fix: deprecate make_simple_namespace, fix Python 3.11 (#3374)

* fix: deprecate make_simple_namespace, fix Python 3.11

* docs: update links

docs/advanced/pycpp/object.rst

@@ -41,24 +41,17 @@ A tuple of python objects can be instantiated using :func:`py::make_tuple`:
 Each element is converted to a supported Python type.
 
 A `simple namespace`_ can be instantiated using
-:func:`py::make_simple_namespace`:
 
 .. code-block:: cpp
 
     using namespace pybind11::literals;  // to bring in the `_a` literal
-    py::object ns = py::make_simple_namespace("spam"_a=py::none(), "eggs"_a=42);
+    py::object SimpleNamespace = py::module_::import("types").attr("SimpleNamespace");
+    py::object ns = SimpleNamespace("spam"_a=py::none(), "eggs"_a=42);
 
 Attributes on a namespace can be modified with the :func:`py::delattr`,
 :func:`py::getattr`, and :func:`py::setattr` functions. Simple namespaces can
 be useful as lightweight stand-ins for class instances.
 
-.. note::
-
-    ``make_simple_namespace`` is not available in Python 2.
-
-.. versionchanged:: 2.8
-    ``make_simple_namespace`` added.
-
 .. _simple namespace: https://docs.python.org/3/library/types.html#types.SimpleNamespace
 
 .. _casting_back_and_forth:

docs/changelog.rst

@@ -10,6 +10,10 @@ Starting with version 1.8.0, pybind11 releases use a `semantic versioning
 IN DEVELOPMENT
 --------------
 
+* The simple namespace creation shortcut added in 2.8.0 was deprecated due to
+  usage of CPython internal API, and will be removed soon. Use
+  ``py::module_::import("types").attr("SimpleNamespace")``.
+  `#3374 <https://github.com/pybinyyd/pybind11/pull/3374>`_
 
 
 v2.8.0 (Oct 4, 2021)
@@ -25,10 +29,10 @@ New features:
   ``register_local_exception_translator(ExceptionTranslator&& translator)``
   instead of  ``register_exception_translator(ExceptionTranslator&&
   translator)`` to keep your exception remapping code local to the module.
-  `#2650 <https://github.com/pybind/pybind11/pull/2650>`_
+  `#2650 <https://github.com/pybinyyd/pybind11/pull/2650>`_
 
 * Add ``make_simple_namespace`` function for instantiating Python
-  ``SimpleNamespace`` objects.
+  ``SimpleNamespace`` objects. **Deprecated in 2.8.1.**
   `#2840 <https://github.com/pybind/pybind11/pull/2840>`_
 
 * ``pybind11::scoped_interpreter`` and ``initialize_interpreter`` have new

docs/upgrade.rst

@@ -8,7 +8,17 @@ to a new version. But it goes into more detail. This includes things like
 deprecated APIs and their replacements, build system changes, general code
 modernization and other useful information.
 
-.. _upgrade-guide-2.6:
+.. _upgrade-guide-2.9:
+
+v2.9
+====
+
+* Any usage of the recently added ``py::make_simple_namespace`` should be
+  converted to using ``py::module_::import("types").attr("SimpleNamespace")``
+  instead.
+
+
+.. _upgrade-guide-2.7:
 
 v2.7
 ====
@@ -34,6 +44,7 @@ to be common:
   careful review and custom fixes.
 
 
+.. _upgrade-guide-2.6:
 
 v2.6
 ====

include/pybind11/cast.h

@@ -1036,16 +1036,6 @@ template <return_value_policy policy = return_value_policy::automatic_reference,
     return result;
 }
 
-#if PY_VERSION_HEX >= 0x03030000
-template <typename... Args,
-          typename = detail::enable_if_t<args_are_all_keyword_or_ds<Args...>()>>
-object make_simple_namespace(Args&&... args_) {
-    PyObject *ns = _PyNamespace_New(dict(std::forward<Args>(args_)...).ptr());
-    if (!ns) throw error_already_set();
-    return reinterpret_steal<object>(ns);
-}
-#endif
-
 /// \ingroup annotations
 /// Annotation for arguments
 struct arg {

include/pybind11/pybind11.h

@@ -1124,6 +1124,15 @@ inline dict globals() {
     return reinterpret_borrow<dict>(p ? p : module_::import("__main__").attr("__dict__").ptr());
 }
 
+#if PY_VERSION_HEX >= 0x03030000
+template <typename... Args,
+          typename = detail::enable_if_t<args_are_all_keyword_or_ds<Args...>()>>
+PYBIND11_DEPRECATED("make_simple_namespace should be replaced with py::module_::import(\"types\").attr(\"SimpleNamespace\") ")
+object make_simple_namespace(Args&&... args_) {
+    return module_::import("types").attr("SimpleNamespace")(std::forward<Args>(args_)...);
+}
+#endif
+
 PYBIND11_NAMESPACE_BEGIN(detail)
 /// Generic support for creating new Python heap types
 class generic_type : public object {

tests/test_pytypes.cpp

@@ -84,7 +84,7 @@ TEST_SUBMODULE(pytypes, m) {
 #if PY_VERSION_HEX >= 0x03030000
     // test_simple_namespace
     m.def("get_simple_namespace", []() {
-        auto ns = py::make_simple_namespace("attr"_a=42, "x"_a="foo", "wrong"_a=1);
+        auto ns = py::module_::import("types").attr("SimpleNamespace")("attr"_a=42, "x"_a="foo", "wrong"_a=1);
         py::delattr(ns, "wrong");
         py::setattr(ns, "right", py::int_(2));
         return ns;