Deprecate functions from PEP 623

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Deprecate FFI definition `PyOS_AfterFork` for Python 3.7 and up. [#1348](https://github.com/PyO3/pyo3/pull/1348)
 - Deprecate FFI definition `PyCoro_Check` and `PyAsyncGen_Check` in favor of `PyCoro_CheckExact` and `PyAsyncGen_CheckExact` respectively to mirror Python API. [#1348](https://github.com/PyO3/pyo3/pull/1348)
 - Deprecate FFI definition `PyCoroWrapper_Check` which has never been in the Python API. [#1348](https://github.com/PyO3/pyo3/pull/1348)
+- Deprecate FFI definitions for `PyUnicode_FromUnicode`, `PyUnicode_AsUnicode` and `PyUnicode_AsUnicodeAndSize`, which will be removed from 3.12 and up due to [PEP 613](https://www.python.org/dev/peps/pep-0623/). [#1370](https://github.com/PyO3/pyo3/pull/1370)
 
 ### Removed
 - Remove FFI definition `PyFrame_ClearFreeList` when building for Python 3.9. [#1341](https://github.com/PyO3/pyo3/pull/1341)

src/ffi/unicodeobject.rs

@@ -58,7 +58,8 @@ extern "C" {
  length: Py_ssize_t,
  fill_char: Py_UCS4,
  ) -> Py_ssize_t;
- #[cfg(not(Py_LIMITED_API))]
+ #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
+ #[deprecated]
  #[cfg_attr(PyPy, link_name = "PyPyUnicode_FromUnicode")]
  pub fn PyUnicode_FromUnicode(u: *const Py_UNICODE, size: Py_ssize_t) -> *mut PyObject;
 
@@ -85,10 +86,12 @@ extern "C" {
  copy_null: c_int,
  ) -> *mut Py_UCS4;
  pub fn PyUnicode_AsUCS4Copy(unicode: *mut PyObject) -> *mut Py_UCS4;
- #[cfg(not(Py_LIMITED_API))]
+ #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
+ #[deprecated]
  #[cfg_attr(PyPy, link_name = "PyPyUnicode_AsUnicode")]
  pub fn PyUnicode_AsUnicode(unicode: *mut PyObject) -> *mut Py_UNICODE;
- #[cfg(not(Py_LIMITED_API))]
+ #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
+ #[deprecated]
  #[cfg_attr(PyPy, link_name = "PyPyUnicode_AsUnicodeAndSize")]
  pub fn PyUnicode_AsUnicodeAndSize(
  unicode: *mut PyObject,