python3.11/00383-gh-93442-make-c-versi...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
<31488909+miss-islington@users.noreply.github.com>
Date: Sat, 4 Jun 2022 22:15:59 -0700
Subject: [PATCH] 00383: gh-93442: Make C++ version of _Py_CAST work with
0/NULL
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Add C++ overloads for _Py_CAST_impl() to handle 0/NULL. This will allow
C++ extensions that pass 0 or NULL to macros using _Py_CAST() to
continue to compile. Without this, you get an error like:
invalid static_cast from type int to type _object*
The modern way to use a NULL value in C++ is to use nullptr. However,
we want to not break extensions that do things the old way.
Co-authored-by: serge-sans-paille
(cherry picked from commit 8bcc3fa3453e28511d04eaa0aa7d8e1a3495d518)
Co-authored-by: Neil Schemenauer <nas-github@arctrix.com>
---
Include/pyport.h | 14 ++++++++++++++
Lib/test/_testcppext.cpp | 4 ++++
.../2022-06-04-13-15-41.gh-issue-93442.4M4NDb.rst | 3 +++
3 files changed, 21 insertions(+)
create mode 100644 Misc/NEWS.d/next/C API/2022-06-04-13-15-41.gh-issue-93442.4M4NDb.rst
diff --git a/Include/pyport.h b/Include/pyport.h
index 5a9adf162b..a78e290931 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -24,9 +24,23 @@
//
// The type argument must not be a constant type.
#ifdef __cplusplus
+#include <cstddef>
# define _Py_STATIC_CAST(type, expr) static_cast<type>(expr)
extern "C++" {
namespace {
+ template <typename type>
+ inline type _Py_CAST_impl(long int ptr) {
+ return reinterpret_cast<type>(ptr);
+ }
+ template <typename type>
+ inline type _Py_CAST_impl(int ptr) {
+ return reinterpret_cast<type>(ptr);
+ }
+ template <typename type>
+ inline type _Py_CAST_impl(std::nullptr_t) {
+ return static_cast<type>(nullptr);
+ }
+
template <typename type, typename expr_type>
inline type _Py_CAST_impl(expr_type *expr) {
return reinterpret_cast<type>(expr);
diff --git a/Lib/test/_testcppext.cpp b/Lib/test/_testcppext.cpp
index eade7ccdaa..70f434e678 100644
--- a/Lib/test/_testcppext.cpp
+++ b/Lib/test/_testcppext.cpp
@@ -74,6 +74,10 @@ test_api_casts(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
Py_INCREF(strong_ref);
Py_DECREF(strong_ref);
+ // gh-93442: Pass 0 as NULL for PyObject*
+ Py_XINCREF(0);
+ Py_XDECREF(0);
+
Py_DECREF(obj);
Py_RETURN_NONE;
}
diff --git a/Misc/NEWS.d/next/C API/2022-06-04-13-15-41.gh-issue-93442.4M4NDb.rst b/Misc/NEWS.d/next/C API/2022-06-04-13-15-41.gh-issue-93442.4M4NDb.rst
new file mode 100644
index 0000000000..f48ed37c81
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2022-06-04-13-15-41.gh-issue-93442.4M4NDb.rst
@@ -0,0 +1,3 @@
+Add C++ overloads for _Py_CAST_impl() to handle 0/NULL. This will allow C++
+extensions that pass 0 or NULL to macros using _Py_CAST() to continue to
+compile.