Windows CI: VINCA_CUSTOM_CMAKE_BUILD_DIR stripped by rattler-build env isolation, causing MAX_PATH failures #76

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Issue

The Windows build of ros2-rosbag2-performance-benchmarking-msgs fails in CI with an MSVC long-path error:

• Run: https://github.com/RoboStack/ros-lyrical/actions/runs/37698125442/job/113054782544

%SRC_DIR%\build\rosidl_generator_py\rosbag2_performance_benchmarking_msgs\_rosbag2_performance_benchmarking_msgs_s.ep.rosidl_typesupport_introspection_c.c(1,1):
error C1083: Cannot open compiler generated file: '': Invalid argument

The full path is C:\bld\bld\rattler-build_ros2-rosbag2-performance-benchmarking-msgs_1791414638\work\build\.... Combined with rosidl's generated file and folder names, it goes over MAX_PATH. The 3 jobs that follow in the run were skipped because of this failure.

Root cause: the C:\x short-build-dir workaround is not reaching the build script.

The generated win.yml sets VINCA_CUSTOM_CMAKE_BUILD_DIR: C:\x\, and vinca's bld_ament_cmake.bat is supposed to cd there before building. In the log, that variable expands to an empty value inside the build script:

%SRC_DIR%>if defined VINCA_CUSTOM_CMAKE_BUILD_DIR (
 if not exist "\" (mkdir "" )
  cd /d ""
 )
%SRC_DIR%>rd /s /q build

As a result, CMake builds in %SRC_DIR%\build instead of C:\x\build. CI uses rattler-build 0.76.1, which runs build scripts with --env-isolation strict by default. That mode starts from a clean environment, which likely strips variables such as VINCA_CUSTOM_CMAKE_BUILD_DIR. This means the workaround is currently disabled for every Windows build, not only this package.

Proposed fixes:

1. Short-term (ros-lyrical): add --no-build-id to .scripts/build_win.bat, matching what testpr.yml already does. This removes the timestamp suffix from the build directory.
2. Proper fix (vinca): forward VINCA_CUSTOM_CMAKE_BUILD_DIR explicitly through the generated recipes, for example via build.script.env with ${{ env.get("VINCA_CUSTOM_CMAKE_BUILD_DIR", default="") }}, so that it works under strict env isolation. The alternative is passing --env-isolation conda-build/none in CI, but that lets the whole CI environment into every build.

Installed packages

N/A — CI build failure (rattler-build 0.76.1, windows-2022 runner)

Environment info

N/A — CI build failure on GitHub Actions win-64 (build_win workflow, buildbranch_win)

This issue description was AI-generated using Claude Opus 5.5.