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 *.

1 files changed, 4 insertions, 4 deletions

diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index cc75e4570e..76a4ab3e01 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -15,7 +15,7 @@ static PyMemberDef module_members[] = {
 };
 
 PyObject *
-PyModule_New(char *name)
+PyModule_New(const char *name)
 {
 	PyModuleObject *m;
 	PyObject *nameobj;
@@ -149,10 +149,10 @@ _PyModule_Clear(PyObject *m)
 static int
 module_init(PyModuleObject *m, PyObject *args, PyObject *kwds)
 {
-	static char *kwlist[] = {"name", "doc", NULL};
+	static const char *kwlist[] = {"name", "doc", NULL};
 	PyObject *dict, *name = Py_None, *doc = Py_None;
-	if (!PyArg_ParseTupleAndKeywords(args, kwds, "S|O:module.__init__", kwlist,
-					 &name, &doc))
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "S|O:module.__init__",
+                                         kwlist, &name, &doc))
 		return -1;
 	dict = m->md_dict;
 	if (dict == NULL) {