Fabrice Desré (Jan 20 2023 at 02:02): Fabrice Desré (Jan 20 2023 at 02:02):I'm trying to generate the JS host for a WIT world but I can´t figure out which input it expects. Passing the *.wit file such as the one in https://bytecodealliance.github.io/wit-bindgen/ fails with
Error: expected `(`
--> demo.wit:1:1
|
1 | interface host-funcs {
| ^
Using a wat file also fails ("attempted to parse a wasm module with a component parser").
Peter Huene (Jan 20 2023 at 04:57):I believe the JS host bindings expect a WebAssembly component as input, which it infers the world from. It needs the component because it generates some glue (polyfills what a component-model-native host like Wasmtime would do) that depends on the inner core modules of the component.
Fabrice Desré (Jan 20 2023 at 05:03):ok, so in the case of the demo, was the wit file also generated from this component? If so, how?
Alex Crichton (Jan 20 2023 at 05:13):The demo takes a wit, synthesizes a dummy core wasm module that implements the world, then makes a component with all that, and then runs the js bindings over that component output
Alex Crichton (Jan 20 2023 at 05:14):You can inspect the wasm outputs and see one should be full of unused imports and functions that only have unreachable instructions
Fabrice Desré (Jan 20 2023 at 06:37):ok, but what command is used to go from .wit -> core wasm & component?
Alex Crichton (Jan 20 2023 at 15:36):With the latest wasm-tools CLI you can do:
$ wasm-tools component embed foo.wit --dummy --world foo | wasm-tools component new -t
where foo.wit looks like:
default world foo {}
and that'll print out the component (in the wasm text format)
Last updated: Dec 23 2024 at 12:05 UTC