void diagnose(Node &, Node &, Diagnostic::Severity, const std::string &);
void diagnose(Node &n, Diagnostic::Severity s, const std::string &m) { diagnose(n, n, s, m); }
void diagnose(Node &, Node &, Diagnostic::Severity, const std::string &);
void diagnose(Node &n, Diagnostic::Severity s, const std::string &m) { diagnose(n, n, s, m); }