ci: Fix llvm detection on macOS CI

Downgrade to LLVM-14 from LLVM-15 which is somewhat broken when using
static linking at present:

Homebrew/discussions#3666 (comment)

We can't use LLVM's lld instead of ld on macOS because we don't detect
it as an Apple linker and pass --as-needed etc to it.

LLVM is keg-only now, so we need to add CPPFLAGS / LDFLAGS to the keg
subdir inside /usr/local

Author: nirbheek

.github/workflows/macos.yml

@@ -34,16 +34,18 @@ jobs:
     - run: |
         python -m pip install --upgrade pip
         python -m pip install pytest pytest-xdist pytest-subtests jsonschema coverage codecov
-    - run: brew install pkg-config ninja llvm qt@5
+    # Use llvm-14 for now to fix llvm framework static tests, see
+    # https://github.com/Homebrew/discussions/discussions/3666#discussioncomment-3681821
+    - run: brew install pkg-config ninja llvm@14 qt@5
     - env:
-        CPPFLAGS: "-I/usr/local/include"
-        LDFLAGS: "-L/usr/local/lib"
+        CPPFLAGS: "-I/usr/local/include -I$(brew --prefix llvm@14)/include"
+        LDFLAGS: "-L/usr/local/lib -L$(brew --prefix llvm@14)/lib"
         MESON_CI_JOBNAME: unittests-appleclang
         MESON_UNIT_TEST_BACKEND: ninja
         # These cannot evaluate anything, so we cannot set PATH or SDKROOT here
       run: |
         export SDKROOT="$(xcodebuild -version -sdk macosx Path)"
-        export PATH="$HOME/tools:/usr/local/opt/qt@5/bin:$PATH:$(brew --prefix llvm)/bin"
+        export PATH="$HOME/tools:/usr/local/opt/qt@5/bin:$PATH:$(brew --prefix llvm@14)/bin"
         export PKG_CONFIG_PATH="/usr/local/opt/qt@5/lib/pkgconfig:$PKG_CONFIG_PATH"
         ./tools/run_with_cov.py ./run_unittests.py
     - name: Upload coverage report
@@ -69,20 +71,22 @@ jobs:
     - uses: actions/checkout@v2
     # use python3 from homebrew because it is a valid framework, unlike the actions one:
     # https://github.com/actions/setup-python/issues/58
-    - run: brew install pkg-config ninja llvm qt@5 boost ldc hdf5 openmpi lapack scalapack sdl2 python3 boost-python3 gtk-doc
+    # Use llvm-14 for now to fix llvm framework static tests, see
+    # https://github.com/Homebrew/discussions/discussions/3666#discussioncomment-3681821
+    - run: brew install pkg-config ninja llvm@14 qt@5 boost ldc hdf5 openmpi lapack scalapack sdl2 python3 boost-python3 gtk-doc
     - run: |
         python3 -m pip install --upgrade setuptools
         python3 -m pip install --upgrade pip
         python3 -m pip install cython coverage codecov
     - env:
-        CPPFLAGS: "-I/usr/local/include"
-        LDFLAGS: "-L/usr/local/lib"
+        CPPFLAGS: "-I/usr/local/include -I$(brew --prefix llvm@14)/include"
+        LDFLAGS: "-L/usr/local/lib -L$(brew --prefix llvm@14)/lib"
         MESON_ARGS: --unity=${{ matrix.unity }}
         CI: 1
         # These cannot evaluate anything, so we cannot set PATH or SDKROOT here
       run: |
         export SDKROOT="$(xcodebuild -version -sdk macosx Path)"
-        export PATH="$HOME/tools:/usr/local/opt/qt@5/bin:$PATH:$(brew --prefix llvm)/bin"
+        export PATH="$HOME/tools:/usr/local/opt/qt@5/bin:$PATH:$(brew --prefix llvm@14)/bin"
         export PKG_CONFIG_PATH="/usr/local/opt/qt@5/lib/pkgconfig:$PKG_CONFIG_PATH"
         export XML_CATALOG_FILES="/usr/local/etc/xml/catalog"
         ./tools/run_with_cov.py ./run_project_tests.py --backend=ninja