Compilation error E0716 in Rust 1.74

[Tarnum-tst]

Hello! I ran into this problem while compiling latest pyca cryptography main branch with PR 13740: pyca/cryptography#13740
I'm currently on Windows 7 SP1 x64 using Rust 1.74 (latest cryptography raises MSRV to 1.83 for Windows 10+ so I reverted few commits to satisfy my system).
When building I got compilation error E0716 in this code fragment (pyo3::types::PyNone, latest pyo3):

error[E0716]: temporary value dropped while borrowed
   --> src\backend\rsa.rs:508:14
... |
500 |    fn recover_data_from_signature<'p>(
501 |        &self,
502 |        py: pyo3::Python<'p>,
503 |        signature: &[u8],
504 |        padding: &pyo3::Bound<'_, pyo3::PyAny>,
505 |        algorithm: &pyo3::Bound<'_, pyo3::PyAny>,
506 |    ) -> CryptographyResult<pyo3::Bound<'p, pyo3::types::PyBytes>> {
507 |         let algorithm = if algorithm.is_instance(&types::NO_DIGEST_INFO.get(py)?)? {
    |             --------- borrow later stored here
508 |             &pyo3::types::PyNone::get(py).to_owned().into_any()
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
509 |         } else {
    |         - temporary value is freed at the end of this statement
510 |             algorithm
511 |         };
... |
    = note: consider using a `let` binding to create a longer lived value

For more information about this error, try `rustc --explain E0716`.
error: could not compile `cryptography-rust` (lib) due to previous error

Looks like it is specific to Rust 1.74, there is no such problems with Rust 1.83.

Please advise how this problem could be solved with Rust 1.74? I really wouldn't like using unsafe static mut approach. Thanks!

[davidhewitt]

I think something like this will work:

let algo_owned;
let algorithm = if algorithm.is_instance(&types::NO_DIGEST_INFO.get(py)?)? {
    algo_owned = pyo3::types::PyNone::get(py).to_owned().into_any();
    &algo_owned
} else {
    algorithm
};

[Tarnum-tst]

Thanks very much for Your quick reply! Everything works now! :-)