Enabled coverage report for Clang builds

On all but macOS 13, because that host has a version of
llvm-cov that is too old to support the `--source` CLI option.
We could probably conditionally skip that option, but its not
worth the effort currently.

Squashed commit of the following:

commit 265d95a1e232856152adfb14b499a1f2a3b3a858
Author: Paul Colby <git@colby.id.au>
Date:   Wed Oct 9 18:28:47 2024 +1100

    Remove the diagnostic `--help` command

commit 3286c55
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 23:43:16 2024 +1100

    Correct workflow syntax

commit 45587d7
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 23:39:17 2024 +1100

    Correct workflow syntax

commit 89e5c3e
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 23:35:24 2024 +1100

    Exclude coverage for Clang on macOS 13

    Since that GitHub hosted runner has an old version of llvm-cov,
    that doesn't support the `--source` CLI option (in fact, it
    doesn't even support `--version`).

    Also restored the remaining (non-coverage, and Windows) builds.

commit 38efb74
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 23:34:03 2024 +1100

    Choose an arch when using universal builds

commit aac9e55
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 22:28:01 2024 +1100

    Try the prefix path given by brew

commit 2c54dec
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 22:23:17 2024 +1100

    Handle '@' char

commit d241b35
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 22:08:51 2024 +1100

    Try the common path

commit 048b176
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 22:05:22 2024 +1100

    Correct YAML syntax

commit 606d20e
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 21:57:10 2024 +1100

    Look closer for llvm

commit 2fbe208
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 21:41:16 2024 +1100

    Try looking up the path to LLVM

commit db986d4
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 21:38:21 2024 +1100

    Use a modern (brew) LLVM version

    The macOS ones is so old, it can't even handle `--version`! :(

commit a963e9a
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 21:13:25 2024 +1100

    Get some versoin info

commit 4121f0c
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 20:52:41 2024 +1100

    Tell CMake where to find llvm-profdata and llvm-cov

commit 1a80658
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 20:22:28 2024 +1100

    Find where (if anyway) llvm-profdata and llvm-cov are

commit 86cc54f
Author: Paul Colby <git@colby.id.au>
Date:   Tue Oct 8 19:12:54 2024 +1100

    Try llvm-cov on CI

.github/workflows/build.yaml

@@ -30,14 +30,15 @@ jobs:
           - 6.8.0
         env:
           - { cc: clang, cxx: clang++, coverage: false }
+          - { cc: clang, cxx: clang++, coverage: true }
           - { cc: gcc, cxx: g++, coverage: false }
           - { cc: gcc, cxx: g++, coverage: true }
     steps:
       - name: Upgrade OS
         run: |
           sudo apt-mark hold grub-efi-amd64-signed
           sudo apt update && sudo apt upgrade
-          sudo apt install lcov libfuse2
+          sudo apt install lcov libfuse2 llvm
       - uses: actions/setup-python@v5
         with:
           python-version: '>=3.9'
@@ -167,6 +168,7 @@ jobs:
         os: [ 'macos-13', 'macos-14', 'macos-15' ]
         env:
           - { cc: clang, cxx: clang++, coverage: false }
+          - { cc: clang, cxx: clang++, coverage: true }
           - { cc: gcc-14, cxx: g++-14, coverage: false }
           - { cc: gcc-14, cxx: g++-14, coverage: true }
         exclude:
@@ -213,6 +215,8 @@ jobs:
           - { qt: '6.6.3', env: { cc: gcc-14 } }
           - { qt: '6.7.3', env: { cc: gcc-14 } }
           - { qt: '6.8.0', env: { cc: gcc-14 } }
+          # Exclude code coverage builds with Clang on macOS 13, since the runner's llvm-cov does not support --source.
+          - { os: macos-13, env: { cc: clang, coverage: true } }
     steps:
       - uses: actions/checkout@v4
       - name: Install lcov
@@ -259,6 +263,8 @@ jobs:
           cmake -D CMAKE_BUILD_TYPE=Release \
                 -D CODECOV_GCOV=${{ startsWith(matrix.env.cc, 'gcc') && '/usr/local/bin/gcov-14' || '/usr/bin/gcov'}} \
                 -D ENABLE_COVERAGE=${{ matrix.env.coverage }} \
+                -D LLVM_COV=/Library/Developer/CommandLineTools/usr/bin/llvm-cov \
+                -D LLVM_PROFDATA=/Library/Developer/CommandLineTools/usr/bin/llvm-profdata \
                 -D QT_INSTALL_DOCS="$RUNNER_WORKSPACE/Qt/Docs/Qt-${{ matrix.qt }}" \
                 -S "$GITHUB_WORKSPACE" -B "$RUNNER_TEMP"
           echo "dokitVersion=$(cat "$RUNNER_TEMP/version.txt")" | tee -a "$GITHUB_OUTPUT"

test/CMakeLists.txt

@@ -21,11 +21,16 @@ if (ENABLE_COVERAGE AND CMAKE_CXX_COMPILER_ID MATCHES "Clang$")
       "${PROJECT_SOURCE_DIR}/include/*.h"
       "${PROJECT_SOURCE_DIR}/src/*.cpp"
       "${PROJECT_SOURCE_DIR}/src/*.h")
+    if (APPLE AND CMAKE_OSX_ARCHITECTURES MATCHES ".*;.*")
+      list(GET CMAKE_OSX_ARCHITECTURES 0 LLVM_COV_ARCH)
+    endif()
     add_custom_target(
       coverage
       COMMAND ${LLVM_PROFDATA} merge --output coverage.profdata "${LLVM_PROFILE_FILES}"
       COMMAND ${LLVM_PROFDATA} show coverage.profdata
-      COMMAND ${LLVM_COV} export --format lcov --instr-profile coverage.profdata
+      COMMAND ${LLVM_COV} export
+        "$<$<BOOL:${LLVM_COV_ARCH}>:--arch;${LLVM_COV_ARCH}>"
+        --format lcov --instr-profile coverage.profdata
         "--object;$<JOIN:$<TARGET_OBJECTS:QtPokit>,;--object;>"
         "$<$<TARGET_EXISTS:cli-lib>:--object;$<JOIN:$<TARGET_OBJECTS:cli-lib>,;--object;>>"
         --sources "${LLVM_COV_SOURCES}" > coverage.info