[libcxx-commits] [libcxx] [libcxx] adds ranges::fold_left_with_iter and ranges::fold_left (PR #75259)
Christopher Di Bella via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Dec 13 13:23:05 PST 2023
https://github.com/cjdb updated https://github.com/llvm/llvm-project/pull/75259
>From e36a06d3b88c1f2d2169080fc242ee3203a6942d Mon Sep 17 00:00:00 2001
From: Christopher Di Bella <cjdb at google.com>
Date: Wed, 6 Dec 2023 22:41:33 +0000
Subject: [PATCH 1/3] [libcxx] extends test range types to take a value-type
This increases the types' versatility so that they're not restricted
just to `int*`.
---
.../range.ref.view/borrowing.compile.pass.cpp | 2 +-
libcxx/test/support/test_range.h | 54 ++++++++++---------
2 files changed, 29 insertions(+), 27 deletions(-)
diff --git a/libcxx/test/std/ranges/range.adaptors/range.all/range.ref.view/borrowing.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.all/range.ref.view/borrowing.compile.pass.cpp
index 4405742eb023a1..2887ef10b09786 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.all/range.ref.view/borrowing.compile.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.all/range.ref.view/borrowing.compile.pass.cpp
@@ -15,6 +15,6 @@
#include "test_range.h"
-static_assert(std::ranges::borrowed_range<std::ranges::ref_view<BorrowedRange>>);
+static_assert(std::ranges::borrowed_range<std::ranges::ref_view<BorrowedRange<>>>);
static_assert(std::ranges::borrowed_range<std::ranges::ref_view<BorrowedView>>);
static_assert(std::ranges::borrowed_range<std::ranges::ref_view<NonBorrowedView>>);
diff --git a/libcxx/test/support/test_range.h b/libcxx/test/support/test_range.h
index eea8ce16ce7fa3..22bed476666db2 100644
--- a/libcxx/test/support/test_range.h
+++ b/libcxx/test/support/test_range.h
@@ -22,55 +22,57 @@ struct sentinel {
bool operator==(std::input_or_output_iterator auto const&) const;
};
-template <template <class...> class I>
-requires std::input_or_output_iterator<I<int*> >
+template <template <class...> class I, class T = int>
+ requires std::input_or_output_iterator<I<T*> >
struct test_range {
- I<int*> begin();
- I<int const*> begin() const;
+ I<T*> begin();
+ I<T const*> begin() const;
sentinel end();
sentinel end() const;
};
-template <template <class...> class I>
-requires std::input_or_output_iterator<I<int*> >
+template <template <class...> class I, class T = int>
+ requires std::input_or_output_iterator<I<T*> >
struct test_non_const_range {
- I<int*> begin();
+ I<T*> begin();
sentinel end();
};
-template <template <class...> class I>
-requires std::input_or_output_iterator<I<int*> >
+template <template <class...> class I, class T = int>
+ requires std::input_or_output_iterator<I<T*> >
struct test_common_range {
- I<int*> begin();
- I<int const*> begin() const;
- I<int*> end();
- I<int const*> end() const;
+ I<T*> begin();
+ I<T const*> begin() const;
+ I<T*> end();
+ I<T const*> end() const;
};
-template <template <class...> class I>
-requires std::input_or_output_iterator<I<int*> >
+template <template <class...> class I, class T = int>
+ requires std::input_or_output_iterator<I<T*> >
struct test_non_const_common_range {
- I<int*> begin();
- I<int*> end();
+ I<T*> begin();
+ I<T*> end();
};
-template <template <class...> class I>
-requires std::input_or_output_iterator<I<int*> >
+template <template <class...> class I, class T = int>
+ requires std::input_or_output_iterator<I<T*> >
struct test_view : std::ranges::view_base {
- I<int*> begin();
- I<int const*> begin() const;
+ I<T*> begin();
+ I<T const*> begin() const;
sentinel end();
sentinel end() const;
};
+template <class T = int>
struct BorrowedRange {
- int *begin() const;
- int *end() const;
+ T* begin() const;
+ T* end() const;
BorrowedRange(BorrowedRange&&) = delete;
};
-template<> inline constexpr bool std::ranges::enable_borrowed_range<BorrowedRange> = true;
-static_assert(!std::ranges::view<BorrowedRange>);
-static_assert(std::ranges::borrowed_range<BorrowedRange>);
+template <class T>
+inline constexpr bool std::ranges::enable_borrowed_range<BorrowedRange<T>> = true;
+static_assert(!std::ranges::view<BorrowedRange<>>);
+static_assert(std::ranges::borrowed_range<BorrowedRange<>>);
using BorrowedView = std::ranges::empty_view<int>;
static_assert(std::ranges::view<BorrowedView>);
>From b373740807a7426c3089d8e864f7f71b1c398010 Mon Sep 17 00:00:00 2001
From: Christopher Di Bella <cjdb at google.com>
Date: Wed, 13 Dec 2023 00:15:37 +0000
Subject: [PATCH 2/3] [libcxx] adds `ranges::fold_left_with_iter` and
`ranges::fold_left`
---
libcxx/include/CMakeLists.txt | 1 +
libcxx/include/__algorithm/fold.h | 118 ++++++++++++
libcxx/include/algorithm | 1 +
libcxx/include/module.modulemap.in | 1 +
.../ranges.nodiscard_extensions.verify.cpp | 13 ++
.../fold_left/requirements.compile.pass.cpp | 99 ++++++++++
.../fold_left/return_types.compile.pass.cpp | 171 +++++++++++++++++
.../alg.fold/fold_left/valid.pass.cpp | 93 ++++++++++
.../requirements.compile.pass.cpp | 107 +++++++++++
.../return_types.compile.pass.cpp | 174 ++++++++++++++++++
.../fold_left_with_iter/valid.pass.cpp | 116 ++++++++++++
.../alg.nonmodifying/alg.fold/gaussian_sum.h | 19 ++
.../alg.nonmodifying/alg.fold/requirements.h | 82 +++++++++
.../input_iterator.compile.pass.cpp | 1 +
.../niebloid.compile.pass.cpp | 4 +
15 files changed, 1000 insertions(+)
create mode 100644 libcxx/include/__algorithm/fold.h
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/requirements.compile.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/return_types.compile.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/valid.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/requirements.compile.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/return_types.compile.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/valid.pass.cpp
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/gaussian_sum.h
create mode 100644 libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/requirements.h
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index d8faf6467b79ae..95702288a3c2f3 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -22,6 +22,7 @@ set(files
__algorithm/find_first_of.h
__algorithm/find_if.h
__algorithm/find_if_not.h
+ __algorithm/fold.h
__algorithm/for_each.h
__algorithm/for_each_n.h
__algorithm/for_each_segment.h
diff --git a/libcxx/include/__algorithm/fold.h b/libcxx/include/__algorithm/fold.h
new file mode 100644
index 00000000000000..ad4e9820b479f6
--- /dev/null
+++ b/libcxx/include/__algorithm/fold.h
@@ -0,0 +1,118 @@
+// -*- 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___ALGORITHM_FOLD_H
+#define _LIBCPP___ALGORITHM_FOLD_H
+
+#include <__concepts/assignable.h>
+#include <__concepts/convertible_to.h>
+#include <__concepts/invocable.h>
+#include <__concepts/movable.h>
+#include <__config>
+#include <__functional/invoke.h>
+#include <__functional/reference_wrapper.h>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/invoke.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+namespace ranges {
+template <class _Ip, class _Tp>
+struct in_value_result {
+ _Ip in;
+ _Tp result;
+};
+
+template <class _Ip, class _Tp>
+using fold_left_with_iter_result = in_value_result<_Ip, _Tp>;
+
+template <class _Fp, class _Tp, class _Ip, class _Rp, class _Up = decay_t<_Rp>>
+concept __indirectly_binary_left_foldable_impl =
+ convertible_to<_Rp, _Up> && //
+ movable<_Tp> && //
+ movable<_Up> && //
+ convertible_to<_Tp, _Up> && //
+ invocable<_Fp&, _Up, iter_reference_t<_Ip>> && //
+ assignable_from<_Up&, invoke_result_t<_Fp&, _Up, iter_reference_t<_Ip>>>;
+
+template <class _Fp, class _Tp, class _Ip>
+concept __indirectly_binary_left_foldable =
+ copy_constructible<_Fp> && //
+ invocable<_Fp&, _Tp, iter_reference_t<_Ip>> && //
+ __indirectly_binary_left_foldable_impl<_Fp, _Tp, _Ip, invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
+
+struct __fold_left_with_iter {
+ template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto
+ operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) const {
+ using _Up = decay_t<invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
+
+ if (__first == __last) {
+ return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), _Up(std::move(__init))};
+ }
+
+ _Up __result = std::invoke(__f, std::move(__init), *__first);
+ for (++__first; __first != __last; ++__first) {
+ __result = std::invoke(__f, std::move(__result), *__first);
+ }
+
+ return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), std::move(__result)};
+ }
+
+ template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) const {
+ auto __result = (*this)(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
+
+ using _Up = decay_t<invoke_result_t<_Fp&, _Tp, range_reference_t<_Rp>>>;
+ return fold_left_with_iter_result<borrowed_iterator_t<_Rp>, _Up>{
+ std::move(__result.in), std::move(__result.result)};
+ }
+};
+
+inline namespace __cpo {
+inline constexpr auto fold_left_with_iter = __fold_left_with_iter();
+} // namespace __cpo
+
+struct __fold_left {
+ template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto
+ operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) const {
+ return fold_left_with_iter(std::move(__first), std::move(__last), std::move(__init), std::ref(__f)).result;
+ }
+
+ template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) const {
+ return fold_left_with_iter(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f)).result;
+ }
+};
+
+inline namespace __cpo {
+inline constexpr auto fold_left = __fold_left();
+} // namespace __cpo
+} // namespace ranges
+
+#endif // _LIBCPP_STD_VER >= 23
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ALGORITHM_FOLD_H
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 627e7d20213fe8..3fd9ba10f6310b 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -1778,6 +1778,7 @@ template <class BidirectionalIterator, class Compare>
#include <__algorithm/find_first_of.h>
#include <__algorithm/find_if.h>
#include <__algorithm/find_if_not.h>
+#include <__algorithm/fold.h>
#include <__algorithm/for_each.h>
#include <__algorithm/for_each_n.h>
#include <__algorithm/generate.h>
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 90ee7fbb2157c2..359de41fdd128d 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -665,6 +665,7 @@ module std_private_algorithm_find_end [system
module std_private_algorithm_find_first_of [system] { header "__algorithm/find_first_of.h" }
module std_private_algorithm_find_if [system] { header "__algorithm/find_if.h" }
module std_private_algorithm_find_if_not [system] { header "__algorithm/find_if_not.h" }
+module std_private_algorithm_fold [system] { header "__algorithm/fold.h" }
module std_private_algorithm_for_each [system] { header "__algorithm/for_each.h" }
module std_private_algorithm_for_each_n [system] { header "__algorithm/for_each_n.h" }
module std_private_algorithm_for_each_segment [system] { header "__algorithm/for_each_segment.h" }
diff --git a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
index d11dcfcd0d2e41..f0a0e4889a7603 100644
--- a/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/ranges.nodiscard_extensions.verify.cpp
@@ -12,6 +12,8 @@
#include <algorithm>
+#include "test_macros.h"
+
void test() {
int range[1];
int* iter = range;
@@ -87,4 +89,15 @@ void test() {
std::ranges::unique(iter, iter); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
std::ranges::upper_bound(range, 1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
std::ranges::upper_bound(iter, iter, 1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+#if TEST_STD_VER >= 23
+ std::ranges::fold_left(range, 0, std::plus());
+ // expected-warning at -1{{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::ranges::fold_left(iter, iter, 0, std::plus());
+ // expected-warning at -1{{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::ranges::fold_left_with_iter(range, 0, std::plus());
+ // expected-warning at -1{{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::ranges::fold_left_with_iter(iter, iter, 0, std::plus());
+ // expected-warning at -1{{ignoring return value of function declared with 'nodiscard' attribute}}
+#endif
}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/requirements.compile.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/requirements.compile.pass.cpp
new file mode 100644
index 00000000000000..0b1c1e4eae1ea5
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/requirements.compile.pass.cpp
@@ -0,0 +1,99 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// Checks that `std::ranges::fold_left`'s requirements are correct.
+
+#include <algorithm>
+#include <concepts>
+#include <functional>
+#include <iterator>
+#include <ranges>
+
+#include "test_iterators.h"
+#include "../requirements.h"
+
+// Covers indirectly_readable<I> too
+template <std::input_or_output_iterator T>
+ requires(!std::input_iterator<T>)
+void requires_input_iterator() {
+ static_assert(!requires(T t) { std::ranges::fold_left(t, std::unreachable_sentinel, 0, std::plus()); });
+}
+
+template <std::equality_comparable T>
+ requires(!std::sentinel_for<int*, T>)
+void requires_sentinel() {
+ static_assert(!requires(T first, T last) { std::ranges::fold_left(first, last, 0, std::plus()); });
+}
+
+template <class F>
+ requires(!std::copy_constructible<F>)
+void requires_copy_constructible_F() {
+ static_assert(!requires(int* first, int* last, F f) { std::ranges::fold_left(first, last, 0, std::move(f)); });
+}
+
+template <class F>
+ requires(!std::invocable<F&, int, std::iter_reference_t<int*>>)
+void requires_raw_invocable() {
+ static_assert(!requires(int* first, int* last, F f) { std::ranges::fold_left(first, last, 0, f); });
+}
+
+template <class F>
+ requires(!std::convertible_to<std::invoke_result_t<F&, S, std::iter_reference_t<S*>>,
+ std::decay_t<std::invoke_result_t<F&, S, std::iter_reference_t<S*>>>>)
+void requires_decaying_invoke_result() {
+ static_assert(!requires(S* first, S* last, S init, F f) { std::ranges::fold_left(first, last, init, f); });
+}
+
+template <class T>
+ requires(!std::movable<T>)
+void requires_movable_init() {
+ static_assert(!requires(copyable_non_movable* first, copyable_non_movable* last, T init) {
+ std::ranges::fold_left(first, last, init, std::plus());
+ });
+}
+
+template <class T>
+ requires(!std::movable<T>)
+void requires_movable_decayed() {
+ static_assert(!requires(T* first, T* last) { std::ranges::fold_left(first, last, 0, std::minus()); });
+}
+
+template <class T>
+ requires(!std::convertible_to<T, int>)
+void requires_init_is_convertible_to_decayed() {
+ static_assert(!requires(int* first, int* last, T init) { std::ranges::fold_left(first, last, init, std::plus()); });
+}
+
+template <class T>
+ requires(!std::invocable<std::plus<>&, T, T&>)
+void requires_invocable_with_decayed() {
+ static_assert(!requires(T* first, T* last, int init) { std::ranges::fold_left(first, last, init, std::plus()); });
+}
+
+template <class T>
+ requires(!std::assignable_from<T&, T volatile&>)
+void requires_assignable_from_invoke_result() {
+ static_assert(!requires(T* first, T* last, T init) { std::ranges::fold_left(first, last, init, std::plus()); });
+}
+
+void test() {
+ requires_input_iterator<bad_iterator_category>();
+ requires_sentinel<cpp17_input_iterator<int*>>();
+ requires_copy_constructible_F<non_copy_constructible_callable>();
+ requires_raw_invocable<not_invocable>();
+ requires_decaying_invoke_result<non_decayable_result>();
+ requires_movable_init<non_movable>();
+ requires_movable_decayed<copyable_non_movable>();
+ requires_init_is_convertible_to_decayed<not_convertible_to_int>();
+ requires_invocable_with_decayed<not_invocable_with_decayed>();
+ requires_assignable_from_invoke_result<not_assignable_to_decayed>();
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/return_types.compile.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/return_types.compile.pass.cpp
new file mode 100644
index 00000000000000..911ce1615a1c75
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/return_types.compile.pass.cpp
@@ -0,0 +1,171 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// Checks that `std::ranges::fold_left`'s return type is correct.
+
+#include <algorithm>
+#include <concepts>
+#include <functional>
+#include <ranges>
+
+#include "test_iterators.h"
+#include "test_range.h"
+
+template <class Result, class T>
+concept is_T = std::same_as<Result, T>;
+
+using std::ranges::fold_left;
+[[maybe_unused]] auto f = [](int x, double y) { return x * y; };
+
+struct Int {
+ int value;
+};
+
+struct Long {
+ int value;
+
+ Long plus(Int) const;
+};
+
+namespace sentinel_based_ranges {
+template <class T>
+using cpp17_input_range = test_range<cpp17_input_iterator, T>;
+
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left(r, 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left(std::move(r), 0, std::plus()) } -> std::same_as<int>;
+});
+
+template <class T>
+using cpp20_input_range = test_range<cpp20_input_iterator, T>;
+
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left(r, 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left(std::move(r), 0, std::plus()) } -> std::same_as<int>;
+});
+
+template <class T>
+using forward_range = test_range<forward_iterator, T>;
+
+static_assert(requires(forward_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(forward_range<int> r) {
+ { fold_left(r, 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(forward_range<int> r) {
+ { fold_left(std::move(r), 0, std::plus()) } -> std::same_as<int>;
+});
+
+template <class T>
+using bidirectional_range = test_range<bidirectional_iterator, T>;
+
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left(r.begin(), r.end(), 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left(r, 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left(std::move(r), 0, f) } -> std::same_as<double>;
+});
+
+template <class T>
+using random_access_range = test_range<random_access_iterator, T>;
+
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(r, 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(std::move(r), 0, f) } -> std::same_as<double>;
+});
+
+template <class T>
+using contiguous_range = test_range<contiguous_iterator, T>;
+
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0.0f, std::plus()) } -> std::same_as<float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(r, 0.0f, std::plus()) } -> std::same_as<float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(std::move(r), 0.0f, std::plus()) } -> std::same_as<float>;
+});
+} // namespace sentinel_based_ranges
+
+namespace common_ranges {
+template <class T>
+using forward_range = test_common_range<forward_iterator, T>;
+
+static_assert(requires(forward_range<Int> r) {
+ { fold_left(r.begin(), r.end(), Long(0), &Long::plus) } -> std::same_as<Long>;
+});
+static_assert(requires(forward_range<Int> r) {
+ { fold_left(r, Long(0), &Long::plus) } -> std::same_as<Long>;
+});
+static_assert(requires(forward_range<Int> r) {
+ { fold_left(std::move(r), Long(0), &Long::plus) } -> std::same_as<Long>;
+});
+
+template <class T>
+using bidirectional_range = test_common_range<bidirectional_iterator, T>;
+
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left(r, 0, std::plus()) } -> std::same_as<int>;
+});
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left(std::move(r), 0, std::plus()) } -> std::same_as<int>;
+});
+
+template <class T>
+using random_access_range = test_common_range<random_access_iterator, T>;
+
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(r, 0, f) } -> std::same_as<double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left(std::move(r), 0, f) } -> std::same_as<double>;
+});
+
+template <class T>
+using contiguous_range = test_common_range<contiguous_iterator, T>;
+
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(r.begin(), r.end(), 0.0f, std::plus()) } -> std::same_as<float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(r, 0.0f, std::plus()) } -> std::same_as<float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left(std::move(r), 0.0f, std::plus()) } -> std::same_as<float>;
+});
+} // namespace common_ranges
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/valid.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/valid.pass.cpp
new file mode 100644
index 00000000000000..ef0fbb4b2a6d39
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left/valid.pass.cpp
@@ -0,0 +1,93 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// template<input_iterator I, sentinel_for<I> S, class T,
+// indirectly-binary-left-foldable<T, I> F>
+// constexpr see below ranges::fold_left(I first, S last, T init, F f);
+//
+// template<input_range R, class T, indirectly-binary-left-foldable<T, iterator_t<R>> F>
+// constexpr see below ranges::fold_left(R&& r, T init, F f);
+
+#include <algorithm>
+#include <cassert>
+#include <vector>
+#include <functional>
+
+#include "test_range.h"
+#include "../gaussian_sum.h"
+
+constexpr bool test() {
+ {
+ auto data = std::vector<int>{1, 2, 3, 4};
+ auto const result = std::ranges::fold_left(data.begin(), data.begin(), 0, std::plus());
+
+ assert(result == 0);
+
+ auto range = std::span(data.data(), 0);
+ assert(std::ranges::fold_left(range, 0, std::plus()) == result);
+ }
+ {
+ auto data = std::vector<int>{1, 2, 3, 4};
+ constexpr auto init = 100.1;
+ auto const result = std::ranges::fold_left(data.begin(), data.begin(), init, std::plus());
+
+ assert(result == init);
+
+ auto range = std::span(data.data(), 0);
+ assert(std::ranges::fold_left(range, init, std::plus()) == result);
+ }
+ {
+ auto data = std::vector{1, 3, 5, 7, 9};
+ auto const result = std::ranges::fold_left(data.begin(), data.end(), 0, std::plus());
+
+ assert(result == gaussian_sum(data)); // sum of n ascending odd numbers = n^2
+ assert(std::ranges::fold_left(data, 0, std::plus()) == result);
+ }
+ {
+ auto data = std::vector{2, 4, 6, 8, 10, 12};
+ auto const result = std::ranges::fold_left(data.begin(), data.end(), 0L, std::plus<long>());
+
+ assert(result == gaussian_sum(data));
+ assert(std::ranges::fold_left(data, 0, std::plus()) == result);
+ }
+ {
+ auto data = std::vector{-1.1, -2.2, -3.3, -4.4, -5.5, -6.6};
+ auto plus = [](int const x, double const y) { return x + y; };
+ auto const result = std::ranges::fold_left(data.begin(), data.end(), 0.0, plus);
+
+ assert(result == -21.6); // int( 0.0) + -1.1 = 0 + -1.1 = -1.1
+ // int(- 1.1) + -2.2 = - 1 + -2.2 = -3.2
+ // int(- 3.2) + -3.3 = - 3 + -3.3 = -6.3
+ // int(- 6.3) + -4.4 = - 6 + -4.4 = -10.4
+ // int(-10.4) + -5.5 = -10 + -5.5 = -15.5
+ // int(-15.5) + -6.6 = -15 + -6.6 = -21.6.
+
+ assert(std::ranges::fold_left(data, 0, plus) == result);
+ }
+ {
+ auto data = std::vector<double>{1.1, 2.1, 3.1, 4.1, 5.1, 6.1, 7.1, 8.1, 9.1};
+ auto plus = [](double const x, double const y) { return static_cast<short>(x + y); };
+ constexpr auto init = 10.0;
+ auto const result = std::ranges::fold_left(data.begin(), data.end(), init, plus);
+
+ assert(result == static_cast<short>(gaussian_sum(data) + init));
+ assert(std::ranges::fold_left(data, init, plus) == result);
+ }
+
+ return true;
+}
+
+int main() {
+ test();
+ static_assert(test());
+ return 0;
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/requirements.compile.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/requirements.compile.pass.cpp
new file mode 100644
index 00000000000000..c0f647b5fc88f1
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/requirements.compile.pass.cpp
@@ -0,0 +1,107 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// Checks that `std::ranges::fold_left_with_iter`'s requirements are correct.
+
+#include <algorithm>
+#include <concepts>
+#include <functional>
+#include <iterator>
+#include <ranges>
+
+#include "test_iterators.h"
+#include "../requirements.h"
+
+// Covers indirectly_readable<I> too
+template <std::input_or_output_iterator T>
+ requires(!std::input_iterator<T>)
+void requires_input_iterator() {
+ static_assert(!requires(T t) { std::ranges::fold_left_with_iter(t, std::unreachable_sentinel, 0, std::plus()); });
+}
+
+template <std::equality_comparable T>
+ requires(!std::sentinel_for<int*, T>)
+void requires_sentinel() {
+ static_assert(!requires(T first, T last) { std::ranges::fold_left_with_iter(first, last, 0, std::plus()); });
+}
+
+template <class F>
+ requires(!std::copy_constructible<F>)
+void requires_copy_constructible_F() {
+ static_assert(!requires(int* first, int* last, F f) {
+ std::ranges::fold_left_with_iter(first, last, 0, std::move(f));
+ });
+}
+
+template <class F>
+ requires(!std::invocable<F&, int, std::iter_reference_t<int*>>)
+void requires_raw_invocable() {
+ static_assert(!requires(int* first, int* last, F f) { std::ranges::fold_left_with_iter(first, last, 0, f); });
+}
+
+template <class F>
+ requires(!std::convertible_to<std::invoke_result_t<F&, S, std::iter_reference_t<S*>>,
+ std::decay_t<std::invoke_result_t<F&, S, std::iter_reference_t<S*>>>>)
+void requires_decaying_invoke_result() {
+ static_assert(!requires(S* first, S* last, S init, F f) { std::ranges::fold_left_with_iter(first, last, init, f); });
+}
+
+template <class T>
+ requires(!std::movable<T>)
+void requires_movable_init() {
+ static_assert(!requires(copyable_non_movable* first, copyable_non_movable* last, T init) {
+ std::ranges::fold_left_with_iter(first, last, init, std::plus());
+ });
+}
+
+template <class T>
+ requires(!std::movable<T>)
+void requires_movable_decayed() {
+ static_assert(!requires(T* first, T* last) { std::ranges::fold_left_with_iter(first, last, 0, std::minus()); });
+}
+
+template <class T>
+ requires(!std::convertible_to<T, int>)
+void requires_init_is_convertible_to_decayed() {
+ static_assert(!requires(int* first, int* last, T init) {
+ std::ranges::fold_left_with_iter(first, last, init, std::plus());
+ });
+}
+
+template <class T>
+ requires(!std::invocable<std::plus<>&, T, T&>)
+void requires_invocable_with_decayed() {
+ static_assert(!requires(T* first, T* last, int init) {
+ std::ranges::fold_left_with_iter(first, last, init, std::plus());
+ });
+}
+
+template <class T>
+ requires(!std::assignable_from<T&, T volatile&>)
+void requires_assignable_from_invoke_result() {
+ static_assert(!requires(T* first, T* last, T init) {
+ std::ranges::fold_left_with_iter(first, last, init, std::plus());
+ });
+}
+
+void test() {
+ requires_input_iterator<bad_iterator_category>();
+ requires_sentinel<cpp17_input_iterator<int*>>();
+ requires_copy_constructible_F<non_copy_constructible_callable>();
+ requires_raw_invocable<not_invocable>();
+ requires_decaying_invoke_result<non_decayable_result>();
+ requires_movable_init<non_movable>();
+ requires_movable_decayed<copyable_non_movable>();
+ requires_init_is_convertible_to_decayed<not_convertible_to_int>();
+ requires_invocable_with_decayed<not_invocable_with_decayed>();
+ requires_assignable_from_invoke_result<not_assignable_to_decayed>();
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/return_types.compile.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/return_types.compile.pass.cpp
new file mode 100644
index 00000000000000..b930002336294d
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/return_types.compile.pass.cpp
@@ -0,0 +1,174 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// Checks that `std::ranges::fold_left_with_iter`'s return type is correct.
+
+#include <algorithm>
+#include <concepts>
+#include <functional>
+#include <ranges>
+
+#include "test_iterators.h"
+#include "test_range.h"
+
+template <class Result, class Range, class T>
+concept is_in_value_result = std::same_as<Result, std::ranges::in_value_result<std::ranges::iterator_t<Range>, T>>;
+
+template <class Result, class T>
+concept is_dangling_with = std::same_as<Result, std::ranges::in_value_result<std::ranges::dangling, T>>;
+
+using std::ranges::fold_left_with_iter;
+[[maybe_unused]] auto f = [](int x, double y) { return x * y; };
+
+struct Int {
+ int value;
+};
+
+struct Long {
+ int value;
+
+ Long plus(Int) const;
+};
+
+namespace sentinel_based_ranges {
+template <class T>
+using cpp17_input_range = test_range<cpp17_input_iterator, T>;
+
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, std::plus()) } -> is_in_value_result<cpp17_input_range<int>, int>;
+});
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left_with_iter(r, 0, std::plus()) } -> is_in_value_result<cpp17_input_range<int>, int>;
+});
+static_assert(requires(cpp17_input_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, std::plus()) } -> is_dangling_with<int>;
+});
+
+template <class T>
+using cpp20_input_range = test_range<cpp20_input_iterator, T>;
+
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, std::plus()) } -> is_in_value_result<cpp20_input_range<int>, int>;
+});
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left_with_iter(r, 0, std::plus()) } -> is_in_value_result<cpp20_input_range<int>, int>;
+});
+static_assert(requires(cpp20_input_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, std::plus()) } -> is_dangling_with<int>;
+});
+
+template <class T>
+using forward_range = test_range<forward_iterator, T>;
+
+static_assert(requires(forward_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, std::plus()) } -> is_in_value_result<forward_range<int>, int>;
+});
+static_assert(requires(forward_range<int> r) {
+ { fold_left_with_iter(r, 0, std::plus()) } -> is_in_value_result<forward_range<int>, int>;
+});
+static_assert(requires(forward_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, std::plus()) } -> is_dangling_with<int>;
+});
+
+template <class T>
+using bidirectional_range = test_range<bidirectional_iterator, T>;
+
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, f) } -> is_in_value_result<bidirectional_range<short>, double>;
+});
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left_with_iter(r, 0, f) } -> is_in_value_result<bidirectional_range<short>, double>;
+});
+static_assert(requires(bidirectional_range<short> r) {
+ { fold_left_with_iter(std::move(r), 0, f) } -> is_dangling_with<double>;
+});
+
+template <class T>
+using random_access_range = test_range<random_access_iterator, T>;
+
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, f) } -> is_in_value_result<random_access_range<int>, double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(r, 0, f) } -> is_in_value_result<random_access_range<int>, double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, f) } -> is_dangling_with<double>;
+});
+
+template <class T>
+using contiguous_range = test_range<contiguous_iterator, T>;
+
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0.0f, std::plus()) } -> is_in_value_result<contiguous_range<int>, float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(r, 0.0f, std::plus()) } -> is_in_value_result<contiguous_range<int>, float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0.0f, std::plus()) } -> is_dangling_with<float>;
+});
+} // namespace sentinel_based_ranges
+
+namespace common_ranges {
+template <class T>
+using forward_range = test_common_range<forward_iterator, T>;
+
+static_assert(requires(forward_range<Int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), Long(0), &Long::plus) } -> is_in_value_result<forward_range<Int>, Long>;
+});
+static_assert(requires(forward_range<Int> r) {
+ { fold_left_with_iter(r, Long(0), &Long::plus) } -> is_in_value_result<forward_range<Int>, Long>;
+});
+static_assert(requires(forward_range<Int> r) {
+ { fold_left_with_iter(std::move(r), Long(0), &Long::plus) } -> is_dangling_with<Long>;
+});
+
+template <class T>
+using bidirectional_range = test_common_range<bidirectional_iterator, T>;
+
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, std::plus()) } -> is_in_value_result<bidirectional_range<int>, int>;
+});
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left_with_iter(r, 0, std::plus()) } -> is_in_value_result<bidirectional_range<int>, int>;
+});
+static_assert(requires(bidirectional_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, std::plus()) } -> is_dangling_with<int>;
+});
+
+template <class T>
+using random_access_range = test_common_range<random_access_iterator, T>;
+
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0, f) } -> is_in_value_result<random_access_range<int>, double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(r, 0, f) } -> is_in_value_result<random_access_range<int>, double>;
+});
+static_assert(requires(random_access_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0, f) } -> is_dangling_with<double>;
+});
+
+template <class T>
+using contiguous_range = test_common_range<contiguous_iterator, T>;
+
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(r.begin(), r.end(), 0.0f, std::plus()) } -> is_in_value_result<contiguous_range<int>, float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(r, 0.0f, std::plus()) } -> is_in_value_result<contiguous_range<int>, float>;
+});
+static_assert(requires(contiguous_range<int> r) {
+ { fold_left_with_iter(std::move(r), 0.0f, std::plus()) } -> is_dangling_with<float>;
+});
+} // namespace common_ranges
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/valid.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/valid.pass.cpp
new file mode 100644
index 00000000000000..d8fb6525119e0c
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/fold_left_with_iter/valid.pass.cpp
@@ -0,0 +1,116 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// template<input_iterator I, sentinel_for<I> S, class T,
+// indirectly-binary-left-foldable<T, I> F>
+// constexpr see below ranges::fold_left_with_iter(I first, S last, T init, F f);
+//
+// template<input_range R, class T, indirectly-binary-left-foldable<T, iterator_t<R>> F>
+// constexpr see below ranges::fold_left_with_iter(R&& r, T init, F f);
+
+#include <algorithm>
+#include <cassert>
+#include <vector>
+#include <functional>
+
+#include "test_range.h"
+#include "../gaussian_sum.h"
+
+constexpr bool test() {
+ {
+ auto data = std::vector<int>{1, 2, 3, 4};
+ auto result = std::ranges::fold_left_with_iter(data.begin(), data.begin(), 0, std::plus());
+
+ assert(result.in == data.begin());
+ assert(result.result == 0);
+
+ auto range = std::span(data.data(), 0);
+ auto rresult = std::ranges::fold_left_with_iter(range, 0, std::plus());
+
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+ {
+ auto data = std::vector<int>{1, 2, 3, 4};
+ constexpr auto init = 100.1;
+ auto result = std::ranges::fold_left_with_iter(data.begin(), data.begin(), init, std::plus());
+
+ assert(result.in == data.begin());
+ assert(result.result == init);
+
+ auto range = std::span(data.data(), 0);
+ auto rresult = std::ranges::fold_left_with_iter(range, init, std::plus());
+
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+ {
+ auto data = std::vector{1, 3, 5, 7, 9};
+ auto result = std::ranges::fold_left_with_iter(data.begin(), data.end(), 0, std::plus());
+
+ assert(result.in == data.end());
+ assert(result.result == gaussian_sum(data)); // sum of n ascending odd numbers = n^2
+
+ auto rresult = std::ranges::fold_left_with_iter(data, 0, std::plus());
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+ {
+ auto data = std::vector{2, 4, 6, 8, 10, 12};
+ auto const result = std::ranges::fold_left_with_iter(data.begin(), data.end(), 0L, std::plus<long>());
+
+ assert(result.in == data.end());
+ assert(result.result == gaussian_sum(data));
+
+ auto rresult = std::ranges::fold_left_with_iter(data, 0, std::plus());
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+ {
+ auto data = std::vector{-1.1, -2.2, -3.3, -4.4, -5.5, -6.6};
+ auto plus = [](int const x, double const y) { return x + y; };
+ auto result = std::ranges::fold_left_with_iter(data.begin(), data.end(), 0.0, plus);
+
+ assert(result.in == data.end());
+ assert(result.result == -21.6); // int( 0.0) + -1.1 = 0 + -1.1 = -1.1
+ // int(- 1.1) + -2.2 = - 1 + -2.2 = -3.2
+ // int(- 3.2) + -3.3 = - 3 + -3.3 = -6.3
+ // int(- 6.3) + -4.4 = - 6 + -4.4 = -10.4
+ // int(-10.4) + -5.5 = -10 + -5.5 = -15.5
+ // int(-15.5) + -6.6 = -15 + -6.6 = -21.6.
+
+ auto rresult = std::ranges::fold_left_with_iter(data, 0, plus);
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+ {
+ auto data = std::vector<double>{1.1, 2.1, 3.1, 4.1, 5.1, 6.1, 7.1, 8.1, 9.1};
+ auto plus = [](double const x, double const y) { return static_cast<short>(x + y); };
+ constexpr auto init = 10.0;
+ auto result = std::ranges::fold_left_with_iter(data.begin(), data.end(), init, plus);
+
+ assert(result.in == data.end());
+ assert(result.result == static_cast<short>(gaussian_sum(data) + init));
+
+ auto rresult = std::ranges::fold_left_with_iter(data, init, plus);
+ assert(rresult.in == result.in);
+ assert(rresult.result == result.result);
+ }
+
+ return true;
+}
+
+int main() {
+ test();
+ static_assert(test());
+ return 0;
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/gaussian_sum.h b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/gaussian_sum.h
new file mode 100644
index 00000000000000..060beaa6703b1a
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/gaussian_sum.h
@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 LIBCXX_TEST_FOLD_GAUSSIAN_SUM_H
+#define LIBCXX_TEST_FOLD_GAUSSIAN_SUM_H
+
+#include <vector>
+
+template <class T>
+constexpr auto gaussian_sum(std::vector<T> const& input) {
+ return (static_cast<double>(input.size()) / 2) * (input.front() + input.back());
+}
+
+#endif // LIBCXX_TEST_FOLD_GAUSSIAN_SUM_H
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/requirements.h b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/requirements.h
new file mode 100644
index 00000000000000..0104c71b11447e
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.fold/requirements.h
@@ -0,0 +1,82 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 LIBCXX_TEST_FOLD_REQUIREMENTS_H
+#define LIBCXX_TEST_FOLD_REQUIREMENTS_H
+
+#include <cstddef>
+
+// FIXME(cjdb): deduplicate
+struct bad_iterator_category {
+ using value_type = int;
+ using difference_type = std::ptrdiff_t;
+ using iterator_category = void;
+
+ value_type operator*() const;
+
+ bad_iterator_category& operator++();
+ void operator++(int);
+};
+
+struct non_movable {
+ non_movable(non_movable&&) = delete;
+};
+
+struct copyable_non_movable {
+ copyable_non_movable(int);
+ copyable_non_movable(copyable_non_movable&&) = delete;
+ copyable_non_movable(copyable_non_movable const&);
+
+ friend int operator+(copyable_non_movable const&, non_movable const&);
+ friend int operator+(non_movable const&, copyable_non_movable const&);
+
+ friend copyable_non_movable const& operator-(int, copyable_non_movable const&);
+ friend copyable_non_movable const& operator-(copyable_non_movable const&, int);
+ friend copyable_non_movable const& operator-(copyable_non_movable const&, copyable_non_movable const&);
+};
+
+struct non_copy_constructible_callable {
+ non_copy_constructible_callable(non_copy_constructible_callable&&) = default;
+ non_copy_constructible_callable(non_copy_constructible_callable const&) = delete;
+
+ int operator()(int, int) const;
+};
+
+struct not_invocable {
+ int operator()(int, int&&);
+};
+
+struct S {};
+
+struct non_decayable_result {
+ S volatile& operator()(S, S) const;
+};
+
+struct not_convertible_to_int {
+ friend int operator+(not_convertible_to_int, not_convertible_to_int);
+ friend int operator+(not_convertible_to_int, int);
+ friend int operator+(int, not_convertible_to_int);
+};
+
+struct not_invocable_with_decayed {
+ not_invocable_with_decayed(int);
+ friend not_invocable_with_decayed& operator+(int, not_invocable_with_decayed&);
+ friend not_invocable_with_decayed& operator+(not_invocable_with_decayed&, int);
+ friend not_invocable_with_decayed& operator+(not_invocable_with_decayed volatile&, not_invocable_with_decayed&);
+};
+
+struct not_assignable_to_decayed {
+ not_assignable_to_decayed();
+ not_assignable_to_decayed(not_assignable_to_decayed&);
+ not_assignable_to_decayed(not_assignable_to_decayed const&);
+ not_assignable_to_decayed(not_assignable_to_decayed volatile&);
+ not_assignable_to_decayed(not_assignable_to_decayed const volatile&);
+ friend not_assignable_to_decayed volatile& operator+(not_assignable_to_decayed, not_assignable_to_decayed);
+};
+
+#endif // LIBCXX_TEST_FOLD_REQUIREMENTS
diff --git a/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp
index 217c68fea7bc92..0c72c70a72d27f 100644
--- a/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.input/input_iterator.compile.pass.cpp
@@ -81,6 +81,7 @@ struct not_indirectly_readable {
};
static_assert(!std::indirectly_readable<not_indirectly_readable> && !std::input_iterator<not_indirectly_readable>);
+// FIXME(cjdb): deduplicate
struct bad_iterator_category {
using value_type = int;
using difference_type = std::ptrdiff_t;
diff --git a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
index 683f88c19f6784..eeaaa6784353d6 100644
--- a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
+++ b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
@@ -83,6 +83,10 @@ static_assert(test(std::ranges::find_end, a, a));
static_assert(test(std::ranges::find_first_of, a, a));
static_assert(test(std::ranges::find_if, a, odd));
static_assert(test(std::ranges::find_if_not, a, odd));
+#if TEST_STD_VER >= 23
+static_assert(test(std::ranges::fold_left, a, 0, std::plus()));
+static_assert(test(std::ranges::fold_left_with_iter, a, 0, std::plus()));
+#endif
static_assert(test(std::ranges::for_each, a, odd));
static_assert(test(std::ranges::for_each_n, a, 10, odd));
static_assert(test(std::ranges::generate, a, gen));
>From e776610f0b0772bb690e07d07f8fc31832fcb5c7 Mon Sep 17 00:00:00 2001
From: Christopher Di Bella <cjdb at google.com>
Date: Wed, 13 Dec 2023 21:22:45 +0000
Subject: [PATCH 3/3] changes to using static opertaor()
---
libcxx/include/__algorithm/fold.h | 14 +++++++-------
libcxx/modules/std/algorithm.inc | 8 +++++++-
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/libcxx/include/__algorithm/fold.h b/libcxx/include/__algorithm/fold.h
index ad4e9820b479f6..7364b676b787c4 100644
--- a/libcxx/include/__algorithm/fold.h
+++ b/libcxx/include/__algorithm/fold.h
@@ -63,8 +63,8 @@ concept __indirectly_binary_left_foldable =
struct __fold_left_with_iter {
template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto
- operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) const {
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto
+ operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
using _Up = decay_t<invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
if (__first == __last) {
@@ -80,8 +80,8 @@ struct __fold_left_with_iter {
}
template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) const {
- auto __result = (*this)(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
+ auto __result = operator()(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
using _Up = decay_t<invoke_result_t<_Fp&, _Tp, range_reference_t<_Rp>>>;
return fold_left_with_iter_result<borrowed_iterator_t<_Rp>, _Up>{
@@ -95,13 +95,13 @@ inline constexpr auto fold_left_with_iter = __fold_left_with_iter();
struct __fold_left {
template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto
- operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) const {
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto
+ operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
return fold_left_with_iter(std::move(__first), std::move(__last), std::move(__init), std::ref(__f)).result;
}
template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) const {
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
return fold_left_with_iter(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f)).result;
}
};
diff --git a/libcxx/modules/std/algorithm.inc b/libcxx/modules/std/algorithm.inc
index b7900d15c10c2b..dfae1dcaa45de3 100644
--- a/libcxx/modules/std/algorithm.inc
+++ b/libcxx/modules/std/algorithm.inc
@@ -16,7 +16,7 @@ export namespace std {
using std::ranges::in_in_result;
using std::ranges::in_out_out_result;
using std::ranges::in_out_result;
- // using std::ranges::in_value_result;
+ using std::ranges::in_value_result;
using std::ranges::min_max_result;
// using std::ranges::out_value_result;
} // namespace ranges
@@ -48,6 +48,12 @@ export namespace std {
} // namespace ranges
#endif
+ // [alg.fold], fold
+ namespace ranges {
+ using std::ranges::fold_left;
+ using std::ranges::fold_left_with_iter;
+ } // namespace ranges
+
// [alg.foreach], for each
using std::for_each;
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