From e5d123bfd6ec7d59ae7cae9b6b3a65d0145c2fa1 Mon Sep 17 00:00:00 2001
From: luka <tycket033@gmail.com>
Date: Sat, 5 Sep 2026 01:54:27 +0800
Subject: [PATCH] <ranges>: Fix C2382 when mixing #include <ranges> with import
 std;

_Zip_iterator_sentinel_equal's noexcept-specifier contains a fold
expression, which the compiler fails to match as equivalent between the
textually-included and module-imported declarations, emitting C2382.
Extract it into a variable template so both declarations reference a
simple name, which is trivially matched.

Fixes #6121
---
 stl/inc/ranges | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/stl/inc/ranges b/stl/inc/ranges
index 8317ea26049..7e42f98c7e7 100644
--- a/stl/inc/ranges
+++ b/stl/inc/ranges
@@ -7140,14 +7140,23 @@ namespace ranges {
         return _Get_smallest_distance_closure(index_sequence_for<_LHSTupleTypes...>{});
     }
 
+    // Work around C2382 when mixing #include <ranges> with import std;: a noexcept fold expression prevents
+    // the compiler from matching the textual and module declarations, while a variable template is trivially matched.
+    template <class _LHSTupleType, class _RHSTupleType>
+    inline constexpr bool _Zip_iterator_sentinel_equal_is_nothrow = false;
+
+    template <class... _LHSTupleTypes, class... _RHSTupleTypes>
+    inline constexpr bool _Zip_iterator_sentinel_equal_is_nothrow<tuple<_LHSTupleTypes...>, tuple<_RHSTupleTypes...>> =
+        (noexcept(_STD declval<const _LHSTupleTypes&>() == _STD declval<const _RHSTupleTypes&>()) && ...);
+
     template <class... _LHSTupleTypes, class... _RHSTupleTypes>
         requires (sizeof...(_LHSTupleTypes) == sizeof...(_RHSTupleTypes))
     _NODISCARD constexpr bool _Zip_iterator_sentinel_equal(
         const tuple<_LHSTupleTypes...>& _Lhs_tuple, const tuple<_RHSTupleTypes...>& _Rhs_tuple)
-        noexcept((noexcept(_STD declval<const _LHSTupleTypes&>() == _STD declval<const _RHSTupleTypes&>()) && ...)) {
+        noexcept(_Zip_iterator_sentinel_equal_is_nothrow<tuple<_LHSTupleTypes...>, tuple<_RHSTupleTypes...>>) {
         const auto _Evaluate_equality_closure =
             [&_Lhs_tuple, &_Rhs_tuple]<size_t... _Indices>(index_sequence<_Indices...>) noexcept(
-                (noexcept(_STD declval<const _LHSTupleTypes&>() == _STD declval<const _RHSTupleTypes&>()) &&...)) {
+                _Zip_iterator_sentinel_equal_is_nothrow<tuple<_LHSTupleTypes...>, tuple<_RHSTupleTypes...>>) {
                 return ((_STD get<_Indices>(_Lhs_tuple) == _STD get<_Indices>(_Rhs_tuple)) || ... || false);
             };