CI: add CICD job for code coverage

.github/workflows/CICD.yml

@@ -2,7 +2,7 @@ name: CICD
 
 # spell-checker:ignore (abbrev/names) CICD CodeCOV MacOS MinGW MSVC musl taiki
 # spell-checker:ignore (env/flags) Awarnings Ccodegen Coverflow Cpanic Dwarnings RUSTDOCFLAGS RUSTFLAGS Zpanic CARGOFLAGS
-# spell-checker:ignore (jargon) SHAs deps dequote softprops subshell toolchain fuzzers dedupe devel
+# spell-checker:ignore (jargon) SHAs deps dequote softprops subshell toolchain fuzzers dedupe devel profdata
 # spell-checker:ignore (people) Peltoche rivy dtolnay Anson dawidd
 # spell-checker:ignore (shell/tools) binutils choco clippy dmake dpkg esac fakeroot fdesc fdescfs gmake grcov halium lcov libclang libfuse libssl limactl mkdir nextest nocross pacman popd printf pushd redoxer rsync rustc rustfmt rustup shopt sccache utmpdump xargs
 # spell-checker:ignore (misc) aarch alnum armhf bindir busytest coreutils defconfig DESTDIR gecos getenforce gnueabihf issuecomment maint manpages msys multisize noconfirm nullglob onexitbegin onexitend pell runtest Swatinem tempfile testsuite toybox uutils
@@ -997,6 +997,123 @@ jobs:
         name: toybox-result.json
         path: ${{ steps.vars.outputs.TEST_SUMMARY_FILE }}
 
+  coverage:
+    name: Code Coverage
+    runs-on: ${{ matrix.job.os }}
+    timeout-minutes: 90
+    env:
+      SCCACHE_GHA_ENABLED: "true"
+      RUSTC_WRAPPER: "sccache"
+    strategy:
+      fail-fast: false
+      matrix:
+        job:
+          - { os: ubuntu-latest  , features: unix, toolchain: nightly }
+          # FIXME: Re-enable macos code coverage
+          # - { os: macos-latest   , features: macos, toolchain: nightly }
+          # FIXME: Re-enable Code Coverage on windows, which currently fails due to "profiler_builtins". See #6686.
+          # - { os: windows-latest , features: windows, toolchain: nightly-x86_64-pc-windows-gnu }
+    steps:
+    - uses: actions/checkout@v4
+    - uses: dtolnay/rust-toolchain@master
+      with:
+        toolchain: ${{ matrix.job.toolchain }}
+        components: rustfmt
+    - uses: taiki-e/install-action@v2
+      with:
+        tool: nextest,grcov@0.8.24
+    - uses: Swatinem/rust-cache@v2
+
+    - name: Run sccache-cache
+      uses: mozilla-actions/sccache-action@v0.0.6
+
+    # - name: Reattach HEAD ## may be needed for accurate code coverage info
+    #   run: git checkout ${{ github.head_ref }}
+
+    - name: Initialize workflow variables
+      id: vars
+      shell: bash
+      run: |
+        ## VARs setup
+        outputs() { step_id="${{ github.action }}"; for var in "$@" ; do echo steps.${step_id}.outputs.${var}="${!var}"; echo "${var}=${!var}" >> $GITHUB_OUTPUT; done; }
+
+        # toolchain
+        TOOLCHAIN="nightly" ## default to "nightly" toolchain (required for certain required unstable compiler flags) ## !maint: refactor when stable channel has needed support
+
+        # * specify gnu-type TOOLCHAIN for windows; `grcov` requires gnu-style code coverage data files
+        case ${{ matrix.job.os }} in windows-*) TOOLCHAIN="$TOOLCHAIN-x86_64-pc-windows-gnu" ;; esac;
+
+        # * use requested TOOLCHAIN if specified
+        if [ -n "${{ matrix.job.toolchain }}" ]; then TOOLCHAIN="${{ matrix.job.toolchain }}" ; fi
+        outputs TOOLCHAIN
+
+        # target-specific options
+
+        # * CARGO_FEATURES_OPTION
+        CARGO_FEATURES_OPTION='--all-features' ;  ## default to '--all-features' for code coverage
+        if [ -n "${{ matrix.job.features }}" ]; then CARGO_FEATURES_OPTION='--features=${{ matrix.job.features }}' ; fi
+        outputs CARGO_FEATURES_OPTION
+
+        # * CODECOV_FLAGS
+        CODECOV_FLAGS=$( echo "${{ matrix.job.os }}" | sed 's/[^[:alnum:]]/_/g' )
+        outputs CODECOV_FLAGS
+
+    - name: Install/setup prerequisites
+      shell: bash
+      run: |
+        ## Install/setup prerequisites
+        case '${{ matrix.job.os }}' in
+          macos-latest) brew install coreutils ;; # needed for testing
+        esac
+
+        case '${{ matrix.job.os }}' in
+          ubuntu-latest)
+            # pinky is a tool to show logged-in users from utmp, and gecos fields from /etc/passwd.
+            # In GitHub Action *nix VMs, no accounts log in, even the "runner" account that runs the commands. The account also has empty gecos fields.
+            # To work around this for pinky tests, we create a fake login entry for the GH runner account...
+            FAKE_UTMP='[7] [999999] [tty2] [runner] [tty2] [] [0.0.0.0] [2022-02-22T22:22:22,222222+00:00]'
+            # ... by dumping the login records, adding our fake line, then reverse dumping ...
+            (utmpdump /var/run/utmp ; echo $FAKE_UTMP) | sudo utmpdump -r -o /var/run/utmp
+            # ... and add a full name to each account with a gecos field but no full name.
+            sudo sed -i 's/:,/:runner name,/' /etc/passwd
+            # We also create a couple optional files pinky looks for
+            touch /home/runner/.project
+            echo "foo" > /home/runner/.plan
+            ;;
+        esac
+
+        case '${{ matrix.job.os }}' in
+          # Update binutils if MinGW due to https://github.com/rust-lang/rust/issues/112368
+          windows-latest) C:/msys64/usr/bin/pacman.exe -Sy --needed mingw-w64-x86_64-gcc --noconfirm ; echo "C:\msys64\mingw64\bin" >> $GITHUB_PATH ;;
+        esac
+
+        ## Install the llvm-tools component to get access to `llvm-profdata`
+        rustup component add llvm-tools
+
+    - name: Run test and coverage
+      id: run_test_cov
+      run: |
+        outputs() { step_id="${{ github.action }}"; for var in "$@" ; do echo steps.${step_id}.outputs.${var}="${!var}"; echo "${var}=${!var}" >> $GITHUB_OUTPUT; done; }
+
+        # Run the coverage script
+        ./util/build-run-test-coverage-linux.sh
+
+        outputs REPORT_FILE
+      env:
+        COVERAGE_DIR: ${{ github.workspace }}/coverage
+        FEATURES_OPTION: ${{ steps.vars.outputs.CARGO_FEATURES_OPTION }}
+        # RUSTUP_TOOLCHAIN: ${{ steps.vars.outputs.TOOLCHAIN }}
+
+    - name: Upload coverage results (to Codecov.io)
+      uses: codecov/codecov-action@v4
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}
+        file: ${{ steps.run_test_cov.outputs.report }}
+        ## flags: IntegrationTests, UnitTests, ${{ steps.vars.outputs.CODECOV_FLAGS }}
+        flags: ${{ steps.vars.outputs.CODECOV_FLAGS }}
+        name: codecov-umbrella
+        fail_ci_if_error: false
+
   test_separately:
     name: Separate Builds
     runs-on: ${{ matrix.os }}