option + number bugs

[MartinKavik]

Hi, I've probably found a bug.

When option<a_number> is a function parameter type then Func::call often panics or the function body is not called at all. It doesn't matter whether the parameter is option or the parameter is a record containing the option.

I've made a runnable example in my fork, see the component's lib.rs:

impl exports::test::guest::foo::Guest for Foo {
    fn fn_calling_host_fn() {
        // 1)
        // Works as expected - prints `A message from host.`
        // WIT: `host-fn: func(param: option<s32>);`
        // Params: `[ValueType::Option(OptionType::new(ValueType::S32))]`
        test::guest::host::host_fn(None);

        // 2)
        // Panics with the error `Invalid discriminant value.`
        // WIT: `host-fn: func(param: option<s32>);`
        // Params: `[ValueType::Option(OptionType::new(ValueType::S32))]`
        // test::guest::host::host_fn(Some(123));

        // 3)
        // Panics with the error `Incorrect type. src\func.rs:816:27` (see updated `require_matches` below)
        // WIT: `host-fn: func(param: option<f64>);`
        // Params: `[ValueType::Option(OptionType::new(ValueType::F64))]`
        // test::guest::host::host_fn(None);
    }
}

Also it may behave differently on each runtime. For example, in my project, a function like host-fn: func(param: option<f64>) -> result; returns immediately Ok without running the Func body at all on the js_wasm_runtime_layer runtime and it works correctly when I change param: option<f64> to option<string> or option<s32>.

I've tried to upgrade wit-bindgen = "0.16.0" to "0.26.0" but it doesn't affect the issue.

Context: I was writing an example with wasm_component_layer in MoonZoon and then I would like to use it in another OS project with Tauri where I want to use both js_wasm_runtime_layer and wasmtime_runtime_layer. These bugs and missing bindgen are stoppers for me, unfortunately.

Hope it helps, ask me any questions.

[Clunt]

I don't know if this PR(#19) has anything to do with your problem.
If you have time, you can run the example and have a look. (README.md example part, run value_none example)
Feel free to contact me if you have any further questions, I am trying to implement WASIp2 with this repo.