declarative modules: #[pymodule_export] macro cannot be gated in `cfg_attr`
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Description
The following code fails to work properly because #[pymodule_export] gets ignored even if the pyo3 feature is enabled:
#[cfg(feature = "pyo3")]
use pyo3::prelude::*;
#[cfg_attr(feature = "pyo3", pymodule)]
pub mod py_const {
#[cfg_attr(feature = "pyo3", pymodule_export)]
pub const MY_CONST: () = ();
}
We should update the pymodule macro code to support cfg_attr and not blindly match on #[pymodule_export].
Issue initially reported by @SichangHe (I reused the example): https://github.com/PyO3/pyo3/issues/3900#issuecomment-2944213501
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Research direction
Start from the pymodule macro code and reproduce the issue with the Rust example and the pyo3 feature enabled. Trace how pymodule_export attributes are recognized through cfg_attr; done means the constant is exported when the feature is enabled without the direct attribute form.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python, rust
- Domain
- api
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100