Uniffi multiple crates not supported

[Hinton]

Bug Description

Uniffi supports using types from dependent crates, https://mozilla.github.io/uniffi-rs/proc_macro/index.html#types-from-dependent-crates. Consider a crate a which depends on b. This results in two python files being generated, a.py and b.py.

The types exposed by crate a are exported in a.py, and b in b.py. In order to correctly use the library both python files needs to be imported.

The sample repository https://github.com/Hinton/maturin-repro produces the following wheel:

a.whl
  a/
    __init__.py
    a.py
    liba.dylib
  a-0.1.0.dist-info/

As noted, b.py is missing which is referenced by a.py.

Your maturin version (maturin --version)

1.4.0

Your Python version (python -V)

3.9.6

Your pip version (pip -V)

21.2.4

What bindings you're using

uniffi

Does cargo build work?

• Yes, it works

If on windows, have you checked that you aren't accidentally using unix path (those with the forward slash /)?

• Yes

Steps to Reproduce

1. Checkout https://github.com/Hinton/maturin-repro
2. Run maturin build
3. Unpack target/wheels/a-0.1.0-py3-none-macosx_11_0_arm64.whl
4. Note missing b.py.
5. Attempt to run and get an error complaining about b missing since it's imported from a.py.