Add label or failing check to Pull Request with (merge) conflict on GitHub?

If you work with GitHub project boards for PR management, it is quite important to be able to know about the status of a PR. Test failures are made available via the read x or green checkmark via checks, but (merge) conflicts are not visible in any way - you have to actually open the PR in a new tab.

Is there a way to add an automated conflict label or a failing check to a PR on GitHub if there is a (merge) conflict? (Both would be visible in a GitHub project board.)

I know its been a couple of years now but you can try setting up a Github Action using something like https://github.com/marketplace/actions/auto-label-merge-conflicts .

Example:

name: 'Check for merge conflicts'
on:
  push:
    branches:
      - master
jobs:
  triage:
    runs-on: ubuntu-latest
    steps:
      - uses: mschilde/auto-label-merge-conflicts@master
        with:
          CONFLICT_LABEL_NAME: 'has conflicts'
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}