[libcxx-commits] [libcxx] [libc++] Fix _CopySegment helper in ranges::copy(join_view, out) replacing `const` with `constexpr` (PR #69593)

[Rajveer Singh Bharadwaj via libcxx-commits]

https://github.com/Rajveer100 created https://github.com/llvm/llvm-project/pull/69593

Part of Issue #69083

The `_CopySegment` helper for `ranges::copy(join_view, out)` is not `constexpr` causing rejection in `libc++` for static assertion as in the issue snippet.

>From 271fa26dc53cd4420da66d11afc50c6740343e62 Mon Sep 17 00:00:00 2001
From: Rajveer <rajveer.developer at icloud.com>
Date: Thu, 19 Oct 2023 17:08:57 +0530
Subject: [PATCH] [libc++] Fix _CopySegment helper in ranges::copy(join_view,
 out) replacing `const` with `constexpr`

Part of Issue #69083
---
 libcxx/include/__algorithm/copy.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libcxx/include/__algorithm/copy.h b/libcxx/include/__algorithm/copy.h
index dfe9898c6480cf8..175c6c0fc682026 100644
--- a/libcxx/include/__algorithm/copy.h
+++ b/libcxx/include/__algorithm/copy.h
@@ -35,7 +35,7 @@ template <class _AlgPolicy>
 struct __copy_loop {
   template <class _InIter, class _Sent, class _OutIter>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
-  operator()(_InIter __first, _Sent __last, _OutIter __result) const {
+  operator()(_InIter __first, _Sent __last, _OutIter __result) constexpr {
     while (__first != __last) {
       *__result = *__first;
       ++__first;
@@ -61,7 +61,7 @@ struct __copy_loop {
 
   template <class _InIter, class _OutIter, __enable_if_t<__is_segmented_iterator<_InIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
-  operator()(_InIter __first, _InIter __last, _OutIter __result) const {
+  operator()(_InIter __first, _InIter __last, _OutIter __result) constexpr {
     std::__for_each_segment(__first, __last, _CopySegment<_InIter, _OutIter>(__result));
     return std::make_pair(__last, std::move(__result));
   }
@@ -72,7 +72,7 @@ struct __copy_loop {
                               !__is_segmented_iterator<_InIter>::value && __is_segmented_iterator<_OutIter>::value,
                           int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, _OutIter>
-  operator()(_InIter __first, _InIter __last, _OutIter __result) const {
+  operator()(_InIter __first, _InIter __last, _OutIter __result) constexpr {
     using _Traits = __segmented_iterator_traits<_OutIter>;
     using _DiffT  = typename common_type<__iter_diff_t<_InIter>, __iter_diff_t<_OutIter> >::type;
 
@@ -99,7 +99,7 @@ struct __copy_trivial {
   // At this point, the iterators have been unwrapped so any `contiguous_iterator` has been unwrapped to a pointer.
   template <class _In, class _Out, __enable_if_t<__can_lower_copy_assignment_to_memmove<_In, _Out>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>
-  operator()(_In* __first, _In* __last, _Out* __result) const {
+  operator()(_In* __first, _In* __last, _Out* __result) constexpr {
     return std::__copy_trivial_impl(__first, __last, __result);
   }
 };