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, 2 insertions, 2 deletions

diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index c853160..d1def24 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1724,8 +1724,8 @@ pyexpat_ParserCreate(PyObject *notused, PyObject *args, PyObject *kw)
     PyObject *intern = NULL;
     PyObject *result;
     int intern_decref = 0;
-    static char *kwlist[] = {"encoding", "namespace_separator",
-			     "intern", NULL};
+    static const char *kwlist[] = {"encoding", "namespace_separator",
+                                   "intern", NULL};
 
     if (!PyArg_ParseTupleAndKeywords(args, kw, "|zzO:ParserCreate", kwlist,
                                      &encoding, &namespace_separator, &intern))