[libc++][CI] Updates to Clang 19. (#85301)

Since we have released Clang 16 is no longer actively supported. However
the FreeBSD runner is still using this, so some tests still guard
against Clang 16.

Author: mordante

.github/workflows/libcxx-build-and-test.yaml

@@ -38,11 +38,11 @@ env:
   # LLVM POST-BRANCH bump version
   # LLVM POST-BRANCH add compiler test for ToT - 1, e.g. "Clang 17"
   # LLVM RELEASE bump remove compiler ToT - 3, e.g. "Clang 15"
-  LLVM_HEAD_VERSION: "18"   # Used compiler, update POST-BRANCH.
-  LLVM_PREVIOUS_VERSION: "17"
-  LLVM_OLDEST_VERSION: "16"
+  LLVM_HEAD_VERSION: "19"   # Used compiler, update POST-BRANCH.
+  LLVM_PREVIOUS_VERSION: "18"
+  LLVM_OLDEST_VERSION: "17"
   GCC_STABLE_VERSION: "13"
-  LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-18"
+  LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-19"
   CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
 
 
@@ -59,8 +59,8 @@ jobs:
           'generic-cxx26',
           'generic-modules'
         ]
-        cc: [  'clang-18' ]
-        cxx: [ 'clang++-18' ]
+        cc: [  'clang-19' ]
+        cxx: [ 'clang++-19' ]
         clang_tidy: [ 'ON' ]
         include:
           - config: 'generic-gcc'
@@ -100,22 +100,22 @@ jobs:
           'generic-cxx20',
           'generic-cxx23'
         ]
-        cc: [ 'clang-18' ]
-        cxx: [ 'clang++-18' ]
+        cc: [ 'clang-19' ]
+        cxx: [ 'clang++-19' ]
         clang_tidy: [ 'ON' ]
         include:
           - config: 'generic-gcc-cxx11'
             cc: 'gcc-13'
             cxx: 'g++-13'
             clang_tidy: 'OFF'
-          - config: 'generic-cxx23'
-            cc: 'clang-16'
-            cxx: 'clang++-16'
-            clang_tidy: 'OFF'
           - config: 'generic-cxx23'
             cc: 'clang-17'
             cxx: 'clang++-17'
             clang_tidy: 'OFF'
+          - config: 'generic-cxx26'
+            cc: 'clang-18'
+            cxx: 'clang++-18'
+            clang_tidy: 'ON'
     steps:
       - uses: actions/checkout@v4
       - name: ${{ matrix.config }}
@@ -186,8 +186,8 @@ jobs:
       - name: ${{ matrix.config }}
         run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
         env:
-          CC: clang-18
-          CXX: clang++-18
+          CC: clang-19
+          CXX: clang++-19
           ENABLE_CLANG_TIDY: "OFF"
       - uses: actions/upload-artifact@26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
         if: always()

libcxx/docs/index.rst

@@ -134,7 +134,7 @@ velocity, libc++ drops support for older compilers as newer ones are released.
 ============ =============== ========================== =====================
 Compiler     Versions        Restrictions               Support policy
 ============ =============== ========================== =====================
-Clang        16, 17, 18-git                             latest two stable releases per `LLVM's release page <https://releases.llvm.org>`_ and the development version
+Clang        17, 18, 19-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 (AIX)                                 latest stable release per `Open XL's documentation page <https://www.ibm.com/docs/en/openxl-c-and-cpp-aix>`_
 GCC          13              In C++11 or later only     latest stable release per `GCC's release page <https://gcc.gnu.org/releases.html>`_

libcxx/test/libcxx/atomics/diagnose_invalid_memory_order.verify.cpp

@@ -9,7 +9,7 @@
 // This test fails with Clang <18 because diagnose_if doesn't emit all of the
 // diagnostics when -fdelayed-template-parsing is enabled, like it is in MSVC
 // mode.
-// XFAIL: msvc && (clang-16 || clang-17)
+// XFAIL: msvc && clang-17
 
 // REQUIRES: diagnose-if-support
 

libcxx/test/libcxx/ranges/range.adaptors/range.lazy.split/no_unique_address.compile.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc && (clang-16 || clang-17)
+// XFAIL: msvc && clang-17
 
 // class lazy_split_view {
 //   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();

libcxx/test/libcxx/ranges/range.adaptors/range.split/no_unique_address.compile.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc && (clang-16 || clang-17)
+// XFAIL: msvc && clang-17
 
 // class split_view {
 //   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();

libcxx/test/libcxx/ranges/range.factories/range.istream.view/no_unique_address.compile.pass.cpp

@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc && (clang-16 || clang-17)
+// XFAIL: msvc && clang-17
 
 // Test the libc++ extension that the value stored in `std::ranges::istream_view` has been marked
 // as _LIBCPP_NO_UNIQUE_ADDRESS