Document one of the many problems with the buffer object.
diff --git a/Objects/bufferobject.c b/Objects/bufferobject.c
index fe2be73..561d6c1 100644
--- a/Objects/bufferobject.c
+++ b/Objects/bufferobject.c
@@ -228,10 +228,17 @@
if ( self->b_hash != -1 )
return self->b_hash;
+ /* XXX potential bugs here, a readonly buffer does not imply that the
+ * underlying memory is immutable. b_readonly is a necessary but not
+ * sufficient condition for a buffer to be hashable. Perhaps it would
+ * be better to only allow hashing if the underlying object is known to
+ * be immutable (e.g. PyString_Check() is true). Another idea would
+ * be to call tp_hash on the underlying object and see if it raises
+ * an error. */
if ( !self->b_readonly )
{
- /* ### use different wording, since this is conditional? */
- PyErr_SetString(PyExc_TypeError, "unhashable type");
+ PyErr_SetString(PyExc_TypeError,
+ "writable buffers are not hashable");
return -1;
}