[libcxx] [llvm] [libc++] Remove official Clang 18 support. (PR #130142)

[Mark de Wever via llvm-commits]

https://github.com/mordante created https://github.com/llvm/llvm-project/pull/130142

Since Clang 20 has been release we no longer support Clang 18 per our policy.

Note the Clang 18 workarounds will be removed in a follow-up patch.

>From f862c0bd85bb78a79f8f6e67eb6a9fb5f364661c Mon Sep 17 00:00:00 2001
From: Mark de Wever <koraq at xs4all.nl>
Date: Thu, 6 Mar 2025 18:08:47 +0100
Subject: [PATCH] [libc++] Remove official Clang 18 support.

Since Clang 20 has been release we no longer support Clang 18 per our
policy.

Note the Clang 18 workarounds will be removed in a follow-up patch.
---
 .github/workflows/libcxx-build-and-test.yaml | 4 ----
 libcxx/docs/index.rst                        | 2 +-
 libcxx/include/__configuration/compiler.h    | 4 ++--
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 5d4394435890a..74889adfa070f 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -100,10 +100,6 @@ jobs:
           - config: 'generic-cxx26'
             cc: 'clang-19'
             cxx: 'clang++-19'
-          # Release transition
-          - config: 'generic-cxx23'
-            cc: 'clang-18'
-            cxx: 'clang++-18'
     steps:
       - uses: actions/checkout at v4
       - name: ${{ matrix.config }}
diff --git a/libcxx/docs/index.rst b/libcxx/docs/index.rst
index e2c62e9ecac02..a8b0d5ce1ee97 100644
--- a/libcxx/docs/index.rst
+++ b/libcxx/docs/index.rst
@@ -131,7 +131,7 @@ velocity, libc++ drops support for older compilers as newer ones are released.
 ============ =================== ========================== =====================
 Compiler     Versions            Restrictions               Support policy
 ============ =================== ========================== =====================
-Clang        18, 19, 20, 21-git                             latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
+Clang        19, 20, 21-git                                 latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
 AppleClang   15                                             latest stable release per `Xcode's release page <https://developer.apple.com/documentation/xcode-release-notes>`_
 Open XL      17.1.3 (AIX)                                   latest stable release per `Open XL's documentation page <https://www.ibm.com/docs/en/openxl-c-and-cpp-aix>`_
 GCC          14                  In C++11 or later only     latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_
diff --git a/libcxx/include/__configuration/compiler.h b/libcxx/include/__configuration/compiler.h
index cf459a0619b23..4b6c6cad353e3 100644
--- a/libcxx/include/__configuration/compiler.h
+++ b/libcxx/include/__configuration/compiler.h
@@ -33,8 +33,8 @@
 // Warn if a compiler version is used that is not supported anymore
 // LLVM RELEASE Update the minimum compiler versions
 #  if defined(_LIBCPP_CLANG_VER)
-#    if _LIBCPP_CLANG_VER < 1800
-#      warning "Libc++ only supports Clang 18 and later"
+#    if _LIBCPP_CLANG_VER < 1900
+#      warning "Libc++ only supports Clang 19 and later"
 #    endif
 #  elif defined(_LIBCPP_APPLE_CLANG_VER)
 #    if _LIBCPP_APPLE_CLANG_VER < 1500