GH-125498: Update JIT builds to use LLVM 19 and preserve_none (GH-125499)

.github/workflows/jit.yml

@@ -61,7 +61,7 @@ jobs:
           - true
           - false
         llvm:
-          - 18
+          - 19
         include:
           - target: i686-pc-windows-msvc/msvc
             architecture: Win32
@@ -121,10 +121,15 @@ jobs:
           choco install llvm --allow-downgrade --no-progress --version ${{ matrix.llvm }}.1.0
           ./PCbuild/build.bat --experimental-jit ${{ matrix.debug && '-d' || '' }} -p ${{ matrix.architecture }}
 
+        # The `find` line is required as a result of https://github.com/actions/runner-images/issues/9966.
+        # This is a bug in the macOS runner image where the pre-installed Python is installed in the same
+        # directory as the Homebrew Python, which causes the build to fail for macos-13. This line removes 
+        # the symlink to the pre-installed Python so that the Homebrew Python is used instead.
       - name: Native macOS
         if: runner.os == 'macOS'
         run: |
           brew update
+          find /usr/local/bin -lname '*/Library/Frameworks/Python.framework/*' -delete
           brew install llvm@${{ matrix.llvm }}
           SDKROOT="$(xcrun --show-sdk-path)" \
             ./configure --enable-experimental-jit ${{ matrix.debug && '--with-pydebug' || '--enable-optimizations --with-lto' }}
@@ -165,6 +170,10 @@ jobs:
     name: Free-Threaded (Debug)
     needs: interpreter
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        llvm:
+          - 19
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
@@ -172,8 +181,8 @@ jobs:
           python-version: '3.11'
       - name: Build with JIT enabled and GIL disabled
         run: |
-          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh 18
-          export PATH="$(llvm-config-18 --bindir):$PATH"
+          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh ${{ matrix.llvm }}
+          export PATH="$(llvm-config-${{ matrix.llvm }} --bindir):$PATH"
           ./configure --enable-experimental-jit --with-pydebug --disable-gil
           make all --jobs 4
       - name: Run tests