Upgrade to latest `wasmtime` and component model

[dicej]

I've been experimenting with upgrading to the latest wasmtime (i.e. the main branch for now, but I would use the most recent release in a PR). As a consequence of the upgrade, instantiate_smw fails to build due to its use of the module linking API, which has been removed as of wasmtime 0.36.

I'd like to update instantiate_smw to use the component model, although I realize it's not yet fully implemented as of this writing. I don't know whether wasmtime's implementation is complete enough yet for wit-bindgen's needs; one goal of this experiment is to answer that question. Either way, I'm eager to start using the component model in other projects, so it will be helpful to understand the specific limitations of the current (partial) implementation -- particularly with regard to linking modules together. I'd also be interested in helping move that implementation forward if there are opportunities to do so.

My current (possibly naive) strategy is to change instantiate_smw to create a component::Component which instantiates both the spidermonkey and input module, passing the former as an argument to the latter. Then I would instantiate that component using a component::Linker, call wizer.initialize on the spidermonkey module instance, and return as before. This raises a question:

• Given that the wit_bindgen_wasmtime::export! and wit_bindgen_wasmtime::import! macros (not to mention wasmtime_wasi::add_to_linker, etc.) expect a module Linker, not a component Linker, it's not clear to me how to use them in a component context. Is there (or will there be) some way to add a module Linker into a component Linker for the purpose of dynamic instantiation? Or am I thinking about it the wrong way?

(EDIT: I've moved the second question to bytecodealliance/wasmtime#4303 since it was not specific to wit-bindgen)

[dicej]

Reading over what I wrote above, I realize this might be more appropriate as an issue in the wasmtime repo. If so, I'll be happy to move it over there.

[esoterra]

I think moving it to the wasmtime repo would make sense. You could make your first bullet point its own question here if you do move this one since it is more specifically about how wit-bindgen should work.
e.g. "wit_bindgen_wasmtime is not compatible with component Linker"

[dicej]

BTW, the last paragraph in this comment indicates that we should just disable the spidermonkey tests. So perhaps the answer to this issue is: go ahead and upgrade wit-bindgen to the latest wasmtime and disable the affected tests until the component model is ready. If that's correct, I can make a PR for that.

[dicej]

We discussed this during today's wasmtime project meeting. The conclusion was that disabling the spidermonkey tests for now is a reasonable choice until ecosystem support (not just wasmtime support) is mature enough to allow them to be re-enabled with minimal effort.

[dicej]

BTW, Alex answered answered my question about add_to_linker here: bytecodealliance/wasmtime#4303 (comment)