[llvm] test with libcxx workflow (PR #71836)

[via llvm-commits]

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

>From f99287d421c3758bc6764b488f770950a989e775 Mon Sep 17 00:00:00 2001
From: eric <eric at efcs.ca>
Date: Thu, 9 Nov 2023 13:15:02 -0500
Subject: [PATCH 1/2] test with libcxx workflow

---
 .../workflows/libcxx-example-workflow.yaml    | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 .github/workflows/libcxx-example-workflow.yaml

diff --git a/.github/workflows/libcxx-example-workflow.yaml b/.github/workflows/libcxx-example-workflow.yaml
new file mode 100644
index 000000000000000..c3a7d3ed20bcd8c
--- /dev/null
+++ b/.github/workflows/libcxx-example-workflow.yaml
@@ -0,0 +1,33 @@
+name: Build and Test libc++
+
+on: pull_request
+
+
+# Comment
+jobs:
+  build:
+    runs-on: libcxx-runners-small
+    steps:
+    - uses: actions/checkout at v4
+      with:
+        fetch-depth: 5
+    - name: Create Paths
+      run: |
+        mkdir build install artifacts
+    - name: Configure
+      run: |
+        cd build
+        cmake -GNinja -DCMAKE_BUILD_TYPE=Release \
+          -DCMAKE_CXX_COMPILER=clang++ \
+          -DCMAKE_C_COMPILER=clang \
+          "-DLLVM_ENABLE_RUNTIMES=libcxx;libcxxabi"\
+          "-DCMAKE_INSTALL_PREFIX=../install" \
+          ../runtimes
+    - name: Build
+      run: |
+        cd build
+        ninja
+    - name: Install
+      run: |
+        cd build
+        ninja install

>From 7184c61d90b86b9f3ae8fcec65f0d7b8772e5fa2 Mon Sep 17 00:00:00 2001
From: eric <eric at efcs.ca>
Date: Thu, 9 Nov 2023 14:51:01 -0500
Subject: [PATCH 2/2] attempt to mimic buildkite pipeline

---
 .../workflows/libcxx-example-workflow.yaml    | 26 +++++--------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/libcxx-example-workflow.yaml b/.github/workflows/libcxx-example-workflow.yaml
index c3a7d3ed20bcd8c..119bbec837684df 100644
--- a/.github/workflows/libcxx-example-workflow.yaml
+++ b/.github/workflows/libcxx-example-workflow.yaml
@@ -6,28 +6,14 @@ on: pull_request
 # Comment
 jobs:
   build:
-    runs-on: libcxx-runners-small
+    runs-on: libcxx-runners-large
     steps:
     - uses: actions/checkout at v4
       with:
         fetch-depth: 5
     - name: Create Paths
-      run: |
-        mkdir build install artifacts
-    - name: Configure
-      run: |
-        cd build
-        cmake -GNinja -DCMAKE_BUILD_TYPE=Release \
-          -DCMAKE_CXX_COMPILER=clang++ \
-          -DCMAKE_C_COMPILER=clang \
-          "-DLLVM_ENABLE_RUNTIMES=libcxx;libcxxabi"\
-          "-DCMAKE_INSTALL_PREFIX=../install" \
-          ../runtimes
-    - name: Build
-      run: |
-        cd build
-        ninja
-    - name: Install
-      run: |
-        cd build
-        ninja install
+      run: libcxx/utils/ci/run-buildbot generic-cxx26
+      env:
+        CC: clang-18
+        CXX: clang++-18
+        CMAKE: /opt/bin/cmake