[libc++] Fix local runs of the bootstrapping-build job

ldionne · ldionne · commit 11291865304a · 2025-11-08T09:32:52.000-10:00
The bootstrapping-build job defined in run-buildbot required the
CC and CXX environment variables to be defined even though run-buildbot
documents these environment variables as being optional.

It also required ccache, which may not be available for local builds.

This patch tweaks the script slightly to better deal with the absence
of these environment variables/tools.
diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
@@ -223,6 +223,9 @@ jobs:
           source .venv/bin/activate
           python -m pip install psutil
           xcrun bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+        env:
+          CC: clang
+          CXX: clang++
       - uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
         if: always()  # Upload artifacts even if the build or test suite fails
         with:
@@ -241,16 +244,16 @@ jobs:
       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 }
-        - { config: mingw-incomplete-sysroot, mingw: true }
-        - { config: mingw-static, mingw: true, runner: windows-11-arm }
+        - { config: clang-cl-dll,             mingw: false, cc: clang-cl, cxx: clang-cl }
+        - { config: clang-cl-static,          mingw: false, cc: clang-cl, cxx: clang-cl }
+        - { config: clang-cl-no-vcruntime,    mingw: false, cc: clang-cl, cxx: clang-cl }
+        - { config: clang-cl-debug,           mingw: false, cc: clang-cl, cxx: clang-cl }
+        - { config: clang-cl-static-crt,      mingw: false, cc: clang-cl, cxx: clang-cl }
+        - { config: mingw-dll,                mingw: true,  cc: clang-cl, cxx: clang-cl }
+        - { config: mingw-dll,                mingw: true,  cc: i686-w64-mingw32-clang, cxx: i686-w64-mingw32-clang++ }
+        - { config: mingw-static,             mingw: true,  cc: clang-cl, cxx: clang-cl }
+        - { config: mingw-incomplete-sysroot, mingw: true,  cc: clang-cl, cxx: clang-cl }
+        - { config: mingw-static,             mingw: true,  cc: clang-cl, cxx: clang-cl, runner: windows-11-arm }
     runs-on: ${{ matrix.runner != '' && matrix.runner || 'windows-2022' }}
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
@@ -286,5 +289,7 @@ jobs:
         run: |
           echo "c:\Program Files\LLVM\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
       - name: Build and test
-        run: |
-          bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+        run: bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+        env:
+          CC: ${{ matrix.cc }}
+          CXX: ${{ matrix.cxx }}
diff --git a/.github/workflows/libcxx-check-generated-files.yml b/.github/workflows/libcxx-check-generated-files.yml
@@ -22,3 +22,6 @@ jobs:
 
       - name: Check generated files
         run: libcxx/utils/ci/run-buildbot check-generated-output
+        env:
+          CC: cc
+          CXX: c++
diff --git a/libcxx/docs/AddingNewCIJobs.rst b/libcxx/docs/AddingNewCIJobs.rst
@@ -28,6 +28,9 @@ An example of a job definition is:
 
   - label: "C++11"
     command: "libcxx/utils/ci/run-buildbot generic-cxx11"
+    env:
+      CC: clang
+      CXX: clang++
     artifact_paths:
       - "**/test-results.xml"
     agents:
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -37,55 +37,79 @@ steps:
   steps:
   - label: AArch64
     command: libcxx/utils/ci/run-buildbot aarch64
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: aarch64
     <<: *common
 
   - label: AArch64 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot aarch64-no-exceptions
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: aarch64
     <<: *common
 
   - label: Armv8
     command: libcxx/utils/ci/run-buildbot armv8
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: armv8l
     <<: *common
 
   - label: Armv8 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot armv8-no-exceptions
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: armv8l
     <<: *common
 
   - label: Armv7
     command: libcxx/utils/ci/run-buildbot armv7
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: armv8l
     <<: *common
 
   - label: Armv7 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot armv7-no-exceptions
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: armv8l
     <<: *common
 
   - label: Armv7-M picolibc
     command: libcxx/utils/ci/run-buildbot armv7m-picolibc
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: aarch64
     <<: *common
 
   - label: Armv7-M picolibc -fno-exceptions
     command: libcxx/utils/ci/run-buildbot armv7m-picolibc-no-exceptions
+    env:
+      CC: clang
+      CXX: clang++
     agents:
       queue: libcxx-builders-linaro-arm
       arch: aarch64
@@ -131,13 +155,19 @@ steps:
   steps:
   - label: Android 5.0, x86 NDK
     command: libcxx/utils/ci/run-buildbot android-ndk-21-def-x86
+    env:
+      CC: /opt/android/clang/clang-current/bin/clang
+      CXX: /opt/android/clang/clang-current/bin/clang++
     agents:
       queue: libcxx-builders
       os: android
     <<: *common
 
   - label: Android 13, x86_64 NDK
     command: libcxx/utils/ci/run-buildbot android-ndk-33-goog-x86_64
+    env:
+      CC: /opt/android/clang/clang-current/bin/clang
+      CXX: /opt/android/clang/clang-current/bin/clang++
     agents:
       queue: libcxx-builders
       os: android
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
@@ -30,17 +30,41 @@ ${PROGNAME} [options] <BUILDER>
 
 Environment variables
 CC                  The C compiler to use, this value is used by CMake. This
-                    variable is optional.
+                    variable is mandatory.
 
 CXX                 The C++ compiler to use, this value is used by CMake. This
-                    variable is optional.
-
-CLANG_FORMAT        The clang-format binary to use when generating the format
-                    ignore list.
+                    variable is mandatory.
 
+CCACHE              The ccache binary to use. This variable is optional and is only
+                    used by the bootstrapping build.
 EOF
 }
 
+function step() {
+  endstep
+  set +x
+  if [[ ! -z ${GITHUB_ACTIONS+x} ]]; then
+    echo "::group::$1"
+    export IN_GROUP=1
+  else
+    echo "--- $1"
+  fi
+  set -x
+}
+
+function endstep() {
+  set +x
+  if [[ ! -z ${GITHUB_ACTIONS+x} ]] && [[ ! -z ${IN_GROUP+x} ]]; then
+    echo "::endgroup::"
+    unset IN_GROUP
+  fi
+  set -x
+}
+
+function error() {
+    echo "::error::$1"
+}
+
 if [[ $# == 0 ]]; then
    usage
    exit 0
@@ -96,6 +120,23 @@ function error() {
     echo "::error::$1"
 }
 
+if [ -z ${CC+x} ]; then
+    error "Environment variable CC must be defined"
+    exit 1
+fi
+
+if [ -z ${CXX+x} ]; then
+    error "Environment variable CXX must be defined"
+    exit 1
+fi
+
+# Print the version of a few tools to aid diagnostics in some cases
+step "Diagnose tools in use"
+cmake --version
+ninja --version
+${CC} --version
+${CXX} --version
+
 function clean() {
     rm -rf "${BUILD_DIR}"
 }
@@ -127,11 +168,7 @@ function generate-cmake() {
 }
 
 function generate-cmake-libcxx-win() {
-    generate-cmake-base \
-          -DLLVM_ENABLE_RUNTIMES="libcxx" \
-          -DCMAKE_C_COMPILER=clang-cl \
-          -DCMAKE_CXX_COMPILER=clang-cl \
-          "${@}"
+    generate-cmake-base -DLLVM_ENABLE_RUNTIMES="libcxx" "${@}"
 }
 
 function generate-cmake-android() {
@@ -215,12 +252,6 @@ function test-armv7m-picolibc() {
     check-runtimes
 }
 
-# Print the version of a few tools to aid diagnostics in some cases
-step "Diagnose tools in use"
-cmake --version
-ninja --version
-if [ ! -z "${CXX}" ]; then ${CXX} --version; fi
-
 case "${BUILDER}" in
 check-generated-output)
     # `! foo` doesn't work properly with `set -e`, use `! foo || false` instead.
@@ -357,12 +388,16 @@ generic-ubsan)
 bootstrapping-build)
     clean
 
+    if [ ! -z ${CCACHE+x} ]; then
+        COMPILER_LAUNCHER="-DCMAKE_CXX_COMPILER_LAUNCHER=${CCACHE}"
+    fi
+
     step "Generating CMake"
     cmake \
           -S "${MONOREPO_ROOT}/llvm" \
           -B "${BUILD_DIR}" \
           -GNinja \
-          -DCMAKE_CXX_COMPILER_LAUNCHER="ccache" \
+          ${COMPILER_LAUNCHER} \
           -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
           -DLLVM_ENABLE_PROJECTS="clang;lldb" \
@@ -689,14 +724,6 @@ mingw-static)
           -DLIBUNWIND_ENABLE_SHARED=OFF
     check-runtimes
 ;;
-mingw-dll-i686)
-    clean
-    generate-cmake \
-          -DCMAKE_C_COMPILER=i686-w64-mingw32-clang \
-          -DCMAKE_CXX_COMPILER=i686-w64-mingw32-clang++ \
-          -C "${MONOREPO_ROOT}/libcxx/cmake/caches/MinGW.cmake"
-    check-runtimes
-;;
 mingw-incomplete-sysroot)
     # When bringing up a new cross compiler from scratch, we build
     # libunwind/libcxx in a setup where the toolchain is incomplete and
@@ -741,10 +768,6 @@ android-ndk-*)
     fi
     ARCH=$(arch_of_emu_img ${ANDROID_EMU_IMG})
 
-    # Use the Android compiler by default.
-    export CC=${CC:-/opt/android/clang/clang-current/bin/clang}
-    export CXX=${CXX:-/opt/android/clang/clang-current/bin/clang++}
-
     # The NDK libc++_shared.so is always built against the oldest supported API
     # level. When tests are run against a device with a newer API level, test
     # programs can be built for any supported API level, but building for the
