#[derive(IntoPyObject)] error a bit unhelpful when lifetime not called 'py #4704
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In pydantic-core some (legacy) lifetimes were 'a instead of 'py, and using the new #[derive(IntoPyObject)] led to some interesting errors:
use pyo3::{Bound, IntoPyObject, PyAny};
#[derive(IntoPyObject)]
pub struct Wrap<'a>(Bound<'a, PyAny>);gets lots of errors like
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'py` due to conflicting requirements
--> src/lib.rs:3:10
|
3 | #[derive(IntoPyObject)]
| ^^^^^^^^^^^^
|
note: first, the lifetime cannot outlive the lifetime `'a` as defined here...
--> src/lib.rs:4:17
|
4 | pub struct Wrap<'a>(Bound<'a, PyAny>);
| ^^
note: ...but the lifetime must also be valid for the lifetime `'py` as defined here...
--> src/lib.rs:3:10
|
3 | #[derive(IntoPyObject)]
| ^^^^^^^^^^^^
note: ...so that the types are compatible
--> src/lib.rs:3:10
|
3 | #[derive(IntoPyObject)]
| ^^^^^^^^^^^^
= note: expected `pyo3::IntoPyObject<'py>`
found `pyo3::IntoPyObject<'_>`
= note: this error originates in the derive macro `IntoPyObject` (in Nightly builds, run with -Z macro-backtrace for more info)
changing the struct lifetime from 'a to 'py trivially resolves, though I wonder if there's any tricks we can do to improve the UX 🤔
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