@juliantaylor That would make me nervous and another rc would probably be indicated. The problem with changes in the C code is that it can be difficult to predict the consequences. In this case, did anyone use this structure? Sebastian mentions theano as one possibility. OTOH, if there is good reason to believe that no one depends on direct access to the structure, we could probably move it or even deprecate direct access in 1.9. The latter might be the best way to go if the structure has really been public since 1.7.