From e3ab977ffaee274de8de6f77e8149988089bdbad Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 11 Nov 2024 11:26:44 +1000
Subject: [PATCH] ranges/adjacent: use more cvref_t

This fixes some errors calling the range closure with stack variables.
---
 cruft/util/ranges/adjacent.hpp | 2 +-
 test/ranges/adjacent.cpp       | 8 +++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/cruft/util/ranges/adjacent.hpp b/cruft/util/ranges/adjacent.hpp
index 5848940a..16934080 100644
--- a/cruft/util/ranges/adjacent.hpp
+++ b/cruft/util/ranges/adjacent.hpp
@@ -158,7 +158,7 @@ namespace cruft::ranges {
             decltype (auto)
             operator () (V &&v) const
             {
-                return adjacent_view<V, N> (
+                return adjacent_view<std::remove_cvref_t<V>, N> (
                     std::forward<V> (v)
                 );
             }
diff --git a/test/ranges/adjacent.cpp b/test/ranges/adjacent.cpp
index 97cae2d6..15b95815 100644
--- a/test/ranges/adjacent.cpp
+++ b/test/ranges/adjacent.cpp
@@ -6,8 +6,8 @@
 
 int main()
 {
-    static int constexpr INPUT[] = { 1, 1, 2, 3, 5, 8 };
-    static int constexpr EXPECTED[][2] = {
+    static int const constexpr INPUT[] = { 1, 1, 2, 3, 5, 8 };
+    static int const constexpr EXPECTED[][2] = {
         { 1, 1 },
         { 1, 2 },
         { 2, 3 },
@@ -17,8 +17,10 @@ int main()
 
     cruft::TAP::logger tap;
 
+    // Use a temporary in an attempt to trigger cvref related type errors when calling the range closure.
+    std::span<int const> input_span (INPUT);
     const bool same = std::ranges::equal (
-        std::views::all (INPUT) | cruft::ranges::pairwise,
+        input_span | cruft::ranges::pairwise,
         EXPECTED,
         [] (auto const &a, auto const &b) { return std::ranges::equal (a, b); }
     );