ffi: update modsupport.rs for Python 3.13 (#4420)

Author: davidhewitt

newsfragments/4420.fixed.md

@@ -0,0 +1 @@
+Correct FFI definition `PyArg_ParseTupleAndKeywords` to take `*const *const c_char` instead of `*mut *mut c_char` on Python 3.13 and up.

newsfragments/4420.removed.md

@@ -0,0 +1 @@
+Remove FFI definition of private variable `_Py_PackageContext`.

pyo3-ffi/src/modsupport.rs

@@ -14,9 +14,14 @@ extern "C" {
         arg1: *mut PyObject,
         arg2: *mut PyObject,
         arg3: *const c_char,
-        arg4: *mut *mut c_char,
+        #[cfg(not(Py_3_13))] arg4: *mut *mut c_char,
+        #[cfg(Py_3_13)] arg4: *const *const c_char,
         ...
     ) -> c_int;
+
+    // skipped PyArg_VaParse
+    // skipped PyArg_VaParseTupleAndKeywords
+
     pub fn PyArg_ValidateKeywordArguments(arg1: *mut PyObject) -> c_int;
     #[cfg_attr(PyPy, link_name = "PyPyArg_UnpackTuple")]
     pub fn PyArg_UnpackTuple(
@@ -26,32 +31,10 @@ extern "C" {
         arg4: Py_ssize_t,
         ...
     ) -> c_int;
+
     #[cfg_attr(PyPy, link_name = "PyPy_BuildValue")]
     pub fn Py_BuildValue(arg1: *const c_char, ...) -> *mut PyObject;
-    // #[cfg_attr(PyPy, link_name = "_PyPy_BuildValue_SizeT")]
-    //pub fn _Py_BuildValue_SizeT(arg1: *const c_char, ...)
-    // -> *mut PyObject;
-    // #[cfg_attr(PyPy, link_name = "PyPy_VaBuildValue")]
-
-    // skipped non-limited _PyArg_UnpackStack
-    // skipped non-limited _PyArg_NoKeywords
-    // skipped non-limited _PyArg_NoKwnames
-    // skipped non-limited _PyArg_NoPositional
-    // skipped non-limited _PyArg_BadArgument
-    // skipped non-limited _PyArg_CheckPositional
-
-    //pub fn Py_VaBuildValue(arg1: *const c_char, arg2: va_list)
-    // -> *mut PyObject;
-
-    // skipped non-limited _Py_VaBuildStack
-    // skipped non-limited _PyArg_Parser
-
-    // skipped non-limited _PyArg_ParseTupleAndKeywordsFast
-    // skipped non-limited _PyArg_ParseStack
-    // skipped non-limited _PyArg_ParseStackAndKeywords
-    // skipped non-limited _PyArg_VaParseTupleAndKeywordsFast
-    // skipped non-limited _PyArg_UnpackKeywords
-    // skipped non-limited _PyArg_Fini
+    // skipped Py_VaBuildValue
 
     #[cfg(Py_3_10)]
     #[cfg_attr(PyPy, link_name = "PyPyModule_AddObjectRef")]
@@ -159,9 +142,3 @@ pub unsafe fn PyModule_FromDefAndSpec(def: *mut PyModuleDef, spec: *mut PyObject
         },
     )
 }
-
-#[cfg(not(Py_LIMITED_API))]
-#[cfg_attr(windows, link(name = "pythonXY"))]
-extern "C" {
-    pub static mut _Py_PackageContext: *const c_char;
-}

tests/test_pyfunction.rs

@@ -363,8 +363,7 @@ fn test_pycfunction_new() {
 #[test]
 fn test_pycfunction_new_with_keywords() {
     use pyo3::ffi;
-    use std::ffi::CString;
-    use std::os::raw::{c_char, c_long};
+    use std::os::raw::c_long;
     use std::ptr;
 
     Python::with_gil(|py| {
@@ -375,28 +374,38 @@ fn test_pycfunction_new_with_keywords() {
         ) -> *mut ffi::PyObject {
             let mut foo: c_long = 0;
             let mut bar: c_long = 0;
-            let foo_ptr: *mut c_long = &mut foo;
-            let bar_ptr: *mut c_long = &mut bar;
 
-            let foo_name = CString::new("foo").unwrap();
-            let foo_name_raw: *mut c_char = foo_name.into_raw();
-            let kw_bar_name = CString::new("kw_bar").unwrap();
-            let kw_bar_name_raw: *mut c_char = kw_bar_name.into_raw();
+            #[cfg(not(Py_3_13))]
+            let foo_name = std::ffi::CString::new("foo").unwrap();
+            #[cfg(not(Py_3_13))]
+            let kw_bar_name = std::ffi::CString::new("kw_bar").unwrap();
+            #[cfg(not(Py_3_13))]
+            let mut args_names = [foo_name.into_raw(), kw_bar_name.into_raw(), ptr::null_mut()];
 
-            let mut arglist = vec![foo_name_raw, kw_bar_name_raw, ptr::null_mut()];
-            let arglist_ptr: *mut *mut c_char = arglist.as_mut_ptr();
-
-            let arg_pattern: *const c_char = CString::new("l|l").unwrap().into_raw();
+            #[cfg(Py_3_13)]
+            let args_names = [
+                c_str!("foo").as_ptr(),
+                c_str!("kw_bar").as_ptr(),
+                ptr::null_mut(),
+            ];
 
             ffi::PyArg_ParseTupleAndKeywords(
                 args,
                 kwds,
-                arg_pattern,
-                arglist_ptr,
-                foo_ptr,
-                bar_ptr,
+                c_str!("l|l").as_ptr(),
+                #[cfg(Py_3_13)]
+                args_names.as_ptr(),
+                #[cfg(not(Py_3_13))]
+                args_names.as_mut_ptr(),
+                &mut foo,
+                &mut bar,
             );
 
+            #[cfg(not(Py_3_13))]
+            drop(std::ffi::CString::from_raw(args_names[0]));
+            #[cfg(not(Py_3_13))]
+            drop(std::ffi::CString::from_raw(args_names[1]));
+
             ffi::PyLong_FromLong(foo * bar)
         }