[libcxx-commits] [libcxx] [libc++][ranges] Mark LWG3664 as resolved (PR #210550)

[via libcxx-commits]

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Lucas Mellone (lknknm)

<details>
<summary>Changes</summary>

Closes https://github.com/llvm/llvm-project/issues/105066. 
References:
- https://wg21.link/LWG3664
- https://eel.is/c++draft/range.iter.op.distance

Follows-up: https://github.com/llvm/llvm-project/commit/c965d5448ecdf9a5513983862a78a2ba8f7fbab8

---
Full diff: https://github.com/llvm/llvm-project/pull/210550.diff


4 Files Affected:

- (modified) libcxx/docs/Status/Cxx23Issues.csv (+1-1) 
- (modified) libcxx/include/__iterator/distance.h (+3-2) 
- (modified) libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/iterator_sentinel.pass.cpp (+1-1) 
- (modified) libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/lwg3664.pass.cpp (+1-1) 


``````````diff
diff --git a/libcxx/docs/Status/Cxx23Issues.csv b/libcxx/docs/Status/Cxx23Issues.csv
index 91c4dc462c0c9..617c89508b7a3 100644
--- a/libcxx/docs/Status/Cxx23Issues.csv
+++ b/libcxx/docs/Status/Cxx23Issues.csv
@@ -249,7 +249,7 @@
 "`LWG2295 <https://wg21.link/LWG2295>`__","Locale name when the provided ``Facet`` is a ``nullptr``","2023-02 (Issaquah)","","","`#105063 <https://github.com/llvm/llvm-project/issues/105063>`__",""
 "`LWG3032 <https://wg21.link/LWG3032>`__","``ValueSwappable`` requirement missing for ``push_heap`` and ``make_heap``","2023-02 (Issaquah)","","","`#105064 <https://github.com/llvm/llvm-project/issues/105064>`__",""
 "`LWG3085 <https://wg21.link/LWG3085>`__","``char_traits::copy`` precondition too weak","2023-02 (Issaquah)","","","`#105065 <https://github.com/llvm/llvm-project/issues/105065>`__",""
-"`LWG3664 <https://wg21.link/LWG3664>`__","`LWG 3392 <https://wg21.link/LWG3392>`__ ``broke std::ranges::distance(a, a+3)``","2023-02 (Issaquah)","","","`#105066 <https://github.com/llvm/llvm-project/issues/105066>`__",""
+"`LWG3664 <https://wg21.link/LWG3664>`__","`LWG 3392 <https://wg21.link/LWG3392>`__ ``broke std::ranges::distance(a, a+3)``","2023-02 (Issaquah)","|Complete|","24","`#105066 <https://github.com/llvm/llvm-project/issues/105066>`__",""
 "`LWG3720 <https://wg21.link/LWG3720>`__","Restrict the valid types of ``arg-id`` for width and precision in ``std-format-spec``","2023-02 (Issaquah)","|Complete|","17","`#105067 <https://github.com/llvm/llvm-project/issues/105067>`__",""
 "`LWG3756 <https://wg21.link/LWG3756>`__","Is the ``std::atomic_flag`` class signal-safe?","2023-02 (Issaquah)","","","`#105068 <https://github.com/llvm/llvm-project/issues/105068>`__",""
 "`LWG3769 <https://wg21.link/LWG3769>`__","``basic_const_iterator::operator==`` causes infinite constraint recursion","2023-02 (Issaquah)","","","`#105069 <https://github.com/llvm/llvm-project/issues/105069>`__",""
diff --git a/libcxx/include/__iterator/distance.h b/libcxx/include/__iterator/distance.h
index c7c4ff22d6e9f..e0a2590253c71 100644
--- a/libcxx/include/__iterator/distance.h
+++ b/libcxx/include/__iterator/distance.h
@@ -86,11 +86,12 @@ struct __distance {
   }
 
   template <class _Ip, sized_sentinel_for<decay_t<_Ip>> _Sp>
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip&& __first, _Sp __last) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<decay_t<_Ip>>
+  operator()(_Ip&& __first, _Sp __last) const {
     if constexpr (sized_sentinel_for<_Sp, __remove_cvref_t<_Ip>>) {
       return __last - __first;
     } else {
-      return __last - decay_t<_Ip>(__first);
+      return __last - static_cast<decay_t<_Ip>>(__first);
     }
   }
 
diff --git a/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/iterator_sentinel.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/iterator_sentinel.pass.cpp
index c34d59e405a9e..1888f606465b2 100644
--- a/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/iterator_sentinel.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/iterator_sentinel.pass.cpp
@@ -13,7 +13,7 @@
 //     constexpr iter_difference_t<I> ranges::distance(I first, S last);
 //
 // template<class I, sized_sentinel_for<decay_t<I>> S>
-//   constexpr iter_difference_t<I> ranges::distance(I&& first, S last); // TODO: update when LWG3664 is resolved
+//   constexpr iter_difference_t<decay_t<I>> ranges::distance(I&& first, S last);
 
 #include <array>
 #include <cassert>
diff --git a/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/lwg3664.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/lwg3664.pass.cpp
index 164101c2bf5a8..bac0ffba1e7f1 100644
--- a/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/lwg3664.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.distance/lwg3664.pass.cpp
@@ -13,7 +13,7 @@
 //     constexpr iter_difference_t<I> ranges::distance(I first, S last);
 //
 // template<class I, sized_sentinel_for<decay_t<I>> S>
-//   constexpr iter_difference_t<I> ranges::distance(const I& first, S last);
+//   constexpr iter_difference_t<decay_t<I>> ranges::distance(I&& first, S last);
 
 #include <cassert>
 #include <iterator>

``````````

</details>


https://github.com/llvm/llvm-project/pull/210550