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/_hashopenssl.c b/Modules/_hashopenssl.c
index bfa180c..c0df605 100644
--- a/Modules/_hashopenssl.c
+++ b/Modules/_hashopenssl.c
@@ -230,7 +230,7 @@ EVP_repr(PyObject *self)
 static int
 EVP_tp_init(EVPobject *self, PyObject *args, PyObject *kwds)
 {
-    static char *kwlist[] = {"name", "string", NULL};
+    static const char *kwlist[] = {"name", "string", NULL};
     PyObject *name_obj = NULL;
     char *nameStr;
     unsigned char *cp = NULL;
@@ -366,7 +366,7 @@ The MD5 and SHA1 algorithms are always supported.\n");
 static PyObject *
 EVP_new(PyObject *self, PyObject *args, PyObject *kwdict)
 {
-    static char *kwlist[] = {"name", "string", NULL};
+    static const char *kwlist[] = {"name", "string", NULL};
     PyObject *name_obj = NULL;
     char *name;
     const EVP_MD *digest;