test suite failures and missing symbols on macOS

[damaxwell]

🐛 Bug Reports

There are failures in the test suite on macOS with pyenv installed Python 3.7.6.

failures:

---- buffer::test::test_array_buffer stdout ----
thread 'buffer::test::test_array_buffer' panicked at 'called `Result::unwrap()` on an `Err` value: PyErr { type: Py(0x10b9fa4f0, PhantomData) }', src/libcore/result.rs:1189:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

---- exceptions::test::test_check_exception stdout ----
thread 'exceptions::test::test_check_exception' panicked at 'Can not import module: socket: PyErr { type: Py(0x10b9fa4f0, PhantomData) }', src/libcore/result.rs:1189:5


failures:
    buffer::test::test_array_buffer
    exceptions::test::test_check_exception

The issue is caused by missing Python library symbols in the final linked rust executable. For example, the failure in test_check_exception happens on an import socket. The Python socket module imports a C extension module _socket that references _PyTime_AsMilliseconds, which is missing:

Traceback (most recent call last):
  File "/Users/david/.pyenv/versions/3.7.6/lib/python3.7/socket.py", line 49, in <module>
    import _socket
ImportError: dlopen(/Users/david/.pyenv/versions/3.7.6/lib/python3.7/lib-dynload/_socket.cpython-37m-darwin.so, 2): Symbol not found: __PyTime_AsMilliseconds
  Referenced from: /Users/david/.pyenv/versions/3.7.6/lib/python3.7/lib-dynload/_socket.cpython-37m-darwin.so
  Expected in: flat namespace
 in /Users/david/.pyenv/versions/3.7.6/lib/python3.7/lib-dynload/_socket.cpython-37m-darwin.so

The issue may be related to the fact that the pyenv installation only provides a static Python library.

The issue may be known; it was obliquely mentioned in #704 before being deleted from the original issue report.

🌍 Environment

• Your operating system and version:
  macOS 10.15.2

• Your python version:
  3.7.6

• How did you install python (e.g. apt or pyenv)? Did you use a virtualenv?:
  pyenv

• Your rust version (rustc --version):
  1.41.0-nightly

• Are you using the latest pyo3 version? Have you tried using latest master (replace version = "0.x.y" with git = "https://github.com/PyO3/pyo3")?
  Yes.

💥 Reproducing

cargo test

[damaxwell]

Oh, hey, look at that. If you install Python with a shared library:

env PYTHON_CONFIGURE_OPTS="--enable-shared" pyenv install 3.7.6

then all your problems go away. So this is my mistake. But others seem to have hit it. Maybe just note this somewhere in the docs?

[kngwyu]

Thank you for sharing the workaround!
I added a note on README based on your snippet :)