[libc++][CI] Updates to Clang 19.

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