gitlab-org--gitlab-foss/app/services/merge_requests/ff_merge_service.rb

module MergeRequests
  # MergeService class
  #
  # Do git fast-forward merge and in case of success
  # mark merge request as merged and execute all hooks and notifications
  # Executed when you do fast-forward merge via GitLab UI
  #
  class FfMergeService < MergeRequests::MergeService
    private

    def commit
      repository.ff_merge(current_user,
                          source,
                          merge_request.target_branch,
                          merge_request: merge_request)
    rescue Gitlab::Git::PreReceiveError => e
      raise MergeError, e.message
    rescue StandardError => e
      raise MergeError, "Something went wrong during merge: #{e.message}"
    ensure
      merge_request.update(in_progress_merge_commit_sha: nil)
    end
  end
end