requires range<const _View>
+ {
+ return iterator<true>{ranges::begin(__base_)};
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr auto end()
+ requires(!__simple_view<_View>)
+ {
+ return ranges::end(__base_);
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
+ requires range<const _View>
+ {
+ return ranges::end(__base_);
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr auto size()
+ requires sized_range<_View>
+ {
+ return ranges::size(__base_);
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
+ requires sized_range<const _View>
+ {
+ return ranges::size(__base_);
+ }
+
+ // TODO: Implement when P2846R6 is available.
+ // constexpr auto reserve_hint()
+ // requires approximately_sized_range<_View>
+ // {
+ // return ranges::reserve_hint(__base_);
+ // }
+ // constexpr auto reserve_hint() const
+ // requires approximately_sized_range<const _View>
+ // {
+ // return ranges::reserve_hint(__base_);
+ // }
+};
+
+template <class _Range>
+to_input_view(_Range&&) -> to_input_view<views::all_t<_Range>>;
+
+// [range.to.input.iterator]
+
+template <input_range _View>
+ requires view<_View>
+template <bool _Const>
+class to_input_view<_View>::iterator {
+ using _Base = __maybe_const<_Const, _View>; // exposition only
+
+ iterator_t<_Base> __current_ = iterator_t<_Base>(); // exposition only
+
+ constexpr explicit iterator(iterator_t<_Base> __current) : __current_(std::move(__current)) {} // exposition only
+
+ friend class to_input_view<_View>;
+
+public:
+ using difference_type = range_difference_t<_Base>;
+ using value_type = range_value_t<_Base>;
+ using iterator_concept = input_iterator_tag;
+
+ _LIBCPP_HIDE_FROM_ABI iterator()
+ requires default_initializable<iterator_t<_Base>>
+ = default;
+
+ _LIBCPP_HIDE_FROM_ABI iterator(iterator&&) = default;
+ _LIBCPP_HIDE_FROM_ABI iterator& operator=(iterator&&) = default;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr iterator(iterator<!_Const> __i)
+ requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
+ : __current_(std::move(__i.__current_)) {}
+
+ _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); }
+ _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const { return *__current_; }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr iterator& operator++() {
+ ++__current_;
+ return *this;
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++*this; }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const iterator& __x, const sentinel_t<_Base>& __y) {
+ return __x.__current_ == __y;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const sentinel_t<_Base>& __y, const iterator& __x)
+ requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
+ {
+ return __y - __x.__current_;
+ }
+ _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const iterator& __x, const sentinel_t<_Base>& __y)
+ requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
+ {
+ return __x.__current_ - __y;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr range_rvalue_reference_t<_Base> _LIBCPP_HIDE_FROM_ABI
+ iter_move(const iterator& __i) noexcept(noexcept(ranges::iter_move(__i.__current_))) {
+ return ranges::iter_move(__i.__current_);
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr void
+ iter_swap(const iterator& __x,
+ const iterator& __y) noexcept(noexcept(ranges::iter_swap(__x.__current_, __y.__current_)))
+ requires indirectly_swappable<iterator_t<_Base>>
+ {
+ ranges::iter_swap(__x.__current_, __y.__current_);
+ }
+};
+
+template <class _View>
+constexpr bool enable_borrowed_range<to_input_view<_View>> = enable_borrowed_range<_View>;
+
+namespace views {
+namespace __to_input_view {
+
+struct __fn : __range_adaptor_closure<__fn> {
+ template <class _Range>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto
+ operator()(_Range&& __range) noexcept(noexcept(/**/ to_input_view(std::forward<_Range>(__range))))
+ -> decltype(/*--*/ to_input_view(std::forward<_Range>(__range))) {
+ return /*---------*/ to_input_view(std::forward<_Range>(__range));
+ }
+
+ template <class _Range>
+ requires(!common_range<_Range> && !forward_range<_Range>)
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto
+ operator()(_Range&& __range) noexcept(noexcept(views::all(std::forward<_Range>(__range))))
+ -> decltype(/*--------------------------*/ views::all(std::forward<_Range>(__range))) {
+ return /*---------------------------------*/ views::all(std::forward<_Range>(__range));
+ }
+};
+
+} // namespace __to_input_view
+
+inline namespace __cpo {
+inline constexpr auto to_input = __to_input_view::__fn{};
+} // namespace __cpo
+} // namespace views
+} // namespace ranges
+
+#endif // _LIBCPP_STD_VER >= 26
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_TO_INPUT_VIEW_H
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 117556edb5d20..96680c505699f 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1929,6 +1929,9 @@ module std [system] {
header "__ranges/to.h"
export std.functional.bind_back
}
+ module to_input_view {
+ header "__ranges/to_input_view.h"
+ }
module transform_view {
header "__ranges/transform_view.h"
export std.functional.bind_back
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
index 96d7a6b897188..2855377f8165a 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -362,6 +362,17 @@ namespace std::ranges {
class chunk_by_view; // C++23
namespace views { inline constexpr unspecified chunk_by = unspecified; } // C++23
+
+ // [range.to.input], to input view
+ template<input_range V>
+ requires view<V>
+ class to_input_view; // C++26
+
+ template<class V>
+ constexpr bool enable_borrowed_range<to_input_view<V>> =
+ enable_borrowed_range<V>; // C++26
+
+ namespace views { inline constexpr unspecified to_input = unspecified; } // C++26
}
namespace std {
@@ -453,6 +464,10 @@ namespace std {
# include <__ranges/zip_view.h>
# endif
+# if _LIBCPP_STD_VER >= 26
+# include <__ranges/to_input_view.h>
+# endif
+
# include <version>
// standard-mandated includes
diff --git a/libcxx/include/version b/libcxx/include/version
index d98049bd57046..1bfce9578f3a6 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -211,6 +211,7 @@ __cpp_lib_ranges_repeat 202207L <ranges>
__cpp_lib_ranges_slide 202202L <ranges>
__cpp_lib_ranges_starts_ends_with 202106L <algorithm>
__cpp_lib_ranges_to_container 202202L <ranges>
+__cpp_lib_ranges_to_input 202502L <ranges>
__cpp_lib_ranges_zip 202110L <ranges> <tuple> <utility>
__cpp_lib_ratio 202306L <ratio>
__cpp_lib_raw_memory_algorithms 201606L <memory>
@@ -590,6 +591,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_out_ptr 202311L
// # define __cpp_lib_philox_engine 202406L
// # define __cpp_lib_ranges_concat 202403L
+# define __cpp_lib_ranges_to_input 202502L
# define __cpp_lib_ratio 202306L
// # define __cpp_lib_rcu 202306L
# define __cpp_lib_reference_wrapper 202403L
diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index 7ede42e4f7b0a..fb79dcfd35019 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -351,6 +351,16 @@ export namespace std {
using std::ranges::views::cartesian_product;
}
#endif
+
+#if _LIBCPP_STD_VER >= 26
+ // [range.to.input], to input view
+ using std::ranges::to_input_view;
+
+ namespace views {
+ using std::ranges::views::to_input;
+ }
+#endif
+
} // namespace ranges
namespace views = ranges::views;
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
index df19f03e7dba1..4235bd3ca2383 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
@@ -64,6 +64,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -114,6 +118,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -164,6 +172,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -217,6 +229,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -312,6 +328,10 @@
# error "__cpp_lib_ranges_to_container should have the value 202202L in c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should be defined in c++23"
@@ -434,6 +454,13 @@
# error "__cpp_lib_ranges_to_container should have the value 202202L in c++26"
# endif
+# ifndef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should be defined in c++26"
+# endif
+# if __cpp_lib_ranges_to_input != 202502L
+# error "__cpp_lib_ranges_to_input should have the value 202502L in c++26"
+# endif
+
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should be defined in c++26"
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index 962688e06188a..99b187984c6af 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -688,6 +688,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -1628,6 +1632,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -2739,6 +2747,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -4123,6 +4135,10 @@
# error "__cpp_lib_ranges_to_container should not be defined before c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# ifdef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should not be defined before c++23"
# endif
@@ -5726,6 +5742,10 @@
# error "__cpp_lib_ranges_to_container should have the value 202202L in c++23"
# endif
+# ifdef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should not be defined before c++26"
+# endif
+
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should be defined in c++23"
@@ -7650,6 +7670,13 @@
# error "__cpp_lib_ranges_to_container should have the value 202202L in c++26"
# endif
+# ifndef __cpp_lib_ranges_to_input
+# error "__cpp_lib_ranges_to_input should be defined in c++26"
+# endif
+# if __cpp_lib_ranges_to_input != 202502L
+# error "__cpp_lib_ranges_to_input should have the value 202502L in c++26"
+# endif
+
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_ranges_zip
# error "__cpp_lib_ranges_zip should be defined in c++26"
diff --git a/libcxx/test/std/library/description/conventions/customization.point.object/cpo.compile.pass.cpp b/libcxx/test/std/library/description/conventions/customization.point.object/cpo.compile.pass.cpp
index 678483b9b2f2f..038c6c39ee99e 100644
--- a/libcxx/test/std/library/description/conventions/customization.point.object/cpo.compile.pass.cpp
+++ b/libcxx/test/std/library/description/conventions/customization.point.object/cpo.compile.pass.cpp
@@ -130,5 +130,5 @@ static_assert(test(std::views::zip, a, a));
#if TEST_STD_VER >= 26
// static_assert(test(std::views::cache_latest, a));
// static_assert(test(std::views::concat, a, a));
-// static_assert(test(std::views::to_input, a));
+static_assert(test(std::views::to_input, a));
#endif
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/adaptor.pass.cpp
new file mode 100644
index 0000000000000..675d561682e5c
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/adaptor.pass.cpp
@@ -0,0 +1,257 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+#include <ranges>
+#include <vector>
+
+#include "test_iterators.h"
+#include "test_range.h"
+
+static_assert(std::is_same_v<decltype(std::views::to_input), decltype(std::ranges::views::to_input)>);
+
+struct NonView {};
+
+static_assert(std::default_initializable<NonView>);
+
+struct DefaultInitializableView : std::ranges::view_base {
+ int i_;
+
+ int* begin();
+ int* end();
+};
+
+static_assert(std::default_initializable<DefaultInitializableView>);
+static_assert(std::ranges::common_range<DefaultInitializableView>);
+static_assert(std::ranges::input_range<DefaultInitializableView>);
+
+struct CommonView : std::ranges::view_base {
+ int i_;
+
+ constexpr forward_iterator<int*> begin() { return forward_iterator<int*>(&i_); }
+ constexpr forward_iterator<int*> end() { return begin(); }
+};
+
+static_assert(std::ranges::common_range<CommonView>);
+static_assert(std::ranges::forward_range<CommonView>);
+static_assert(std::ranges::input_range<CommonView>);
+
+struct NonCommonView : std::ranges::view_base {
+ int i_;
+
+ constexpr forward_iterator<int*> begin() { return forward_iterator<int*>(&i_); }
+ constexpr sentinel_wrapper<forward_iterator<int*>> end() { return sentinel_wrapper<forward_iterator<int*>>(begin()); }
+};
+
+static_assert(!std::ranges::common_range<NonCommonView>);
+static_assert(std::ranges::forward_range<NonCommonView>);
+static_assert(std::ranges::input_range<NonCommonView>);
+static_assert(
+ std::derived_from< typename std::iterator_traits<std::ranges::iterator_t<NonCommonView>>::iterator_category,
+ std::input_iterator_tag>);
+
+// Check that the `to_input` adaptor can be used with a view.
+
+static_assert(!std::is_invocable_v<decltype(std::views::to_input)>);
+static_assert(!std::is_invocable_v<decltype(std::views::to_input), NonView>);
+static_assert(std::is_invocable_v<decltype(std::views::to_input), DefaultInitializableView>);
+static_assert(std::is_invocable_v<decltype(std::views::to_input), CommonView>);
+static_assert(std::is_invocable_v<decltype(std::views::to_input), NonCommonView>);
+
+static_assert(!CanBePiped<NonView, decltype(std::views::to_input)>);
+static_assert(CanBePiped<DefaultInitializableView&, decltype(std::views::to_input)>);
+static_assert(CanBePiped<CommonView&, decltype(std::views::to_input)>);
+static_assert(CanBePiped<NonCommonView&, decltype(std::views::to_input)>);
+
+constexpr bool test() {
+ { // view | views::to_input
+ {
+ DefaultInitializableView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<DefaultInitializableView>> decltype(auto) v = view | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ {
+ CommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<CommonView>> decltype(auto) v = view | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ {
+ NonCommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<NonCommonView>> decltype(auto) v = view | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ }
+
+ { // adaptor | views::to_input
+ {
+ DefaultInitializableView view{{}, 94};
+ const auto partial = std::views::transform(std::identity{}) | std::views::to_input;
+ std::same_as<std::ranges::to_input_view<
+ std::ranges::transform_view<DefaultInitializableView, std::identity>>> decltype(auto) v = partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ {
+ CommonView view{{}, 94};
+ const auto partial = std::views::transform(std::identity{}) | std::views::to_input;
+ std::same_as<std::ranges::to_input_view< std::ranges::transform_view<CommonView, std::identity>>> decltype(auto)
+ v = partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ {
+ NonCommonView view{{}, 94};
+ const auto partial = std::views::transform(std::identity{}) | std::views::to_input;
+ std::same_as<
+ std::ranges::to_input_view< std::ranges::transform_view<NonCommonView, std::identity>>> decltype(auto) v =
+ partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(std::ranges::input_range<decltype(v)>);
+ }
+ }
+
+ { // views::to_input | adaptor
+ {
+ DefaultInitializableView view{{}, 94};
+ const auto partial = std::views::to_input | std::views::transform(std::identity{});
+ std::same_as<std::ranges::transform_view<std::ranges::to_input_view<DefaultInitializableView>,
+ std::identity>> decltype(auto) v = partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ CommonView view{{}, 94};
+ const auto partial = std::views::to_input | std::views::transform(std::identity{});
+ std::same_as<std::ranges::transform_view<std::ranges::to_input_view<CommonView>, std::identity>> decltype(auto)
+ v = partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ NonCommonView view{{}, 94};
+ const auto partial = std::views::to_input | std::views::transform(std::identity{});
+ std::same_as<std::ranges::transform_view<std::ranges::to_input_view<NonCommonView>, std::identity>> decltype(auto)
+ v = partial(view);
+ assert(v.base().base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ }
+
+ { // views::to_input | views::all
+ {
+ DefaultInitializableView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<DefaultInitializableView>> decltype(auto) v =
+ std::views::all(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ CommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<CommonView>> decltype(auto) v =
+ std::views::all(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ NonCommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<NonCommonView>> decltype(auto) v =
+ std::views::all(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ }
+
+ { // views::to_input | views::all_t
+ {
+ DefaultInitializableView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<DefaultInitializableView>> decltype(auto) v =
+ std::views::all_t<DefaultInitializableView>(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ CommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<CommonView>> decltype(auto) v =
+ std::views::all_t<CommonView>(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ {
+ NonCommonView view{{}, 94};
+ std::same_as<std::ranges::to_input_view<NonCommonView>> decltype(auto) v =
+ std::views::all_t<NonCommonView>(view) | std::views::to_input;
+ assert(v.base().i_ == 94);
+
+ static_assert(std::ranges::input_range<decltype(v)>);
+ static_assert(!std::ranges::forward_range<decltype(v)>);
+ static_assert(!std::ranges::common_range<decltype(v)>);
+ }
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/base.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/base.pass.cpp
new file mode 100644
index 0000000000000..e66d762ca23c9
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/base.pass.cpp
@@ -0,0 +1,85 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// constexpr V base() const & requires copy_constructible<V> { return base_; }
+// constexpr V base() && { return std::move(base_); }
+
+#include <cassert>
+#include <concepts>
+#include <ranges>
+
+#include <utility>
+
+#include "MoveOnly.h"
+
+struct SimpleView : std::ranges::view_base {
+ int i_;
+
+ int* begin() const;
+ int* end() const;
+};
+
+struct MoveOnlyView : public SimpleView {
+ MoveOnly m_;
+};
+
+template <class T>
+concept HasBase = requires(T&& t) { std::forward<T>(t).base(); };
+
+static_assert(HasBase<std::ranges::to_input_view<SimpleView> const&>);
+static_assert(HasBase<std::ranges::to_input_view<SimpleView>&&>);
+
+static_assert(!HasBase<std::ranges::to_input_view<MoveOnlyView> const&>);
+static_assert(HasBase<std::ranges::to_input_view<MoveOnlyView>&&>);
+
+constexpr bool test() {
+ { // &
+ std::ranges::to_input_view<SimpleView> view(SimpleView{{}, 94});
+ std::same_as<SimpleView> decltype(auto) v = view.base();
+ assert(v.i_ == 94);
+ }
+
+ { // const &
+ const std::ranges::to_input_view<SimpleView> view(SimpleView{{}, 94});
+ std::same_as<SimpleView> decltype(auto) v = view.base();
+ assert(v.i_ == 94);
+ }
+
+ { // &&
+ std::ranges::to_input_view<SimpleView> view(SimpleView{{}, 94});
+ std::same_as<SimpleView> decltype(auto) v = std::move(view).base();
+ assert(v.i_ == 94);
+ }
+
+ { // const &&
+ const std::ranges::to_input_view<SimpleView> view(SimpleView{{}, 94});
+ std::same_as<SimpleView> decltype(auto) v = std::move(view).base();
+ assert(v.i_ == 94);
+ }
+
+ { // move only
+ std::ranges::to_input_view<MoveOnlyView> view(MoveOnlyView{{}, 94});
+ std::same_as<MoveOnlyView> decltype(auto) v = std::move(view).base();
+ assert(v.m_.get() == 94);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/begin.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/begin.pass.cpp
new file mode 100644
index 0000000000000..795e442eebfbd
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/begin.pass.cpp
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// constexpr auto begin() requires (!simple-view<V>);
+// constexpr auto begin() const requires range<const V>;
+
+constexpr bool test() { return true; }
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/ctad.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctad.compile.pass.cpp
new file mode 100644
index 0000000000000..e7ef8418c0bba
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctad.compile.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// template<class R>
+// to_input_view(R&&) -> to_input_view<views::all_t<R>>;
+
+#include <concepts>
+#include <ranges>
+#include <utility>
+#include <vector>
+
+static_assert(std::same_as<decltype(std::ranges::to_input_view(std::vector<int>{})),
+ std::ranges::to_input_view<std::views::all_t<std::vector<int>>>>);
+
+static_assert(std::same_as<decltype(std::ranges::to_input_view(std::declval<std::vector<int>&>())),
+ std::ranges::to_input_view<std::views::all_t<std::vector<int>&>>>);
+
+static_assert(std::same_as<decltype(std::ranges::to_input_view(std::ranges::empty_view<int>{})),
+ std::ranges::to_input_view<std::ranges::empty_view<int>>>);
\ No newline at end of file
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.default.pass.cpp
new file mode 100644
index 0000000000000..ef901628beebe
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.default.pass.cpp
@@ -0,0 +1,81 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// to_input_view() requires default_initializable<V> = default;
+
+#include <cassert>
+#include <concepts>
+#include <ranges>
+
+struct DefaultInitializableView : std::ranges::view_base {
+ int i_ = 94;
+
+ int* begin();
+ int* end();
+};
+
+static_assert(std::default_initializable<DefaultInitializableView>);
+static_assert(std::default_initializable<std::ranges::to_input_view<DefaultInitializableView>>);
+
+struct NoDefaultInitializableView : std::ranges::view_base {
+ NoDefaultInitializableView() = delete;
+
+ int* begin();
+ int* end();
+};
+
+static_assert(!std::default_initializable<NoDefaultInitializableView>);
+static_assert(!std::default_initializable<std::ranges::to_input_view<NoDefaultInitializableView>>);
+
+struct NoexceptView : std::ranges::view_base {
+ NoexceptView() noexcept;
+
+ int const* begin() const;
+ int const* end() const;
+};
+
+static_assert(noexcept(std::ranges::to_input_view<NoexceptView>()));
+
+struct NoNoexceptView : std::ranges::view_base {
+ NoNoexceptView() noexcept(false);
+
+ int const* begin() const;
+ int const* end() const;
+};
+
+static_assert(!noexcept(std::ranges::to_input_view<NoNoexceptView>()));
+
+constexpr bool test() {
+ { // value-initialized (i.e., whether T() is well-formed).
+ std::ranges::to_input_view<DefaultInitializableView> to_input_view{};
+ assert(to_input_view.base().i_ == 94);
+ }
+ { // direct-list-initialized from an empty initializer list (i.e., whether T{} is well-formed).
+ std::ranges::to_input_view<DefaultInitializableView> to_input_view = {};
+ assert(to_input_view.base().i_ == 94);
+ }
+ { // default-initialized (i.e., whether T t; is well-formed).
+ std::ranges::to_input_view<DefaultInitializableView> to_input_view;
+ assert(to_input_view.base().i_ == 94);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.view.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.view.pass.cpp
new file mode 100644
index 0000000000000..9a532891b9446
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/ctor.view.pass.cpp
@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// constexpr explicit to_input_view(V base);
+
+constexpr bool test() { return true; }
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/enable_borrowed_range.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/enable_borrowed_range.compile.pass.cpp
new file mode 100644
index 0000000000000..15710b8b57281
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/enable_borrowed_range.compile.pass.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// template<class V>
+// constexpr bool enable_borrowed_range<to_input_view<V>> =
+// enable_borrowed_range<V>;
+
+#include <ranges>
+#include <tuple>
+
+struct BorrowedView : std::ranges::view_base {
+ int* begin();
+ int* end();
+};
+
+template <>
+inline constexpr bool std::ranges::enable_borrowed_range<BorrowedView> = true;
+
+static_assert(std::ranges::borrowed_range<std::ranges::to_input_view<BorrowedView>>);
+
+struct NonBorrowedView : std::ranges::view_base {
+ int* begin();
+ int* end();
+};
+
+static_assert(!std::ranges::borrowed_range<std::ranges::to_input_view<NonBorrowedView>>);
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/end.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/end.pass.cpp
new file mode 100644
index 0000000000000..98ba9515daa04
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/end.pass.cpp
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// constexpr auto end() requires (!simple-view<V>);
+// constexpr auto end() const requires range<const V>;
+
+constexpr bool test() { return true; }
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/general.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/general.pass.cpp
new file mode 100644
index 0000000000000..ebfc3e166b214
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/general.pass.cpp
@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// Functional tests of std::ranges::to_input_view.
+
+#include <cassert>
+#include <ranges>
+#include <string>
+#include <vector>
+#include <algorithm>
+
+template <class R, class I>
+constexpr bool isEqual(R& r, I i) {
+ for (auto e : r)
+ if (e != *i++)
+ return false;
+
+ return true;
+}
+
+constexpr bool test() {
+ std::vector<std::string> vec{"Hello", ",", " ", "World", "!"};
+ std::string expectedStr = "Hello, World!";
+
+ {
+ auto view = vec | std::views::join;
+ assert(isEqual(view, expectedStr.begin()));
+ }
+ { // Test to_input_view with a vector of strings.
+ auto view = vec | std::views::to_input | std::views::join;
+ assert(isEqual(view, expectedStr.begin()));
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/iterator/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/iterator/ctor.default.pass.cpp
new file mode 100644
index 0000000000000..233607517052e
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/iterator/ctor.default.pass.cpp
@@ -0,0 +1,80 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// template<input_range V>
+// requires view<V>
+// template<bool Const>
+// class to_input_view<V>::iterator
+
+// iterator() requires default_initializable<iterator_t<Base>> = default;
+
+#include <cassert>
+#include <ranges>
+#include <type_traits>
+
+#include "test_iterators.h"
+
+struct DefaultInitializableIterator {
+ int i_; // Deliberately uninitialized.
+
+ using difference_type = std::intptr_t;
+ using value_type = int;
+ using iterator_category = std::random_access_iterator_tag;
+
+ constexpr int operator*() const { return i_; }
+
+ constexpr DefaultInitializableIterator& operator++() { return *this; }
+ constexpr void operator++(int) {}
+
+ friend constexpr bool operator==(const DefaultInitializableIterator&, const DefaultInitializableIterator&) = default;
+};
+
+static_assert(std::default_initializable<DefaultInitializableIterator>);
+
+struct DefaultInitializableIteratorView : std::ranges::view_base {
+ DefaultInitializableIterator begin() const;
+ DefaultInitializableIterator end() const;
+};
+
+struct NonDefaultInitializableIteratorView : std::ranges::view_base {
+ static_assert(!std::default_initializable<cpp20_input_iterator<int*>>);
+
+ cpp20_input_iterator<int*> begin() const;
+ sentinel_wrapper<cpp20_input_iterator<int*>> end() const;
+};
+
+template <class View>
+using ToInputViewIteratorT = std::ranges::iterator_t<std::ranges::to_input_view<View>>;
+
+// Check that the to_input_view's iterator is default initializable when the underlying iterator is.
+static_assert(std::default_initializable<ToInputViewIteratorT<DefaultInitializableIteratorView>>);
+static_assert(!std::default_initializable<ToInputViewIteratorT<NonDefaultInitializableIteratorView>>);
+
+constexpr bool test() {
+ {
+ ToInputViewIteratorT<DefaultInitializableIteratorView> it;
+ assert(*it == 0); // DefaultInitializableIterator has to be initialized to have value 0.
+ }
+ {
+ ToInputViewIteratorT<DefaultInitializableIteratorView> it = {};
+ assert(*it == 0); // DefaultInitializableIterator has to be initialized to have value 0.
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.to_input/size.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.to_input/size.pass.cpp
new file mode 100644
index 0000000000000..40ab3362076bd
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.to_input/size.pass.cpp
@@ -0,0 +1,109 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <ranges>
+
+// class to_input_view
+
+// constexpr auto size() requires sized_range<V>;
+// constexpr auto size() const requires sized_range<const V>;
+
+#include <array>
+#include <cassert>
+#include <ranges>
+#include <utility>
+
+#include "test_iterators.h"
+
+template <class T>
+concept HasSize = requires(T t) { t.size(); };
+
+constexpr bool test() {
+ {
+ struct SubtractableIteratorsView : std::ranges::view_base {
+ forward_iterator<int*> begin();
+ sized_sentinel<forward_iterator<int*>> end();
+ };
+
+ using ToInputViewT = std::ranges::to_input_view<SubtractableIteratorsView>;
+
+ static_assert(std::ranges::sized_range<ToInputViewT&>);
+ static_assert(!std::ranges::range<const ToInputViewT&>); // no begin()/end()
+
+ static_assert(HasSize<ToInputViewT&>);
+ static_assert(HasSize<ToInputViewT&&>);
+ static_assert(!HasSize<const ToInputViewT&>);
+ static_assert(!HasSize<const ToInputViewT&&>);
+ }
+ {
+ struct NonSizedView : std::ranges::view_base {
+ bidirectional_iterator<int*> begin();
+ bidirectional_iterator<int*> end();
+ };
+
+ using ToInputViewT = std::ranges::to_input_view<NonSizedView>;
+
+ static_assert(!HasSize<ToInputViewT&>);
+ static_assert(!HasSize<ToInputViewT&&>);
+ static_assert(!HasSize<const ToInputViewT&>);
+ static_assert(!HasSize<const ToInputViewT&&>);
+ }
+ {
+ struct SizedView : std::ranges::view_base {
+ bidirectional_iterator<int*> begin();
+ bidirectional_iterator<int*> end();
+
+ int size() const;
+ };
+
+ using ToInputViewT = std::ranges::to_input_view<SizedView>;
+
+ static_assert(std::ranges::sized_range<ToInputViewT&>);
+ static_assert(!std::ranges::range<const ToInputViewT&>); // no begin()/end()
+
+ static_assert(HasSize<ToInputViewT&>);
+ static_assert(HasSize<ToInputViewT&&>);
+ static_assert(!HasSize<const ToInputViewT&>); // not a view, therefore no size()
+ static_assert(!HasSize<const ToInputViewT&&>);
+ }
+ {
+ // Test an empty view.
+ int arr[] = {94};
+ auto view = std::ranges::to_input_view(std::ranges::subrange(arr, arr));
+
+ assert(view.size() == 0);
+ assert(std::as_const(view).size() == 0);
+ }
+ {
+ // Test a non-empty view.
+ int arr[] = {94};
+ auto view = std::ranges::to_input_view(std::ranges::subrange(arr, arr + 1));
+
+ assert(view.size() == 1);
+ assert(std::as_const(view).size() == 1);
+ }
+ {
+ // Test a non-view.
+ std::array<int, 2> arr = {94, 82};
+ auto view = std::ranges::to_input_view(std::move(arr));
+
+ assert(view.size() == 2);
+ assert(std::as_const(view).size() == 2);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index fe175fd758726..e04150dce8c9b 100644
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1147,6 +1147,11 @@ def add_version_header(tc):
"values": {"c++23": 202202},
"headers": ["ranges"],
},
+ {
+ "name": "__cpp_lib_ranges_to_input",
+ "values": {"c++26": 202502},
+ "headers": ["ranges"],
+ },
{
"name": "__cpp_lib_ranges_zip",
"values": {"c++23": 202110},
More information about the libcxx-commits
mailing list