temp: fix ros builds when FETCHCONTENT_FULLY_DISABLE is ON, aka the ros build farm (#45)

* clean up ament target dependencies deprecation

* update bonxai version

* add bonxai core source to dependencies/bonxai with a check to include only on specific conditions

Author: mehermvr

cmake/dependencies/bonxai/README.md

@@ -0,0 +1,12 @@
+The code here is covered by Bonxai's [LICENSE](../LICENSE) file.
+Please note that this is essentially a hack to fix a very specific case encountered in the ROS build farm.
+I'm repeating the comment i have from [bonxai.cmake](bonxai.cmake) here.
+
+The ros build farm uses `FETCHCONTENT_FULLY_DISCONNECTED` to perform an isolated build.
+But as per the author of FetchContent himself, this is an abuse of the flag.
+See https://github.com/Homebrew/brew/pull/17075 and https://gitlab.kitware.com/cmake/cmake/-/issues/25946.
+Nevertheless this is a problem for us since Bonxai is not part of rosdistro (or any upstream system package repo) yet.
+See here for possible progress: https://github.com/facontidavide/Bonxai/issues/55.
+
+Since a user can use this flag as valid behavior, my best attempt at fixing this issue for the build farm is to vendor Bonxai code right here.
+Hopefully soon enough, one way or another, I can remove this hack and stop vendoring bonxai code in my own repository.

cmake/dependencies/bonxai/bonxai.cmake

@@ -1,10 +1,38 @@
 FetchContent_Declare(
   Bonxai
   GIT_REPOSITORY https://github.com/facontidavide/Bonxai.git
-  GIT_TAG 47ffd0a2917c899f6199dfa71445481164298006 # apr 7 2025 master
+  GIT_TAG 02d401b1ce38bce870c6704bcd4e35a56a641411 # sep 14 2025 master
   SOURCE_SUBDIR
   bonxai_core
   SYSTEM
   EXCLUDE_FROM_ALL
   OVERRIDE_FIND_PACKAGE)
 FetchContent_MakeAvailable(Bonxai)
+
+if(FETCHCONTENT_FULLY_DISCONNECTED)
+  # the ros build farm uses this option to perform an isolated build. but as per
+  # the author of FetchContent himself, this is an abuse of the flag. See
+  # https://github.com/Homebrew/brew/pull/17075 and
+  # https://gitlab.kitware.com/cmake/cmake/-/issues/25946. Nevertheless this is
+  # a problem for us since Bonxai is not part of rosdistro yet. See here for
+  # progress: https://github.com/facontidavide/Bonxai/issues/55. Since a user
+  # can use this flag as valid behavior, the following is my best attempt at
+  # catching the specific situation in the build farm. Hopefully soon enough, i
+  # can remove this hack and stop vendoring bonxai code in my own repository.
+
+  file(
+    GLOB_RECURSE bonxai_source_files
+    LIST_DIRECTORIES false
+    "${bonxai_SOURCE_DIR}/*")
+
+  list(LENGTH bonxai_source_files bonxai_source_count)
+
+  if(bonxai_source_count EQUAL 0)
+    message(
+      WARNING
+        "Bonxai source directory (${bonxai_SOURCE_DIR}) is empty and FETCHCONTENT_FULLY_DISCONNECTED is ON. This is likely unintended. Bonxai will be manually included for now as it is a required dependency."
+    )
+    add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/bonxai_core)
+  endif()
+
+endif()

cmake/dependencies/bonxai/bonxai_core/CMakeLists.txt

@@ -0,0 +1,10 @@
+add_library(bonxai_core INTERFACE
+    include/bonxai/bonxai.hpp
+    include/bonxai/serialization.hpp
+    include/bonxai/grid_coord.hpp
+)
+set_target_properties(bonxai_core PROPERTIES LINKER_LANGUAGE CXX)
+
+target_include_directories(bonxai_core PUBLIC INTERFACE
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+    $<INSTALL_INTERFACE:include>)