CI: Consolidate linting workflows into one

This patch consolidates the

  - `check-mem-files`
  - `dco-check`
  - `formatting-check`
  - `license-check`
  - `pr-title-check`
  - `pylint`

workflows into a single `lint` workflow.  Previously, each workflow
had only one or two jobs, which were all meant to be run in parallel
on each pull request.  By including each of these jobs in a single
workflow, they still run in parallel, but they do not clog up the
Actions views with individual workflow runs.

In addition, this patch takes the step of running these jobs on
`ubuntu-slim` runners, which are containerized runners rather than
VMs, which start more quickly.  These runners are only 1 vCPU and 5 GB
RAM, and jobs running on them can take a maximum of 15 minutes before
they fail, which is well-suited for these lightweight checks.

There is one remaining check that could reasonably go in this
workflow, the `pytest-coverage` workflow.  However, unlike all the
workflows that were consolidated here, this one also runs on a cron
job.  It’s not clear to me whether it should or not, but this patch
does not take the step of consolidating this workflow in case we do
need this.

Signed-off-by: Patrick M. Niedzielski <pniedzielski@bloomberg.net>

Author: pniedzielski

.github/workflows/check-mem-files.yaml

@@ -0,0 +1,150 @@
+name: Lint
+
+on:
+  pull_request:
+    types:
+      - "opened"
+      - "reopened"
+      - "synchronize"
+      - "labeled"
+      - "unlabeled"
+
+jobs:
+  commits_check_job:
+    runs-on: ubuntu-slim
+    name: DCO Check
+    steps:
+      - name: Get PR Commits
+        id: "get-pr-commits"
+        uses: tim-actions/get-pr-commits@198af03565609bb4ed924d1260247b4881f09e7d  # 26 Feb 2024
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+      - name: DCO Check
+        uses: tim-actions/dco@f2279e6e62d5a7d9115b0cb8e837b777b1b02e21  # 10 Jun 2021
+        with:
+          commits: ${{ steps.get-pr-commits.outputs.commits }}
+
+  license_check:
+    runs-on: ubuntu-slim
+    name: License Check
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: license check
+        run: |
+          python3 ${{ github.workspace }}/.github/workflows/ext/check_license.py --path=${{ github.workspace }} | tee missing_licenses.txt
+          if [ -s missing_licenses.txt ]; then exit 1; fi
+
+  pr_title_check:
+    runs-on: ubuntu-slim
+    name: PR Title Check
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: pr title check
+        env:
+          PR_TITLE: ${{ github.event.pull_request.title }}
+        run: |
+          python3 ${{ github.workspace }}/.github/workflows/ext/check_pr_title.py
+
+  check_mem_sorting:
+    runs-on: ubuntu-slim
+    name: Check .mem files sorting
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Check alphabetical order in .mem files
+        run: |
+          #!/usr/bin/env bash
+          set -euo pipefail
+
+          echo "Checking all .mem files in src/ for sorted order..."
+
+          # Find all .mem files recursively under src/
+          files=$(find src -type f -name "*.mem")
+
+          # Track whether we find any unsorted files
+          unsorted=0
+
+          for f in $files; do
+            # Compare file with its sorted version
+            if ! diff -q <(sort "$f") "$f" > /dev/null; then
+              echo "❌ File not sorted alphabetically: $f"
+              echo "   To fix, run: sort -o $f $f"
+              unsorted=1
+            fi
+          done
+
+          if [ "$unsorted" -eq 1 ]; then
+            echo
+            echo "Some .mem files are not sorted alphabetically."
+            exit 1
+          fi
+
+          echo "✅ All .mem files are sorted."
+
+  cpp_formatting_check:
+    name: C++ Formatting Check
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: clang-format style check
+        run: |
+          git clang-format-18 --diff -q origin/main | tee format_diff.txt
+          if [ -s format_diff.txt ]; then exit 1; fi
+
+  python_formatting_check:
+    # There might be differences how the formatter refactors the code locally
+    # and in the CI. If there is a problem with CI formatter mismatch, consider
+    # wrapping a troublesome python code with comments:
+    # "# fmt: off"
+    # "<Python code we don't want to format>"
+    # "# fmt: on"
+    name: Python Formatting Check
+    runs-on: ubuntu-slim
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@v5
+      - name: ruff style check
+        run: |
+          pip3 install ruff
+          ruff format .
+          git diff -q | tee format_diff.txt
+          if [ -s format_diff.txt ]; then exit 1; fi
+
+  python_linter_check:
+    name: Python Linter Check
+    runs-on: ubuntu-slim
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12.4'
+      - name: Install dependencies
+        run: |
+          pip3 install -r ${{ github.workspace }}/src/python/requirements.txt
+          pip3 install pylint lint-diffs
+          ln -s ${{ github.workspace }}/src/python/pylintrc ${{ github.workspace }}/.pylintrc
+          echo [pylint] > ${{ github.workspace }}/.lint-diffs
+          echo extensions=.py >> ${{ github.workspace }}/.lint-diffs
+          echo [clang-tidy] >> ${{ github.workspace }}/.lint-diffs
+          echo extensions= >> ${{ github.workspace }}/.lint-diffs
+          echo [rubocop] >> ${{ github.workspace }}/.lint-diffs
+          echo extensions= >> ${{ github.workspace }}/.lint-diffs
+      - name: Check the whole repo with pylint
+        run: |
+          export PYTHONPATH=${{ github.workspace }}/src/python:$PYTHONPATH
+          pylint -j 8 src || true
+      - name: Check the PR with pylint
+        run: |
+          export PYTHONPATH=${{ github.workspace }}/src/python:$PYTHONPATH
+          git diff -U0 origin/main | lint-diffs