17 Language support library [language.support]

17.7 Type identification [support.rtti]

17.7.4 Class bad_­typeid [bad.typeid]

namespace std {
  class bad_typeid : public exception {
  public:
    // see [exception] for the specification of the special member functions
    const char* what() const noexcept override;
  };
}
The class bad_­typeid defines the type of objects thrown as exceptions by the implementation to report a null pointer in a typeid expression ([expr.typeid]).
const char* what() const noexcept override;
Returns: An implementation-defined ntbs.