Added missing field to PyCodeObject. Changed definitions on the struct

condition to be smarter (any versions that are above 3.7 (not
including))

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Fix missing field in `PyCodeObject` struct (`co_posonlyargcount`) - caused invalid access to other fields in Python >3.7. [#1260](https://github.com/PyO3/pyo3/pull/1260)
 ### Packaging
 - Drop support for Python 3.5 (as it is now end-of-life). [#1250](https://github.com/PyO3/pyo3/pull/1250)
 

src/ffi/code.rs

@@ -10,6 +10,8 @@ pub enum _PyOpcache {}
 pub struct PyCodeObject {
  pub ob_base: PyObject,
  pub co_argcount: c_int,
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
+ pub co_posonlyargcount: c_int,
  pub co_kwonlyargcount: c_int,
  pub co_nlocals: c_int,
  pub co_stacksize: c_int,
@@ -28,13 +30,13 @@ pub struct PyCodeObject {
  pub co_zombieframe: *mut c_void,
  pub co_weakreflist: *mut PyObject,
  pub co_extra: *mut c_void,
- #[cfg(Py_3_8)]
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
  pub co_opcache_map: *mut c_uchar,
- #[cfg(Py_3_8)]
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
  pub co_opcache: *mut _PyOpcache,
- #[cfg(Py_3_8)]
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
  pub co_opcache_flag: c_int,
- #[cfg(Py_3_8)]
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
  pub co_opcache_size: c_uchar,
 }
 
@@ -99,7 +101,7 @@ extern "C" {
  firstlineno: c_int,
  lnotab: *mut PyObject,
  ) -> *mut PyCodeObject;
- #[cfg(Py_3_8)]
+ #[cfg(not(any(Py_3_7, Py_3_6)))]
  pub fn PyCode_NewWithPosOnlyArgs(
  argcount: c_int,
  posonlyargcount: c_int,