[libc++][ci] Add a configuration testing Apple's system library build

[ldionne]

CI passed!

libcxx/utils/ci/buildkite-pipeline.yml

- label: "With LLVM's libunwind"
     command: "set -o pipefail && libcxx/utils/ci/run-buildbot.sh x86_64-ubuntu-with_llvm_unwinder | libcxx/utils/ci/phabricator-report"
     agents:
       queue: "libcxx-builders"
 
   - label: "Single-threaded"
     command: "set -o pipefail && libcxx/utils/ci/run-buildbot.sh x86_64-ubuntu-singlethreaded | libcxx/utils/ci/phabricator-report"
     agents:
       queue: "libcxx-builders"
+
+  # Build with the configuration we use to generate libc++.dylib on Apple platforms
+  - label: "Apple system"
+    command: "set -o pipefail && libcxx/utils/ci/run-buildbot.sh x86_64-apple-system | libcxx/utils/ci/phabricator-report"
+    agents:
+      queue: "libcxx-macos-builders"
+  - label: "Apple system -fno-exceptions"
+    command: "set -o pipefail && libcxx/utils/ci/run-buildbot.sh x86_64-apple-system-noexceptions | libcxx/utils/ci/phabricator-report"
+    agents:
+      queue: "libcxx-macos-builders"

libcxx/utils/ci/run-buildbot.sh

 #!/usr/bin/env bash
 #===----------------------------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 #===----------------------------------------------------------------------===##
 
 set -ex
 
 BUILDER="${1}"
+MONOREPO_ROOT="$(git rev-parse --show-toplevel)"
+BUILD_DIR="${MONOREPO_ROOT}/build/${BUILDER}"
 
 args=()
 args+=("-DLLVM_ENABLE_PROJECTS=libcxx;libunwind;libcxxabi")
 args+=("-DLIBCXX_CXX_ABI=libcxxabi")
 
 case "${BUILDER}" in
 x86_64-ubuntu-cxx03)
     export CC=clang

 x86_64-ubuntu-singlethreaded)
     export CC=clang
     export CXX=clang++
     args+=("-DLLVM_LIT_ARGS=-sv --show-unsupported")
     args+=("-DLIBCXX_ENABLE_THREADS=OFF")
     args+=("-DLIBCXXABI_ENABLE_THREADS=OFF")
     args+=("-DLIBCXX_ENABLE_MONOTONIC_CLOCK=OFF")
 ;;
+x86_64-apple-system)
+    export CC=clang
+    export CXX=clang++
+    args+=("-DLLVM_LIT_ARGS=-sv --show-unsupported")
+    args+=("-C${MONOREPO_ROOT}/libcxx/cmake/caches/Apple.cmake")
+;;
+x86_64-apple-system-noexceptions)
+    export CC=clang
+    export CXX=clang++
+    args+=("-DLLVM_LIT_ARGS=-sv --show-unsupported")
+    args+=("-C${MONOREPO_ROOT}/libcxx/cmake/caches/Apple.cmake")
+    args+=("-DLIBCXX_ENABLE_EXCEPTIONS=OFF")
+    args+=("-DLIBCXXABI_ENABLE_EXCEPTIONS=OFF")
+;;
 *)
     echo "${BUILDER} is not a known configuration"
     exit 1
 ;;
 esac
 
-UMBRELLA_ROOT="$(git rev-parse --show-toplevel)"
-LLVM_ROOT="${UMBRELLA_ROOT}/llvm"
-BUILD_DIR="${UMBRELLA_ROOT}/build/${BUILDER}"
-
 echo "--- Generating CMake"
 rm -rf "${BUILD_DIR}"
-cmake -S "${LLVM_ROOT}" -B "${BUILD_DIR}" -GNinja -DCMAKE_BUILD_TYPE=RelWithDebInfo "${args[@]}"
+cmake -S "${MONOREPO_ROOT}/llvm" -B "${BUILD_DIR}" -GNinja -DCMAKE_BUILD_TYPE=RelWithDebInfo "${args[@]}"
 
 echo "--- Building libc++ and libc++abi"
 ninja -C "${BUILD_DIR}" check-cxx-deps cxxabi
 
 echo "+++ Running the libc++ tests"
 ninja -C "${BUILD_DIR}" check-cxx
 
 echo "+++ Running the libc++abi tests"
 ninja -C "${BUILD_DIR}" check-cxxabi
 
 # echo "+++ Running the libc++ benchmarks"
 # ninja -C "${BUILD_DIR}" check-cxx-benchmarks