Stream: wit-bindgen

Topic: Issues importing some wasi interfaces

Hazel Rowell (Sep 18 2023 at 19:26):

Hey all!

I'm encountering an odd issue when adding imports for some wasi interfaces in my wit world, for example wasi:io/streams. I've run out of debugging ideas..

The error is being thrown when attempting to create the component using wasm-tools component new.

error: decoding custom section component-type:function-world

Caused by:
    0: record type must have at least one field (at offset 0xc)

and the world

world function-world {
  import wasi:clocks/wall-clock // this works!
  import wasi:io/streams // this produces the error

  use types.{http-request, http-response}

  export handle-request: func(req: http-request) -> http-response
}

Note: I am able to add use wasi:io/streams or use wasi:sockets/tcp Importing either creates the error .

Am I doing something wrong here? Looking though the tests / examples in github put me on the path of using import.

Guy Bedford (Sep 18 2023 at 19:28):

it looks like you might be using an older definition of wasi - the component model was updated to no longer support empty records, while older versions of wasi still had empty records in use.

Hazel Rowell (Sep 18 2023 at 19:41):

I see, thank you!

I'm pulling the wasi wits via wit-deps.

clocks = "https://github.com/WebAssembly/wasi-clocks/archive/main.tar.gz"
http = "https://github.com/WebAssembly/wasi-http/archive/main.tar.gz"

Searching though my deps folder and sure enough

...
interface streams {
    use wasi:poll/poll.{pollable}

    /// An error type returned from a stream operation. Currently this
    /// doesn't provide any additional information.
    record stream-error {}
...

I'll give the following a go and see how that works out
https://github.com/bytecodealliance/wasmtime/tree/main/crates/wasi

Hazel Rowell (Sep 18 2023 at 20:45):

I was able to resolve this by linking to the preview deps

preview = "https://gitpkg.now.sh/bytecodealliance/wasmtime/crates/wasi?e250334b8ebfba9359802ab7f61bdd7c6085d87a"

However, looking though the wits I'm getting the feeling I should just be avoiding relying on anything wasi until the component model stabilizes more.

Eduardo Rodrigues (Sep 18 2023 at 20:45):

i have been using GitPkg successfully to help point to a specific folder and commit hash. something like this:

wasi = "https://gitpkg.now.sh/bytecodealliance/wasmtime/crates/wasi?e250334b8ebfba9359802ab7f61bdd7c6085d87a"

Hazel Rowell (Sep 18 2023 at 20:46):

Eduardo Rodrigues said:

i have been using GitPkg successfully to help point to a specific folder and commit hash. something like this:

wasi = "https://gitpkg.now.sh/bytecodealliance/wasmtime/crates/wasi?e250334b8ebfba9359802ab7f61bdd7c6085d87a"

Just ended up with this same solution :smile:. Thank you!!

Last updated: Dec 23 2024 at 13:07 UTC