robostack-lyrical ships rosidl_runtime_c (5.2.1) with rosidl_buffer-extended primitive sequences, but Rust bindings use the 24-byte layout → rclrs nodes corrupt/segfault on primitive-sequence messages

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Issue

Summary

ros-lyrical-rosidl-runtime-c 5.2.1 defines primitive sequences with the rosidl_buffer extension (is_rosidl_buffer/owns_rosidl_buffer → 32-byte struct), but the Rust bindings used in the same channel (ros-lyrical-rosidl-generator-rs 5.2.1 + rosidl_runtime_rs 0.6.0) use the standard 24-byte Sequence<T>. The C and Rust ABIs therefore disagree for every primitive-sequence field, so any rclrs node silently corrupts or segfaults on such messages.

Environment

robostack-lyrical (linux-64); ros-lyrical-rosidl-runtime-c 5.2.1 (build np2py314…_22), ros-lyrical-rosidl-generator-rs 5.2.1; rosidl_runtime_rs 0.6.0; rclrs 0.7; rustc 1.97.0, edition 2024.

Root cause

This channel's primitives_sequence.h gives primitive sequences two extra trailing fields:

<T>* data; size_t size; size_t capacity;         // 0 / 8 / 16
bool is_rosidl_buffer;  bool owns_rosidl_buffer;  // 24 / 25 -> struct padded to 32

rosidl_runtime_rs::Sequence<T> is the standard 24-byte, 3-field struct for all T.

C type	C size	Rust Sequence<T>
uint8__Sequence / double__Sequence (primitive)	32	24
Point__Sequence / ColorRGBA__Sequence (message)	24	24

Measured (gcc sizeof/offsetof on the installed headers vs Rust size_of/offset_of): primitive sequences 32 vs 24; visualization_msgs/Marker C sizeof 480 vs Rust 464, agreeing through texture (offset 256) then shifting +8 at uv_coordinates/text/mesh_resource — introduced by the primitive CompressedImage.data sequence (C CompressedImage 88 vs Rust 80).

Symptom

Marker::default() round-trips via from_rmw_message, .to_string()-ing text at the shifted offset:

debug:   panic: slice::from_raw_parts requires the pointer to be aligned and non-null
release: SIGSEGV (invalid memory reference)
  <String as Display>::fmt        rosidl_runtime_rs-0.6.0/src/string.rs:187
  Marker::from_rmw_message        visualization_msgs/rust/src/msg.rs:1133  (field: text)
  Marker::default                 visualization_msgs/rust/src/msg.rs:1035

Same corruption for any primitive sequence with fields after it — sensor_msgs/JointState (velocity/effort), trajectory_msgs/JointTrajectoryPoint (positions). Benign only when the misread lands on zeroed empty-default memory.

Upstream comparison

ros2/rosidl master primitives_sequence.h has only data/size/capacity, so this is specific to packages built with the rosidl_buffer extension in this channel.

Ask

Is the Rust binding set in robostack-lyrical expected to be ABI-consistent with these rosidl_buffer-extended C sequences? If so, the shipped Rust runtime/generator needs to model the 32-byte primitive layout; if the extension is unintended for this channel, the C packages need rebuilding without it.

Upstream Rust tracking: https://github.com/ros2-rust/ros2_rust/issues/659

Installed packages

$ pixi list --explicit
Installed for: linux-64
Name                             Version  Build                      Size  Kind   Source
ccache                           4.13.6   hedf47ba_0           835.64 KiB  conda  https://prefix.dev/conda-forge
clangdev                         22.1.8   default_h1b9a2e9_3    59.08 MiB  conda  https://prefix.dev/conda-forge
cmake                            4.4.0    hc85cc9f_0            22.56 MiB  conda  https://prefix.dev/conda-forge
colcon-common-extensions         0.3.0    py314hdafbbf9_4       12.82 KiB  conda  https://prefix.dev/conda-forge
colcon-mixin                     0.2.3    pyhd8ed1ab_1          24.56 KiB  conda  https://prefix.dev/conda-forge
colcon_cargo                     0.2.0                                     pypi   https://pypi.org/simple
colcon_ros_cargo                 0.2.0                                     pypi   https://pypi.org/simple
compilers                        1.11.0   ha770c72_0             7.31 KiB  conda  https://prefix.dev/conda-forge
curl                             8.21.0   hae6b9f4_2           190.21 KiB  conda  https://prefix.dev/conda-forge
filelock                         3.29.7   pyhd8ed1ab_0          38.72 KiB  conda  https://prefix.dev/conda-forge
libcurl                          8.21.0   hae6b9f4_2           469.07 KiB  conda  https://prefix.dev/conda-forge
lld                              22.1.8   hef48ded_0            11.84 MiB  conda  https://prefix.dev/conda-forge
ninja                            1.13.2   h171cf75_0           181.96 KiB  conda  https://prefix.dev/conda-forge
patch                            2.8      hb03c661_1002        114.47 KiB  conda  https://prefix.dev/conda-forge
pkg-config                       0.29.2   h4bc722e_1009        112.48 KiB  conda  https://prefix.dev/conda-forge
python                           3.14.6   habeac84_100_cp314    35.02 MiB  conda  https://prefix.dev/conda-forge
ros-lyrical-rmw-zenoh-cpp        0.10.4   np2py314h19ba983_22  350.58 KiB  conda  https://prefix.dev/robostack-lyrical
ros-lyrical-ros-base             0.13.0   np2py314hb48eaa3_22   21.67 KiB  conda  https://prefix.dev/robostack-lyrical
ros-lyrical-rosidl-generator-rs  0.4.12   np2py314hb48eaa3_22   47.02 KiB  conda  https://prefix.dev/robostack-lyrical
rust                             1.97.0   h53717f1_0           165.58 MiB  conda  https://prefix.dev/conda-forge
vcstool                          1.1.7    hd8ed1ab_0            10.24 KiB  conda  https://prefix.dev/conda-forge

Environment info

System
------------
       Pixi version: 0.73.0
        TLS backend: rustls
           Platform: linux-64
   Virtual packages: __unix=0=0
                   : __linux=7.0.2=0
                   : __glibc=2.41=0
                   : __archspec=1=x86_64_v4
          Cache dir: /root/.cache/rattler/cache
       Auth storage: /root/.rattler/credentials.json
   Config locations: No config files found

Global
------------
            Bin dir: /root/.pixi/bin
    Environment dir: /root/.pixi/envs
       Manifest dir: /root/.pixi/manifests/pixi-global.toml

Workspace
------------
               Name: eit_robot
            Version: 1.0.0
      Manifest file: /root/eit/eit_robot/pixi.toml
       Last updated: 21-07-2026 11:36:59

Environments
------------
        Environment: default
           Features: linux, default
           Channels: https://prefix.dev/pixi-build-backends, https://prefix.dev/conda-forge, https://prefix.dev/robostack-lyrical
   Dependency count: 19
       Dependencies: python, rust, ros-lyrical-ros-base, ros-lyrical-rmw-zenoh-cpp, ros-lyrical-rosidl-generator-rs, colcon-common-extensions, colcon-mixin, compilers, cmake, ninja, pkg-config, libcurl, filelock, ccache, lld, curl, clangdev, patch, vcstool
  PyPI Dependencies: colcon-cargo, colcon-ros-cargo
   Target platforms: linux-aarch64, linux-64
  Resolved platform: linux-64 (archspec=x86_64, glibc=2.28, linux=4.18, __unix)
   Minimum platform: linux-64 (glibc=2.28, __unix)
    Prefix location: /root/eit/eit_robot/.pixi/envs/default
              Tasks: colcon_mixin_setup, update_deps, build_clean, test_teleop, test_capture_kinematics, clean, pytests, test, test_capture_solver, setup, test_teleop_pure, test_capture_executor, test_control, setup_ros_rust, test_capture_interfaces, build

Compare the installed rosidl_runtime_c/include/rosidl_runtime_c/primitives_sequence.h layout with rosidl_runtime_rs 0.6.0's Sequence, then reproduce the Marker::default/from_rmw_message failure in visualization_msgs/rust/src/msg.rs. Check rosidl_runtime_rs-0.6.0/src/string.rs at the reported panic and verify that primitive-sequence fields no longer shift later fields or corrupt messages.