servo/shell.nix

# This provides a shell with all the necesarry packages required to run mach and build servo
# NOTE: This does not work offline or for nix-build

{
  buildAndroid ? false
}:
with import (builtins.fetchTarball {
  # NixOS users: if servoshell crashes with an assertion failure in surfman’s x11/connection.rs,
  # eglInitialize() may be failing, or you may be building with an incompatible version of glibc.
  # Use your system nixpkgs here, change `llvmPackages` below if necessary, then do a clean build.
  url = "https://github.com/NixOS/nixpkgs/archive/ffbc9f8cbaacfb331b6017d5a5abb21a492c9a38.tar.gz";
}) {
  overlays = [
    (import (builtins.fetchTarball {
      # Bumped the channel in rust-toolchain.toml? Bump this commit too!
      # Use the latest commit hash for the manifest associated with the relevant version number in
      # https://github.com/oxalica/rust-overlay/tree/master/manifests
      url = "https://github.com/oxalica/rust-overlay/archive/99cc5667eece98bb35dcf35f7e511031a8b7a125.tar.gz";
    }))
  ];
  config = {
    android_sdk.accept_license = buildAndroid;
    allowUnfree = buildAndroid;
  };
};
let
    rustToolchain = rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
    rustPlatform = makeRustPlatform {
      cargo = rustToolchain;
      rustc = rustToolchain;
    };
    pkgs_gnumake_4_3 = import (builtins.fetchTarball {
      url = "https://github.com/NixOS/nixpkgs/archive/6adf48f53d819a7b6e15672817fa1e78e5f4e84f.tar.gz";
    }) {};

    llvmPackages = llvmPackages_20;
    stdenv = llvmPackages.stdenv;

    buildToolsVersion = "34.0.0";
    androidComposition = androidenv.composeAndroidPackages {
      buildToolsVersions = [ buildToolsVersion ];
      includeEmulator = true;
      platformVersions = [ "33" ];
      includeSources = false;
      includeSystemImages = true;
      systemImageTypes = [ "google_apis" ];
      abiVersions = [ "x86" "armeabi-v7a" ];
      includeNDK = true;
      ndkVersion = "28.2.13676358";
      useGoogleAPIs = false;
      useGoogleTVAddOns = false;
      includeExtras = [
        "extras;google;gcm"
      ];
  };
  androidSdk = androidComposition.androidsdk;

  # FHS wrappers for Python tools installed via venv (e.g ruff, pyrefly)
  # These allow running dynamically linked binaries on NixOS without patching them.
  # The wrappers provide an FHS environment at runtime.
  mkVenvFhsWrapper =
    name:
    buildFHSEnv {
      inherit name;
      runScript = writeShellScript "${name}-fhs" ''
        exec "${toString ./.}/.venv/bin/${name}" "$@"
      '';
    };

  # Required by ./mach build --android
  androidEnvironment = lib.optionalAttrs buildAndroid rec {
    ANDROID_SDK_ROOT = "${androidSdk}/libexec/android-sdk";
    ANDROID_NDK_ROOT = "${ANDROID_SDK_ROOT}/ndk-bundle";
    GRADLE_OPTS = "-Dorg.gradle.project.android.aapt2FromMavenOverride=${ANDROID_SDK_ROOT}/build-tools/${buildToolsVersion}/aapt2";
  };
in
stdenv.mkDerivation (androidEnvironment // {
  name = "servo-env";

  # NOTE: tshark(1) for etc/devtools-parser.py can’t be installed here, because it requires
  # CAP_NET_RAW and CAP_NET_ADMIN. Install Wireshark with your system package manager,
  # or for NixOS, enable the option: `programs.wireshark.enable = true;`
  buildInputs = [
    # Native dependencies
    fontconfig freetype libunwind
    xorg.libxcb
    xorg.libX11

    gst_all_1.gstreamer
    gst_all_1.gst-plugins-base
    gst_all_1.gst-plugins-good
    gst_all_1.gst-plugins-bad
    gst_all_1.gst-plugins-ugly

    rustup
    taplo
    cargo-deny
    cargo-nextest
    llvmPackages.bintools # provides lld

    udev # Needed by libudev-sys for GamePad API.

    # Build utilities
    cmake dbus gcc git pkg-config which llvm perl yasm m4

    # Ensure the Python version is same as the one in `.python-version` file so
    # that `uv` will just symlink to the one in nix store. Otherwise `uv` will
    # download a pre-built binary that won't work on nix.
    python311
    uv

    # This pins gnumake to 4.3 since 4.4 breaks jobserver
    # functionality in mozjs and causes builds to be extremely
    # slow as it behaves as if -j1 was passed.
    # See https://github.com/servo/mozjs/issues/375
    pkgs_gnumake_4_3.gnumake

    (rustPlatform.buildRustPackage {
      name = "crown";
      src = ./support/crown;
      doCheck = false;
      cargoLock = {
        # crown is not in our Cargo workspace, so this only pulls crown and crown’s dependencies
        # into the Nix store, not Servo and Servo’s dependencies.
        lockFile = ./support/crown/Cargo.lock;
      };
      RUSTC_BOOTSTRAP = "crown";
    })
  ] ++ (lib.optionals stdenv.isDarwin [
    darwin.apple_sdk.frameworks.AppKit
  ]) ++ (lib.optionals buildAndroid [
    # for android builds
    openjdk17_headless
    androidSdk
  ]);

  LIBCLANG_PATH = lib.makeLibraryPath [ llvmPackages.clang-unwrapped.lib ];

  # Allow cargo to download crates
  SSL_CERT_FILE = "${cacert}/etc/ssl/certs/ca-bundle.crt";

  # Enable colored cargo and rustc output
  TERMINFO = "${ncurses.out}/share/terminfo";


  # Provide libraries that aren’t linked against but somehow required
  LD_LIBRARY_PATH = lib.makeLibraryPath [
    # Fixes missing library errors
    wayland xorg.libXcursor xorg.libXrandr xorg.libXi libxkbcommon

    # [WARN  script::dom::gpu] Could not get GPUAdapter ("NotFound")
    # TLA Err: Error: Couldn't request WebGPU adapter.
    vulkan-loader

    # $ cargo run -p servo --example winit_minimal
    # Unable to load the libEGL shared object
    libGL
  ];

  shellHook = ''
    # Fix invalid option errors during linking
    # https://github.com/mozilla/nixpkgs-mozilla/commit/c72ff151a3e25f14182569679ed4cd22ef352328
    unset AS

    # Compiling programs under Nix sets the interpreter (ELF INTERP) and rpath (ELF DT_RUNPATH [1])
    # to ensure that it can find the needed (ELF DT_NEEDED) libraries in the Nix store.
    #
    # This is good on NixOS, but bad everywhere else. Using the Nix interpreter makes the programs
    # dependent on the Nix store, making them impossible to distribute and run on other machines
    # without `nix bundle`. Even on the same machine, the program will crash in a variety of ways
    # because of the “OpenGL problem” [2] and other mismatches in X11 and Wayland libraries. Worse
    # still, it makes everyone else suffer the problems NixOS has, like needing $LD_LIBRARY_PATH
    # (see above) and needing to disable rust-lld (servo#30123).
    #
    # We can make the programs independent of Nix by resetting $NIX_DYNAMIC_LINKER to the system
    # interpreter, setting $NIX_DONT_SET_RPATH to prevent the clang and ld wrappers from adding
    # -rpath options to $NIX_LDFLAGS [3][4], and removing any -rpath options that get added by
    # clangStdenv despite $NIX_DONT_SET_RPATH.
    #
    # This is comparable to fixing target/*/servo after the fact with:
    #
    #     patchelf --remove-rpath --set-interpreter $(patchelf --print-interpreter /usr/bin/env)
    #
    # [1] DT_RPATH breaks LD_LIBRARY_PATH and is no longer used
    #     https://medium.com/obscure-system/rpath-vs-runpath-883029b17c45
    # [2] “Using Nix on non-NixOS distros, it’s common to see GL application errors:”
    #     https://github.com/nix-community/nixGL
    # [3] https://ryantm.github.io/nixpkgs/stdenv/stdenv/#bintools-wrapper
    # [4] https://matklad.github.io/2022/03/14/rpath-or-why-lld-doesnt-work-on-nixos.html
    if ! [ -e /etc/NIXOS ]; then
      set -- $NIX_LDFLAGS
      for i; do
        shift
        if [ "$i" = -rpath ]; then
          shift
        else
          set -- "$@" "$i"
        fi
      done
      export NIX_DYNAMIC_LINKER=$(patchelf --print-interpreter /usr/bin/env)
      export NIX_DONT_SET_RPATH=1
      export NIX_LDFLAGS="$@"

      # Don’t pollute ~/.rustup with toolchains installed by nixpkgs rustup, because they
      # get patched in a way that makes them dependent on the Nix store.
      repo_root=$(git rev-parse --show-toplevel)
      export RUSTUP_HOME=$repo_root/.rustup
    else
      # On NixOS, export FHS wrapper paths so mach can prepend them to PATH at runtime
      # This ensures the FHS-wrapped binaries take precedence over .venv/bin
      export SERVO_NIX_BIN_DIR="${
        lib.makeBinPath [
          (mkVenvFhsWrapper "ruff")
          (mkVenvFhsWrapper "pyrefly")
        ]
      }"
    fi
  '';
})