> And, probably not closely related to stack graph, but about using tree-sitter for c/c++ understanding, how to handle the preprocessor?

Ha yeah that's a good question. Some uses of the preprocessor won't be problematic ­— it would require deep token mangling, for instance, to really start to cause a problem. You can treat more basic `#ifdef` style conditional compilation as parsing/analyzing both sides and showing both as potential definitions. (And from there you could extend it further to try to identify (or define) "profiles" that have different preprocessor symbols defined, and use that to actually prune some of the results.)