Compilation error when using emscripten

[dariost]

Trying to compile this crate using asmjs-unknown-emscripten or wasm32-unknown-emscripten as targets results in the following error:

$ cargo build --target=asmjs-unknown-emscripten
   Compiling adler32 v1.0.4 (/tmp/adler32-rs)
Referencing function in another module!
  call void <badref>(i8* %22), !dbg !35
; ModuleID = '3nlanbjp406orsjk'
void (i8*)* <badref>
; ModuleID = '
error: could not compile `adler32`.

Caused by:
  process didn't exit successfully: `rustc --crate-name adler32 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type lib --emit=dep-info,metadata,link -C debuginfo=2 -C metadata=cf98768c19d4c01d -C extra-filename=-cf98768c19d4c01d --out-dir /tmp/adler32-rs/target/asmjs-unknown-emscripten/debug/deps --target asmjs-unknown-emscripten -C incremental=/tmp/adler32-rs/target/asmjs-unknown-emscripten/debug/incremental -L dependency=/tmp/adler32-rs/target/asmjs-unknown-emscripten/debug/deps -L dependency=/tmp/adler32-rs/target/debug/deps` (signal: 11, SIGSEGV: invalid memory reference)```

[remram44]

It's hard to tell what the problem is from this error. It works on my simple tests, using both asmjs-unknown-emscripten and wasm32-unknown-emscripten.

What kind of Read object are you passing it?

My test

src/main.rs:

extern crate adler32;

use std::io::Cursor;

fn main() {
    let data = b"abcdefghijklmnopqrstuvwxyz";
    println!("{:x}", adler32::adler32(Cursor::new(data)).unwrap());
}

Cargo.toml:

[package]
name = "testadler32"
version = "0.1.0"
authors = ["Remi Rampin <[email protected]>"]

[dependencies]
adler32 = "1.0.4"

$ cargo web deploy --target asmjs-unknown-emscripten

In browser console, see 90860b20

[dariost]

What kind of Read object are you passing it?

I was just trying to compile this crate without any main function, but trying with the example you provided gives the same error:

$ cargo web deploy --target asmjs-unknown-emscripten
   Compiling adler32 v1.0.4
Referencing function in another module!
  call void <badref>(i8* %22), !dbg !35
; ModuleID = 'adler32.3rv277ty-cgu.3'
void (i8*)* <badref>
; ModuleID = '
error: could not compile `adler32`.

error: build failed

I don't know how to get a more verbose output, but I can at least give you the versions I am using:

$ rustc --version
rustc 1.40.0 (73528e339 2019-12-16)
$ cargo --version
cargo 1.40.0 (bc8e4c8be 2019-11-22)
$ emcc --version
emcc (Emscripten gcc/clang-like replacement) 1.39.6 ((unknown revision))
Copyright (C) 2014 the Emscripten authors (see AUTHORS.txt)
This is free and open source software under the MIT license.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ lsb_release -a
LSB Version:	1.4
Distributor ID:	Arch
Description:	Arch Linux
Release:	rolling
Codename:	n/a

[remram44]

A web search brings up some LLVM-related issues? I don't know enough about emscripten to track this down, sorry. You might have some luck trying different versions (I'm using rustc 1.39.0 and emscripten 1.38.19).

[dariost]

Turns out it's a LLVM bug, and it has been already addressed here: rust-lang/rust#66308