[compiler-rt] [llvm] [lld] [flang] [clang-tools-extra] [libcxx] [clang] [libc++][ranges] P2116R9: Implements `views::enumerate` (PR #73617)

[Christopher Di Bella via cfe-commits]

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@@ -0,0 +1,114 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <ranges>
+
+// class enumerate_view
+
+// constexpr auto end() requires (!simple-view<V>);
+// constexpr auto end() const requires range-with-movable-references<const V>;
+
+#include <cassert>
+#include <concepts>
+#include <ranges>
+
+#include "test_iterators.h"
+#include "types.h"
+
+constexpr bool test() {
+  int buff[] = {1, 2, 3, 4, 5, 6, 7, 8};
+
+  // Check the return type of .end()
+  {
+    RangeView range(buff, buff + 1);
+
+    std::ranges::enumerate_view view(range);
+    using Iterator = std::ranges::iterator_t<decltype(view)>;
+    static_assert(std::same_as<Iterator, decltype(view.end())>);
+    using Sentinel = std::ranges::sentinel_t<decltype(view)>;
+    static_assert(std::same_as<Sentinel, decltype(view.end())>);
+  }
+
+  // Check the return type of .end() const
+  {
+    RangeView range(buff, buff + 1);
+
+    const std::ranges::enumerate_view view(range);
+    using Iterator = std::ranges::iterator_t<decltype(view)>;
+    static_assert(std::same_as<Iterator, decltype(view.end())>);
+    using Sentinel = std::ranges::sentinel_t<decltype(view)>;
+    static_assert(std::same_as<Sentinel, decltype(view.end())>);
+  }
----------------
cjdb wrote:

This feels like it's testing `ranges::iterator_t` and `ranges::sentinel_t` more than anything in `enumerate_view`. I think we can remove it, or at least condense it to checking that we have a common range in both cases.

https://github.com/llvm/llvm-project/pull/73617