Hartmut Goebel writes: >> the python-build-system does not cross-compile. > > In any case, this is a current limitation only :-) I see. If we actually do plan on implementing some kind of cross-compilation support for the python-build-system, then I can understand why it makes sense to proactively put into the native-inputs those things which might possibly need to be native-inputs when that time comes. Can we at least mention in the manual that the python-build-system doesn't currently cross-compile, so native-inputs will be treated the same as inputs for now, but we still recommend putting the "build-only dependencies" in native-inputs in order to future-proof our package definitions? That alone would have helped clarify things for me when I was starting out. After reading about Python extension modules a little more, it seems that they can in fact be cross-compiled. I didn't look into Python 2, and I don't know what it would take to enable such cross-compilation in the python-build-system. For those following along, here are some related links. An explanation of Python extension modules: https://docs.python.org/3/extending/building.html#distributing-your-extension-modules Some Python open bugs that mention cross-compilation: https://bugs.python.org/issue?%40columns=id%2Cactivity%2Ctitle%2Ccreator%2Cassignee%2Cstatus&%40sort=-activity&%40group=priority&%40filter=status&status=-1%2C1%2C3&%40search_text=cross-compile&submit=search+in+open+issues -- Chris