After I create a merge request in GitLab, GitLab remind me this branch cannot be merged automatically.
As I open context menu from my project and try to resolve conflict issues, select Team --> Merge. But the menu option had been disabled.
1. Change to Git perspective. Branches => Remote Tracking => origin/master
2. Open context menu => Synchronize with Workspace
3. The conflict list is the source code which had been marked red.
4. Fix the foregoing conflict problems and open context menu => Marked as Merged
5. After fixed conflict problems, then push and commit to master again.