gh-92135: Fix _Py_reinterpret_cast() for const (#92138)

Fix C++ compiler warnings on cast macros, like _PyObject_CAST(), when
casting a constant expression to a non constant type: use
const_cast<> in C++.

* In C++, Py_SAFE_DOWNCAST() now uses static_cast<> rather than
  reinterpret_cast<>.
* Add tests to the _testcppext C++ extension.
* test_cppext no longer captures stdout in verbose mode.

1 files changed, 1 insertions, 2 deletions

diff --git a/Include/methodobject.h b/Include/methodobject.h
index 2046ab9..f4be385 100644
--- a/Include/methodobject.h
+++ b/Include/methodobject.h
@@ -43,8 +43,7 @@ typedef PyObject *(*PyCMethod)(PyObject *, PyTypeObject *, PyObject *const *,
 // it triggers an undefined behavior when Python calls it with 2 parameters
 // (bpo-33012).
 #define _PyCFunction_CAST(func) \
-    _Py_reinterpret_cast(PyCFunction, \
-        _Py_reinterpret_cast(void(*)(void), (func)))
+    _Py_reinterpret_cast(PyCFunction, _Py_reinterpret_cast(void(*)(void), (func)))
 
 PyAPI_FUNC(PyCFunction) PyCFunction_GetFunction(PyObject *);
 PyAPI_FUNC(PyObject *) PyCFunction_GetSelf(PyObject *);