[libc++] Remove old CI configurations and update the supported compiler versions

`_LIBCPP_REMOVE_TRANSITIVE_INCLUDES` doesn't do anything anymore in C++23 mode, so it's now just a duplicate of the C++23 configuration.
Also add new steps to the post-release checklist for updating the supported compilers.

Reviewed By: ldionne, #libc

Spies: arichardson, libcxx-commits, arphaman

Differential Revision: https://reviews.llvm.org/D133364

Author: philnik777

libcxx/cmake/caches/Generic-no-transitive-includes.cmake

@@ -70,6 +70,8 @@ After branching for an LLVM release:
 2. Update the version number in ``libcxx/docs/conf.py``
 3. Update ``_LIBCPPABI_VERSION`` in ``libcxxabi/include/cxxabi.h``
 4. Update ``_LIBUNWIND_VERSION`` in ``libunwind/include/__libunwind_config.h``
+5. Update the list of supported clang versions in ``libcxx/docs/index.rst``
+6. Remove the in-progress warning from ``libcxx/docs/ReleaseNotes.rst``
 
 Exporting new symbols from the library
 ======================================

libcxx/docs/Contributing.rst

@@ -105,7 +105,7 @@ velocity, libc++ drops support for older compilers as newer ones are released.
 ============ =============== ========================== =====================
 Compiler     Versions        Restrictions               Support policy
 ============ =============== ========================== =====================
-Clang        14, 15                                     latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_
+Clang        14, 15, 16-git                             latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
 AppleClang   14                                         latest stable release per `Xcode's release page <https://developer.apple.com/documentation/xcode-release-notes>`_
 Open XL      17.1 (AIX)                                 latest stable release per `Open XL's documentation page <https://www.ibm.com/docs/en/openxl-c-and-cpp-aix>`_
 GCC          12              In C++11 or later only     latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_

libcxx/docs/index.rst

@@ -436,23 +436,6 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No transitive includes"
-    command: "libcxx/utils/ci/run-buildbot generic-no-transitive-includes"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    env:
-        CC: "clang-${LLVM_HEAD_VERSION}"
-        CXX: "clang++-${LLVM_HEAD_VERSION}"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
   - label: "With LLVM's libunwind"
     command: "libcxx/utils/ci/run-buildbot generic-with_llvm_unwinder"
     artifact_paths:

libcxx/utils/ci/buildkite-pipeline.yml

@@ -358,11 +358,6 @@ generic-debug-mode)
     check-runtimes
     # We don't check the ABI lists because the debug mode ABI is not stable
 ;;
-generic-no-transitive-includes)
-    clean
-    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-transitive-includes.cmake"
-    check-runtimes
-;;
 generic-with_llvm_unwinder)
     clean
     generate-cmake -DLIBCXXABI_USE_LLVM_UNWINDER=ON