You can do some great things when you have a reusable open-source C++ parser:

AST matchers and Clang refactoring tools

by Eli Bendersky

From the article:

Clang tooling sees lots of interest and development focus in the past few years. At last, we have a convenient, accurate, open-source and well supported framework for programmatically analyzing and refactoring C++ code; I find this very exciting.

A great outcome of this rapid pace of development is that new APIs and tools spring up all the time. For example, some time ago the Clang tooling developers figured out folks doing AST traversals have to write a lot of repetitive code to find interesting AST nodes, so they came up with a great new API called AST matchers, which I want to discuss here...