It seems that build_runner crashes while using "flutter_localizations".

[FrancescoJo]

It seems that build_runner crashes while using flutter_localizations.

Thanks for reading and we hope to see this error is fixed soon.

Environment

• Dart version (run dart --version): 3.0.5 (stable)
• OS kind and version (e.g. "Windows 10, version 1809" or "macOS 12.4"): Linux 5.19.0-43-generic on x86_64
• Are you using the Chinese community mirror or a corporate firewall? nope

Problem

Error happens like below if we apply Internationalizing Flutter apps in our project.

$ flutter pub run build_runner build --delete-conflicting-outputs
Deprecated. Use `dart run` instead.
Null check operator used on a null value


package:pub/src/entrypoint.dart 562:48   Entrypoint.resolveExecutable
package:pub/src/executable.dart 79:35    runExecutable
package:pub/src/command/run.dart 100:26  RunCommand.runProtected

This is an unexpected error. The full log and other details are collected in:

    /home/USER/.pub-cache/log/pub_log.txt

Consider creating an issue on https://github.com/dart-lang/pub/issues/new
and attaching the relevant parts of that log file.

Expected behavior

Build should be successful and various files dependes on builld_runner are created.

Actual behavior

Cannot continue build unless we comment out build_runner.

--trace output

The pub_log.txt file:

Information about the latest pub run.

If you believe something is not working right, you can go to
https://github.com/dart-lang/pub/issues/new to post a new issue and attach this file.

Before making this file public, make sure to remove any sensitive information!

Pub version: 3.0.5
Created: 2023-06-19T09:43:09+09:00
FLUTTER_ROOT: /home/USER/snap/flutter/common/flutter
PUB_HOSTED_URL: <not set>
PUB_CACHE: "<not set>"
Command: dart pub --suppress-analytics run build_runner build --delete-conflicting-outputs
Platform: linux

---- /home/USER/documents/my_project/app/pubspec.yaml ----
name: my_project
description: My flutter project.
publish_to: none
version: 1.0.0+1

environment:
  sdk: ^3.0.5
  flutter: ^3.10.5

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  core:
    path: ../core/
  data:
    path: ../data/
  util:
    path: ../util/

  android_id: ^0.1.3+1
  flutter_bloc: ^8.1.1
  firebase_core: ^2.4.1
  firebase_messaging: ^14.2.1
  flutter_local_notifications: ^13.0.0
  firebase_analytics: ^10.1.0
  html: ^0.15.1
  intl: any
  rxdart: ^0.27.7
  tap_debouncer: ^2.0.2
  url_launcher: ^6.1.8
  webview_flutter: ^4.0.2
  webview_flutter_android: ^3.2.1
  webview_flutter_wkwebview: ^3.0.2
  shared_preferences: ^2.0.20
  go_router: 7.0.0

dev_dependencies:
  flutter_test:
    sdk: flutter

  # Error occurs if we uncomment this dependency upon build. It seems that flutter l10n causes problems with dart build_runner. Read https://github.com/dart-lang/build/issues/2835 for further information.
  # 2023-06-01: Error still happens with version 2.3.3!!
  # build_runner: ^1.10.3
  bloc_test: ^9.1.1
  mockito: ^5.3.2
  network_image_mock: ^2.1.1
  flutter_lints: ^2.0.1
  faker: ^2.1.0


flutter:
  generate: true
  uses-material-design: true
  assets:
    - assets/images/
  fonts:
    - family: NotoSans
      fonts:
        - asset: assets/fonts/noto_sans/NotoSans-Regular.otf
          weight: 400
flutter_intl:
  enabled: true

---- End pubspec.yaml ----

---- /home/USER/documents/my_project/app/pubspec.lock ----
# Generated by pub
# See https://dart.dev/tools/pub/glossary#lockfile
packages:
  _fe_analyzer_shared:
    dependency: transitive
    description:
      name: _fe_analyzer_shared
      sha256: "98d1d33ed129b372846e862de23a0fc365745f4d7b5e786ce667fcbbb7ac5c07"
      url: "https://pub.dev"
    source: hosted
    version: "55.0.0"
  _flutterfire_internals:
    dependency: transitive
    description:
      name: _flutterfire_internals
      sha256: "330d7fcbb72624f5b6d374af8b059b0ef4ba96ba5b8987f874964a1287eb617d"
      url: "https://pub.dev"
    source: hosted
    version: "1.0.18"
  analyzer:
    dependency: transitive
    description:
      name: analyzer
      sha256: "881348aed9b0b425882c97732629a6a31093c8ff20fc4b3b03fb9d3d50a3a126"
      url: "https://pub.dev"
    source: hosted
    version: "5.7.1"
  android_id:
    dependency: "direct main"
    description:
      name: android_id
      sha256: e60b3c96bf256014d6c1d0a03e2712ef49d717817c13cbdb4c72b939199a4993
      url: "https://pub.dev"
    source: hosted
    version: "0.1.3+1"
  args:
    dependency: transitive
    description:
      name: args
      sha256: "4cab82a83ffef80b262ddedf47a0a8e56ee6fbf7fe21e6e768b02792034dd440"
      url: "https://pub.dev"
    source: hosted
    version: "2.4.0"
  asn1lib:
    dependency: transitive
    description:
      name: asn1lib
      sha256: ab96a1cb3beeccf8145c52e449233fe68364c9641623acd3adad66f8184f1039
      url: "https://pub.dev"
    source: hosted
    version: "1.4.0"
  async:
    dependency: transitive
    description:
      name: async
      sha256: "947bfcf187f74dbc5e146c9eb9c0f10c9f8b30743e341481c1e2ed3ecc18c20c"
      url: "https://pub.dev"
    source: hosted
    version: "2.11.0"
  bloc:
    dependency: transitive
    description:
      name: bloc
      sha256: "658a5ae59edcf1e58aac98b000a71c762ad8f46f1394c34a52050cafb3e11a80"
      url: "https://pub.dev"
    source: hosted
    version: "8.1.1"
  bloc_test:
    dependency: "direct dev"
    description:
      name: bloc_test
      sha256: ffbb60c17ee3d8e3784cb78071088e353199057233665541e8ac6cd438dca8ad
      url: "https://pub.dev"
    source: hosted
    version: "9.1.1"
  webkit_inspection_protocol:
    dependency: transitive
    description:
      name: webkit_inspection_protocol
      sha256: "67d3a8b6c79e1987d19d848b0892e582dbb0c66c57cc1fef58a177dd2aa2823d"
      url: "https://pub.dev"
    source: hosted
    version: "1.2.0"
  webview_flutter:
    dependency: "direct main"
    description:
      name: webview_flutter
      sha256: b6cd42db3ced5411f3d01599906156885b18e4188f7065a8a351eb84bee347e0
      url: "https://pub.dev"
    source: hosted
    version: "4.0.6"
  webview_flutter_android:
    dependency: "direct main"
    description:
      name: webview_flutter_android
      sha256: c849dcb6bf7367f696869006fb9575c15bdc6a1d624ae13f12de5a147a740b12
      url: "https://pub.dev"
    source: hosted
    version: "3.4.2"
  webview_flutter_platform_interface:
    dependency: transitive
    description:
      name: webview_flutter_platform_interface
      sha256: "1939c39e2150fb4d30fd3cc59a891a49fed9935db53007df633ed83581b6117b"
      url: "https://pub.dev"
    source: hosted
    version: "2.1.0"
  webview_flutter_wkwebview:
    dependency: "direct main"
    description:
      name: webview_flutter_wkwebview
      sha256: ab12479f7a0cf112b9420c36aaf206a1ca47cd60cd42de74a4be2e97a697587b
      url: "https://pub.dev"
    source: hosted
    version: "3.2.1"
  win32:
    dependency: transitive
    description:
      name: win32
      sha256: c9ebe7ee4ab0c2194e65d3a07d8c54c5d00bb001b76081c4a04cdb8448b59e46
      url: "https://pub.dev"
    source: hosted
    version: "3.1.3"
  xdg_directories:
    dependency: transitive
    description:
      name: xdg_directories
      sha256: bd512f03919aac5f1313eb8249f223bacf4927031bf60b02601f81f687689e86
      url: "https://pub.dev"
    source: hosted
    version: "0.2.0+3"
  xml:
    dependency: transitive
    description:
      name: xml
      sha256: "979ee37d622dec6365e2efa4d906c37470995871fe9ae080d967e192d88286b5"
      url: "https://pub.dev"
    source: hosted
    version: "6.2.2"
  yaml:
    dependency: transitive
    description:
      name: yaml
      sha256: "23812a9b125b48d4007117254bca50abb6c712352927eece9e155207b1db2370"
      url: "https://pub.dev"
    source: hosted
    version: "3.1.1"
sdks:
  dart: ">=3.0.0 <4.0.0"
  flutter: ">=3.3.0"

---- End pubspec.lock ----
---- Log transcript ----
FINE: Pub 3.0.5
MSG : Deprecated. Use `dart run` instead.
FINE: The pubspec.yaml file has changed since the pubspec.lock file was generated.
MSG : Resolving dependencies...
SLVR: fact: my_project is 1.0.0+1
SLVR: derived: my_project
ERR : Null check operator used on a null value
FINE: Exception type: _TypeError
ERR : package:pub/src/entrypoint.dart 562:48   Entrypoint.resolveExecutable
    | package:pub/src/executable.dart 79:35    runExecutable
    | package:pub/src/command/run.dart 100:26  RunCommand.runProtected
ERR : This is an unexpected error. The full log and other details are collected in:
    | 
    |     /home/USER/.pub-cache/log/pub_log.txt
    | 
    | Consider creating an issue on https://github.com/dart-lang/pub/issues/new
    | and attaching the relevant parts of that log file.
---- End log transcript ----

flutter doctor results:

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.10.5, on Ubuntu 22.04.2 LTS 5.19.0-43-generic, locale en_GB.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[✓] Android Studio (version 2022.1)
[✓] IntelliJ IDEA Ultimate Edition (version 2023.1)
[✓] IntelliJ IDEA Community Edition (version 2022.3)
[✓] VS Code (version 1.79.2)
[✓] Connected device (2 available)
[✓] Network resources

[sigurdm]

Thanks for reporting!

So the crash in pub as reported here is a bug in pub, pub run should (after 3.0) do a dependency resolution if the pubspec.lock is out of date. We did that, but missed awaiting the result, ending up with a race-condition. All that is entirely unrelated to localization and build_runner.

The other side of the issue seems to be dart-lang/build#2835 where build_runner tries to follow the dependency graph by finding the pubspec.yaml of each package. But flutter pub get (not dart pub get) will create a synthetic package inside .dart_tool/ when flutter_gen: true is specified.
pub has special handling of this synthetic package, but build_runner doesn't and crashes.

Here is an issue about fixing this situation: flutter/flutter#102983

[FrancescoJo]

@sigurdm Thanks for your rapid feedback. We're longing to see this error is fixed soon.

[FrancescoJo]

@sigurdm Your comment was a great hint for us. We investigated the error situation again and changed our pubspec.yml like below:

pubspec.yml

environment:
  sdk: ^3.0.5
  flutter: ^3.10.5

dev_dependencies:
  build_runner: ^2.4.5

and did these things:

1. dart pub cache clean
2. delete all pubspec.lock files in modules
3. flutter pub get && flutter pub run build_runner build
4. IT WORKS!!

Thanks for your support. Hope this comment helps to other flutter devs.

[astronomico]

For my case - simple solution
I only have to remove flutter generate specification on pubspec.yaml with my localizations builds

#The following section is specific to Flutter packages.
flutter:
# generate: true // remove this

[WongueShin]

I'm not sure why this phenomenon occurs, but I have identified the following reproduction conditions and a solution.

Reproduction conditions:

If you run pub get even once in a Flutter package that depends on both l10n and build_runner, errors will occur in all subsequent "dart run build_runner build" operations.

Solution:

Delete the pubspec.lock file right before each "dart run build_runner build".
I have automated this process with a script that I am currently using.

I hope my case will be helpful.