Is that a typo? It makes no sense for something to inherit itself. (Unless we're talking about Curiously Recurring Template Pattern, which is a slightly different topic.)
10:23: error: invalid use of incomplete type 'class hash0'
10:8: error: forward declaration of 'class hash0'
Since you're getting a compiler error, I suggest making a backup of your code, and then strip out everything in your code that is not causing the problem, until you get to the absolute minimal amount of code needed to reproduce your problem. That will increase the likelihood of someone here being able to help you.