Hopefully fix CI problems

Author: stellar-aria

.github/workflows/test.yml

@@ -39,11 +39,14 @@ jobs:
           echo "CXX=$(brew --prefix llvm@20)/bin/clang++" >> $GITHUB_ENV
         if: ${{ matrix.compiler == 'llvm-20' && (matrix.os == 'macos-14' || matrix.os == 'macos-15') }}
 
-      - name: Use LLVM and Clang
+      - name: Install LLVM and Clang (Ubuntu)
         run: |
+          wget https://apt.llvm.org/llvm.sh
+          chmod +x llvm.sh
+          sudo ./llvm.sh 20
           echo "CC=clang-20" >> $GITHUB_ENV
           echo "CXX=clang++-20" >> $GITHUB_ENV
-        if: ${{ matrix.compiler == 'llvm-20' && (matrix.os != 'macos-14' && matrix.os != 'macos-15') }}
+        if: ${{ matrix.compiler == 'llvm-20' && matrix.os == 'ubuntu-latest' }}
 
       - name: Use GCC
         run: |

CMakeLists.txt

@@ -44,6 +44,10 @@ if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
   target_compile_options(c++spec INTERFACE -Wno-missing-template-arg-list-after-template-kw -Wno-dollar-in-identifier-extension)
 endif()
 
+if(APPLE)
+  target_compile_definitions(c++spec INTERFACE _LIBCPP_DISABLE_AVAILABILITY_ANNOTATIONS=1)
+endif()
+
 FILE(GLOB_RECURSE c++spec_headers ${CMAKE_CURRENT_LIST_DIR}/include/*.hpp)
 
 option(CPPSPEC_PRECOMPILE_HEADERS "Precompile the C++Spec headers")