[libc++] Use GitHub-provided runners for the windows CI (#79326)

Co-authored-by: Martin Storsjö <martin@martin.st>

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

@@ -199,3 +199,45 @@ jobs:
             **/CMakeError.log
             **/CMakeOutput.log
             **/crash_diagnostics/*
+  windows:
+    runs-on: windows-2022
+    needs: [ stage1 ]
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - { config: clang-cl-dll, mingw: false }
+        - { config: clang-cl-static, mingw: false }
+        - { config: clang-cl-no-vcruntime, mingw: false }
+        - { config: clang-cl-debug, mingw: false }
+        - { config: clang-cl-static-crt, mingw: false }
+        - { config: mingw-dll, mingw: true }
+        - { config: mingw-static, mingw: true }
+        - { config: mingw-dll-i686, mingw: true }
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          choco install -y ninja wget
+          pip install psutil
+      - name: Install a current LLVM
+        if: ${{ matrix.mingw != true }}
+        run: |
+          choco install -y llvm --version=17.0.6
+      - name: Install llvm-mingw
+        if: ${{ matrix.mingw == true }}
+        run: |
+          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20231128/llvm-mingw-20231128-ucrt-x86_64.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: 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 }}

libcxx/utils/ci/buildkite-pipeline.yml

@@ -57,56 +57,6 @@ environment_definitions:
 
 
 steps:
-- group: ':windows: Windows'
-  steps:
-  - label: Clang-cl (DLL)
-    command: bash libcxx/utils/ci/run-buildbot clang-cl-dll
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: Clang-cl (Static)
-    command: bash libcxx/utils/ci/run-buildbot clang-cl-static
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: Clang-cl (no vcruntime exceptions)
-    command: bash libcxx/utils/ci/run-buildbot clang-cl-no-vcruntime
-    <<: *common
-    agents:
-      queue: windows
-
-  - label: Clang-cl (Debug mode)
-    command: bash libcxx/utils/ci/run-buildbot clang-cl-debug
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: Clang-cl (Static CRT)
-    command: bash libcxx/utils/ci/run-buildbot clang-cl-static-crt
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: MinGW (DLL, x86_64)
-    command: bash libcxx/utils/ci/run-buildbot mingw-dll
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: MinGW (Static, x86_64)
-    command: bash libcxx/utils/ci/run-buildbot mingw-static
-    agents:
-      queue: windows
-    <<: *common
-
-  - label: MinGW (DLL, i686)
-    command: bash libcxx/utils/ci/run-buildbot mingw-dll-i686
-    agents:
-      queue: windows
-    <<: *common
-
 - group: ':mac: Apple'
   steps:
   - label: MacOS x86_64

runtimes/CMakeLists.txt

@@ -155,6 +155,9 @@ set(LLVM_COMPILER_CHECKED ON)
 include(AddLLVM)
 include(HandleLLVMOptions)
 
+# Loot at the PATH first to avoid a version mismatch between the command-line
+# python and the CMake-found version
+set(Python3_FIND_REGISTRY LAST)
 find_package(Python3 REQUIRED COMPONENTS Interpreter)
 
 # Host triple is used by tests to check if they are running natively.