So I just ran into this todo!() since we still use wit-bindgen-core in jco:
https://github.com/bytecodealliance/wit-bindgen/blob/main/crates/core/src/abi.rs#L1080
Before trying to add the impl here, wanted to reach out and ask if this wit-bindgen-core should be used at this point -- are we de-prioritizing it in any way? It's pretty load bearing in Jco but obviously doesn't have to be used.
Use in jco is up to you, it's not well-tested in-repo for host use cases that jco has but that doesn't make it fundamentally unmaintainable to the point of removal. Async bits on the host and in other locations though have required some special care at "the top" where the generic bindings in wit-bindgen-core aren't suitable. If needed lower-level helpers could be exposed to get access to direct lifts/lowers to drive the "guts" from wit-bindgen-core but still have custom bits at the edge
Ah thanks -- yeah Jco wit-bindgen-core pretty heavily so I didn't want to try to rip it out, and this seems to be the only part that I've run into so far that was not usable!
I'll do the implementation and put up a PR which should be easier to chat about concretely. Thanks!
Last updated: Dec 06 2025 at 07:03 UTC