wizer: support init func as a wave function call (components only)#13582
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pchickey merged 8 commits intoJun 8, 2026
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| .await | ||
| .with_context(|| format!("the initialization function trapped"))?; | ||
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| // TODO: do we want some way to report the values of `rets` back up? |
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Not a blocker for this PR, but it would be nice to return them from Wizer::run_component and, in the case of the CLI, print them to stdout.
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Agreed, and already done :) They actually already print to stdout in the cli because its using the run --invoke code under the hood in there -- command/wizer.rs is integrated so nicely with command/run.rs! great work @alexcrichton it was a joy to realize how little I had to do to benefit from that.
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Wizer now supports wave function call expressions being used as an init func for components, e.g.
local:local/init.add-string@0.1.0("hello, world")This works from both the crate interface and the wasmtime-cli interface.
When
wasmtime wizer --init-func (func expr)is used with a component, it will print the function results in wave to stdout. This opens up a clever mode where you can use a component on disk as a stateful rpc server with wave encoding for the request and response.The diff for the change is straightforward. New test-program to exercise, and a test exercising this functionality has been added to the wizer crate and wasmtime-cli.
Docs for the wasmtime-cli options were updated, including a case I missed from
run --invokein #13564