WIP: Test with a custom command sequence

This should make sure to use a native aarch64 python, in case
that makes any difference anywhere.

Author: mstorsjo

.github/workflows/libcxx-build-and-test.yaml

@@ -225,41 +225,44 @@ jobs:
 
   windows:
     runs-on: windows-11-arm
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-        - { config: mingw-dll, mingw: true }
     steps:
       - uses: actions/checkout@v4
       - name: Install dependencies
         run: |
           choco install -y ninja
           pip install psutil
-      - name: Install a current LLVM
-        if: ${{ matrix.mingw != true }}
-        run: |
-          choco install -y llvm --version=19.1.7 --allow-downgrade
       - name: Install llvm-mingw
-        if: ${{ matrix.mingw == true }}
         run: |
-          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250114/llvm-mingw-20250114-ucrt-aarch64.zip
+          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250417/llvm-mingw-20250417-ucrt-aarch64.zip
           powershell Expand-Archive llvm-mingw*.zip -DestinationPath .
           del llvm-mingw*.zip
           mv llvm-mingw* c:\llvm-mingw
           echo "c:\llvm-mingw\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
-      - name: Simulate a from-scratch build of llvm-mingw
-        if: ${{ matrix.config == 'mingw-incomplete-sysroot' }}
-        run: |
-          rm -r c:\llvm-mingw\include\c++
-          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libc++*
-          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libunwind*
+          echo "c:\llvm-mingw\python\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
+          echo "PYTHON_EXE=c:/llvm-mingw/python/bin/python3.exe" | Out-File -FilePath $Env:GITHUB_ENV -Encoding utf8 -Append
       - name: Add Git Bash to the path
         run: |
           echo "c:\Program Files\Git\usr\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
-      - name: Set up the MSVC dev environment
-        if: ${{ matrix.mingw != true }}
-        uses: ilammy/msvc-dev-cmd@v1
       - name: Build and test
         run: |
-          bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+          mkdir build
+          cd build
+          cmake ../runtimes `
+            -G Ninja `
+            -DCMAKE_BUILD_TYPE=Release `
+            -DPython3_EXECUTABLE="$Env:PYTHON_EXE" `
+            -DLIBCXX_ENABLE_WERROR=YES `
+            -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" `
+            -DLIBCXX_CXX_ABI=libcxxabi `
+            -DCMAKE_C_COMPILER=clang `
+            -DCMAKE_CXX_COMPILER=clang++ `
+            -DLIBCXXABI_ENABLE_SHARED=NO `
+            -DLIBCXX_ENABLE_STATIC_ABI_LIBRARY=YES `
+            -DLIBCXX_USE_COMPILER_RT=YES `
+            -DLIBCXXABI_USE_COMPILER_RT=YES `
+            -DLIBUNWIND_USE_COMPILER_RT=YES `
+            -DLIBCXXABI_USE_LLVM_UNWINDER=YES `
+            -DLIBCXX_EXTRA_SITE_DEFINES="__USE_MINGW_ANSI_STDIO=1" `
+            -DLLVM_LIT_ARGS="-v --time-tests"
+          ninja
+          ninja check-cxx