From 72c51f59dc75f52c6603e034bc8c631d9cc285d4 Mon Sep 17 00:00:00 2001
From: Adam Panzica <adampanzica@gmail.com>
Date: Fri, 10 Jul 2026 15:50:07 -0400
Subject: [PATCH] fix(tests): read cbor byte view via std::span, not
 basic_string_view<byte>
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libc++ shipped with Xcode 26.5 (the current macos-latest runner image)
deprecates std::char_traits<T> for T outside {char, wchar_t, char8_t,
char16_t, char32_t}. std::basic_string_view<std::byte> instantiates the
now-deprecated std::char_traits<std::byte>, and tests build with -Werror,
so tests/cbor/test_read_byte_containers.cpp fails to compile on
macos-latest (the only matrix cell that both compiles the tests and uses
the new libc++).

Switch the byte view to std::span<const std::byte>. It is the idiomatic
non-owning byte view, does not depend on char_traits at all, and
satisfies the same rfl::concepts::ContiguousByteContainer that
rfl::cbor::read requires — so the test exercises the identical read
overload. The sibling std::uint8_t-array test is unchanged.

This library specialization is slated for removal, not just deprecation,
so migrating off it is the durable fix rather than suppressing the
warning.
---
 tests/cbor/test_read_byte_containers.cpp | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tests/cbor/test_read_byte_containers.cpp b/tests/cbor/test_read_byte_containers.cpp
index ed863b469..660b60ff7 100644
--- a/tests/cbor/test_read_byte_containers.cpp
+++ b/tests/cbor/test_read_byte_containers.cpp
@@ -2,7 +2,9 @@
 
 #include <algorithm>
 #include <array>
+#include <cstddef>
 #include <rfl/cbor.hpp>
+#include <span>
 
 // Make sure things still compile when
 // rfl.hpp is included after rfl/cbor.hpp.
@@ -31,8 +33,13 @@ TEST(cbor, test_read_from_byte_view) {
   std::transform(rfl_buffer.begin(), rfl_buffer.end(), my_buffer.begin(),
                  [](char c) { return static_cast<std::byte>(c); });
 
-  std::basic_string_view<std::byte> byte_view(my_buffer.data(),
-                                              rfl_buffer.size());
+  // Note: std::span<const std::byte> rather than
+  // std::basic_string_view<std::byte>. libc++ (Xcode 26.5+) deprecates
+  // std::char_traits<std::byte> — the non-standard specialization that a
+  // basic_string_view<std::byte> instantiates — which is a hard error under
+  // -Werror. A span is the idiomatic non-owning byte view and exercises the
+  // same rfl::cbor::read overload (concepts::ContiguousByteContainer).
+  std::span<const std::byte> byte_view(my_buffer.data(), rfl_buffer.size());
 
   auto result = rfl::cbor::read<TestBox>(byte_view);
   EXPECT_TRUE(result);