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 {
    bad_typeid() noexcept;
    bad_typeid(const bad_typeid&) noexcept;
    bad_typeid& operator=(const bad_typeid&) noexcept;
    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.
Remarks: The message may be a null-terminated multibyte string, suitable for conversion and display as a wstring ([string.classes], [locale.codecvt])