Conditional compilation of attributes defined by attribute macros

[Nuramon27]

When an attribute macro like #[pyclass] defines further attributes to be used on the fields of a struct, like in the following example:

use pyo3::prelude::*;

#[pyclass]
struct Point {
    #[pyo3(get, set)]
    x: i32,
    y: i32,
}

is it possible to apply these attributes conditionally, gated by a crate feature?

When trying something like the following:

#[cfg(feature = "pyo3")]
use pyo3::prelude::*;

#[cfg_attr(feature = "pyo3", pyclass)]
struct Point {
    #[cfg_attr(feature = "pyo3", pyo3(get, set))]
    x: i32,
    y: i32,
}

and compiling with the feature activated:

cargo check --features pyo3

rustc complains about the unknown attribute pyo3.

[mejrs]

You can't do that, basically. For a workaround see `pyo3(get, set)` attribute not found when using `cfg_attr` · Issue #1003 · PyO3/pyo3 · GitHub

See that thread and the links in it if you are curious why it doesnt work.