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/complexobject.c	Sat Dec 10 17:44:27 2005 +0000
+++ b/Objects/complexobject.c	Sat Dec 10 18:50:16 2005 +0000
@@ -829,7 +829,7 @@
 	Py_complex cr, ci;
 	int own_r = 0;
 	static PyObject *complexstr;
-	static char *kwlist[] = {"real", "imag", 0};
+	static const char *kwlist[] = {"real", "imag", 0};
 
 	r = Py_False;
 	i = NULL;