[libc++][ci] Update to Clang 13.

[Mordante]

Summary

Per our support plan we should now support Clang 12 and 13. Adjust the
documentation and the CI runners. The change indirectly moves the main
CI runners to use the Clang 14 nightly builds.

[Mordante]

libcxx/utils/ci/Dockerfile

31

@ldionne Since you maintain this Docker image, would it be a good time to move the Ubuntu 20.04 (focal)?

[ldionne]

LGTM. I'll work on updating the apple-clang on our Mac builders. It's a bit of a can of worms because that requires updating the OS, and that means we won't be able to run back-deployment testing anymore -- but there are technical solutions to that, and it shouldn't prevent us from rolling forward our compiler support per the policy, even if that means temporarily disabling back-deployment tests.

libcxx/docs/index.rst

 
 Libc++ aims to support common compilers that implement the C++11 Standard. In order to strike a
 good balance between stability for users and maintenance cost, testing coverage and development
 velocity, libc++ drops support for older compilers as newer ones are released.
 
 ============ =============== ========================== =====================
 Compiler     Versions        Restrictions               Support policy
 ============ =============== ========================== =====================
-Clang        11, 12                                     latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_
+Clang        12, 13                                     latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_
 AppleClang   12                                         latest stable release per `Xcode's release page <https://developer.apple.com/documentation/xcode-release-notes>`_
 GCC          11              In C++11 or later only     latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_
 ============ =============== ========================== =====================
 
 Libc++ also supports common platforms and architectures:
 
 =============== ========================= ============================
 Target platform Target architecture       Notes

libcxx/utils/ci/Dockerfile

 # A pre-built version of this image is maintained on DockerHub as ldionne/libcxx-builder.
 # To update the image, rebuild it and push it to ldionne/libcxx-builder (which
 # will obviously only work if you have permission to do so).
 #
 #   $ docker build -t ldionne/libcxx-builder libcxx/utils/ci
 #   $ docker push ldionne/libcxx-builder
 #
 
 FROM ubuntu:bionic
 
 # Make sure apt-get doesn't try to prompt for stuff like our time zone, etc.
 ENV DEBIAN_FRONTEND=noninteractive
 
 # This dummy command is meant to be edited from time to time, which causes the
 # CI builders to rebuild their copy of the Docker image. This is not a great
 # solution, however without that, the CI builders will keep the same cached
 # Docker image forever.
RUN apt-get update && apt-get install -y language-pack-en language-pack-fr \
                                          language-pack-ru language-pack-zh-hans
 # These two are not enabled by default so generate them
 RUN printf "fr_CA ISO-8859-1\ncs_CZ ISO-8859-2" >> /etc/locale.gen
 RUN mkdir /usr/local/share/i1en/
 RUN printf "fr_CA ISO-8859-1\ncs_CZ ISO-8859-2" >> /usr/local/share/i1en/SUPPORTED
 RUN locale-gen
 
 # Install Clang <latest>, <latest-1> and ToT, which are the ones we support.
-ENV LLVM_LATEST_VERSION=12
+ENV LLVM_LATEST_VERSION=13
 RUN apt-get update && apt-get install -y lsb-release wget software-properties-common
 RUN wget https://apt.llvm.org/llvm.sh -O /tmp/llvm.sh
 RUN bash /tmp/llvm.sh $(($LLVM_LATEST_VERSION - 1)) # previous release
 RUN bash /tmp/llvm.sh $LLVM_LATEST_VERSION          # latest release
 RUN bash /tmp/llvm.sh $(($LLVM_LATEST_VERSION + 1)) # current ToT
 
 # Make the ToT Clang the "default" compiler on the system
 RUN ln -fs /usr/bin/clang++-$(($LLVM_LATEST_VERSION + 1)) /usr/bin/c++ && [ -e $(readlink /usr/bin/c++) ]

libcxx/utils/ci/buildkite-pipeline.yml

agents:
       queue: "libcxx-builders"
       os: "linux"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Clang 11"
-    command: "libcxx/utils/ci/run-buildbot generic-clang-11"
+  - label: "Clang 12"
+    command: "libcxx/utils/ci/run-buildbot generic-clang-12"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "libcxx-builders"
       os: "linux"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Clang 12"
-    command: "libcxx/utils/ci/run-buildbot generic-clang-12"
+  - label: "Clang 13"
+    command: "libcxx/utils/ci/run-buildbot generic-clang-13"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "libcxx-builders"
       os: "linux"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost

libcxx/utils/ci/run-buildbot

 ;;
 generic-32bit)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-32bits.cmake" \
                    -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
 ;;
-generic-clang-11)
-    export CC=clang-11
-    export CXX=clang++-11
+generic-clang-12)
+    export CC=clang-12
+    export CXX=clang++-12
     clean
     generate-cmake -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
 ;;
-generic-clang-12)
-    export CC=clang-12
-    export CXX=clang++-12
+generic-clang-13)
+    export CC=clang-13
+    export CXX=clang++-13
     clean
     generate-cmake -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
 ;;
 generic-gcc)
     export CC=gcc-11
     export CXX=g++-11