Shameless plug: I've written difftastic[1], a tool that builds ASTs and then does a structural diff of them. You can use it with git too.
It's an incredibly hard problem though, both from a computational complexity point of view, and trying to build a comprehensible UI once you've done the structural AST diff.
It's an incredibly hard problem though, both from a computational complexity point of view, and trying to build a comprehensible UI once you've done the structural AST diff.
[1]: https://github.com/wilfred/difftastic