Yup, I've ran into this when my entire program ended up being a single massive Future struct, which caused a stack overflow :)

I wish there was a Clippy lint for this (https://github.com/rust-lang/rust-clippy/issues/5263).

My current practice is to sprinkle `Box::pin` on code paths that are less common (fallbacks, error handling) or expensive anyway. This cuts down the inlined state considerably without actually causing that many allocations.