Stream: wasmtime

Topic: Building wasmtime for @unstable wit features

Colin D Murphy (Jul 02 2024 at 14:20):

I recently added timezones to wasi-clocks https://github.com/WebAssembly/wasi-clocks/pull/61 using the @unstable wit feature that @Yoshua Wuyts has been working on. Unfortunately I can't seem to build the wasmtime binary and component adapter to run a trivial example. I was able to get the example to work if I don't add the @unstable flags to the wit files, so I'm clearly missing something related to the wit feature.

Is there anything obvious I'm doing wrong here in this PR? https://github.com/bytecodealliance/wasmtime/pull/6899
Here is the example:

 wit_bindgen::generate!({
     features: ["clocks-timezone"],
 });

  fn main() {
     let datetime = wasi::clocks::wall_clock::now();
     let timezone_display = wasi::clocks::timezone::display(datetime);
     println!("{:?}", timezone_display.name);
  }

When I run cargo expand on the example, it shows the timezone code bindings. Creating the component with the adapter does not throw an error, but when I try to run the example with my wasmtime changes I get the following:

wasm-tools component new --adapt ~/workspaces/github/bytecodealliance/wasmtime/target/wasm32-wasi/release/wasi_snapshot_preview1.wasm -o component0.wasm ~/workspaces/colmurph/clock-test/target/wasm32-wasi/debug/clock-test.wasm

~/workspaces/github/bytecodealliance/wasmtime/target/debug/wasmtime component0.wasm
Error: failed to run main module `component0.wasm`

Caused by:
    0: component imports instance `wasi:clocks/timezone@0.2.0`, but a matching implementation was not found in the linker
    1: instance export `display` has the wrong type
    2: function implementation is missing

Colin D Murphy (Jul 02 2024 at 15:46):

I just realized that I was manually editing generated files. My additions were features: ["clocks-timezone"], as an argument to bindgen!. I'll try to figure out how those files are generated.

Alex Crichton (Jul 08 2024 at 14:27):

It looks like the component was built using time zones correctly and all but the wasmtime binary was missing support (or it's gated by a flag). I think you might need to update/add some add_to_linker calls in the main CLI?

Colin D Murphy (Jul 09 2024 at 00:33):

Yes. Exactly right. I forgot to add_to_linker in crates/wasi/src/lib.rs. All set now. Thank you!

Last updated: Dec 23 2024 at 13:07 UTC