[llvm] [libcxx] Add libc++ github actions workflow to replace buildkite (PR #71836)

[via llvm-commits]

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+# This file defines pre-commit CI for libc++ [bla bla bla].
+#
+# We split the configurations in multiple stages with the intent of saving compute time
+# when a job fails early in the pipeline. This is why the jobs are marked as `continue-on-error: false`.
+# We try to run the CI configurations with the most signal in the first stage.
+#
+# Stages 1 & 2 are meant to be "smoke tests", and are meant to catch most build/test failures quickly and without using
+# too many resources.
+# Stage 3 is "everything else", and is meant to catch breakages on more niche or unique configurations.
+#
+# Therefore, we "fail-fast" for any failures during stages 1 & 2, meaning any job failing cancels all other running jobs,
+# under the assumption that if the "smoke tests" fail, then the other configurations will likely fail in the same way.
+# However, stage 3 does not fail fast, as it's more likely that any one job failing is a flake or a configuration-specific
+#
+name: Build and Test libc++
+on:
+  pull_request:
+    paths:
+      - 'libcxx/**'
+      - 'libcxxabi/**'
+      - 'libunwind/**'
+      - 'runtimes/**'
+      - 'cmake/**'
+      - '.github/workflows/libcxx-build-and-test.yaml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+
+env:
+  CMAKE: "/opt/bin/cmake"
+  # LLVM POST-BRANCH bump version
+  # LLVM POST-BRANCH add compiler test for ToT - 1, e.g. "Clang 17"
+  # LLVM RELEASE bump remove compiler ToT - 3, e.g. "Clang 15"
+  LLVM_HEAD_VERSION: "18"   # Used compiler, update POST-BRANCH.
+  LLVM_PREVIOUS_VERSION: "17"
+  LLVM_OLDEST_VERSION: "16"
+  GCC_STABLE_VERSION: "13"
+  LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-18"
+  CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
+
+
+# Job breakdown:
+#   The jobs run in three stages to save resources while providing actionalable feedback as soon as possible.
+#   The stages are broken down as follows:
+#   - stage1:
+#     Stage1 contains the bots that most often fail.
+jobs:
+  stage1:
+    runs-on: libcxx-runners-16
+    continue-on-error: false
+    strategy:
+      fail-fast: true
+      matrix:
+        config: [ 'generic-cxx26', 'generic-cxx03', 'generic-modules' ]
+        cc: [  clang-18 ]
+        cxx: [ clang++-18 ]
+        clang_tidy: [ 'ON' ]
+        include:
+          - config: 'generic-gcc'
+            cc: 'gcc-13'
+            cxx: 'g++-13'
+            clang_tidy: 'OFF'
+    steps:
+      - uses: actions/checkout at v4
+      - name: ${{ matrix.config }}.${{ matrix.cxx }}
+        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+        env:
+          CC: ${{ matrix.cc }}
+          CXX: ${{ matrix.cxx }}
+          ENABLE_CLANG_TIDY: ${{ matrix.clang_tidy }}
+      - uses: actions/upload-artifact at v3
+        if: always()
+        with:
+          name: ${{ matrix.config }}-${{ matrix.cxx }}-results
+          path: |
+            **/test-results.xml
+            **/*.abilist
+            **/CMakeError.log
+            **/CMakeOutput.log
+            **/crash_diagnostics/*
+  stage2:
+    runs-on: libcxx-runners-8
+    needs: [ stage1 ]
+    continue-on-error: false
+    strategy:
+      fail-fast: true
+      matrix:
+        config: [ 'generic-cxx11', 'generic-cxx14', 'generic-cxx17',
+                  'generic-cxx20', 'generic-cxx23' ]
+        cc: [ 'clang-18' ]
+        cxx: [ 'clang++-18' ]
+        clang_tidy: [ 'ON' ]
+        include:
+          - config: 'generic-gcc-cxx11'
+            cc: 'gcc-13'
+            cxx: 'g++-13'
+            clang_tidy: 'OFF'
+          - config: 'generic-cxx23'
+            cc: 'clang-16'
+            cxx: 'clang++-16'
+            clang_tidy: 'OFF'
+          - config: 'generic-cxx23'
+            cc: 'clang-17'
+            cxx: 'clang++-17'
+            clang_tidy: 'OFF'
+    steps:
+      - uses: actions/checkout at v4
+      - name: ${{ matrix.config }}
+        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+        env:
+          CC: ${{ matrix.cc }}
+          CXX: ${{ matrix.cxx }}
+          ENABLE_CLANG_TIDY: ${{ matrix.clang_tidy }}
+      - uses: actions/upload-artifact at v3
+        if: always()  # Upload artifacts even if the build or test suite fails
+        with:
+          name: ${{ matrix.config }}-results
+          path: |
+            **/test-results.xml
+            **/*.abilist
+            **/CMakeError.log
+            **/CMakeOutput.log
+            **/crash_diagnostics/*
+  stage3:
+    needs: [ stage1, stage2 ]
+    continue-on-error: false
+    strategy:
+      fail-fast: false
+      max-parallel: 8
+      matrix:
+        config: [ 'generic-no-threads', 'generic-no-filesystem', 'generic-no-random_device',
+          'generic-no-localization', 'generic-no-unicode', 'generic-no-wide-characters',
+          'generic-no-experimental', 'generic-no-exceptions', 'generic-abi-unstable',
+          'generic-hardening-mode-fast',
+          'generic-hardening-mode-fast-with-abi-breaks',
+          'generic-hardening-mode-extensive',
+          'generic-hardening-mode-debug', 'generic-with_llvm_unwinder', 'generic-static', 'generic-merged',
+          'generic-modules-lsv', 'generic-no-tzdb' ]
----------------
EricWF wrote:

Using json here seems canonical. All the docs do it.

But  in the spirit of your comment, I've made the array one item per line, and I've sorted it.
I've done this for all the config lists.

https://github.com/llvm/llvm-project/pull/71836