[cfallin]

> It'll be interesting to see what the second non-browser-based WASM runtime to fully support 3.0 will be (I'm guessing wasmtime will be first; ...)

Wasmtime already supports every major feature in the Wasm 3.0 release, I believe. Of the big ones: garbage collection was implemented by my colleague Nick Fitzgerald a few years ago; tail calls by Jamey Sharp and Trevor Elliott last year (with full generality, any signature to any signature, no trampolines required!); and I built our exceptions support which merged last month and is about to go out in Wasmtime 37 in 3 days.

The "3.0" release of the Wasm spec is meant to show progress and provide a shorthand for a level of features, I think, but the individual proposals have been in progress for a long time so all the engine maintainers have known about them, given their feedback, and built their implementations for the most part already.

(Obligatory: I'm a core maintainer of Wasmtime and its compiler Cranelift)

[azakai]

> garbage collection was implemented by my colleague Nick Fitzgerald a few years ago

The wasm features page says it is still behind a flag on wasmtime (--wasm=gc). Is that page out of date?

[cfallin]

No, it's still behind a flag (and so transitively, exceptions are too, because we built exception objects on top of GC).

Our docs (https://docs.wasmtime.dev/stability-tiers.html) put GC at tier 2 with reason "production quality" and I believe the remaining concerns there are that we want to do a semi-space copying implementation rather than current DRC eventually. Nick could say more. But we're spec-compliant as-is and the question was whether we've implemented these features -- which we have :-)