Add const to several API functions that take char *. In C++, it's an error to pass a string literal to a char* function without a const_cast(). Rather than require every C++ extension module to put a cast around string literals, fix the API to state the const-ness. I focused on parts of the API where people usually pass literals: PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type slots, etc. Predictably, there were a large set of functions that needed to be fixed as a result of these changes. The most pervasive change was to make the keyword args list passed to PyArg_ParseTupleAndKewords() to be a const char *kwlist[]. One cast was required as a result of the changes: A type object mallocs the memory for its tp_doc slot and later frees it. PyTypeObject says that tp_doc is const char *; but if the type was created by type_new(), we know it is safe to cast to char *.

--- a/Objects/weakrefobject.c	Sat Dec 10 17:44:27 2005 +0000
+++ b/Objects/weakrefobject.c	Sat Dec 10 18:50:16 2005 +0000
@@ -126,7 +126,7 @@
 static PyObject *
 weakref_call(PyWeakReference *self, PyObject *args, PyObject *kw)
 {
-    static char *argnames[] = {NULL};
+    static const char *argnames[] = {NULL};
 
     if (PyArg_ParseTupleAndKeywords(args, kw, ":__call__", argnames)) {
         PyObject *object = PyWeakref_GET_OBJECT(self);