WASM/WebAssembly fail in debug, success in release

[adiba]

The playground on nightly in debug mode fails to compile the below code to WASM with following error:

error: expected function name count (598) <= function count (441)
00257ca: error: OnFunctionNamesCount callback failed

It compiles fine in release mode.

I should also mention that there is a bug in the resulting wasm code when opt-level=0, see rust-lang/rust#47776.

fn main() {}
extern {
    fn log_i32(val: i32);
}

#[no_mangle]
pub fn run() {
    let s = "Tre".as_bytes();
    let len = s.len();
    unsafe {
        log_i32(len as i32);
    }
}

[shepmaster]

That error is pretty ugly which makes me think it's not coming from Rust.

You can see the steps we perform after compilation:

https://github.com/integer32llc/rust-playground/blob/964fff159d7925c8121244b4db3fa29d2f5bcdad/compiler/base/cargo-wasm#L38-L51

Perhaps you could try those with your code and see if either tool fails? It might help pinpoint details with your correctness issue as well.

[shepmaster]

This works now, so assuming it was an upstream issue.