incompatible function arguments, for cross platform build only

[bpuchala]

I'm trying to do a multi Python namespace package build for our project, where each namespace package has a shared C++ library and one or more Python modules bound using pybind11. It works when all the packages are built on the same platform (tested with macos, ubuntu, and with cibuildwheel using manylinux2014) but fails with "TypeError: incompatible function arguments" if the first package is built into a wheel with cibuildwheel using manylinux2014 and the second package is built on ubuntu for CI testing. When, for example, the second package is also built with cibuildwheel using manylinux2014, the tests all pass.

From issues, it seems like it's a symbol visibility issue? But I can't seem to figure out what needs to be done to fix it. Here is the package layout:

mypackage-a:

include/ # C++ only
  mypackage/a/classA.hh
python/
  mypackage/ # python only
    a/
      __init__.py 
  src/ # pybind11 bindings
    _a.cpp 
src/ # C++ only
  mypackage/a/classA.cc 

mypackage-b:

include/ # C++ only
  b/
    subpackage1/classB1.hh
    subpackage2/classB1.hh
python/
  mypackage/ # python only
    b/ 
      __init__.py
      subpackage1/
        __init__.py
      subpackage2/
        __init__.py
  src/ # pybind11 bindings
    _b_subpackage1.cpp
    _b_subpackage2.cpp
src/  # C++ only
  b/
    subpackage1/classB1.cc
    subpackage2/classB2.cc

install in site-packages:

mypackage/
  a/
    __init__.py
    _a.cpython-310-x86_64-linux-gnu.so
  b/
    __init__.py
    subpackage1/
       __init__.py
       _b_subpackage1.cpython-310-x86_64-linux-gnu.so
    subpackage2/
      __init__.py
      _b_subpackage2.cpython-310-x86_64-linux-gnu.so
  include/
    a/classA.hh
    b/subpackage1/classB1.hh
    b/subpackage2/classB2.hh
  lib/
    libmypackage_a.so
    libmypackage_b.so

Everything is built with scikit-build / CMake.

Example issue:

In mypackage-a:

• mypackage::a::ClassA is declared in mypackage/a/classA.hh and implemented in libmypackage_a.so
• pybind11 is used to bind mypackage::a::ClassA to mypackage.a._a.ClassA
• In mypackage/a/__init__.py we do: from ._a import ClassA
• In mypackage/a/_a.cpython-310-x86_64-linux-gnu.so we set rpath "$ORIGIN/../lib"

mypackage-a is built into a wheel using cibuildwheel with manylinux2014, but without auditwheel.

In mypackage-b:

• In mypackage_b.so we set rpath "$ORIGIN"
• In mypackage/b/subpackage1/_b_subpackage1.cpython-310-x86_64-linux-gnu.so we set rpath "$ORIGIN/../../lib"
• In python/src/_b_subpackage1.cpp of mypackage-b we bind using pybind11:
  • includes apy::module_::import("mypackage.a"); statement
  • binds some_function in that has mypackage::a::ClassA as arguments so that mypackage.a._a has a function some_function that takes mypackage.a.ClassA as arguments
• In mypackage/b/subpackage1/__init__.py we do: from ._b_subpackage1 import some_function

mypackage-a is installed using the wheel, and mypackage-b is built on ubuntu:latest with github actions and installed.

Then a Python test is run in which mypackage.a.ClassA objects are used as arguments to mypackage.b.subpackage1.some_function.

The tests fail with the following type of errors:

TypeError: some_function(): incompatible function arguments. The following argument types are supported:
1. (arg0: mypackage::a::ClassA, arg1: mypackage::a::ClassA) -> int

Invoked with: <mypackage.a._a.classA object at 0x7ff2f052fd70>, <mypackage.a._a.classA object at 0x7ff2f0826c70>

C++ tests in mypackage-b all pass using the shared library from mypackage-a.

Again, everything passes if both packages are built using the same platform, for all the platforms I'ved tried (macos, ubuntu, cibuildwheel with manylinux2014, centos).

Thanks for any suggestions.