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

[Lucas Mellone via libcxx-commits]

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

>From 92f4c7a8395330e3ee69c772ff6f7e0a559e6ec0 Mon Sep 17 00:00:00 2001
From: Lucas Mellone <github.snugness349 at passinbox.com>
Date: Fri, 28 Aug 2026 15:31:24 +0200
Subject: [PATCH 1/3] add: is_nothrow_move_constructible test case

---
 .../iterator/iter_move.pass.cpp               | 34 ++++++++++++++-----
 1 file changed, 25 insertions(+), 9 deletions(-)

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..57f7fce0e4312 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
@@ -29,6 +29,11 @@
 
 #include "../types.h"
 
+struct ThrowingMove {
+  ThrowingMove() = default;
+  ThrowingMove(ThrowingMove&&) {}
+};
+
 template <class Iterator, bool HasNoexceptIterMove>
 constexpr void test() {
   using Sentinel          = sentinel_wrapper<Iterator>;
@@ -38,19 +43,30 @@ 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();
+  {
+    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);
 
-  auto&& result = iter_move(it);
+    using DifferenceT = std::iter_difference_t<EnumerateIterator>;
+    static_assert(std::is_same_v<decltype(result), std::tuple<DifferenceT, int&&>&&>);
 
-  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())));
 
-  assert(get<0>(result) == 0);
-  assert(&get<1>(result) == std::to_address(base(array.begin())));
+    static_assert(noexcept(iter_move(it)) == HasNoexceptIterMove);
+  }
 
-  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)));
+  }
 }
 
 constexpr bool tests() {

>From 14126502ad44f5639542366a2a62e9f07a31725c Mon Sep 17 00:00:00 2001
From: Lucas Mellone <github.snugness349 at passinbox.com>
Date: Fri, 28 Aug 2026 15:36:43 +0200
Subject: [PATCH 2/3] add: underlying iterator iter_move is called through
 ranges::iter_move

---
 .../iterator/iter_move.pass.cpp                | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

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 57f7fce0e4312..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 +28,7 @@
 #include "test_iterators.h"
 
 #include "../types.h"
+#include "../../range_adaptor_types.h"
 
 struct ThrowingMove {
   ThrowingMove() = default;
@@ -44,6 +45,7 @@ constexpr void test() {
   std::array array{0, 1, 2, 3, 4};
 
   {
+    // 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();
@@ -67,6 +69,22 @@ constexpr void test() {
     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() {

>From 8b15a9b3394a42b4ac3cb26b84c895ae0dfc1b89 Mon Sep 17 00:00:00 2001
From: Lucas Mellone <github.snugness349 at passinbox.com>
Date: Fri, 28 Aug 2026 15:42:43 +0200
Subject: [PATCH 3/3] fix: clang-format

---
 .../range.adaptors/range.enumerate/iterator/iter_move.pass.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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 2a9b462717711..e401f3525509c 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
@@ -64,7 +64,8 @@ constexpr void test() {
   {
     // !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{}; });
+    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)));