Under this framework, Rust's async fns would not be colored, since any function in the callstack could be blocking on an executor. if you consider "spawn point" a part of the callstack, many other languages are similar.

This doesn't feel like a useful distinction, but i don't think "function coloring" in general is a useful framework.

I think that's an interesting take, I have been chewing on the "so what" of function coloring myself, but haven't reached any conclusions.

Would be interested to hear why you don't find it a useful framework either.