ci.yml

name: ci

# What this checks that a plain `mcpp build` does not: that the generated
# pnp-id-table.c still matches the pinned pnp.ids beside it, and that the
# manufacturer lookup it exists for gives the right answer on a real monitor's
# EDID.
on:
  push:
    branches: [ '**' ]
  pull_request:
  workflow_dispatch:

concurrency:
  group: ci-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # XLINGS_NON_INTERACTIVE is what makes the installer usable here: without
      # it the script takes its `curl | bash` branch (`xlings self install <
      # /dev/tty`) and a runner's /dev/tty is readable but not connected.
      #
      # XLINGS_VERSION pins the INSTALLER so a red run can be told apart from an
      # ecosystem change. mcpp itself stays unpinned on purpose — this package
      # depends on the current ecosystem, and a pinned mcpp carries a frozen
      # snapshot of it.
      #
      # TWO PATH entries, and the second is the one that matters: `xlings`
      # itself lands in ~/.xlings/bin, but `mcpp` is installed INTO THE SUBOS,
      # so without `subos/default/bin` the next step dies with a bare
      # `mcpp: command not found` (exit 127) that says nothing about why.
      - name: Install xlings + mcpp
        env:
          XLINGS_NON_INTERACTIVE: "1"
          XLINGS_VERSION: "2026.8.27.5"
        run: |
          curl -fsSL https://d2learn.org/xlings-install.sh | bash
          echo "$HOME/.xlings/bin" >> "$GITHUB_PATH"
          "$HOME/.xlings/bin/xlings" --version
          "$HOME/.xlings/bin/xlings" install mcpp
          echo "$HOME/.xlings/subos/default/bin" >> "$GITHUB_PATH"

      - name: build and test
        run: |
          cd mcpp/displayinfo
          mcpp test

      # No regenerate-and-diff step, and none is possible: build.mcpp PRODUCES
      # the table during `mcpp test` above, so a mismatch between the data and
      # the code is not a state this repo can be in. That is the difference
      # between generating at build time and checking a generated file in.
      #
      # What is still worth printing is that the pinned input is not the
      # runner's — the failure this fork exists to prevent looks exactly like a
      # passing build.
      - name: the pinned pnp.ids is NOT the runner's
        run: |
          if [ -f /usr/share/hwdata/pnp.ids ]; then
            d=$(diff <(sort mcpp/data/pnp.ids) <(sort /usr/share/hwdata/pnp.ids) | grep -c '^[<>]' || true)
            echo "pinned pnp.ids differs from the runner's by $d line(s)"
          else
            echo "the runner has no /usr/share/hwdata/pnp.ids — which is why upstream's fallback is a trap"
          fi

      - name: upstream/ is the release tarball, unmodified
        run: |
          curl -fsSL -o /tmp/u.tar.gz \
            https://gitlab.freedesktop.org/emersion/libdisplay-info/-/archive/0.2.0/libdisplay-info-0.2.0.tar.gz
          mkdir -p /tmp/u && tar xzf /tmp/u.tar.gz -C /tmp/u --strip-components=1
          if ! diff -r -q /tmp/u upstream >/dev/null 2>&1; then
            echo "::error::upstream/ differs from libdisplay-info 0.2.0"
            diff -r -q /tmp/u upstream | head -20
            exit 1
          fi
          echo "upstream/ is 0.2.0, unmodified"