[libcxx-commits] [libcxx] [libc++][ranges] LWG3610: `iota_view::size` sometimes rejects integer-class types (PR #155169)

[Hristo Hristov via libcxx-commits]

https://github.com/H-G-Hristov updated https://github.com/llvm/llvm-project/pull/155169

>From 44284cde6d74a8c0a849f9f30feb23a37a796820 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Sun, 24 Aug 2025 13:44:49 +0300
Subject: [PATCH 1/2] [libc++][ranges] LWG3610: iota_view::size sometimes
 rejects integer-class types

Fixes #104948

- https://wg21.link/LWG3610
---
 libcxx/docs/Status/Cxx23Issues.csv             |  2 +-
 libcxx/include/__ranges/iota_view.h            |  2 +-
 .../range.iota.view/size.pass.cpp              | 18 ++++++++++++++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/libcxx/docs/Status/Cxx23Issues.csv b/libcxx/docs/Status/Cxx23Issues.csv
index 189f8452e0678..38571dabae463 100644
--- a/libcxx/docs/Status/Cxx23Issues.csv
+++ b/libcxx/docs/Status/Cxx23Issues.csv
@@ -143,7 +143,7 @@
 "`LWG3598 <https://wg21.link/LWG3598>`__","``system_category().default_error_condition(0)`` is underspecified","2022-02 (Virtual)","","",""
 "`LWG3601 <https://wg21.link/LWG3601>`__","common_iterator's postfix-proxy needs ``indirectly_readable`` ","2022-02 (Virtual)","","",""
 "`LWG3607 <https://wg21.link/LWG3607>`__","``contiguous_iterator`` should not be allowed to have custom ``iter_move`` and ``iter_swap`` behavior","2022-02 (Virtual)","|Nothing To Do|","",""
-"`LWG3610 <https://wg21.link/LWG3610>`__","``iota_view::size`` sometimes rejects integer-class types","2022-02 (Virtual)","","",""
+"`LWG3610 <https://wg21.link/LWG3610>`__","``iota_view::size`` sometimes rejects integer-class types","2022-02 (Virtual)","|Complete|","22",""
 "`LWG3612 <https://wg21.link/LWG3612>`__","Inconsistent pointer alignment in ``std::format`` ","2022-02 (Virtual)","|Complete|","14",""
 "`LWG3616 <https://wg21.link/LWG3616>`__","LWG 3498 seems to miss the non-member ``swap`` for ``basic_syncbuf`` ","2022-02 (Virtual)","|Complete|","18",""
 "`LWG3618 <https://wg21.link/LWG3618>`__","Unnecessary ``iter_move`` for ``transform_view::iterator`` ","2022-02 (Virtual)","|Complete|","19",""
diff --git a/libcxx/include/__ranges/iota_view.h b/libcxx/include/__ranges/iota_view.h
index 4b84585258b91..cf401a4665fcd 100644
--- a/libcxx/include/__ranges/iota_view.h
+++ b/libcxx/include/__ranges/iota_view.h
@@ -348,7 +348,7 @@ class iota_view : public view_interface<iota_view<_Start, _BoundSentinel>> {
 
   _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
     requires(same_as<_Start, _BoundSentinel> && __advanceable<_Start>) ||
-            (integral<_Start> && integral<_BoundSentinel>) || sized_sentinel_for<_BoundSentinel, _Start>
+            (__integer_like<_Start> && __integer_like<_BoundSentinel>) || sized_sentinel_for<_BoundSentinel, _Start>
   {
     if constexpr (__integer_like<_Start> && __integer_like<_BoundSentinel>) {
       return (__value_ < 0)
diff --git a/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp b/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
index b894bc542be10..90afec2fba177 100644
--- a/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
+++ b/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
@@ -16,8 +16,21 @@
 #include <ranges>
 
 #include "test_macros.h"
+#define TEST_HAS_NO_INT128
+#include "type_algorithms.h"
 #include "types.h"
 
+template <typename T>
+concept HasSize = requires(const T t) { t.size(); };
+
+struct CheckForSize {
+  template <class T>
+  constexpr void operator()() {
+    static_assert(HasSize<std::ranges::iota_view<T, int>>);
+    static_assert(HasSize<std::ranges::iota_view<T, T>>);
+  }
+};
+
 constexpr bool test() {
   // Both are integer like and both are less than zero.
   {
@@ -99,6 +112,11 @@ constexpr bool test() {
     assert(sz == 10);
   }
 
+  // LWG3610: `iota_view::size` sometimes rejects integer-class types
+  {
+    types::for_each(types::integer_types{}, CheckForSize{});
+  }
+
   return true;
 }
 

>From bee2ac2a7a4da6b6f234106cbb3070577bf49a96 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Mon, 25 Aug 2025 11:28:26 +0300
Subject: [PATCH 2/2] Updated test

---
 .../ranges/range.factories/range.iota.view/size.pass.cpp   | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp b/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
index 90afec2fba177..315e581aed577 100644
--- a/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
+++ b/libcxx/test/std/ranges/range.factories/range.iota.view/size.pass.cpp
@@ -24,10 +24,11 @@ template <typename T>
 concept HasSize = requires(const T t) { t.size(); };
 
 struct CheckForSize {
-  template <class T>
+  template <class IntegerLikeT>
   constexpr void operator()() {
-    static_assert(HasSize<std::ranges::iota_view<T, int>>);
-    static_assert(HasSize<std::ranges::iota_view<T, T>>);
+    types::for_each(types::integer_types{}, []<typename BoundT>() {
+      static_assert(HasSize<std::ranges::iota_view<IntegerLikeT, BoundT>>);
+    });
   }
 };