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/Objects/descrobject.c b/Objects/descrobject.c
index df7435aade..f763832a65 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -579,7 +579,7 @@ PyTypeObject PyWrapperDescr_Type = {
 };
 
 static PyDescrObject *
-descr_new(PyTypeObject *descrtype, PyTypeObject *type, char *name)
+descr_new(PyTypeObject *descrtype, PyTypeObject *type, const char *name)
 {
 	PyDescrObject *descr;
 
@@ -1182,7 +1182,7 @@ static int
 property_init(PyObject *self, PyObject *args, PyObject *kwds)
 {
 	PyObject *get = NULL, *set = NULL, *del = NULL, *doc = NULL;
-	static char *kwlist[] = {"fget", "fset", "fdel", "doc", 0};
+	static const char *kwlist[] = {"fget", "fset", "fdel", "doc", 0};
 	propertyobject *gs = (propertyobject *)self;
 
 	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OOOO:property",