Issue: dart run build_runner Cannot Find Flutter SDK in Nixpkgs

[Steffen70]

Issue: dart run build_runner Cannot Find Flutter SDK in Nixpkgs

Environment:

• Flutter Version: nixpkgs-flutter.url = "github:NixOS/nixpkgs/d4f247e89f6e10120f911e2e2d2254a050d0f732";
• Dart Version: Version provided by the above Flutter
• Operating Systems:
  • Intel Mac with macOS Sonoma
  • ARM Mac with macOS Sonoma
  • ARM Mac with macOS Sequoia
  • Kubuntu 24.04
• Issue Type: SDK Configuration / Build Issue

Description:

I am encountering an issue where running dart run build_runner does not work with the Flutter SDK from nixpkgs. It fails to locate the Flutter SDK, even though the app builds without any issues. However, when I switch to using Flutter installed via Homebrew, the command works as expected and the freezed models are generated successfully.

Specifically:

• Running dart run build_runner results in an error that the Flutter SDK cannot be found.
• Running flutter pub run does run, but it incorrectly sets the type Color to InvalidType. This appears to happen because flutter pub run internally runs dart run, which cannot find the Flutter SDK.

Steps to Reproduce:

1. Use latest Flutter Version from nixpkgs (github:NixOS/nixpkgs/d4f247e89f6e10120f911e2e2d2254a050d0f732)
2. Run dart run build_runner build --delete-conflicting-outputs in a project that uses freezed models (no source code provided, but this should reproduce the issue).
3. Observe the error indicating that the Flutter SDK cannot be found.
4. Alternatively, run flutter pub run and observe that the Color type is set to InvalidType, which is likely caused by dart run not finding the Flutter SDK.

Expected Behavior:

• dart run build_runner should find the Flutter SDK and generate freezed models without errors.
• Types should not be incorrectly set to InvalidType when using flutter pub run.

Actual Behavior:

• dart run build_runner cannot find the Flutter SDK.
• flutter pub run sets the Color type to InvalidType.

Affected Platforms:

• Intel Mac with macOS Sonoma
• ARM Mac with macOS Sonoma
• ARM Mac with macOS Sequoia
• Kubuntu 24.04

Additional Information:

• The issue only occurs when using the Flutter SDK from nixpkgs.
• Using Flutter installed via Homebrew resolves the issue, and dart run build_runner works as expected.

{
  description = "A Nix Flake for Flutter mobile development and fastlane CI/CD";

  inputs = {
    # Use the unstable channel for the latest packages
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

    flake-utils.url = "github:numtide/flake-utils";

    # Custom powershell modules
    powershell_modules.url = "github:seventymx/powershell_modules";

    # Specific nixpkgs reference for Flutter
    nixpkgs-flutter.url = "github:NixOS/nixpkgs/d4f247e89f6e10120f911e2e2d2254a050d0f732";
  };

  outputs =
    { self, ... }@inputs:
    inputs.flake-utils.lib.eachDefaultSystem (
      system:
      let
        unstable = import inputs.nixpkgs {
          inherit system;
          config = {
            android_sdk.accept_license = true;
            allowUnfree = true;
          };
        };

        flutterPkgs = import inputs.nixpkgs-flutter { inherit system; };

        androidComposition = unstable.androidenv.composeAndroidPackages {
          # API levels for Android 13 and 14
          platformVersions = [
            "31"
            "32"
            "33"
            "34"
          ];
          buildToolsVersions = [
            "30.0.3"
            "33.0.0"
            "34.0.0"
          ];
          abiVersions = [ "x86_64" ];
          includeEmulator = true;
          includeSystemImages = true;
          systemImageTypes = [ "google_apis_playstore" ];
          includeExtras = [ "extras;google;gcm" ];
        };

        # TODO: Make it work on Apple Silicon - Currently only works on x86_64-linux
        androidSdk = androidComposition.androidsdk;

        hostPlatform = unstable.stdenv.hostPlatform.system;

        appleInputs =
          if
            builtins.elem hostPlatform [
              "aarch64-darwin"
              "x86_64-darwin"
            ]
          then
            [ unstable.cocoapods ]
          else
            [ ];
      in
      {
        devShell = unstable.mkShellNoCC {
          buildInputs = [
            unstable.nixfmt-rfc-style
            unstable.git
            androidSdk
            unstable.jdk17
            unstable.fastlane
            unstable.ruby
            unstable.powershell
            unstable.scrcpy
            flutterPkgs.flutter
          ] ++ appleInputs;

          shellHook = ''
            export SHELL="${unstable.powershell}/bin/pwsh"

            export PSModulePath=${inputs.powershell_modules}

            # Call pwsh with inline commands
            pwsh -NoExit -Command "& {
              Import-Module ShellUtils

              # Restore the environment variables from the .secrets file - not included in the repository (do not use in ci/cd, use environment variables instead)
              Restore-EnvVariables -FilePath "../flutter_secrets/.secrets"

              Set-AndroidEnvironment -AndroidSdkPath "${androidSdk}"

              Initialize-Fastlane -FastlaneAppIdentifier "mx.seventy.demo" -FastlaneAppName "SPMobile"

              Import-Module FlutterBuildUtils
            }"

            exit 0
          '';
        };
      }
    );
}

[Steffen70]

I found a seemingly related issue here: #322871.

After reviewing it, I tried adding FLUTTER_ROOT in the shell hook, and now both dart run and flutter pub run work. However, I still get the same InvalidType error when running the build (screenshot attached).

Could you please help investigate this?

Notify maintainers: @babariviere
@ericdallo
@mkg20001
@RossComputerGuy
@FlafyDev
@hacker1024

[jeanlucthumm]

What are you setting FLUTTER_ROOT to?

[Steffen70]

I’m getting the original error again: Because spmobile depends on flutter_test from sdk which doesn't exist (the Flutter SDK is not available), version solving failed. This is the same error as when I don’t set FLUTTER_ROOT at all. It looks like I need to set FLUTTER_ROOT to the main Flutter directory (not bin) for dart run to work.