🚀 Add FLANN as bundled dependency to fix Python wheel builds

Critical fix for Python wheel failures:

**FLANN Bundled Integration:**
- Added flann.cmake with FetchContent from official flann-lib/flann repo
- Integrated into find_dependencies.cmake system
- Linked flann_cpp to kiss_matcher_core library

**CI Configuration Updates:**
- Set USE_SYSTEM_FLANN=OFF across all workflows
- Python wheels now use bundled FLANN (no system dependency needed)
- C++ builds also use bundled FLANN for consistency
- ROS2 builds updated with FLANN settings

**Build System:**
- pyproject.toml: Added -DUSE_SYSTEM_FLANN=OFF flag
- All platforms now build with static FLANN library
- No external FLANN installation required

This should resolve all Python wheel build failures by eliminating
the FLANN system dependency that was causing issues in cibuildwheel.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: LimHyungTae

.github/workflows/ci-cpp.yml

@@ -112,7 +112,8 @@ jobs:
                 -DUSE_CCACHE=ON \
                 -DUSE_SYSTEM_EIGEN3=ON \
                 -DUSE_SYSTEM_TBB=ON \
-                -DUSE_SYSTEM_ROBIN=OFF
+                -DUSE_SYSTEM_ROBIN=OFF \
+                -DUSE_SYSTEM_FLANN=OFF
 
       - name: Configure CMake (Windows)
         if: runner.os == 'Windows'
@@ -125,7 +126,8 @@ jobs:
                 -DUSE_CCACHE=OFF `
                 -DUSE_SYSTEM_EIGEN3=OFF `
                 -DUSE_SYSTEM_TBB=OFF `
-                -DUSE_SYSTEM_ROBIN=OFF
+                -DUSE_SYSTEM_ROBIN=OFF `
+                -DUSE_SYSTEM_FLANN=OFF
 
       - name: Build C++ Core
         run: cmake --build build --config Release --parallel
@@ -200,7 +202,8 @@ jobs:
                 -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
                 -DUSE_SYSTEM_EIGEN3=ON \
                 -DUSE_SYSTEM_TBB=ON \
-                -DUSE_SYSTEM_ROBIN=OFF
+                -DUSE_SYSTEM_ROBIN=OFF \
+                -DUSE_SYSTEM_FLANN=OFF
           cmake --build build/core --config Release --parallel
 
       - name: Install KISS-Matcher Core

.github/workflows/ci-python.yml

@@ -47,6 +47,7 @@ jobs:
             USE_SYSTEM_EIGEN3=OFF
             USE_SYSTEM_TBB=OFF
             USE_SYSTEM_ROBIN=OFF
+            USE_SYSTEM_FLANN=OFF
             CMAKE_BUILD_PARALLEL_LEVEL=2
 
           # Test command

.github/workflows/ci-ros2.yml

@@ -103,6 +103,7 @@ jobs:
               -DUSE_SYSTEM_EIGEN3=ON \
               -DUSE_SYSTEM_TBB=ON \
               -DUSE_SYSTEM_ROBIN=OFF \
+              -DUSE_SYSTEM_FLANN=OFF \
             --parallel-workers $(nproc)
 
       - name: Build ROS2 wrapper

cpp/kiss_matcher/3rdparty/find_dependencies.cmake

@@ -40,5 +40,6 @@ endfunction()
 find_external_dependency("Eigen3" "Eigen3::Eigen" "${CMAKE_CURRENT_LIST_DIR}/eigen/eigen.cmake")
 find_external_dependency("TBB" "TBB::tbb" "${CMAKE_CURRENT_LIST_DIR}/tbb/tbb.cmake")
 find_external_dependency("robin" "robin::robin" "${CMAKE_CURRENT_LIST_DIR}/robin/robin.cmake")
+find_external_dependency("flann" "flann_cpp" "${CMAKE_CURRENT_LIST_DIR}/flann/flann.cmake")
 # ToDos
 # find_external_dependency("tsl-robin-map" "tsl::robin_map" "${CMAKE_CURRENT_LIST_DIR}/tsl_robin/tsl_robin.cmake")

cpp/kiss_matcher/3rdparty/flann/flann.cmake

@@ -0,0 +1,52 @@
+# MIT License
+#
+# Copyright (c) 2025 Hyungtae Lim and coauthors.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+include(FetchContent)
+
+# Build FLANN as static library for easier wheel distribution
+set(BUILD_SHARED_LIBS OFF CACHE BOOL "" FORCE)
+
+FetchContent_Declare(
+  flann
+  GIT_REPOSITORY https://github.com/flann-lib/flann.git
+  GIT_TAG 1.9.2
+  GIT_SHALLOW TRUE
+)
+
+# Configure FLANN options
+set(BUILD_EXAMPLES OFF CACHE BOOL "Build FLANN examples" FORCE)
+set(BUILD_TESTS OFF CACHE BOOL "Build FLANN tests" FORCE)
+set(BUILD_DOC OFF CACHE BOOL "Build FLANN documentation" FORCE)
+set(BUILD_MATLAB_BINDINGS OFF CACHE BOOL "Build MATLAB bindings" FORCE)
+set(BUILD_PYTHON_BINDINGS OFF CACHE BOOL "Build Python bindings" FORCE)
+set(USE_OPENMP ON CACHE BOOL "Use OpenMP" FORCE)
+
+FetchContent_MakeAvailable(flann)
+
+# Ensure FLANN headers are treated as system includes
+if(TARGET flann)
+  get_target_property(flann_include_dirs flann INTERFACE_INCLUDE_DIRECTORIES)
+  set_target_properties(flann PROPERTIES INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${flann_include_dirs}")
+elseif(TARGET flann_cpp)
+  get_target_property(flann_include_dirs flann_cpp INTERFACE_INCLUDE_DIRECTORIES)
+  set_target_properties(flann_cpp PROPERTIES INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${flann_include_dirs}")
+endif()

cpp/kiss_matcher/CMakeLists.txt

@@ -71,7 +71,7 @@ add_library(${TARGET_NAME} STATIC
 add_library(kiss_matcher::kiss_matcher_core ALIAS kiss_matcher_core)
 
 target_link_libraries(${TARGET_NAME}
-    PUBLIC Eigen3::Eigen robin::robin ${OpenMP_LIBS} ${EIGEN3_LIBS} TBB::tbb ${LZ4_LIBRARY}
+    PUBLIC Eigen3::Eigen robin::robin flann_cpp ${OpenMP_LIBS} ${EIGEN3_LIBS} TBB::tbb ${LZ4_LIBRARY}
 )
 
 # To make kiss_matcher::core global for Pybinding

python/pyproject.toml

@@ -48,7 +48,8 @@ cmake.build-type = "Release"
 cmake.args = [
     "-DUSE_SYSTEM_EIGEN3=OFF",
     "-DUSE_SYSTEM_TBB=OFF",
-    "-DUSE_SYSTEM_ROBIN=OFF"
+    "-DUSE_SYSTEM_ROBIN=OFF",
+    "-DUSE_SYSTEM_FLANN=OFF"
 ]
 cmake.define = {
     CMAKE_CXX_STANDARD = "17",