[Pkg-rust-maintainers] Bug#903110: rustc: wasm32 target is enabled, but doesn't work

[Niels Langager Ellegaard]

Package: rustc
Version: 1.26.2+dfsg1-1
Severity: minor

Dear Maintainers,

The wasm32-unknown-unknown target is enabled in rustc, but it doesn't work. 
Alledgedly the problem is that the coresponding webassembly target isn't enabled in 
llvm. I guess that the target should be disabled in rustc if it doesn't work.
(But in the long run it would be great to have the target enabled)

$ rustc --print target-list | grep wasm

wasm32-experimental-emscripten
wasm32-unknown-emscripten
wasm32-unknown-unknown

$ rustc --version
rustc 1.26.2

$ cat hello.rs 
fn main() {
    println!("Hello, world!");
}

$ rustc hello.rs --target wasm32-unknown-unknown
error: Could not create LLVM TargetMachine for triple: wasm32- 
unknown-unknown-wasm: No available targets are compatible with this triple.

Related reddit thread
https://www.reddit.com/r/rust/comments/8w9mfy/debian_is_starting_to_package_rust_crates/e1vq9as/?context=3

Thank you for packaging rustc

     Niels

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)

Kernel: Linux 4.16.0-2-686-pae (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages rustc depends on:
ii  binutils              2.30.90.20180705-1
ii  gcc                   4:7.3.0-3
ii  libc6                 2.27-3
ii  libc6-dev [libc-dev]  2.27-3
ii  libgcc1               1:8.1.0-9
ii  libllvm6.0            1:6.0.1-2
ii  libstd-rust-dev       1.26.2+dfsg1-1
ii  libstdc++6            8.1.0-9

Versions of packages rustc recommends:
ii  cargo     0.27.0-2
ii  rust-gdb  1.26.2+dfsg1-1

Versions of packages rustc suggests:
pn  rust-doc  <none>
pn  rust-src  <none>

-- no debconf information