What feature would you like added to Rust?

This can be a feature from another language, or a feature that you came up with yourself.

I'd like to be able to have macros on types as functions or methods that would have access to Self/self.

While implementing the macro, you would specify if it takes self, &self, &mut self, or is just a function.

Speaking of macros, I would also like them to be more powerful than what they currently are. There are a lot of limitations that bother me. For example, if you want to make a macro with a macro, there are some limitations that can get in the way with defining the branches (iirc).

Edit: 35 comments by 0 upvotes. Come on, guys. I don't care about votes, but the people commenting clearly want to have this conversation. It just doesn't make sense why Reddit is like this.