Callback::run(const MatchFinder::MatchResult& result) {   const clang::StringLiteral* literal =       result.Nodes.getNodeAs<clang::StringLiteral>("literal");   if (literal->getLength() > 0)     return;    const clang::CXXConstructExpr* call =       result.Nodes.getNodeAs<clang::CXXConstructExpr>("call");   