In the example above, the method MyASTConsumer::HandleTranslationUnit() is called by the Clang compiler when the AST is generated for the translation unit. The method then retrieves the DiagnosticsEngine object using the ASTContext::getDiagnostics() method and sets a custom diagnostic handler using the setClient() method provided by DiagnosticsEngine. In this case, the custom diagnostic handler is MyDiagnosticHandler(). Example 2:c++ void MyASTConsumer::HandleTranslationUnit(ASTContext &Context) { DiagnosticsEngine &diagEngine = Context.getDiagnostics(); if (diagEngine.hasErrorOccurred()) { // Handle errors. } } ``` In this example, the HandleTranslationUnit() method checks if any error diagnostic message was reported by the compiler. This is done by calling the hasErrorOccurred() method of the DiagnosticsEngine object retrieved using ASTContext::getDiagnostics(). The method returns true if at least one error diagnostic message was reported, and the code can handle this situation accordingly. Package/Library: Clang (LLVM) C++ compiler infrastructure.