duplicate definitions with name __pymethod_clear__

[awolverp]

Bug Description

After updating crate to version 0.22.4, I got this error:

error[E0592]: duplicate definitions with name `__pymethod_clear__`
  --> src/bridge/cache.rs:21:1
   |
21 | #[pyo3::pymethods]
   | ^^^^^^^^^^^^^^^^^^
   | |
   | duplicate definitions for `__pymethod_clear__`
   | other definition for `__pymethod_clear__`
   |
   = note: this error originates in the attribute macro `pyo3::pymethods` (in Nightly builds, run with -Z macro-backtrace for more info)

This is my code:

#[pyo3::pyclass(name="Cache")]
pub struct Cache {
    // fields ...
}

#[pyo3::pymethods]
impl Cache {
    pub fn __traverse__(&self, visit: pyo3::PyVisit<'_>) -> Result<(), pyo3::PyTraverseError> {
        // some code ...
        Ok(())
    }

    pub fn __clear__(&self) {
        // some code ...
    }

    #[pyo3(signature=(*, reuse=false))]
    pub fn clear(&self, reuse: bool) {
        // some code ...
    }
}

I know this is because I have __clear__ and clear methods together, but this was OK before, and now I cannot remove or change them. How can I fix that?

Steps to Reproduce

1. Initialize a PyO3 project with maturin init
2. Write this code in src/lib.rs:

use pyo3::prelude::*;

#[pyo3::pyclass(name="Cache")]
pub struct Cache {}

#[pyo3::pymethods]
impl Cache {
    pub fn __traverse__(&self, visit: pyo3::PyVisit<'_>) -> Result<(), pyo3::PyTraverseError> {
        Ok(())
    }

    pub fn __clear__(&self) {
    }

    #[pyo3(signature=(*, reuse=false))]
    pub fn clear(&self, reuse: bool) {
    }
}

/// A Python module implemented in Rust.
#[pymodule]
fn py_test_pyo3(m: &Bound<'_, PyModule>) -> PyResult<()> {
    m.add_class::<Cache>()?;
    Ok(())
}

3. You will see this error (run maturin develop):

error[E0592]: duplicate definitions with name `__pymethod_clear__`
 --> src/lib.rs:8:1
  |
8 | #[pyo3::pymethods]
  | ^^^^^^^^^^^^^^^^^^
  | |
  | duplicate definitions for `__pymethod_clear__`
  | other definition for `__pymethod_clear__`
  |
  = note: this error originates in the attribute macro `pyo3::pymethods` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0308]: mismatched types
  --> src/lib.rs:9:6
   |
8  |   #[pyo3::pymethods]
   |   ------------------ arguments to this function are incorrect
9  |   impl Cache {
   |  ______^
10 | |     pub fn __traverse__(&self, visit: pyo3::PyVisit<'_>) -> Result<(), pyo3::PyTraverseError> {
11 | |         // some code ...
12 | |         Ok(())
...  |
19 | |     #[pyo3(signature=(*, reuse=false))]
20 | |     pub fn clear(&self, reuse: bool) {
   | |________________^ expected "Rust" fn, found "C" fn
   |
   = note: expected fn pointer `unsafe for<'py> fn(Python<'py>, *mut PyObject, *const *mut PyObject, isize, *mut PyObject) -> Result<*mut PyObject, PyErr>`
                 found fn item `unsafe extern "C" fn(*mut PyObject) -> i32 {Cache::__pymethod_clear__}`
note: function defined here
  --> /home/awolverp/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pyo3-0.22.4/src/impl_/trampoline.rs:56:12
   |
56 |     pub fn fastcall_with_keywords(
   |            ^^^^^^^^^^^^^^^^^^^^^^

Some errors have detailed explanations: E0308, E0592.
For more information about an error, try `rustc --explain E0308`.
warning: `py-test-pyo3` (lib) generated 2 warnings
error: could not compile `py-test-pyo3` (lib) due to 2 previous errors; 2 warnings emitted
💥 maturin failed
  Caused by: Failed to build a native library through cargo
  Caused by: Cargo build finished with "exit status: 101": `env -u CARGO PYO3_ENVIRONMENT_SIGNATURE="cpython-3.12-64bit" PYO3_PYTHON="/home/awolverp/Projects/py-test-pyo3/.venv/bin/python" PYTHON_SYS_EXECUTABLE="/home/awolverp/Projects/py-test-pyo3/.venv/bin/python" "cargo" "rustc" "--features" "pyo3/extension-module" "--message-format" "json-render-diagnostics" "--manifest-path" "/home/awolverp/Projects/py-test-pyo3/Cargo.toml" "--lib"`

Backtrace

No response

Your operating system and version

Linux awolverp-82h8 6.10.13-3-MANJARO #1 SMP PREEMPT_DYNAMIC Tue Oct 8 03:24:49 UTC 2024 x86_64 GNU/Linux

Your Python version (python --version)

Python 3.12.6

Your Rust version (rustc --version)

rustc 1.81.0 (eeb90cda1 2024-09-04)

Your PyO3 version

0.22.4

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

Python is installed by default
Yes, I used virtualenv.

Additional Info

No response

[davidhewitt]

Ooof, yes this is a regression. Should be easy to fix; I think I will have to ship a 0.22.5 given that we yanked all the rest of 0.22 except for 0.22.4.

[davidhewitt]

Sorry for the bug and thank you for the report 🙏

[awolverp]

Thank you for this great crate ❤️

[Icxolu]

#4619 should fix this