Static linking issue with _rosidl_generator_py.so in build _17

[eholum]

Solution to issue cannot be found in the documentation.

• I checked the documentation.

Issue

I've been running into a linking issue with our roboplan-ros wrappers: open-planning/roboplan-ros#38.

I believe the issue is summarized in this project: https://github.com/eholum/kilted-libpython-bug

Basically, I tried bumping our deps up to the latest build _17 of the kilted packages, and it seems like the _rosidl_generator_py.so libraries have an issue with static linking - namely, they don't pull in libpython. This means I get crashes like:

...libunique_identifier_msgs__rosidl_generator_py.so: undefined symbol: PyObject_GetAttrString

This seems to affect message packages in build _17 — I've confirmed it on unique_identifier_msgs, geometry_msgs, sensor_msgs, trajectory_msgs, and others. The previous build _15 (mutex 0.13.0) did not seem to have this issue. From the linked PR in roboplan, you can see those libraries were previously dynamically linked with libpython3.12.so as a dependency.

The repro project has a simple script to try loading a lib with dl_open:

int main() {
    void* h = dlopen("libunique_identifier_msgs__rosidl_generator_py.so", RTLD_NOW);
    if (!h) {
        printf("dlopen failed: %s\n", dlerror());
        return 1;
    }
    printf("OK\n");
    dlclose(h);
    return 0;
}

It does it both a kilted and jazzy environment:

pixi run -e kilted check   # static-pie, no libpython shows up
pixi run -e kilted crash   # crashes
pixi run -e jazzy check    # dynamically linked, libpython present
pixi run -e jazzy crash    # OK

Did something change in the rosidl_generator_py / rosidlcpp_generator_py recipe between 15 and 17? Or is there some other issue that I'm not understanding?

Installed packages

Name                                               Version       Build                       Size  Kind   Source
_openmp_mutex                                      4.5           20_gnu                 28.25 KiB  conda  https://conda.anaconda.org/conda-forge
argcomplete                                        3.6.3         pyhd8ed1ab_0           41.39 KiB  conda  https://conda.anaconda.org/conda-forge
bzip2                                              1.0.8         h4777abc_9            187.90 KiB  conda  https://conda.anaconda.org/conda-forge
c-ares                                             1.34.6        he30d5cf_0            212.12 KiB  conda  https://conda.anaconda.org/conda-forge
ca-certificates                                    2026.2.25     hbd8a1cb_0            143.96 KiB  conda  https://conda.anaconda.org/conda-forge
catkin_pkg                                         1.1.0         pyhd8ed1ab_0           52.84 KiB  conda  https://conda.anaconda.org/conda-forge
cmake                                              4.3.2         hc9d863e_0             21.18 MiB  conda  https://conda.anaconda.org/conda-forge
cppcheck                                           2.20.1        py312h5677ec4_0         2.81 MiB  conda  https://conda.anaconda.org/conda-forge
docutils                                           0.22.4        pyhd8ed1ab_0          427.74 KiB  conda  https://conda.anaconda.org/conda-forge
empy                                               3.3.4         pyh9f0ad1d_1           39.27 KiB  conda  https://conda.anaconda.org/conda-forge
flake8                                             7.3.0         pyhd8ed1ab_0          109.29 KiB  conda  https://conda.anaconda.org/conda-forge
flake8-builtins                                    3.1.0         pyhd8ed1ab_0           19.04 KiB  conda  https://conda.anaconda.org/conda-forge
flake8-comprehensions                              3.17.0        pyhd8ed1ab_0           13.72 KiB  conda  https://conda.anaconda.org/conda-forge
flake8-docstrings                                  1.7.0         pyhd8ed1ab_0           10.15 KiB  conda  https://conda.anaconda.org/conda-forge
flake8-import-order                                0.19.2        pyhd8ed1ab_0           20.55 KiB  conda  https://conda.anaconda.org/conda-forge
flake8-quotes                                      3.4.0         pyhd8ed1ab_1           14.43 KiB  conda  https://conda.anaconda.org/conda-forge
importlib-metadata                                 8.8.0         pyhcf101f3_0           33.58 KiB  conda  https://conda.anaconda.org/conda-forge
importlib_resources                                7.1.0         pyhd8ed1ab_0           33.99 KiB  conda  https://conda.anaconda.org/conda-forge
keyutils                                           1.6.3         h86ecc28_0            126.02 KiB  conda  https://conda.anaconda.org/conda-forge
krb5                                               1.22.2        hfd895c2_0              1.45 MiB  conda  https://conda.anaconda.org/conda-forge
lark-parser                                        0.12.0        pyhd8ed1ab_1           84.12 KiB  conda  https://conda.anaconda.org/conda-forge
ld_impl_linux-aarch64                              2.45.1        default_h1979696_102  855.07 KiB  conda  https://conda.anaconda.org/conda-forge
libblas                                            3.11.0        6_haddc8a3_openblas    18.24 KiB  conda  https://conda.anaconda.org/conda-forge
libcblas                                           3.11.0        6_hd72aa62_openblas    18.25 KiB  conda  https://conda.anaconda.org/conda-forge
libcurl                                            8.19.0        hc57f145_0            474.31 KiB  conda  https://conda.anaconda.org/conda-forge
libedit                                            3.1.20250104  pl5321h976ea20_0      144.65 KiB  conda  https://conda.anaconda.org/conda-forge
libev                                              4.33          h31becfc_2            112.42 KiB  conda  https://conda.anaconda.org/conda-forge
libexpat                                           2.7.5         hfae3067_0             74.73 KiB  conda  https://conda.anaconda.org/conda-forge
libffi                                             3.5.2         h376a255_0             54.64 KiB  conda  https://conda.anaconda.org/conda-forge
libgcc                                             15.2.0        h8acb6b2_18           608.30 KiB  conda  https://conda.anaconda.org/conda-forge
libgcc-ng                                          15.2.0        he9431aa_18            26.92 KiB  conda  https://conda.anaconda.org/conda-forge
libgfortran                                        15.2.0        he9431aa_18            26.94 KiB  conda  https://conda.anaconda.org/conda-forge
libgfortran5                                       15.2.0        h1b7bec0_18             1.42 MiB  conda  https://conda.anaconda.org/conda-forge
libgomp                                            15.2.0        h8acb6b2_18           574.28 KiB  conda  https://conda.anaconda.org/conda-forge
liblapack                                          3.11.0        6_h88aeb00_openblas    18.26 KiB  conda  https://conda.anaconda.org/conda-forge
liblzma                                            5.8.3         he30d5cf_0            123.15 KiB  conda  https://conda.anaconda.org/conda-forge
libnghttp2                                         1.68.1        hd3077d7_0            709.89 KiB  conda  https://conda.anaconda.org/conda-forge
libnsl                                             2.0.1         h86ecc28_1             34.01 KiB  conda  https://conda.anaconda.org/conda-forge
libopenblas                                        0.3.32        pthreads_h9d3fd7e_0     4.88 MiB  conda  https://conda.anaconda.org/conda-forge
libsqlite                                          3.53.0        h022381a_0            931.98 KiB  conda  https://conda.anaconda.org/conda-forge
libssh2                                            1.11.1        h18c354c_0            304.10 KiB  conda  https://conda.anaconda.org/conda-forge
libstdcxx                                          15.2.0        hef695bb_18             5.28 MiB  conda  https://conda.anaconda.org/conda-forge
libstdcxx-ng                                       15.2.0        hdbbeba8_18            27.00 KiB  conda  https://conda.anaconda.org/conda-forge
libuuid                                            2.42          h1022ec0_0             42.55 KiB  conda  https://conda.anaconda.org/conda-forge
libuv                                              1.51.0        he30d5cf_1            614.49 KiB  conda  https://conda.anaconda.org/conda-forge
libxcrypt                                          4.4.36        h31becfc_1            111.59 KiB  conda  https://conda.anaconda.org/conda-forge
libzlib                                            1.3.2         hdc9db2a_2             68.20 KiB  conda  https://conda.anaconda.org/conda-forge
mccabe                                             0.7.0         pyhd8ed1ab_1           12.63 KiB  conda  https://conda.anaconda.org/conda-forge
ncurses                                            6.5           ha32ae93_3            904.33 KiB  conda  https://conda.anaconda.org/conda-forge
numpy                                              2.4.3         py312h6615c27_0         7.48 MiB  conda  https://conda.anaconda.org/conda-forge
openssl                                            3.6.2         h546c87b_0              3.53 MiB  conda  https://conda.anaconda.org/conda-forge
packaging                                          26.1          pyhc364b38_0           87.27 KiB  conda  https://conda.anaconda.org/conda-forge
pcre                                               8.45          h01db608_0            244.03 KiB  conda  https://conda.anaconda.org/conda-forge
pycodestyle                                        2.14.0        pyhd8ed1ab_0           34.36 KiB  conda  https://conda.anaconda.org/conda-forge
pydocstyle                                         6.3.0         pyhd8ed1ab_1           39.29 KiB  conda  https://conda.anaconda.org/conda-forge
pyflakes                                           3.4.0         pyhd8ed1ab_0           58.20 KiB  conda  https://conda.anaconda.org/conda-forge
pygments                                           2.20.0        pyhd8ed1ab_0          872.10 KiB  conda  https://conda.anaconda.org/conda-forge
pyparsing                                          3.3.2         pyhcf101f3_0          108.29 KiB  conda  https://conda.anaconda.org/conda-forge
python                                             3.12.13       h91f4b29_0_cpython     13.12 MiB  conda  https://conda.anaconda.org/conda-forge
python-dateutil                                    2.9.0.post0   pyhe01879c_2          227.84 KiB  conda  https://conda.anaconda.org/conda-forge
python_abi                                         3.12          8_cp312                 6.79 KiB  conda  https://conda.anaconda.org/conda-forge
readline                                           8.3           hb682ff5_0            349.22 KiB  conda  https://conda.anaconda.org/conda-forge
rhash                                              1.4.6         h86ecc28_1            202.61 KiB  conda  https://conda.anaconda.org/conda-forge
ros-kilted-ament-cmake                             2.7.5         np2py312h61f2ce4_17    22.87 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-core                        2.7.5         np2py312h61f2ce4_17    44.14 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-cppcheck                    0.19.2        np2py312h61f2ce4_17    24.00 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-cpplint                     0.19.2        np2py312h61f2ce4_17    22.90 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-definitions          2.7.5         np2py312h61f2ce4_17    21.63 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-dependencies         2.7.5         np2py312h61f2ce4_17    22.51 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-include-directories  2.7.5         np2py312h61f2ce4_17    22.04 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-interfaces           2.7.5         np2py312h61f2ce4_17    22.22 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-libraries            2.7.5         np2py312h61f2ce4_17    23.56 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-link-flags           2.7.5         np2py312h61f2ce4_17    21.58 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-export-targets              2.7.5         np2py312h61f2ce4_17    22.38 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-flake8                      0.19.2        np2py312h61f2ce4_17    23.87 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-gen-version-h               2.7.5         np2py312h61f2ce4_17    24.31 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-include-directories         2.7.5         np2py312h61f2ce4_17    21.55 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-libraries                   2.7.5         np2py312h61f2ce4_17    21.23 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-pep257                      0.19.2        np2py312h61f2ce4_17    22.69 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-python                      2.7.5         np2py312h61f2ce4_17    23.71 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-ros-core                    0.14.7        np2py312h61f2ce4_17    26.48 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-target-dependencies         2.7.5         np2py312h61f2ce4_17    23.44 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-test                        2.7.5         np2py312h61f2ce4_17    35.32 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-uncrustify                  0.19.2        np2py312h61f2ce4_17    23.28 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cmake-version                     2.7.5         np2py312h61f2ce4_17    21.40 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cppcheck                          0.19.2        np2py312h61f2ce4_17    29.46 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-cpplint                           0.19.2        np2py312h61f2ce4_17   165.40 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-flake8                            0.19.2        np2py312h61f2ce4_17    27.69 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-index-python                      1.11.3        np2py312h61f2ce4_17    29.91 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-lint                              0.19.2        np2py312h61f2ce4_17    17.19 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-package                           0.17.2        np2py312h61f2ce4_17    41.96 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-pep257                            0.19.2        np2py312h61f2ce4_17    26.38 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ament-uncrustify                        0.19.2        np2py312h61f2ce4_17    66.83 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-fastcdr                                 2.3.5         np2py312h61f2ce4_17    84.59 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rcpputils                               2.13.5        np2py312h61f2ce4_17    79.78 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rcutils                                 6.9.10        np2py312h61f2ce4_17   126.03 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rmw                                     7.8.2         np2py312h61f2ce4_17    95.48 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ros-environment                         4.3.1         np2py312h61f2ce4_17    20.97 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-ros-workspace                           1.0.3         np2py312h61f2ce4_17    34.55 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-adapter                          4.9.6         np2py312h61f2ce4_17    66.53 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-cli                              4.9.6         np2py312h61f2ce4_17    45.32 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-cmake                            4.9.6         np2py312h61f2ce4_17    35.53 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-core-runtime                     0.3.2         np2py312h61f2ce4_17    29.40 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-dynamic-typesupport              0.3.1         np2py312h61f2ce4_17    57.55 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-generator-c                      4.9.6         np2py312h61f2ce4_17    50.92 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-generator-cpp                    4.9.6         np2py312h61f2ce4_17    49.22 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-generator-py                     0.24.2        np2py312h61f2ce4_17    58.51 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-generator-rs                     0.4.11        np2py312h61f2ce4_17    47.12 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-generator-type-description       4.9.6         np2py312h61f2ce4_17    45.98 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-parser                           4.9.6         np2py312h61f2ce4_17    64.69 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-pycommon                         4.9.6         np2py312h61f2ce4_17    26.36 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-runtime-c                        4.9.6         np2py312h61f2ce4_17    85.08 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-runtime-cpp                      4.9.6         np2py312h61f2ce4_17    40.26 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-c                    3.3.3         np2py312h61f2ce4_17    49.74 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-cpp                  3.3.3         np2py312h61f2ce4_17    48.95 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-fastrtps-c           3.8.2         np2py312h61f2ce4_17    50.66 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-fastrtps-cpp         3.8.2         np2py312h61f2ce4_17    52.64 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-interface            4.9.6         np2py312h61f2ce4_17    28.83 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-introspection-c      4.9.6         np2py312h61f2ce4_17    46.49 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rosidl-typesupport-introspection-cpp    4.9.6         np2py312h61f2ce4_17    46.60 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-rpyutils                                0.6.3         np2py312h61f2ce4_17    26.78 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-uncrustify-vendor                       3.1.0         np2py312h61f2ce4_17    22.76 KiB  conda  https://prefix.dev/robostack-kilted
ros-kilted-unique-identifier-msgs                  2.7.0         np2py312h61f2ce4_17    75.41 KiB  conda  https://prefix.dev/robostack-kilted
ros2-distro-mutex                                  0.14.0        kilted_17               2.31 KiB  conda  https://prefix.dev/robostack-kilted
setuptools                                         82.0.1        pyh332efcf_0          624.70 KiB  conda  https://conda.anaconda.org/conda-forge
six                                                1.17.0        pyhe01879c_1           18.02 KiB  conda  https://conda.anaconda.org/conda-forge
snowballstemmer                                    3.0.1         pyhd8ed1ab_0           71.30 KiB  conda  https://conda.anaconda.org/conda-forge
tinyxml2                                           11.0.0        h5ad3122_0            130.19 KiB  conda  https://conda.anaconda.org/conda-forge
tk                                                 8.6.13        noxft_h0dc03b3_103      3.21 MiB  conda  https://conda.anaconda.org/conda-forge
tomli                                              2.4.1         pyhcf101f3_0           21.06 KiB  conda  https://conda.anaconda.org/conda-forge
tzdata                                             2025c         hc9c84f9_1            116.34 KiB  conda  https://conda.anaconda.org/conda-forge
uncrustify                                         0.81.0        h7ac5ae9_2            698.84 KiB  conda  https://conda.anaconda.org/conda-forge
zipp                                               3.23.1        pyhcf101f3_0           23.89 KiB  conda  https://conda.anaconda.org/conda-forge
zstd                                               1.5.7         h85ac4a6_6            600.03 KiB  conda  https://conda.anaconda.org/conda-forge

Environment info

System
------------
       Pixi version: 0.65.0
        TLS backend: rustls
           Platform: linux-aarch64
   Virtual packages: __unix=0=0
                   : __linux=5.15.0=0
                   : __glibc=2.35=0
                   : __archspec=1=cortex_a72
          Cache dir: /home/parallels/.cache/rattler/cache
       Auth storage: /home/parallels/.rattler/credentials.json
   Config locations: No config files found

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

Workspace
------------
               Name: roboplan-ros
            Version: 0.1.0
      Manifest file: /home/parallels/ROS/seabass/roboplan-ros/pixi.toml
       Last updated: 21-04-2026 20:58:18

Environments
------------
        Environment: default
           Features: default
           Channels: conda-forge
   Dependency count: 17
       Dependencies: colcon-common-extensions, colcon-mixin, cmake, clangxx, lld, ninja, mold, sccache, python, gtest, viser, tyro, matplotlib, filelock, nanobind, numpy, lttng-ust
  PyPI Dependencies: pycollada, nodeenv
   Target platforms: linux-64, linux-aarch64
    Prefix location: /home/parallels/ROS/seabass/roboplan-ros/.pixi/envs/default
              Tasks: build, setup-colcon, test, build-symlink, test-result

        Environment: kilted
           Features: kilted, default
           Channels: https://prefix.dev/robostack-kilted, conda-forge
   Dependency count: 18
       Dependencies: ros-kilted-ros-base, colcon-common-extensions, colcon-mixin, cmake, clangxx, lld, ninja, mold, sccache, python, gtest, viser, tyro, matplotlib, filelock, nanobind, numpy, lttng-ust
  PyPI Dependencies: pycollada, nodeenv
   Target platforms: linux-aarch64, linux-64
    Prefix location: /home/parallels/ROS/seabass/roboplan-ros/.pixi/envs/kilted
              Tasks: build, setup-colcon, test, build-symlink, test-result

        Environment: jazzy
           Features: jazzy, default
           Channels: https://prefix.dev/robostack-jazzy, conda-forge
   Dependency count: 18
       Dependencies: ros-jazzy-ros-base, colcon-common-extensions, colcon-mixin, cmake, clangxx, lld, ninja, mold, sccache, python, gtest, viser, tyro, matplotlib, filelock, nanobind, numpy, lttng-ust
  PyPI Dependencies: pycollada, nodeenv
   Target platforms: linux-aarch64, linux-64
    Prefix location: /home/parallels/ROS/seabass/roboplan-ros/.pixi/envs/jazzy
              Tasks: build, setup-colcon, test, build-symlink, test-result

        Environment: humble
           Features: humble, default
           Channels: https://prefix.dev/robostack-humble, conda-forge
   Dependency count: 18
       Dependencies: ros-humble-ros-base, colcon-common-extensions, colcon-mixin, cmake, clangxx, lld, ninja, mold, sccache, python, gtest, viser, tyro, matplotlib, filelock, nanobind, numpy, lttng-ust
  PyPI Dependencies: pycollada, nodeenv
   Target platforms: linux-aarch64, linux-64
    Prefix location: /home/parallels/ROS/seabass/roboplan-ros/.pixi/envs/humble
              Tasks: build, setup-colcon, test, build-symlink, test-result

[sea-bass]

Could it be https://github.com/RoboStack/ros-kilted/pull/62/changes#diff-0908cf139523cb29a7d4900368553861753d19f825ea559fe1f649b181f254daR9 ?

[eholum]

Oh yep. Reading through the docs for the change into the upstream in: ros2/rosidl_python#253, and in https://cmake.org/cmake/help/latest/module/FindPython.html:

Python::Module
Python library for Python module. Target defined if component Development.Module is found.

Python::Python
Python library for Python embedding. Target defined if component Development.Embed is found.

So I think this is the intended state. No message packages will actually ship with the libpython dependency in place, which means that any C++ applications that that need to dlopen message libraries will likely crash.

Is that... right?

For now, I manually linked against the old Python::Python in the broken kilted branch and confirmed it resolves the issue. If the embedded dep gets dropped in favor of the module, then I think anything that links against python will have to include:

# Manually link against python to ensure it is loaded in the process.
find_package(Python 3.8 COMPONENTS Interpreter Development REQUIRED)
target_link_libraries(roboplan_ros_cpp PRIVATE
  "-Wl,--no-as-needed"
  Python::Python
  "-Wl,--as-needed"
)

Any advice is appreciated!

[traversaro]

Sorry, I missed this issue, thanks a lot for the detailed report. At this point, I think I am missing a bit of context on how the *__rosidl_generator_py.so libraries are meant to be used. I thought they were regular Python extensions that are loaded in Python, and in that case there is no need to link libpython, as the Python symbols are provided by the Python executable itself. However, I guess I was wrong on this?

[eholum]

Thanks @traversaro! No need to apologize we really appreciate all your work here. And I am also digging into this for the first time...

I think the problem with the upstream is that there is no distinguishing dependencies for C++ vs python message libraries? In our C++ application, linking against things like ${sensor_msgs_TARGETS} brings in a dependency on libsensor_msgs__rosidl_generator_py.so. I don't know if there's a way to separate things out so that the python bindings aren't pulled in for purely C++ processes, but from playing around with this for a bit it seems like the answer is no?

I'm really not sure what the answer is here. This seems like a feature and not a bug?

[traversaro]

However, a simple workaround for now is to only apply the patch https://github.com/robostack/ros-kilted/blob/main/patch/ros-kilted-rosidl-generator-py.patch on macOS, as it is the only platform on which it is important not to link Python::Python. The tricky problem is that we would need to bump the build number for any affected msgs package.

[traversaro]

Thanks, that is also what I found (playing with your pixi file indeed). I wonder if perhaps libsensor_msgs__rosidl_generator_py.so should not be included in ${sensor_msgs_TARGETS}, if it is not meant to be linked by downstream use? I need to investigate more about this.

[eholum]

Thanks, that is also what I found (playing with your pixi file indeed). I wonder if perhaps libsensor_msgs__rosidl_generator_py.so should not be included in ${sensor_msgs_TARGETS}, if it is not meant to be linked by downstream use? I need to investigate more about this.

I feel like that should be the case? Though I don't understand the history there since it seems like it has been there for forever.

I think that export happens here? https://github.com/ros2/rosidl_python/blob/kilted/rosidl_generator_py/cmake/rosidl_generator_py_generate_interfaces.cmake#L260

Checking locally, the python .so is listed in the exported targets:

$  cat .pixi/envs/kilted/share/sensor_msgs/cmake/ament_cmake_export_targets-extras.cmake
# generated from ament_cmake_export_targets/cmake/ament_cmake_export_targets-extras.cmake.in

set(_exported_targets "... export_sensor_msgs__rosidl_generator_py; ...)

But perhaps it shouldn't be?

[traversaro]

The easiest option here is probably to just go back to https://github.com/RoboStack/ros-jazzy/blob/main/patch/ros-jazzy-rosidl-generator-py.osx.patch, and only apply the patch on macOS.