Trigger the Clang/libc++ CI pipeline even when libc++ has been modified

[ldionne]

Summary

Previously, we would trigger the usual libc++ CI pipeline if libc++ were
modified. If Clang was modified too, however, we would not trigger its
sub-pipeline. This change fixes that.

[Mordante]

Should this also fix the issue where the scheduled build sometimes picks the "clang build"?
For example https://buildkite.com/llvm-project/libcxx-ci/builds/17300 but I noticed to at other times too.

[ldionne]

Superseded by D155078

libcxx/utils/ci/buildkite-pipeline-clang.yml

-#===----------------------------------------------------------------------===##
-#
-# 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
-#
-#===----------------------------------------------------------------------===##
-
-#
-# This file describes the various pre-commit CI bots used to test Clang against
-# libc++ under various configurations. Unlike the usual libc++ CI pipeline,
-# which aims to test libc++ itself, this pipeline aims to test Clang by
-# compiling libc++ and running its test suite against the just-built Clang,
-# in various configurations.
-#
-env:
-    LLVM_HEAD_VERSION: "16"
-steps:
-  - label: "Building clang"
-    commands:
-      - "mkdir install"
-      - "cmake -S llvm -B build -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=install -DLLVM_ENABLE_PROJECTS=\"clang;compiler-rt\""
-      - "ninja -C build install-clang install-clang-resource-headers"
-      - "buildkite-agent artifact upload 'install/**/*'"
-    env:
-        CC: "clang-${LLVM_HEAD_VERSION}"
-        CXX: "clang++-${LLVM_HEAD_VERSION}"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - wait
-
-  - label: "C++03"
-    commands:
-      - "buildkite-agent artifact download 'install/**' ."
-      - "export CC=$(pwd)/install/bin/clang"
-      - "export CXX=$(pwd)/install/bin/clang++"
-      - "chmod +x install/bin/clang install/bin/clang++"
-      - "libcxx/utils/ci/run-buildbot generic-cxx03"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/crash_diagnostics/*"
-    env:
-        LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
-        CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "C++2b"
-    commands:
-      - "buildkite-agent artifact download 'install/**' ."
-      - "export CC=$(pwd)/install/bin/clang"
-      - "export CXX=$(pwd)/install/bin/clang++"
-      - "chmod +x install/bin/clang install/bin/clang++"
-      - "libcxx/utils/ci/run-buildbot generic-cxx2b"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/crash_diagnostics/*"
-    env:
-        LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
-        CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Modules"
-    commands:
-      - "buildkite-agent artifact download 'install/**' ."
-      - "export CC=$(pwd)/install/bin/clang"
-      - "export CXX=$(pwd)/install/bin/clang++"
-      - "chmod +x install/bin/clang install/bin/clang++"
-      - "libcxx/utils/ci/run-buildbot generic-modules"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/crash_diagnostics/*"
-    env:
-        LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
-        CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120

libcxx/utils/ci/buildkite-pipeline.yml

 # version number. The Linux CI runners for GCC use the latest stable version.
 # Theses numbers are available in all runners, making it easier to update the
 # version number.
 env:
     LLVM_STABLE_VERSION: "15"
     LLVM_HEAD_VERSION: "16"
     GCC_STABLE_VERSION: "12"
 steps:
+- group: "Running normal libc++ pre-commit CI"
+  if: "build.env('RUN_LIBCXX_PRECOMMIT') != null"
+  steps:
     #
     # Light pre-commit tests for things like formatting or when people forget
     # to update generated files.
     #
     - label: "Format"
       command: "libcxx/utils/ci/run-buildbot check-format"
       artifact_paths:
         - "**/clang-format.patch"
       env:
           GIT_CLANG_FORMAT: "/usr/bin/git-clang-format-${LLVM_STABLE_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       soft_fail:
           - exit_status: 1
       timeout_in_minutes: 120
 
     - label: "Generated output"
       command: "libcxx/utils/ci/run-buildbot check-generated-output"
       artifact_paths:
         - "**/generated_output.patch"
         - "**/generated_output.status"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Documentation"
       command: "libcxx/utils/ci/run-buildbot documentation"
       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
 
     #
     # General testing with the default configuration, under all the supported
     # Standard modes, with Clang and GCC. This catches most issues upfront.
     # The goal of this step is to catch most issues while being very fast.
     #
     - wait
 
     - label: "GCC ${GCC_STABLE_VERSION} / C++latest"
       command: "libcxx/utils/ci/run-buildbot generic-gcc"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "gcc-${GCC_STABLE_VERSION}"
           CXX: "g++-${GCC_STABLE_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "C++2b"
       command: "libcxx/utils/ci/run-buildbot generic-cxx2b"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Modular build"
       command: "libcxx/utils/ci/run-buildbot generic-modules"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "C++11"
       command: "libcxx/utils/ci/run-buildbot generic-cxx11"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "C++03"
       command: "libcxx/utils/ci/run-buildbot generic-cxx03"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     #
     # All other supported configurations of libc++.
     #
     - wait
 
     - label: "C++20"
       command: "libcxx/utils/ci/run-buildbot generic-cxx20"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "C++17"
       command: "libcxx/utils/ci/run-buildbot generic-cxx17"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "C++14"
       command: "libcxx/utils/ci/run-buildbot generic-cxx14"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     # Tests with the supported compilers.
     - label: "GCC ${GCC_STABLE_VERSION} / C++11"
       command: "libcxx/utils/ci/run-buildbot generic-gcc-cxx11"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "gcc-${GCC_STABLE_VERSION}"
           CXX: "g++-${GCC_STABLE_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Clang 14"
       command: "libcxx/utils/ci/run-buildbot generic-cxx2b"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-14"
           CXX: "clang++-14"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Clang 15"
       command: "libcxx/utils/ci/run-buildbot generic-cxx2b"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-15"
           CXX: "clang++-15"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     # Tests with the sanitizers.
     - group: "Sanitizers"
       steps:
       - label: "ASAN"
         command: "libcxx/utils/ci/run-buildbot generic-asan"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "TSAN"
         command: "libcxx/utils/ci/run-buildbot generic-tsan"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "UBSAN"
         command: "libcxx/utils/ci/run-buildbot generic-ubsan"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "MSAN"
         command: "libcxx/utils/ci/run-buildbot generic-msan"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
     # Tests with the various supported ways to build libc++.
     - label: "Bootstrapping build"
       command: "libcxx/utils/ci/run-buildbot bootstrapping-build"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
         - "**/crash_diagnostics/*"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
           LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}"
           CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     # Tests with various build configurations.
     - label: "Static libraries"
       command: "libcxx/utils/ci/run-buildbot generic-static"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Shared library with merged ABI and unwinder libraries"
       command: "libcxx/utils/ci/run-buildbot generic-merged"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Assertions enabled"
       command: "libcxx/utils/ci/run-buildbot generic-assertions"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "Debug mode"
       command: "libcxx/utils/ci/run-buildbot generic-debug-mode"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "No transitive includes"
       command: "libcxx/utils/ci/run-buildbot generic-no-transitive-includes"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - label: "With LLVM's libunwind"
       command: "libcxx/utils/ci/run-buildbot generic-with_llvm_unwinder"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     - group: "Parts disabled"
       steps:
       - label: "No threads"
         command: "libcxx/utils/ci/run-buildbot generic-no-threads"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No filesystem"
         command: "libcxx/utils/ci/run-buildbot generic-no-filesystem"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No random device"
         command: "libcxx/utils/ci/run-buildbot generic-no-random_device"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No fstream"
         command: "libcxx/utils/ci/run-buildbot generic-no-fstream"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No locale"
         command: "libcxx/utils/ci/run-buildbot generic-no-localization"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No Unicode"
         command: "libcxx/utils/ci/run-buildbot generic-no-unicode"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No wide characters"
         command: "libcxx/utils/ci/run-buildbot generic-no-wide-characters"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No experimental features"
         command: "libcxx/utils/ci/run-buildbot generic-no-experimental"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "No exceptions"
         command: "libcxx/utils/ci/run-buildbot generic-noexceptions"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang-${LLVM_HEAD_VERSION}"
             CXX: "clang++-${LLVM_HEAD_VERSION}"
         agents:
           queue: "libcxx-builders"
           os: "linux"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
     - label: "Unstable ABI"
       command: "libcxx/utils/ci/run-buildbot generic-abi-unstable"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     # Other non-testing CI jobs
     - label: "Benchmarks"
       command: "libcxx/utils/ci/run-buildbot benchmarks"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
       env:
           CC: "clang-${LLVM_HEAD_VERSION}"
           CXX: "clang++-${LLVM_HEAD_VERSION}"
       agents:
         queue: "libcxx-builders"
         os: "linux"
       retry:
         automatic:
           - exit_status: -1  # Agent was lost
             limit: 2
       timeout_in_minutes: 120
 
     # Tests on non-Unix platforms
     - group: ":windows: Windows"
       steps:
       - label: "Clang-cl (DLL)"
         command: "bash libcxx/utils/ci/run-buildbot clang-cl-dll"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Clang-cl (Static)"
         command: "bash libcxx/utils/ci/run-buildbot clang-cl-static"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Clang-cl (no vcruntime exceptions)"
         command: "bash libcxx/utils/ci/run-buildbot clang-cl-no-vcruntime"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
 
       - label: "MinGW (DLL, x86_64)"
         command: "bash libcxx/utils/ci/run-buildbot mingw-dll"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "MinGW (Static, x86_64)"
         command: "bash libcxx/utils/ci/run-buildbot mingw-static"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "MinGW (DLL, i686)"
         command: "bash libcxx/utils/ci/run-buildbot mingw-dll-i686"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "windows"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
     - group: ":apple: Apple"
       steps:
       - label: "MacOS x86_64"
         command: "libcxx/utils/ci/run-buildbot apple-cxx20"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "x86_64"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "MacOS arm64"
         command: "libcxx/utils/ci/run-buildbot apple-cxx20"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "arm64"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       # Build with the configuration we use to generate libc++.dylib on Apple platforms
       - label: "Apple system"
         command: "libcxx/utils/ci/run-buildbot apple-system"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "arm64" # This can technically run on any architecture, but we have more resources on arm64 so we pin this job to arm64
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       # Test back-deployment to older Apple platforms
       - label: "Apple back-deployment macosx10.9"
         command: "libcxx/utils/ci/run-buildbot apple-system-backdeployment-10.9"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "x86_64" # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then.
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Apple back-deployment macosx10.15"
         command: "libcxx/utils/ci/run-buildbot apple-system-backdeployment-10.15"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "x86_64" # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then.
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Apple back-deployment macosx11.0 arm64"
         command: "libcxx/utils/ci/run-buildbot apple-system-backdeployment-11.0"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
           arch: "arm64"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Apple back-deployment with assertions enabled"
         command: "libcxx/utils/ci/run-buildbot apple-system-backdeployment-assertions-11.0"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders"
           os: "macos"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
     - group: "ARM"
       steps:
       - label: "AArch64"
         command: "libcxx/utils/ci/run-buildbot aarch64"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "aarch64"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "AArch64 -fno-exceptions"
         command: "libcxx/utils/ci/run-buildbot aarch64-noexceptions"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "aarch64"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Armv8"
         command: "libcxx/utils/ci/run-buildbot armv8"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "armv8l"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Armv8 -fno-exceptions"
         command: "libcxx/utils/ci/run-buildbot armv8-noexceptions"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "armv8l"
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Armv7"
         command: "libcxx/utils/ci/run-buildbot armv7"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "armv8l" # Compiling for v7, running on v8 hardware
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "Armv7 -fno-exceptions"
         command: "libcxx/utils/ci/run-buildbot armv7-noexceptions"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         agents:
           queue: "libcxx-builders-linaro-arm"
           arch: "armv8l" # Compiling for v7, running on v8 hardware
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
     - group: "AIX"
       steps:
       - label: "AIX (32-bit)"
         command: "libcxx/utils/ci/run-buildbot aix"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang"
             CXX: "clang++"
             OBJECT_MODE: "32"
         agents:
             queue: libcxx-builders
             os: aix
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
 
       - label: "AIX (64-bit)"
         command: "libcxx/utils/ci/run-buildbot aix"
         artifact_paths:
           - "**/test-results.xml"
           - "**/*.abilist"
         env:
             CC: "clang"
             CXX: "clang++"
             OBJECT_MODE: "64"
         agents:
             queue: libcxx-builders
             os: aix
         retry:
           automatic:
             - exit_status: -1  # Agent was lost
               limit: 2
         timeout_in_minutes: 120
+
+#
+# This group describes the various pre-commit CI bots used to test Clang against
+# libc++ under various configurations. Unlike the usual libc++ CI pipeline,
+# which aims to test libc++ itself, this pipeline aims to test Clang by
+# compiling libc++ and running its test suite against the just-built Clang,
+# in various configurations.
+#
+- group: "Testing libc++ against just-built Clang"
+  if: "build.env('RUN_CLANG_PRECOMMIT') != null"
+  steps:
+    - label: "Building clang"
+      commands:
+        - "mkdir install"
+        - "cmake -S llvm -B build -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=install -DLLVM_ENABLE_PROJECTS=\"clang;compiler-rt\""
+        - "ninja -C build install-clang install-clang-resource-headers"
+        - "buildkite-agent artifact upload 'install/**/*'"
+      env:
+          CC: "clang-${LLVM_HEAD_VERSION}"
+          CXX: "clang++-${LLVM_HEAD_VERSION}"
+      agents:
+        queue: "libcxx-builders"
+        os: "linux"
+      retry:
+        automatic:
+          - exit_status: -1  # Agent was lost
+            limit: 2
+      timeout_in_minutes: 120
+
+    - wait
+
+    - label: "C++03"
+      commands:
+        - "buildkite-agent artifact download 'install/**' ."
+        - "export CC=$(pwd)/install/bin/clang"
+        - "export CXX=$(pwd)/install/bin/clang++"
+        - "chmod +x install/bin/clang install/bin/clang++"
+        - "libcxx/utils/ci/run-buildbot generic-cxx03"
+      artifact_paths:
+        - "**/test-results.xml"
+        - "**/crash_diagnostics/*"
+      env:
+          LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
+          CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
+      agents:
+        queue: "libcxx-builders"
+        os: "linux"
+      retry:
+        automatic:
+          - exit_status: -1  # Agent was lost
+            limit: 2
+      timeout_in_minutes: 120
+
+    - label: "C++2b"
+      commands:
+        - "buildkite-agent artifact download 'install/**' ."
+        - "export CC=$(pwd)/install/bin/clang"
+        - "export CXX=$(pwd)/install/bin/clang++"
+        - "chmod +x install/bin/clang install/bin/clang++"
+        - "libcxx/utils/ci/run-buildbot generic-cxx2b"
+      artifact_paths:
+        - "**/test-results.xml"
+        - "**/crash_diagnostics/*"
+      env:
+          LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
+          CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
+      agents:
+        queue: "libcxx-builders"
+        os: "linux"
+      retry:
+        automatic:
+          - exit_status: -1  # Agent was lost
+            limit: 2
+      timeout_in_minutes: 120
+
+    - label: "Modules"
+      commands:
+        - "buildkite-agent artifact download 'install/**' ."
+        - "export CC=$(pwd)/install/bin/clang"
+        - "export CXX=$(pwd)/install/bin/clang++"
+        - "chmod +x install/bin/clang install/bin/clang++"
+        - "libcxx/utils/ci/run-buildbot generic-modules"
+      artifact_paths:
+        - "**/test-results.xml"
+        - "**/crash_diagnostics/*"
+      env:
+          LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}" # TODO: Should we build that from scratch?
+          CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
+      agents:
+        queue: "libcxx-builders"
+        os: "linux"
+      retry:
+        automatic:
+          - exit_status: -1  # Agent was lost
+            limit: 2
+      timeout_in_minutes: 120

libcxx/utils/ci/generate-buildkite-pipeline

 #!/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
 #
 #===----------------------------------------------------------------------===##
 
 #
 # This script generates the appropriate libc++ CI pipeline based on which project(s) were changed.
 #
 
 if git diff --name-only HEAD~1 | grep -q -E "^libcxx/|^libcxxabi/|^libunwind/|^runtimes/|^cmake/"; then
-  LIBCXX_CHANGED=true
+  cat <<EOF
+env:
+  - RUN_LIBCXX_PRECOMMIT: "true"
+EOF
 fi
 
 if git diff --name-only HEAD~1 | grep -q -E "^clang/"; then
-  CLANG_CHANGED=true
+  cat <<EOF
+env:
+  - RUN_CLANG_PRECOMMIT: "true"
+EOF
 fi
 
-if [[ "${CLANG_CHANGED}" == "true" && "${LIBCXX_CHANGED}" != "true" ]]; then
-  cat libcxx/utils/ci/buildkite-pipeline-clang.yml
-else
-  cat libcxx/utils/ci/buildkite-pipeline.yml
-fi