support for wasm-bindgen?

[stuebinm]

I use this overlay to build a project to wasm (in a nix shell):

let
  moz_overlay = import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz);
  nixpkgs = import <nixpkgs> { overlays = [ moz_overlay ]; };
in
with nixpkgs;
stdenv.mkDerivation {
  name = "moz_overlay_shell";
  buildInputs = [
    (nixpkgs.latest.rustChannels.stable.rust.override {
      targets = [ "wasm32-unknown-unknown" ];
    })
  ];
}

This works nicely, but now my problem is this: if I call wasm-bindgen on the result, it complains that it is incompatible, since the version in nixpkgs is older than the version in this overlay:

it looks like the Rust project used to create this wasm file was linked against
a different version of wasm-bindgen than this binary:

  rust wasm file: 0.2.73
     this binary: 0.2.67

Currently the bindgen format is unstable enough that these two version must
exactly match, so it's required that these two version are kept in sync by
either updating the wasm-bindgen dependency or this binary. You should be able
to update the wasm-bindgen dependency with:

    cargo update -p wasm-bindgen

or you can update the binary with

    cargo install -f wasm-bindgen-cli

if this warning fails to go away though and you're not sure what to do feel free
to open an issue at https://github.com/rustwasm/wasm-bindgen/issues!

As far as I can see, this overlay does not provide fitting versions of wasm-bindgen along with the versions of rustc, cargo, etc. Could this be added to the overlay, is it declared to be out of scope — or is there some other way which I have missed for now?