bpo-40170: Always define PyExceptionClass_Name() as a function (GH-24553)

Remove macro variant of PyExceptionClass_Name().

Include/cpython/pyerrors.h

@@ -78,10 +78,6 @@ PyAPI_FUNC(void) _PyErr_GetExcInfo(PyThreadState *, PyObject **, PyObject **, Py
 
 PyAPI_FUNC(void) _PyErr_ChainExceptions(PyObject *, PyObject *, PyObject *);
 
-/* */
-
-#define PyExceptionClass_Name(x)  (((PyTypeObject*)(x))->tp_name)
-
 /* Convenience functions */
 
 #ifdef MS_WINDOWS

Misc/NEWS.d/next/C API/2021-02-16-22-29-39.bpo-40170.ahHmOo.rst

@@ -0,0 +1,3 @@
+:c:func:`PyExceptionClass_Name` is now always declared as a function, in
+order to hide implementation details. The macro accessed
+:c:member:`PyTypeObject.tp_name` directly.  Patch by Erlend E. Aasland.

Objects/exceptions.c

@@ -364,8 +364,6 @@ PyException_SetContext(PyObject *self, PyObject *context)
     Py_XSETREF(_PyBaseExceptionObject_cast(self)->context, context);
 }
 
-#undef PyExceptionClass_Name
-
 const char *
 PyExceptionClass_Name(PyObject *ob)
 {