IntoPyResult Trait Missing For PyResult<PyBytes>

[danii]

💥 Reproducing

Make any old Python function in Rust with Pyo3 that:

• Returns a Python bytes / Rust PyBytes object
• That may also throw an exception

#[pyfunction]
fn get_bytes(py: Python, throw: bool) -> PyResult<PyBytes> {
  if throw {
    Err(PyErr::new::<exceptions::Exception, _>("Throw was set."))
  } else {
    Ok(*PyBytes::new(py, &[1, 2, 3, 4]))
  }
}

All names shown are from std or pyo3.

Rust complains that the trait 'pyo3::derive_utils::IntoPyResult<_>' is not implemented for 'std::result::Result<pyo3::types::bytes::PyBytes, pyo3::err::PyErr>'.

🌍 Environment

• Manjaro 19.0.2 Kyria, x86_64 Linux 5.4.31-1-MANJARO
• Python 3.8.2, installed via pamac
• Rustc 1.43.0-nightly (564758c4c 2020-03-08), installed via rustup pamac
• Pyo3 0.9.2

[davidhewitt]

I think your return type needs to be PyResult<&PyBytes>, and then things should work correctly.

(It is expected that this won't work for the non-reference type PyBytes at the moment; this might change after #679)

[davidhewitt]

To clarify, this is the working solution @Daniihh:

#[pyfunction]
fn get_bytes(py: Python, throw: bool) -> PyResult<&PyBytes> {
  if throw {
    Err(PyErr::new::<exceptions::Exception, _>("Throw was set."))
  } else {
    Ok(PyBytes::new(py, &[1, 2, 3, 4]))
  }
}

[danii]

Oh wow, LOL, this is quite embarrassing.
I'm very sorry for wasting your time, I'll be sure to do more tinkering and research before I open any other issues. ;p