[libcxx-commits] [libcxx] [libc++][ranges][enumerate_view] Fix iterator `iter_move` test (PR #219474)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Lucas Mellone (lknknm)

<details>
<summary>Changes</summary>

Completes the [range.enumerate.iterator] `iter_move` test by addressing the review comment https://github.com/llvm/llvm-project/pull/73617/changes#r1416642892 from the original implementation.

---
Full diff: https://github.com/llvm/llvm-project/pull/219474.diff


1 Files Affected:

- (modified) libcxx/test/std/ranges/range.adaptors/range.enumerate/iterator/iter_move.pass.cpp (+47-13) 


``````````diff
diff --git a/libcxx/test/std/ranges/range.adaptors/range.enumerate/iterator/iter_move.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.enumerate/iterator/iter_move.pass.cpp
index ed28662a8a5eb..2a9b462717711 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.enumerate/iterator/iter_move.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.enumerate/iterator/iter_move.pass.cpp
@@ -28,6 +28,12 @@
 #include "test_iterators.h"
 
 #include "../types.h"
+#include "../../range_adaptor_types.h"
+
+struct ThrowingMove {
+  ThrowingMove() = default;
+  ThrowingMove(ThrowingMove&&) {}
+};
 
 template <class Iterator, bool HasNoexceptIterMove>
 constexpr void test() {
@@ -38,19 +44,47 @@ constexpr void test() {
 
   std::array array{0, 1, 2, 3, 4};
 
-  View mv{Iterator(std::to_address(base(array.begin()))), Sentinel(Iterator(std::to_address(base(array.end()))))};
-  EnumerateView ev{std::move(mv)};
-  EnumerateIterator const it = ev.begin();
-
-  auto&& result = iter_move(it);
-
-  using DifferenceT = std::iter_difference_t<EnumerateIterator>;
-  static_assert(std::is_same_v<decltype(result), std::tuple<DifferenceT, int&&>&&>);
-
-  assert(get<0>(result) == 0);
-  assert(&get<1>(result) == std::to_address(base(array.begin())));
-
-  static_assert(noexcept(iter_move(it)) == HasNoexceptIterMove);
+  {
+    // underlying iter_move noexcept
+    View mv{Iterator(std::to_address(base(array.begin()))), Sentinel(Iterator(std::to_address(base(array.end()))))};
+    EnumerateView ev{std::move(mv)};
+    EnumerateIterator const it = ev.begin();
+
+    auto&& result = iter_move(it);
+
+    using DifferenceT = std::iter_difference_t<EnumerateIterator>;
+    static_assert(std::is_same_v<decltype(result), std::tuple<DifferenceT, int&&>&&>);
+
+    assert(get<0>(result) == 0);
+    assert(&get<1>(result) == std::to_address(base(array.begin())));
+
+    static_assert(noexcept(iter_move(it)) == HasNoexceptIterMove);
+  }
+
+  {
+    // !is_nothrow_move_constructible_v<range_rvalue_reference_t<Base>>
+    // underlying iter_move may throw
+    auto throwingMoveRange = std::views::iota(0, 9) | std::views::transform([](auto) noexcept { return ThrowingMove{}; });
+    std::ranges::enumerate_view v(throwingMoveRange);
+    auto it = v.begin();
+    static_assert(!noexcept(std::ranges::iter_move(it)));
+  }
+
+  {
+    // underlying iterator iter_move is called through ranges::iter_move
+    adltest::IterMoveSwapRange r1{};
+    assert(r1.iter_move_called_times == 0);
+    std::ranges::enumerate_view v(r1);
+    auto it = v.begin();
+    {
+      [[maybe_unused]] auto&& i = std::ranges::iter_move(it);
+      assert(r1.iter_move_called_times == 1);
+    }
+    {
+      [[maybe_unused]] auto&& i = std::ranges::iter_move(it);
+      assert(r1.iter_move_called_times == 2);
+    }
+  }
 }
 
 constexpr bool tests() {

``````````

</details>


https://github.com/llvm/llvm-project/pull/219474