Yordan/my wit component

[yordanmadzhunkov]

WIP

[smanilov]

Pesho asked me to review this PR, focusing on the server/host side of things. The following is the account of what followed.

I spent an hour and I managed to build only few packages of the ones affected by this PR. I couldn't run any tests. I'm attaching my review notes, but perhaps I'm doing something wrong. Have I missed some crucial setup step that would allow me to build this and run the tests?

Notes:

---

My eyes hit this PR. They met no README or any sort of instruction of how to proceed.

I built the code. It fails to build. (Actually, realized on a later retry.)

I tried to run the tests. They fail to build. The error message is the following:

  --- stderr
     Compiling proc-macro2 v1.0.86
     Compiling indexmap v2.2.6
     Compiling image v0.24.9
  error[E0658]: use of unstable library feature 'proc_macro_byte_character'
     --> /home/stan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/proc-macro2-1.0.86/src/wrapper.rs:871:21
      |
  871 |                     proc_macro::Literal::byte_character(byte)
      |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
      = note: see issue #115268 <https://github.com/rust-lang/rust/issues/115268> for more information
      = help: add `#![feature(proc_macro_byte_character)]` to the crate attributes to enable
      = note: this compiler was built on 2024-03-17; consider upgrading it if it is out of date

  error[E0658]: use of unstable library feature 'proc_macro_c_str_literals'
     --> /home/stan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/proc-macro2-1.0.86/src/wrapper.rs:898:21
      |
  898 |                     proc_macro::Literal::c_string(string)
      |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
      = note: see issue #119750 <https://github.com/rust-lang/rust/issues/119750> for more information
      = help: add `#![feature(proc_macro_c_str_literals)]` to the crate attributes to enable
      = note: this compiler was built on 2024-03-17; consider upgrading it if it is out of date

---

I started looking for new tests introduced by this PR. I found crates/core/tests/test_host_components/empty_ml.rs.

I get "file not included in crate hierarchy" for it, which after investigation seems to be related to the build configuration. It defines an MLHostComponent which is used in crates/trigger/src/lib.rs. Due to the configuration, however, actually, a different MLHostComponent is used there, the one from ml/src/host_component.rs.

So the purpose of empty_ml.rs remains a mystery to me at this point. Is it used in testing, to mock the type?

---

Skipping through the test_host_components files, I reach crates/ml/Cargo.toml. I try to build just that package with cargo build -p spin-ml. It fails to build with the following message:

error[E0432]: unresolved imports `openvino::Precision`, `openvino::TensorDesc`
  --> crates/ml/src/backend/openvino.rs:10:30
   |
10 | use openvino::{Core, Layout, Precision, TensorDesc};
   |                              ^^^^^^^^^  ^^^^^^^^^^ no `TensorDesc` in the root
   |                              |
   |                              no `Precision` in the root

This is followed with more errors, 14 in total.

So I give up on the spin-ml package and move on.

---

There are what seem to be drive-by changes until I reach crates/trigger/Cargo.toml. It includes spin-ml as a dependency, so I have no hope that it builds. Still, I run direnv reload, in case I have messed something up and run cargo build -p spin-trigger. I get the same error as before.

---

I discover crates/world/wit/ml.wit. Comments! How refreshing! crates/world/wit/world.wit includes it, it's not clear to me how to build it, though, so I skip forwards.

---

I reach examples/http-rust-imagenet/.cargo/config.toml and go there to build that package. This build succeeds! I see that there are also tests in it, but running cargo test fails. The error message is the following:

     Running unittests src/lib.rs (target/wasm32-wasi/debug/deps/http_rust_imagenet-84fec25580a30f29.wasm)
error: test failed, to rerun pass `--lib`

Caused by:
  could not execute process `/home/stan/code/repos/spin/examples/http-rust-imagenet/target/wasm32-wasi/debug/deps/http_rust_imagenet-84fec25580a30f29.wasm` (never executed)

Caused by:
  Exec format error (os error 8)

---

The next example I discover is examples/spin-timer/Cargo.lock. Strangely, there are changes only to the lock file, but I try to build it anyway. Building fails with 14 jobs. I am not looking into the error message, but I guess the problem is as before.

---

There are no more files. The review is done!