PyUnicodeDecodeError::new_utf8 raises TypeError on PyPy

[samuelcolvin]

Bug Description

PyUnicodeDecodeError::new_utf8(py, py_bytes.as_bytes(), err)?;

Appears to be raising/returning a TypeError, on PyPy, specifically

TypeError: expected str, got NoneType object

Here's my full code in case it helps:

pub fn py_bytes_to_str(py_bytes: &PyBytes) -> PyResult<&str> {
    match from_utf8(py_bytes.as_bytes()) {
        Ok(s) => Ok(s),
        Err(err) => {
            let py = py_bytes.py();
            let decode_err = PyUnicodeDecodeError::new_utf8(py, py_bytes.as_bytes(), err)?;
            Err(PyErr::from_value(decode_err))
        }
    }
}

Steps to Reproduce

Run the above code on PyPy, with bytes that raise an error like b'\x81'.

Backtrace

No response

Your operating system and version

Ubuntu

Your Python version (python --version)

Python 3.9.12 (05fbe3aa5b0845e6c37239768aa455451aa5faba, Mar 29 2022, 08:15:34) [PyPy 7.3.9 with GCC 10.2.1 20210130 (Red Hat 10.2.1-11)]

Your Rust version (rustc --version)

rustc 1.67.0-nightly (c1a859b25 2022-11-10)

Your PyO3 version

pyo3 = "0.17.3"

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

pyenv, virtualenv yes

Additional Info

No response

[samuelcolvin]

Maybe UnicodeDecodeError expects reason as a last argument? But that's not passed:

pyo3/pyo3-ffi/src/pyerrors.rs

Lines 82 to 101 in a3edbf4

	pub unsafe fn PyUnicodeDecodeError_Create(
	encoding: *const c_char,
	object: *const c_char,
	length: Py_ssize_t,
	start: Py_ssize_t,
	end: Py_ssize_t,
	_reason: *const c_char,
	) -> *mut PyObject {
	crate::PyObject_CallFunction(
	PyExc_UnicodeDecodeError,
	std::ffi::CStr::from_bytes_with_nul(b"sy#nns\0")
	.unwrap()
	.as_ptr(),
	encoding,
	object,
	length,
	start,
	end,
	)
	}

[mejrs]

I think that Py_BuildValue format string is wrong.