[llvm] Change how libc++ specifies the runners to use. (PR #74188)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-github-workflow

Author: Eric (EricWF)

<details>
<summary>Changes</summary>

Github actions has some quirks with how you use runner groups, labels,
names, etc... One of them is that groups can't "group" more than one set
of builders. To do that, you use the same name. So now we're specifying
the name.


---
Full diff: https://github.com/llvm/llvm-project/pull/74188.diff


1 Files Affected:

- (modified) .github/workflows/libcxx-build-and-test.yaml (+9-12) 


``````````diff
diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 018f0e45a2441ef..83786052a539106 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -50,8 +50,7 @@ env:
 jobs:
   stage1:
     if: github.repository_owner == 'llvm'
-    runs-on:
-      group: libcxx-runners-8
+    runs-on: libcxx-runners-8-set
     continue-on-error: false
     strategy:
       fail-fast: true
@@ -89,8 +88,7 @@ jobs:
             **/crash_diagnostics/*
   stage2:
     if: github.repository_owner == 'llvm'
-    runs-on:
-      group: libcxx-runners-8
+    runs-on: libcxx-runners-8-set
     needs: [ stage1 ]
     continue-on-error: false
     strategy:
@@ -169,27 +167,26 @@ jobs:
           'benchmarks',
           'bootstrapping-build'
         ]
-        machine: [ 'libcxx-runners-8' ]
+        machine: [ 'libcxx-runners-8-set' ]
         std_modules: [ 'OFF' ]
         include:
         - config: 'generic-cxx26'
-          machine: libcxx-runners-8
+          machine: libcxx-runners-8-set
           std_modules: 'ON'
         - config: 'generic-asan'
-          machine: libcxx-runners-8
+          machine: libcxx-runners-8-set
           std_modules: 'OFF'
         - config: 'generic-tsan'
-          machine: libcxx-runners-8
+          machine: libcxx-runners-8-set
           std_modules: 'OFF'
         - config: 'generic-ubsan'
-          machine: libcxx-runners-8
+          machine: libcxx-runners-8-set
           std_modules: 'OFF'
         # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
         - config: 'generic-msan'
-          machine: libcxx-runners-32
+          machine: libcxx-runners-32-set
           std_modules: 'OFF'
-    runs-on:
-      group: ${{ matrix.machine }}
+    runs-on: ${{ matrix.machine }}
     steps:
       - uses: actions/checkout at v4
       - name: ${{ matrix.config }}

``````````

</details>


https://github.com/llvm/llvm-project/pull/74188