[Linux][GTK] Build error on Ubuntu 18.04

[HidenoriMatsubayashi]

Steps to Reproduce

You probably already know, it happens build error on Ubuntu 18.04.
Of course, by removing -Werror option of CMake, the build was successful.

Do you get build error?

1. $ git clone https://github.com/google/flutter-desktop-embedding.git
2. $ cd flutter-desktop-embedding/testbed
3. $ mv linux linux-glfw
4. $ mv gtk linux
5. $ flutter run -d linux --verbose

Actual results:

/home/matsu/workspace/flutter-desktop-embedding/testbed/linux/main.cc
[   +5 ms] /home/matsu/workspace/flutter-desktop-embedding/testbed/linux/main.cc:7:1: error: unused function 'FL_IS_APPLICATION'
[-Werror,-Wunused-function]
[        ] G_DECLARE_FINAL_TYPE(FlApplication, fl_application, FL, APPLICATION,
[        ] ^
[        ] /usr/include/glib-2.0/gobject/gtype.h:1405:26: note: expanded from macro 'G_DECLARE_FINAL_TYPE'
[        ]   static inline gboolean MODULE##_IS_##OBJ_NAME (gpointer ptr) {                                         \
[   +5 ms]                          ^
[        ] <scratch space>:48:1: note: expanded from here
[        ] FL_IS_APPLICATION
[   +3 ms] ^
[        ] 1 error generated.
[  +35 ms] [4/14] Building CXX object CMakeFiles/testbed.dir/window_configuration.cc.o
[        ] ninja: build stopped: subcommand failed.
[  +12 ms] Building Linux application... (completed in 12.5s)
[        ] Exception: Build process failed
[   +3 ms] "flutter run" took 13,375ms.
[  +16 ms] 
           #0      throwToolExit (package:flutter_tools/src/base/common.dart:14:3)
           #1      RunCommand.runCommand (package:flutter_tools/src/commands/run.dart:578:7)
           <asynchronous suspension>
           #2      FlutterCommand.verifyThenRunCommand (package:flutter_tools/src/runner/flutter_command.dart:829:18)
           #3      _rootRunUnary (dart:async/zone.dart:1198:47)
           #4      _CustomZone.runUnary (dart:async/zone.dart:1100:19)
           #5      _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
           #6      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
           #7      Future._propagateToListeners (dart:async/future_impl.dart:725:32)
           #8      Future._completeWithValue (dart:async/future_impl.dart:529:5)
           #9      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:40:15)
           #10     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:311:13)
           #11     RunCommand.usageValues (package:flutter_tools/src/commands/run.dart)
           #12     _rootRunUnary (dart:async/zone.dart:1198:47)
           #13     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
           #14     _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
           #15     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
           #16     Future._propagateToListeners (dart:async/future_impl.dart:725:32)
           #17     Future._completeWithValue (dart:async/future_impl.dart:529:5)
           #18     Future._asyncCompleteWithValue.<anonymous closure> (dart:async/future_impl.dart:567:7)
           #19     _rootRun (dart:async/zone.dart:1190:13)
           #20     _CustomZone.run (dart:async/zone.dart:1093:19)
           #21     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
           #22     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
           #23     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
           #24     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
           #25     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
           #26     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:169:5)
           
           
[ +207 ms] ensureAnalyticsSent: 199ms
[   +2 ms] Running shutdown hooks
[        ] Shutdown hook priority 4
[  +11 ms] Shutdown hooks complete
[        ] exiting with code 1

flutter doctor log

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel master, 1.19.0-6.0.pre.42, on Linux, locale ja_JP.UTF-8)
 
[!] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    ✗ Android licenses not accepted.  To resolve this, run: flutter doctor --android-licenses
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[!] Android Studio (version 3.5)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] VS Code (version 1.45.1)
[✓] Connected device (3 available)

! Doctor found issues in 2 categories.

Thank you.

[gausoft]

Any solution? I got the same issue

[rodrigopizzi]

Same issue here.

[stuartmorgan-g]

This bug was fixed; unless you're using a 5-month-old version of this repository, you don't have the same issue. Builds can fail for thousands of different reasons.