bash output wgpu-rs

$ nix-shell shell.nix
$ git clone https://github.com/gfx-rs/wgpu-rs
$ cd wgpu-rs
$ cargo run --example cube
    Finished dev [unoptimized + debuginfo] target(s) in 0.07s
     Running `target/debug/examples/cube`
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', examples/cube/../framework.rs:117:19
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

framework.rs

// full file: https://github.com/gfx-rs/wgpu-rs/blob/master/examples/framework.rs#L117


    log::info!("Initializing the surface...");

    let instance = wgpu::Instance::new(wgpu::BackendBit::PRIMARY);
    let (size, surface) = unsafe {
        let size = window.inner_size();
        let surface = instance.create_surface(&window);
        (size, surface)
    };
    let adapter = instance
        .request_adapter(&wgpu::RequestAdapterOptions {
            power_preference: wgpu::PowerPreference::Default,
            compatible_surface: Some(&surface),
        })
        .await
        .unwrap();
    let optional_features = E::optional_features();
    let required_features = E::required_features();
    let adapter_features = adapter.features();
    assert!(
        adapter_features.contains(required_features),
        "Adapter does not support required features for this example: {:?}",
        required_features - adapter_features
    );

shell.nix

let
  # Look here for information about how pin version of nixpkgs
  #  → https://nixos.wiki/wiki/FAQ/Pinning_Nixpkgs
  pinnedPkgs = import (builtins.fetchGit {
    name = "nixpkgs-20.03";
    url = "https://github.com/nixos/nixpkgs/";
    ref = "refs/heads/release-20.03";
  }) { };

  # This allows overriding pkgs by passing `--arg pkgs ...`
in { pkgs ? pinnedPkgs }:

let
  isOsX = builtins.currentSystem == "x86_64-darwin";
  darwin-frameworks =
    if isOsX then
      with pkgs.darwin.apple_sdk.frameworks; [
        AppKit
        CoreFoundation
        CoreServices
        CoreVideo
        Foundation
        Metal
        Security
      ]
    else
      [ ];
  llvm = pkgs.llvm_10;
  inputs = with pkgs; [
      rustup
      cargo
      llvm
      # libraries for llvm
      libffi
      libxml2
      zlib

      pkg-config x11 libffi libxml2 rlwrap cargo xorg.libXcursor wlroots libinput xorg.libXrandr
      xorg.libXi
      vulkan-tools
      vulkan-loader
      vulkan-headers
    ];
in pkgs.mkShell {
  buildInputs = inputs ++ darwin-frameworks;
  LLVM_SYS_100_PREFIX = "${llvm}";
}