treewide: nixfmt everything except distros

.github/actions/nix-ros-build-action/eval.nix

@@ -1,22 +1,37 @@
 # Evaluate `release.nix' like Hydra would. Too bad nix-instantiate can't to do this.
-{ lib ? pkgs.lib, pkgs }:
+{
+  lib ? pkgs.lib,
+  pkgs,
+}:
 
 let
   trace = if builtins.getEnv "VERBOSE" == "1" then builtins.trace else (x: y: y);
 
   # Add the ‘recurseForDerivations’ attribute to ensure that
   # nix-instantiate recurses into nested attribute sets.
-  recurse = path: attrs:
+  recurse =
+    path: attrs:
     if (builtins.tryEval attrs).success then
-      if lib.isDerivation attrs
-      then
-        if (builtins.tryEval attrs.drvPath).success
-        then { inherit (attrs) name drvPath; }
-        else { failed = true; }
+      if lib.isDerivation attrs then
+        if (builtins.tryEval attrs.drvPath).success then
+          { inherit (attrs) name drvPath; }
+        else
+          { failed = true; }
       else if lib.isAttrs attrs && (attrs.recurseForDerivations or false) then
-        { recurseForDerivations = true; } //
-           lib.mapAttrs (n: v: let path' = path ++ [n]; in trace path' (recurse path' v)) attrs
-      else { }
-    else { };
+        {
+          recurseForDerivations = true;
+        }
+        // lib.mapAttrs (
+          n: v:
+          let
+            path' = path ++ [ n ];
+          in
+          trace path' (recurse path' v)
+        ) attrs
+      else
+        { }
+    else
+      { };
 
-in recurse [] pkgs
+in
+recurse [ ] pkgs

.github/actions/nix-ros-build-action/shell.nix

@@ -1,4 +1,8 @@
-{ mkShell, nodejs, cachix }:
+{
+  mkShell,
+  nodejs,
+  cachix,
+}:
 
 mkShell {
   name = "nix-ros-build-action-shell";

.github/workflows/check-nix-fmt.yaml

@@ -0,0 +1,66 @@
+# This file was mostly copied from nixpkgs's check-nix-format.yml,
+# which itself wsa mostly copied from nixpkgs's check-maintainers-sorted.yaml.
+
+name: Check that Nix files are formatted
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+permissions:
+  contents: read
+
+jobs:
+  nixos:
+    name: nixfmt-check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 2
+      - name: Calculate changed files
+        id: changed-files
+        run: echo "changed_files=$(git diff --name-only -r HEAD^1 HEAD | xargs)" >> $GITHUB_OUTPUT
+      - uses: cachix/install-nix-action@v30
+        with:
+          extra_nix_config: sandbox = true
+          nix_path: nixpkgs=channel:nixpkgs-unstable
+      - name: Install nixfmt
+        run: "nix-env -f '<nixpkgs>' -iAP nixfmt-rfc-style"
+      - name: Check that Nix files are formatted according to the RFC style
+        run: |
+          # List of changed files
+          changed_files="${{ steps.changed-files.outputs.changed_files }}"
+
+          # Convert the string of changed files into an array
+          IFS=' ' read -r -a files <<< "$changed_files"
+
+          # A variable to track failures
+          failure=0
+
+          # Function to check the file and run nixfmt
+          check_file() {
+            local file="$1"
+            if [[ -f "$file" ]]; then
+              if ! nixfmt --check "$file"; then
+                echo "::error file=$file::Formatting check failed for $file" >&2
+                failure=1
+              fi
+            else
+              echo "File does not exist: $file" >&2
+            fi
+          }
+
+          # Export the function and failure variable for parallel execution
+          export -f check_file
+          export failure
+
+          # Remove distros folder (not nixfmt-ed)
+          rm -rf distros
+
+          # Run the checks in parallel
+          printf "%s\n" "${files[@]}" | xargs -n 1 -P "$(nproc)" -I {} bash -c 'check_file "$@"' _ {}
+
+          # Exit with a status of 1 if any checks failed
+          if [[ $failure -eq 1 ]]; then
+            exit 1
+          fi

default.nix

@@ -5,10 +5,15 @@ let
     sha256 = lock.nodes.nixpkgs.locked.narHash;
   };
 in
-{ nixpkgs ? lockedNixpkgs
-, overlays ? []
-, ... }@args:
+{
+  nixpkgs ? lockedNixpkgs,
+  overlays ? [ ],
+  ...
+}@args:
 
-import nixpkgs (args // {
-  overlays = [ (import ./overlay.nix) ] ++ overlays;
-})
+import nixpkgs (
+  args
+  // {
+    overlays = [ (import ./overlay.nix) ] ++ overlays;
+  }
+)

examples/flake/flake.nix

@@ -1,30 +1,41 @@
 {
   inputs = {
     nix-ros-overlay.url = "github:lopsided98/nix-ros-overlay/master";
-    nixpkgs.follows = "nix-ros-overlay/nixpkgs";  # IMPORTANT!!!
+    nixpkgs.follows = "nix-ros-overlay/nixpkgs"; # IMPORTANT!!!
   };
-  outputs = { self, nix-ros-overlay, nixpkgs }:
-    nix-ros-overlay.inputs.flake-utils.lib.eachDefaultSystem (system:
+  outputs =
+    {
+      self,
+      nix-ros-overlay,
+      nixpkgs,
+    }:
+    nix-ros-overlay.inputs.flake-utils.lib.eachDefaultSystem (
+      system:
       let
         pkgs = import nixpkgs {
           inherit system;
           overlays = [ nix-ros-overlay.overlays.default ];
         };
-      in {
+      in
+      {
         devShells.default = pkgs.mkShell {
           name = "Example project";
           packages = [
             pkgs.colcon
             # ... other non-ROS packages
-            (with pkgs.rosPackages.humble; buildEnv {
-              paths = [
-                ros-core
-                # ... other ROS packages
-              ];
-            })
+            (
+              with pkgs.rosPackages.humble;
+              buildEnv {
+                paths = [
+                  ros-core
+                  # ... other ROS packages
+                ];
+              }
+            )
           ];
         };
-      });
+      }
+    );
   nixConfig = {
     extra-substituters = [ "https://ros.cachix.org" ];
     extra-trusted-public-keys = [ "ros.cachix.org-1:dSyZxI8geDCJrwgvCOHDoAfOm5sV1wCPjBkKL+38Rvo=" ];

examples/ros2-basic.nix

@@ -1,6 +1,8 @@
 # Environment containing basic ROS2 tools
 
-{ pkgs ? import ../. {} }:
+{
+  pkgs ? import ../. { },
+}:
 with pkgs;
 with rosPackages.humble;
 

examples/ros2-gz.nix

@@ -2,42 +2,44 @@
 # to run this dev shell use:
 # NIXPKGS_ALLOW_INSECURE=1 nix develop --impure .\#example-ros2-gz
 
-{pkgs ? import ../. {}}:
+{
+  pkgs ? import ../. { },
+}:
 with pkgs;
 with rosPackages.jazzy;
-  mkShell {
-    nativeBuildInputs = [
-      (buildEnv {
-        paths = [
-          colcon
-          ros-core
-          ament-cmake-core
-          python-cmake-module
-          # ros-gz
+mkShell {
+  nativeBuildInputs = [
+    (buildEnv {
+      paths = [
+        colcon
+        ros-core
+        ament-cmake-core
+        python-cmake-module
+        # ros-gz
 
-          gz-cmake-vendor
-          gz-common-vendor
-          gz-dartsim-vendor
-          gz-fuel-tools-vendor
-          gz-gui-vendor
-          gz-launch-vendor
-          gz-math-vendor
-          gz-msgs-vendor
-          gz-ogre-next-vendor
-          gz-physics-vendor
-          gz-plugin-vendor
-          gz-rendering-vendor
-          gz-sensors-vendor
-          gz-sim-vendor
-          gz-tools-vendor
-          gz-transport-vendor
-          gz-utils-vendor
-        ];
-      })
-    ];
-    # Gazebo is currently broken on Wayland
-    # https://gazebosim.org/docs/ionic/troubleshooting/#wayland-issues
-    shellHook = ''
-      unset QT_QPA_PLATFORM
-    '';
-  }
+        gz-cmake-vendor
+        gz-common-vendor
+        gz-dartsim-vendor
+        gz-fuel-tools-vendor
+        gz-gui-vendor
+        gz-launch-vendor
+        gz-math-vendor
+        gz-msgs-vendor
+        gz-ogre-next-vendor
+        gz-physics-vendor
+        gz-plugin-vendor
+        gz-rendering-vendor
+        gz-sensors-vendor
+        gz-sim-vendor
+        gz-tools-vendor
+        gz-transport-vendor
+        gz-utils-vendor
+      ];
+    })
+  ];
+  # Gazebo is currently broken on Wayland
+  # https://gazebosim.org/docs/ionic/troubleshooting/#wayland-issues
+  shellHook = ''
+    unset QT_QPA_PLATFORM
+  '';
+}

examples/turtlebot3-gazebo.nix

@@ -2,22 +2,26 @@
 # roslaunch turtlebot3_gazebo turtlebot3_world.launch
 # roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch
 
-{ pkgs ? import ../. {} }:
+{
+  pkgs ? import ../. { },
+}:
 with pkgs;
 with rosPackages.noetic;
 with pythonPackages;
 
 mkShell {
   buildInputs = [
     glibcLocales
-    (buildEnv { paths = [
-      rosbash
-      turtlebot3-description
-      turtlebot3-teleop
-      turtlebot3-gazebo
-      gazebo-plugins
-      xacro
-    ]; })
+    (buildEnv {
+      paths = [
+        rosbash
+        turtlebot3-description
+        turtlebot3-teleop
+        turtlebot3-gazebo
+        gazebo-plugins
+        xacro
+      ];
+    })
   ];
 
   ROS_HOSTNAME = "localhost";

flake.nix

@@ -6,35 +6,41 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
     with nixpkgs.lib;
     with flake-utils.lib;
-    eachSystem systems.flakeExposed (system: let
-      pkgs = import nixpkgs {
-        inherit system;
-        overlays = [ self.overlays.default ];
-      };
-    in {
-      legacyPackages = pkgs.rosPackages;
+    eachSystem systems.flakeExposed (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ self.overlays.default ];
+        };
+      in
+      {
+        legacyPackages = pkgs.rosPackages;
 
-      devShells = {
-        example-turtlebot3-gazebo = import ./examples/turtlebot3-gazebo.nix { inherit pkgs; };
-        example-ros2-basic = import ./examples/ros2-basic.nix { inherit pkgs; };
-        example-ros2-gz = import ./examples/ros2-gz.nix { inherit pkgs; };
+        devShells = {
+          example-turtlebot3-gazebo = import ./examples/turtlebot3-gazebo.nix { inherit pkgs; };
+          example-ros2-basic = import ./examples/ros2-basic.nix { inherit pkgs; };
+          example-ros2-gz = import ./examples/ros2-gz.nix { inherit pkgs; };
 
-        # Development environment for the custom GitHub action
-        nix-ros-build-action = pkgs.callPackage ./.github/actions/nix-ros-build-action/shell.nix { };
-      };
-    }) // {
+          # Development environment for the custom GitHub action
+          nix-ros-build-action = pkgs.callPackage ./.github/actions/nix-ros-build-action/shell.nix { };
+        };
+      }
+    )
+    // {
       overlays.default = import ./overlay.nix;
       nixosModules.default = ./modules;
 
-      overlay = nixpkgs.lib.warn
-        "'nix-ros-overlay.overlay' is deprecated, use 'nix-ros-overlay.overlays.default' instead"
-        self.overlays.default;
-      nixosModule = nixpkgs.lib.warn
-        "'nix-ros-overlay.nixosModule' is deprecated, use 'nix-ros-overlay.nixosModules.default' instead"
-        self.nixosModules.default;
+      overlay = nixpkgs.lib.warn "'nix-ros-overlay.overlay' is deprecated, use 'nix-ros-overlay.overlays.default' instead" self.overlays.default;
+      nixosModule = nixpkgs.lib.warn "'nix-ros-overlay.nixosModule' is deprecated, use 'nix-ros-overlay.nixosModules.default' instead" self.nixosModules.default;
       templates.default = {
         path = ./examples/flake;
         description = "Basic ROS flake";