Comment by re | Hacker News Reader

Comment by re | Hacker News Reader

I haven't really been following WASM development in the last year and didn't realize that WASM had moved to a versioned release model. I've been aware of the various features in development[1] and had thought many of the newer features were going to remain optional but I guess now that implementations are expected to support all the features to be able to claim compatibility with e.g. "WASM 3.0"?

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; I'm not counting Deno since it builds on v8). Garbage collection seems like a pretty tricky feature in particular.

Does anyone know how this 3.0 release fits into the previously announced "evergreen" release model?[2]

> With the advent of 2.0, the Working Group is switching to a so-called “evergreen” model for future releases. That means that the Candidate Recommendation will be updated in place when we create new versions of the language, without ever technically moving it to the final Recommendation state. For all intents and purposes, the latest Candidate Recommendation Draft[3] is considered to be the current standard, representing the consensus of the Community Group and Working Group.

[1] https://webassembly.org/features/

[2] https://webassembly.org/news/2025-03-20-wasm-2.0/

[3] https://www.w3.org/TR/wasm-core-2/

> 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)

> 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?

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 :-)

Great, thanks for the info!

Wizard supports all of Wasm 3.0, but as a research tool, it only has an interpreter and baseline compiler tier (no opt compiler), so it doesn't run as fast as, say, V8 or wasmtime.

I suspect the versioning is going to replicate the JavaScript version system where versions are just sets of features that a runtime can support or not, I am not sure how feature discovery works in wasm though

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