Failed to initialize any backend!

[au-phiware]

I am attempting to run the egui_demo_app and I'm encountering the following panic:

$ cargo run --release -p egui_demo_app
    Finished release [optimized] target(s) in 0.12s
     Running `target/release/egui_demo_app`
thread 'main' panicked at 'Failed to initialize any backend! Wayland status: NoWaylandLib X11 status: LibraryOpenError(OpenError { kind: Library, detail: "opening library failed (libX11.so.6: cannot open shared object file: No such file or directory); opening library failed (libX11.so: cannot open shared object file: No such file or directory)" })', /home/corin/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/platform_impl/linux/mod.rs:619:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Here's some extra info:

$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /home/corin/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu (default)
nightly-2020-02-07-x86_64-unknown-linux-gnu
nightly-2020-02-12-x86_64-unknown-linux-gnu
nightly-2021-02-16-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu
1.60.0-x86_64-unknown-linux-gnu

installed targets for active toolchain
--------------------------------------

wasm32-unknown-unknown
x86_64-unknown-linux-gnu

active toolchain
----------------

1.60.0-x86_64-unknown-linux-gnu (overridden by '/home/corin/src/github.com/emilk/egui/rust-toolchain')
rustc 1.60.0 (7737e0b5c 2022-04-04)

Please help!

[coderedart]

references:
alacritty/alacritty#5684
rust-windowing/winit#1474

AvaloniaUI/Avalonia#3020 (comment) points out the necessary config.

also need to add libGL to the pkgs according to rust-windowing/glutin#1399

[au-phiware]

As a NixOS user I needed a particular set of buildInputs and a correctly set LD_LIBRARY_PATH. Here's a minimal flake.nix:

{
  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:nixos/nixpkgs?ref=release-21.11";
  };

  outputs = {
    self,
    nixpkgs,
    flake-utils,
    ...
  }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
      in with pkgs; rec {
        devShell = mkShell rec {
          buildInputs = [
            libxkbcommon
            libGL

            # WINIT_UNIX_BACKEND=wayland
            wayland

            # WINIT_UNIX_BACKEND=x11
            xorg.libXcursor
            xorg.libXrandr
            xorg.libXi
            xorg.libX11
          ];
          LD_LIBRARY_PATH = "${lib.makeLibraryPath buildInputs}";
        };
      });
}