ROS2 cross_compile mistake : Could NOT find Python3 (missing: Python3_NumPy_INCLUDE_DIRS NumPy) (found version "3.10.12")

[Dongzh0915]

env: ubuntu22.04 、cmake 3.22.1、python 3.10.12、NumPy 1.26.01

[seungin-cha]

I have the same problem, but I'm trying to build on gentoo linux.

Anyway, find_package(Python3 ... Numpy) doesn't seem to support cross-compile because this method internally executing python internally like /usr/bin/python3 -c "import numpy; print(numpy.get_include())", so not compatible with cross-compile.

[Dongzh0915]

I have the same problem, but I'm trying to build on gentoo linux.

Anyway, find_package(Python3 ... Numpy) doesn't seem to support cross-compile because this method internally executing python (like import numpy; ...), so not compatible with cross-compile.

Yes, so in the end I used the arm64 architecture docker image to complete the compilation, directly skipping the cross-compilation process. ROS2's support for cross-compilation is indeed not very friendly.

[XQSwx]

I also encountered this problem in the cross-compilation environment. Are there any solutions?

[seungin-cha]

@XQSwx In my case, it's resolved with defining CMAKE variable named Python3_NumPy_INCLUDE_DIR.
You can try to apply below codes and cmake configure.

-DPython3_NumPy_INCLUDE_DIR="<python_site_packages_dir>/numpy/core/include"

[XQSwx]

This is okay, but it doesn't fundamentally solve this problem. There are other packages that can find the numpy module. Why can't it find it

[XQSwx]

The ros2topic package also uses numpy, and that package can be compiled successfully

[seungin-cha]

This is okay, but it doesn't fundamentally solve this problem. There are other packages that can find the numpy module. Why can't it find it

Actually, I didn't analyze deeply but the cause seems to be #546 (comment).

[XQSwx]

I have blocked the python part of this package now