build failed when converting .rs to .wasm

[SimonWang9610]

🐛 Bug description

When I followed the official document Rust and WebAssembly and coded the example Conway's Game of Life, I failed to run wasm-pack build. Error Message as below:

Fatal: error in validating input
Error: failed to execute ``wasm-opt``: exited with exit code: 1
full command: "C:\\Users\\Simon\\AppData\\Local\\.wasm-pack\\wasm-opt-171374efd61df962\\wasm-opt.exe" "C:\\projects\\learn-rust\\wasm-game-of-life\\pkg\\wasm_game_of_life_bg.wasm" "-o" "C:\\projects\\learn-rust\\wasm-game-of-life\\pkg\\wasm_game_of_life_bg.wasm-opt.wasm" "-O" To disable ``wasm-opt``, add ``wasm-opt = false`` to your package metadata in your ``Cargo.toml.`

Even though I disabled wasm-opt = false, the compiled process was passed but it failed to work with the glue code. I mean, run npm run start it did not work as expected.

the Rust code is the same as the example in the Doc Rust and WebAssembly.

🤔 Expected Behavior

I want to know it is a bug? or something wrong I did?
I am totally a beginner on Rust & WebAssembly, hope you guys can help me.

🌍 Your environment

Include the relevant details of your environment.
wasm-pack version: wasm-pack 0.9.1
rustc version: rustc 1.45.0 (5c1f21c3b 2020-07-13)
wee_alloc version: 0.4.5
wasm-bindgen version: 0.2.63
opt-level: 's'

Platform: Windows 10
IDE: VS code

[fermezz]

+1 here. Also very new to Rust/WASM. I was able to track down the error as coming from the render function for Universe. Apparently it's crashing because we return a String into Javascript? I tried commenting that function and it compiles fine. Also, I tried adding a totally unrelated

#[wasm_bindgen]
pub fn greet() -> String {
    format!("Hello")
}

function and the compilation error returned.

If you remove the #[wasm_bindgen] attribute, compilation goes back to normal.

[fermezz]

Problably related to rustwasm/wasm-bindgen#2279

[fermezz]

@SimonWang9610 you should be able to run cargo install --version 0.8.1 wasm-pack --force to go back to wasm-pack's 0.8.1 version, that's the last one I find this to be compiling correctly.

[SimonWang9610]

@SimonWang9610 you should be able to run cargo install --version 0.8.1 wasm-pack --force to go back to wasm-pack's 0.8.1 version, that's the last one I find this to be compiling correctly.

Yeah, I tried your method. The compile process is passed, but the program did not work as expected. Like you said, probably because the returned value is String.
Thanks!

[fermezz]

@SimonWang9610 It should work if compiled successfully. It works for me, at least. What are you seeing?

[SimonWang9610]

@fermezz but actually no. If I comment pun fn render() -> String {}, the compile is successful, and other functions work well.
if the function is pub and returns String type, the compiler will terminate at error in validating input.
if the function is not pub and return String type, the compiler works well.
all functions that return number like i32, u32, u8, f32 also work well.

So i am pretty sure there are some problems related to convert String from rust to wasm to JavaScript.

[fermezz]

@SimonWang9610 oh, yeah, totally. I meant that if you leave the render function untouched but downgrade the version for wasm-pack to 0.8.1 (instead of 0.9.1) you can compile successfully and have it working as expected.

[alvinhochun]

This is probably the same issue as #886. A workaround is mentioned in #886 (comment).

[ashleygwilliams]

closing as duplicate