[BUG] depthai-core 'BUILD_SHARED_LIBS=OFF' targets not found: 'fmt::fmt' in 'depthai::core', 'protobuf::libprotobuf' in 'depthai::messages', 'websocketpp::websocketpp' in 'depthai::foxglove_websocket'

[marc-medley]

Check if issue already exists

• [BUG] Cannot configure project without USB support #1386, which uses -D'BUILD_SHARED_LIBS=false', is specific to USB support lacking a usb-1.0Config.cmake or usb-1.0-config.cmake file.
• Other luxonis/depthai-core open issues are in the context of BUILD_SHARED_LIBS being enabled, and thus not applicable.

Describe the bug

The link phase of a consuming CMake project fails because depthai-core does not provide three targets which are indicated to be present based on lib/cmake/depthai/depthaiTargets.cmake:

• depthai::core is missing fmt::fmt
• depthai::messages is missing protobuf::libprotobuf
• depthai::foxglove_websocket is missing websocketpp::websocketpp

Minimal Reproducible Example

Step 1. Build depthai-core with -DBUILD_SHARED_LIBS=OFF

The variable DEPTHAI_CORE_PATH points to the depthai-core which is build with -DBUILD_SHARED_LIBS=OFF. This path can be adjusted as needed.

DEPTHAI_CORE_VERSION="3.0.0-rc.3-static"
DEPTHAI_CORE_BRANCH="main"
DEPTHAI_CORE_PATH="/opt/luxonis/depthai-core/${DEPTHAI_CORE_VERSION}"

git clone \
    --single-branch \
    --branch ${DEPTHAI_CORE_BRANCH} \
    --recurse-submodules \
    git@github.com:luxonis/depthai-core.git \
    depthai_${DEPTHAI_CORE_VERSION}
cd depthai_${DEPTHAI_CORE_VERSION}

mkdir build && cd build

cmake -S .. -B . \
    -DDEPTHAI_BUILD_EXAMPLES=OFF \
    -DBUILD_SHARED_LIBS=OFF \
    -DCMAKE_INSTALL_PREFIX="${DEPTHAI_CORE_PATH}"

if [[ "$(uname)" == "Darwin" ]]; then
  NUM_CORES=$(sysctl -n hw.ncpu)
else
  NUM_CORES=$(nproc)
fi
cmake --build . --parallel ${NUM_CORES};
cmake --build . --target install

Step 2. Configure and build a cmake project which consumes depthai-core

set(DEPTHAI_CORE_VERSION 3.0.0-rc.3-static)

list(APPEND
    CMAKE_PREFIX_PATH 
        "/opt/luxonis/depthai-core/${DEPTHAI_CORE_VERSION}"
)

find_package(depthai CONFIG REQUIRED)

target_link_libraries(example_app
    PRIVATE
        # ...
        depthai::core
    PUBLIC
        ${OpenCV_LIBS}
)

Step 3. The linker discovers that depthai-core is missing targets which are declared in lib/cmake/depthai/depthaiTargets.cmake to be present, but are not found.

Three targets in particular are stated to be present but found to be missing:

• depthai::core is missing the declared fmt::fmt (depthaiTargets.cmake:87)
• depthai::messages is missing the declared protobuf::libprotobuf (depthaiTargets.cmake:118)
• depthai::foxglove_websocket is missing the declared websocketpp::websocketpp (depthaiTargets.cmake:126)

console output

All three errors have this message pattern:

CMake Error at /opt/luxonis/depthai-core/3.0.0-rc.3/lib/cmake/depthai/depthaiTargets.cmake:87 (set_target_properties):
  The link interface of target "depthai::core" contains:

    fmt::fmt

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

/depthaiTargets.cmake:87

set_target_properties(depthai::core PROPERTIES
  INTERFACE_COMPILE_DEFINITIONS "DEPTHAI_TARGET_CORE;DEPTHAI_TARGET_OPENCV;DEPTHAI_HAVE_OPENCV_SUPPORT;DEPTHAI_MERGED_TARGET;MCAP_STATIC;DEPTHAI_ENABLE_PROTOBUF;DEPTHAI_XTENSOR_SUPPORT"
  INTERFACE_COMPILE_FEATURES "cxx_std_17"
  INTERFACE_INCLUDE_DIRECTORIES "${_IMPORT_PREFIX}/include;${_IMPORT_PREFIX}/include/"
  INTERFACE_LINK_LIBRARIES "opencv_core;opencv_imgproc;opencv_videoio;opencv_highgui;\$<LINK_ONLY:depthai::depthai-resources>;depthai::nlohmann_json;depthai::libnop;depthai::XLinkPublic;\$<LINK_ONLY:fmt::fmt>;\$<LINK_ONLY:yaml-cpp::yaml-cpp>;\$<LINK_ONLY:spdlog::spdlog>;\$<LINK_ONLY:depthai::XLink>;\$<LINK_ONLY:Threads::Threads>;\$<LINK_ONLY:BZip2::BZip2>;\$<LINK_ONLY:LibArchive::LibArchive>;\$<LINK_ONLY:ZLIB::ZLIB>;\$<LINK_ONLY:httplib::httplib>;\$<LINK_ONLY:semver::semver>;\$<LINK_ONLY:magic_enum::magic_enum>;\$<LINK_ONLY:liblzma::liblzma>;\$<LINK_ONLY:lz4::lz4>;\$<LINK_ONLY:mp4v2::mp4v2>;\$<LINK_ONLY:protobuf::libprotobuf>;\$<LINK_ONLY:depthai::messages>;\$<LINK_ONLY:depthai::foxglove_websocket>;\$<LINK_ONLY:apriltag::apriltag>;\$<LINK_ONLY:CURL::libcurl_static>;\$<LINK_ONLY:cpr::cpr>;xtensor;\$<LINK_ONLY:Backward::Backward>"
)

depthaiTargets.cmake

depthaiTargets.cmake.txt

Expected behavior

It is expected that the targets declared in lib/cmake/depthai/depthaiTargets.cmake are actually present at link time of a consuming CMake project.

Screenshots

Not applicable.

Pipeline Graph

Not applicable.

Attach system log

64-bit RPiOS (Debian 12) on RPi 5

log_system_information_rpi5_rpios.json

Ubuntu Server 24.04 on RPi 5

log_system_information_rpi5_ubuntu.json

Additional context

The goal is to statically link depthai-core into another CMake project.

An apt-get install … of libraries, which would otherwise provide the targets, does the resolve the fact that depthai-core does not provide the targets which lib/cmake/depthai/depthaiTargets.cmake states to be present.

sudo apt-get update
sudo apt-get install libfmt-dev \
    libprotobuf-dev protobuf-compiler \
    libwebsocketpp-dev

[moratom]

Hi @marc-medley - installing and integrating DepthAI as a static library is not supported yet and not planned for the near future.

Is something preventing you to use it as a shared library or is this more of a preference?

[rudolflovrencic]

In our use case, we also conusme depthai-core v2 as a static library and our CI/CD relies on that. It makes some things simpler but it is not a hard constraint - still, it makes upgrading to v3 a bit harder.