cannot find value py in this scope when deriving FromPyObject on struct

[lesurp]

Bug Description

There seems to be a missing let py = _pyo3::PyNativeType::py(obj); in the generated code when trying to use from_py_with (note that the problem does not appear when using an item, which explains why the tests pass despite this bug). See cargo expand output.

Steps to Reproduce

fn pouf(py: &PyAny) -> PyResult<usize> {
    Ok(1)
}

// NOT OK
#[derive(Debug, FromPyObject)]
pub(crate) struct Zap {
    #[pyo3(from_py_with = "pouf")]
    pub foo: usize,
}

// OK
#[derive(Debug, FromPyObject)]
pub(crate) struct Zap2 {
    pub foo: usize,
}

Generated code:

impl<'source> _pyo3::FromPyObject<'source> for Zap2 {
            fn extract(obj: &'source _pyo3::PyAny) -> _pyo3::PyResult<Self> {
                ::std::result::Result::Ok(Zap2 {
                    foo: {
                        let py = _pyo3::PyNativeType::py(obj); /////////// This is missing in the Zap implementation!
                        obj.getattr({
                            fn isolate_from_dyn_env(
                                py: ::pyo3::Python<'_>,
                            ) -> &::pyo3::types::PyString {
                                static INTERNED: ::pyo3::once_cell::GILOnceCell<
                                    ::pyo3::Py<::pyo3::types::PyString>,
                                > = ::pyo3::once_cell::GILOnceCell::new();
                                INTERNED
                                    .get_or_init(py, || {
                                        ::pyo3::conversion::IntoPy::into_py(
                                            ::pyo3::types::PyString::intern(py, "foo"),
                                            py,
                                        )
                                    })
                                    .as_ref(py)
                            }
                            isolate_from_dyn_env(py)
                        })?
                        .extract()
                        .map_err(|inner| {
                            let new_err = _pyo3::exceptions::PyTypeError::new_err(
                                "failed to extract field Zap2.foo",
                            );
                            new_err.set_cause(py, ::std::option::Option::Some(inner));
                            new_err
                        })?
                    },
                })
            }
        }

impl<'source> _pyo3::FromPyObject<'source> for Zap {
            fn extract(obj: &'source _pyo3::PyAny) -> _pyo3::PyResult<Self> {
                ::std::result::Result::Ok(Zap {
                    foo: pouf(obj.getattr({
                        fn isolate_from_dyn_env(
                            py: ::pyo3::Python<'_>,
                        ) -> &::pyo3::types::PyString {
                            static INTERNED: ::pyo3::once_cell::GILOnceCell<
                                ::pyo3::Py<::pyo3::types::PyString>,
                            > = ::pyo3::once_cell::GILOnceCell::new();
                            INTERNED
                                .get_or_init(py, || {
                                    ::pyo3::conversion::IntoPy::into_py(
                                        ::pyo3::types::PyString::intern(py, "paf"),
                                        py,
                                    )
                                })
                                .as_ref(py)
                        }
                        isolate_from_dyn_env(py)
                    })?)
                    .map_err(|inner| {
                        let py = _pyo3::PyNativeType::py(obj);
                        let new_err = _pyo3::exceptions::PyTypeError::new_err(
                            "failed to extract field Zap.foo",
                        );
                        new_err.set_cause(py, ::std::option::Option::Some(inner));
                        new_err
                    })?,
                })
            }

Backtrace

error[E0425]: cannot find value `py` in this scope
  --> src\pyo3_types.rs:17:17
   |
17 | #[derive(Debug, FromPyObject)]
   |                 ^^^^^^^^^^^^ not found in this scope
   |
   = note: this error originates in the derive macro `FromPyObject` (in Nightly builds, run with -Z macro-backtrace for more info)
For more information about this error, try `rustc --explain E0425`.

### Your operating system and version

Windows 10

### Your Python version (`python --version`)

Python 3.10.0

### Your Rust version (`rustc --version`)

rustc 1.63.0-nightly (ee160f2f5 2022-05-23)

### Your PyO3 version

0.16.3

### How did you install python? Did you use a virtualenv?

anaconda

### Additional Info

_No response_

[davidhewitt]

Thanks for reporting! I've pushed some clean ups to the macro in #2414 which will fix this case.

[relsunkaev]

Is there a workaround for this in the meantime?

[davidhewitt]

You can use git dependency of PyO3, alternatively I expect to push a release very soon, just need to tidy up some rough edges.