[libcxx] [llvm] [libc++] Updates the compilers used post LLVM-20 branching. (PR #126564)

[Mark de Wever via llvm-commits]

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@@ -88,18 +88,22 @@ jobs:
           'generic-cxx20',
           'generic-cxx23'
         ]
-        cc: [ 'clang-20' ]
-        cxx: [ 'clang++-20' ]
+        cc: [ 'clang-21' ]
+        cxx: [ 'clang++-21' ]
         include:
           - config: 'generic-gcc-cxx11'
             cc: 'gcc-14'
             cxx: 'g++-14'
-          - config: 'generic-cxx23'
-            cc: 'clang-18'
-            cxx: 'clang++-18'
+          - config: 'generic-cxx26'
+            cc: 'clang-20'
+            cxx: 'clang++-20'
           - config: 'generic-cxx26'
             cc: 'clang-19'
             cxx: 'clang++-19'
+          # Release transition
+          - config: 'generic-cxx23'
+            cc: 'clang-18'
+            cxx: 'clang++-18'
----------------
mordante wrote:

Yes we need this. At the moment patches get actively backported to the release branch. Testing clang-18 enures that backporting is easy to do. Once LLVM 20.1.0 is released we can drop clang-18. (We've been doing this is the past too.)

https://github.com/llvm/llvm-project/pull/126564