DLL of dependency not found

[haroonsyed]

OS: Windows 11
PYO3: "0.17.3"

Hello, I am attempting to use cuda from rust in a python notebook via Rust's FFI.

Project Structure:

• root project using pyo3 in a pip venv

  • src (Uses the cuda_lib down below)

  • cargo.toml

  • cuda_lib subcrate

    • cuda_kernels
      • cuda_src
      • build
        • cuda_release.lib
      • CMakeLists.txt
    • lib.rs // Extern C bindings using FFI to cuda_release.lib functions
    • build.rs // Links statically to cudart.lib (native) and cuda_release.lib

The cargo toml of the parent pyo3 crate includes the subcrate with
cuda_lib = { path = "./cuda_lib" }

I have everything work when running tests in both the subcrate and parent crate (I am able to see a print function from cuda).
maturin develop --release resolves without error.
However when I import the library (Rust_Machine_Learning) into python it states:

File [d:\dev\Rust-Machine-Learning\.venv\Lib\site-packages\Rust_Machine_Learning\__init__.py:1](file:///D:/dev/Rust-Machine-Learning/.venv/Lib/site-packages/Rust_Machine_Learning/__init__.py:1)
----> 1 from .Rust_Machine_Learning import *
      3 __doc__ = Rust_Machine_Learning.__doc__
      4 if hasattr(Rust_Machine_Learning, "__all__"):

ImportError: DLL load failed while importing Rust_Machine_Learning: The specified module could not be found.

I am not sure if it is talking about cudart (native lib) or my cuda_lib (possibly both?).
Everything imports fine when I do not use the FFI to the cuda binaries in my cuda_lib and replace them with dummy functions in rust.

I have tried copying the .lib files into the site-packages folder without success. I also tried renaming them to .pyd and .dll.

Not sure where to go from here, help is appreciated :)

[haroonsyed]

Alright so I solved this by using the CC library, which handled compilation and linking for me.
I tested in wsl and my original code worked, so idk what's up on windows with the binary not being moved over.

CC code for those that might want it:
https://github.com/haroonsyed/Rust-Machine-Learning/blob/6c67d920b3663af28c54d7dbf0e45cf949023a04/matrix_lib/build.rs#L1-L17