Stream: general

Topic: Passing arrayref to a host function?

Talin (Dec 17 2024 at 23:28):

I'm getting this error:

types incompatible: expected type `(func (param (ref array (engine 5))))`, found type `(func (param (ref array)))`

The wasm looks like this:

(type $String (;3;) (array i8))
(type $debug.type (;4;) (func (param (ref $String))))
(import "host" "debug" (func $debug (;0;) (type $debug.type)))

And I'm registering the function like this:

let engine = wasmtime::Engine::new(&config).unwrap();
let store = wasmtime::Store::<StoreData>::new(&engine, ());
let mut linker = wasmtime::Linker::new(&engine);
linker
    .func_wrap(
        "host",
        "debug",
        |caller: Caller<'_, StoreData>, param: Rooted<ArrayRef>| {
            // ...
        },
    )
    .unwrap();

Also: what's the best way to access the bytes of the array as a string?

Alex Crichton (Dec 17 2024 at 23:49):

I think that might be a bug because that looks like it's expected to work, mind filing an issue?

For getting the array as a string we need to add APIs to do that, they're not currently present on ArrayRef so you'd have to access it byte-by-byte (which probably isn't the speediest)

Alex Crichton (Dec 17 2024 at 23:51):

hm so my guess is that it's (array mut i8) vs (array i8), we might not have anything in the API to match that

Alex Crichton (Dec 17 2024 at 23:51):

but if you try changing the type to (array mut i8) it may work for now?

Alex Crichton (Dec 17 2024 at 23:52):

(I could also be totally off)

Talin (Dec 18 2024 at 01:01):

Changing from types.ty().array(&StorageType::I8, false) to types.ty().array(&StorageType::I8, true)didn't seem to make any difference. Even the error message was the same.

Alex Crichton (Dec 18 2024 at 01:04):

Ah ok I'm just barking up the wrong tree then, we can properly investigate this in an issue

Talin (Dec 18 2024 at 01:08):

Bug filed: https://github.com/bytecodealliance/wasmtime/issues/9848

Alex Crichton (Dec 18 2024 at 01:09):

Thanks!

Last updated: Dec 23 2024 at 13:07 UTC