ci: Add a Clang 16 code coverage job

.github/workflows/ci.yaml

@@ -175,6 +175,39 @@ jobs:
       - run: export PATH="/usr/local/opt/icu4c/bin:/usr/local/opt/icu4c/sbin:$PATH"; bazelisk build //...
       - run: export PATH="/usr/local/opt/icu4c/bin:/usr/local/opt/icu4c/sbin:$PATH"; bazelisk test //...
 
+  linux-clang-coverage:
+    runs-on: ubuntu-22.04
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/cache@v3
+        with:
+          path: ~/.cache/bazel
+          key: clangcoverage-${{ hashFiles('.bazelversion', 'WORKSPACE', 'third_party/**') }}
+          restore-keys: clangcoverage-
+      - name: Install
+        run: |
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+          sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-16 main"
+          sudo apt-get update
+          sudo apt-get install --no-install-recommends libgl-dev lcov clang-16 libclang-rt-16-dev llvm-16
+      # See: https://github.com/actions/runner-images/issues/8659
+      - name: Work around libstdc++ and Clang incompabilities
+        run: |
+          sudo rm -f /etc/apt/sources.list.d/ubuntu-toolchain-r-ubuntu-test-jammy.list
+          sudo apt-get update
+          sudo apt-get install --allow-downgrades libstdc++6=12.3.0-1ubuntu1~22.04 libgcc-s1=12.3.0-1ubuntu1~22.04
+      - run: echo "CC=clang-16" >> $GITHUB_ENV && echo "CXX=clang++-16" >> $GITHUB_ENV
+      - run: bazel coverage ... --config clang16-coverage
+      - run: lcov --summary bazel-out/_coverage/_coverage_report.dat
+      - name: Upload
+        run: |
+          wget --no-verbose --output-document=codecov https://github.com/codecov/uploader/releases/download/v0.7.1/codecov-linux
+          chmod +x codecov
+          ./codecov -f bazel-out/_coverage/_coverage_report.dat
+
   windows-msvc:
     runs-on: windows-2022
     timeout-minutes: 40