rclcpp warnings not showing as expected

[mini-1235]

Background

To my best knowledge, there are some "bad patterns" we try to avoid when using rclcpp. Two examples that come to my mind:

1. Using rclcpp logging macros without format arguments:

std::string my_std_string = "Foo";
RCLCPP_DEBUG(get_logger(), my_std_string);

This is documented in the galactic changelog: https://docs.ros.org/en/rolling/Releases/Release-Galactic-Geochelone.html#change-in-rclcpp-s-logging-macros

2. Using non-const shared_ptr in subscription callbacks:

sub_ = this->create_subscription(
    input,
    10,
    [](std::shared_ptr msg) { ... }
);

This is documented in the Jazzy changelog: https://docs.ros.org/en/rolling/Releases/Release-Jazzy-Jalisco.html#deprecated-subscription-callback-signatures-were-removed

Problem

When using these "bad patterns", I believe the expected behavior is a compiler warning/error like:

/Users/maurice/nav2_projects/nav2_ws/src/navigation2/nav2_behaviors/plugins/spin.cpp:66:27: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
   66 |     RCLCPP_ERROR(logger_, error_msg.c_str());
      |                           ^~~~~~~~~~~~~~~~~
/Users/maurice/nav2_projects/nav2_ws/.pixi/envs/default/include/rclcpp/rclcpp/logging.hpp:753:82: note: expanded from macro 'RCLCPP_ERROR'
  753 | #define RCLCPP_ERROR(logger, ...) RCLCPP_LOG(RCUTILS_LOG_SEVERITY_ERROR, logger, __VA_ARGS__)
      |                                                                                  ^~~~~~~~~~~
/Users/maurice/nav2_projects/nav2_ws/.pixi/envs/default/include/rclcpp/rclcpp/logging.hpp:48:54: note: expanded from macro 'RCLCPP_LOG'
   48 |     RCUTILS_LOG_NAMED(severity, (logger).get_name(), __VA_ARGS__); \
      |                                                      ^~~~~~~~~~~
/Users/maurice/nav2_projects/nav2_ws/.pixi/envs/default/include/rcutils/rcutils/logging_macros.h:56:73: note: expanded from macro 'RCUTILS_LOG_NAMED'
   56 |       rcutils_log_internal(&__rcutils_logging_location, severity, name, __VA_ARGS__); \

or

/Users/maurice/nav2_projects/nav2_ws/.pixi/envs/default/include/rclcpp/rclcpp/node_impl.hpp:100:18: note: in instantiation of function template specialization 'rclcpp::create_subscription<tf2_msgs::msg::TFMessage_<std::allocator<void>>, (lambda at /Users/maurice/nav2_projects/nav2_ws/src/navigation2/nav2_loopback_sim/test/test_loopback_simulator.cpp:157:5), std::allocator<void>, rclcpp::Subscription<tf2_msgs::msg::TFMessage_<std::allocator<void>>>, rclcpp::message_memory_strategy::MessageMemoryStrategy<tf2_msgs::msg::TFMessage_<std::allocator<void>>>, rclcpp::Node>' requested here
  100 |   return rclcpp::create_subscription<MessageT>(
      |                  ^
/Users/maurice/nav2_projects/nav2_ws/src/navigation2/nav2_loopback_sim/test/test_loopback_simulator.cpp:155:31: note: in instantiation of function template specialization 'rclcpp::Node::create_subscription<tf2_msgs::msg::TFMessage_<std::allocator<void>>, (lambda at /Users/maurice/nav2_projects/nav2_ws/src/navigation2/nav2_loopback_sim/test/test_loopback_simulator.cpp:157:5), std::allocator<void>, rclcpp::Subscription<tf2_msgs::msg::TFMessage_<std::allocator<void>>>, rclcpp::message_memory_strategy::MessageMemoryStrategy<tf2_msgs::msg::TFMessage_<std::allocator<void>>>>' requested here
  155 |   auto tf_sub = helper_node_->create_subscription<tf2_msgs::msg::TFMessage>(
      |                               ^
/Users/maurice/nav2_projects/nav2_ws/.pixi/envs/default/include/rclcpp/rclcpp/any_subscription_callback.hpp:456:5: note: 'set_deprecated<tf2_msgs::msg::TFMessage_<std::allocator<void>>>' has been explicitly marked deprecated here
  456 |   [[deprecated("use 'void(std::shared_ptr<const MessageT>)' instead")]]

However, these warnings/errors only showed up yesterday when I compiled on macOS (pixi + robotstack), and not in my usual workflow (e.g. pulling a fresh ros:rolling image and doing a colcon build), even with -Wall.

I also quickly searched for ::SharedPtr msg across ros2 repos and found that the pattern is still being used : https://docs.ros.org/en/rolling/Tutorials/Advanced/Writing-a-Buffer-Compatible-Conversions-Package.html#publish-and-subscribe, which makes me think CI also doesn't report the warning, same as what I see on Ubuntu.

Additional Information

I would also like to share some of my findings:

• Jun 6 2022: @clalancette reported that the warnings are not shown: Add a check if the second argument of logging macros is a string literal #1918 (comment)
• The shared_ptr callback deprecation history:
  • Deprecated in refactor AnySubscriptionCallback and add/deprecate callback signatures #1598 (Apr 2021)
  • Accidentally removed in Remove the set_deprecated signatures in any_subscription_callback. #2431 (Feb 2024)
  • Reintroduced in Deprecate the shared_ptr<MessageT> subscription callback signatures #2975 (Dec 2025)

My guess (not validated yet) is that the warnings introduced in 2021 were visible at the time, but then something happened between 2021 and 2022 that accidentally hid them, and the problem persists until today.

• When I worked on Deprecate the shared_ptr<MessageT> subscription callback signatures #2975, I first used static_assert to block the bad pattern, I also found the packages using it and fixed them. Then, we agreed to deprecate for one distribution first, so I switched from static_assert to [[deprecated]]. If I remember correctly, I could see the warnings on Ubuntu at that point, which is why I added:

  #define RCLCPP_AVOID_DEPRECATIONS_FOR_UNIT_TESTS 1

But I admittedly didn't carefully recheck everything after switching to [[deprecated]], e.g. testing in downstream packages. So my guess (not validated yet) is that the warning shows up inside rclcpp itself but not in downstream packages consuming it.

I am using macOS (warnings visible) and Ubuntu (no warnings at all) to refer to these two cases, but my best guess is that it might be related to compiler differences or compiler flags. I don't have much time to dig deeper right now, but I am documenting this here so I don't forget, and I hope to get some insights from the community or the PMCs :)

This issue was originally written by hand, assisted by Claude Sonnet 4.6 for formatting the logs, code blocks, and organizing the content more clearly, and finally edited by the author.