[clang-tools-extra] [llvm] [libcxx] [clang] [libcxx] adds ranges::fold_left_with_iter and ranges::fold_left (PR #75259)

[Konstantin Varlamov via cfe-commits]

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@@ -0,0 +1,315 @@
+//===----------------------------------------------------------------------===//
+//
+// 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);
+
+// 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 <concepts>
+#include <deque>
+#include <forward_list>
+#include <functional>
+#include <iterator>
+#include <list>
+#include <ranges>
+#include <sstream>
+#include <string_view>
+#include <string>
+#include <vector>
+
+#include "test_range.h"
+#include "invocable_with_telemetry.h"
+#include "maths.h"
+
+using std::ranges::fold_left;
+using std::ranges::fold_left_with_iter;
+
+template <class Result, class Range, class T>
+concept is_in_value_result =
+    std::same_as<Result, std::ranges::fold_left_with_iter_result<std::ranges::iterator_t<Range>, T>>;
+
+template <class Result, class T>
+concept is_dangling_with = std::same_as<Result, std::ranges::fold_left_with_iter_result<std::ranges::dangling, T>>;
+
+struct Long {
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var-const wrote:

Nit: the name `Long` seems counterintuitive.

https://github.com/llvm/llvm-project/pull/75259