From 0419ab13395ca4c84c292827f4bd14a97de4625a Mon Sep 17 00:00:00 2001
From: Tamaki Nishino <otamachan@gmail.com>
Date: Wed, 25 Feb 2026 15:01:30 +0900
Subject: [PATCH 1/2] Redirect tl_expected to system libexpected-dev when
 available

Signed-off-by: Tamaki Nishino <otamachan@gmail.com>
---
 tl_expected/CMakeLists.txt                   |  6 ++++++
 tl_expected/include/tl_expected/expected.hpp | 11 ++++++++++-
 tl_expected/package.xml                      |  2 ++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/tl_expected/CMakeLists.txt b/tl_expected/CMakeLists.txt
index 3039e6c..df93f6a 100644
--- a/tl_expected/CMakeLists.txt
+++ b/tl_expected/CMakeLists.txt
@@ -7,7 +7,13 @@ project(tl_expected
 
 find_package(ament_cmake REQUIRED)
 
+option(USE_VENDORED_TL_EXPECTED "Use vendored tl_expected instead of system libexpected-dev" OFF)
+
 add_library(tl_expected INTERFACE)
+
+if(USE_VENDORED_TL_EXPECTED)
+  target_compile_definitions(tl_expected INTERFACE USE_VENDORED_TL_EXPECTED)
+endif()
 target_include_directories(tl_expected INTERFACE
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
   $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
diff --git a/tl_expected/include/tl_expected/expected.hpp b/tl_expected/include/tl_expected/expected.hpp
index ae90975..e58f9ae 100644
--- a/tl_expected/include/tl_expected/expected.hpp
+++ b/tl_expected/include/tl_expected/expected.hpp
@@ -13,6 +13,13 @@
 // <http://creativecommons.org/publicdomain/zero/1.0/>.
 ///
 
+// If the system header is available and vendored version is not explicitly
+// requested, redirect to the system header with a deprecation warning.
+#if !defined(USE_VENDORED_TL_EXPECTED) && __has_include(<tl/expected.hpp>)
+#pragma message("tl_expected/expected.hpp is deprecated, use tl/expected.hpp instead")
+#include <tl/expected.hpp>
+#else
+
 #ifndef TL_EXPECTED_HPP
 #define TL_EXPECTED_HPP
 
@@ -2480,4 +2487,6 @@ void swap(expected<T, E> &lhs,
 }
 } // namespace tl
 
-#endif
+#endif // TL_EXPECTED_HPP
+
+#endif // !defined(USE_VENDORED_TL_EXPECTED) && __has_include(<tl/expected.hpp>)
diff --git a/tl_expected/package.xml b/tl_expected/package.xml
index 07dac78..ef78d93 100644
--- a/tl_expected/package.xml
+++ b/tl_expected/package.xml
@@ -14,6 +14,8 @@
 
   <buildtool_depend>ament_cmake</buildtool_depend>
 
+  <build_export_depend>libexpected-dev</build_export_depend>
+
   <export>
     <build_type>ament_cmake</build_type>
   </export>

From 1f91ae73d137a08dce3f5bbf51589bf626602c71 Mon Sep 17 00:00:00 2001
From: Tamaki Nishino <otamachan@gmail.com>
Date: Sun, 1 Mar 2026 20:44:58 +0900
Subject: [PATCH 2/2] Update tl_expected/include/tl_expected/expected.hpp
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Christoph Fröhlich <christophfroehlich@users.noreply.github.com>
---
 tl_expected/include/tl_expected/expected.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tl_expected/include/tl_expected/expected.hpp b/tl_expected/include/tl_expected/expected.hpp
index e58f9ae..b2dea5a 100644
--- a/tl_expected/include/tl_expected/expected.hpp
+++ b/tl_expected/include/tl_expected/expected.hpp
@@ -16,7 +16,7 @@
 // If the system header is available and vendored version is not explicitly
 // requested, redirect to the system header with a deprecation warning.
 #if !defined(USE_VENDORED_TL_EXPECTED) && __has_include(<tl/expected.hpp>)
-#pragma message("tl_expected/expected.hpp is deprecated, use tl/expected.hpp instead")
+#warning("tl_expected/expected.hpp is deprecated, use tl/expected.hpp instead")
 #include <tl/expected.hpp>
 #else