Fixed building on macos with LLVM 21 (#415)

Author: bkryza

.github/workflows/macos.yml

@@ -40,7 +40,7 @@ jobs:
         run: brew update && (brew list cmake || brew install cmake) && brew install llvm@21 ninja yaml-cpp ccache
 
       - name: Build and test
-        run: CC=/opt/homebrew/opt/llvm@21/bin/clang CXX=/opt/homebrew/opt/llvm@21/bin/clang++ CMAKE_PREFIX=/opt/homebrew/opt/llvm@21/lib/cmake/llvm/ CMAKE_OSX_SYSROOT=macosx CMAKE_GENERATOR=Ninja ENABLE_OBJECTIVE_C_TEST_CASES=ON make test
+        run: CC=/opt/homebrew/opt/llvm@21/bin/clang CXX=/opt/homebrew/opt/llvm@21/bin/clang++ CMAKE_PREFIX=/opt/homebrew/opt/llvm@21/lib/cmake/llvm/ CMAKE_EXE_LINKER_FLAGS="-L/opt/homebrew/opt/llvm/lib/c++ -Wl,-rpath,/opt/homebrew/opt/llvm/lib/c++" CMAKE_OSX_SYSROOT=macosx CMAKE_GENERATOR=Ninja ENABLE_OBJECTIVE_C_TEST_CASES=ON make test
 
       - name: Print build version
         run: debug/src/clang-uml --version

CMakeLists.txt

@@ -106,7 +106,8 @@ if(LLVM_VERSION_MAJOR GREATER_EQUAL 17)
 endif()
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
     set(CUSTOM_COMPILE_OPTIONS ${CUSTOM_COMPILE_OPTIONS}
-                               -Wno-unused-private-field)
+                               -Wno-unused-private-field
+			       -D_LIBCPP_INTRODUCED_IN_LLVM_21=0)
     if(CMAKE_BUILD_TYPE MATCHES Debug)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fstandalone-debug")
     endif()

src/class_diagram/visitor/translation_unit_visitor.cc

@@ -1849,7 +1849,7 @@ bool translation_unit_visitor::find_relationships(const clang::Decl *decl,
         }
         else if (type->getAsCXXRecordDecl() != nullptr) {
             relationships.emplace_back(
-                common::to_id(type, decl->getASTContext()), relationship_hint,
+                common::to_id(type, type->getAsCXXRecordDecl()->getASTContext()), relationship_hint,
                 decl);
             result = true;
         }