"WASM module load failed: zero byte expected" error when running modules compiled from Rust

[alepvn33]

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Subject of the issue

I am getting an error when running any WASM module compiled from Rust with wasm32-wasip1 or wasm32-unknown-unknown targets.
Not even an helloworld works. I use a simple cargo build --target=wasm32-wasip1 or cargo build --target=wasm32-unknown-unknown command to compile.

I am getting "WASM module load failed: zero byte expected".

I am running on Linux, iwasm version is 2.1.0.

Does anyone know which is the cause?

Thanks!

Test case

fn main() {
    println!("Hello, world!");
}

Your environment

WAMR:

• Host OS: Linux
• WAMR version: iwasm 2.1.0
• platform: x86_64-unknown-linux-gnu
• cpu architecture: x86_64
• running mode: interpreter mode
  Compiler:
• rustc 1.85.0 (4d91de4e4 2025-02-17)
• commit-hash: 4d91de4e48198da2e33413efdcd9cd2cc0c46688
• commit-date: 2025-02-17
• host: x86_64-unknown-linux-gnu
• release: 1.85.0
• LLVM version: 19.1.7

Steps to reproduce

Compile with cargo build --target=wasm32-wasip1 or cargo build --target=wasm32-unknown-unknown, then run iwasm target/wasm32-wasip1/debug/hello_wasi.wasm

Expected behavior

Printing of the "Hello, World!" string.

Actual behavior

An error is yielded: "WASM module load failed: zero byte expected"

Extra Info

It works fine with modules compiled from C.

[alepvn33]

I found the issue.
Basically, the reference-types proposal is enabled by default in Rust's WebAssembly targets and apparently WAMR does not still support it.

To solve the issue, converting the module to .wat with wasm2wat and then back again to .wasm with wat2wasm removes the reference-types proposal.

[swegmann-hslu]

Potentially relevant for this issue are the following Rust issue: rust-lang/rust#128475 and the section in the Rust book about the "Enabled WebAssembly features" for WASM32-unknown-unknown: https://doc.rust-lang.org/beta/rustc/platform-support/wasm32-unknown-unknown.html#enabled-webassembly-features

The short version is to compile your Rust code with

$ export RUSTFLAGS=-Ctarget-cpu=mvp
$ cargo +nightly build -Zbuild-std=panic_abort,std --target wasm32-unknown-unknown