GCC主要数据结构之cxx_dialect

/* The supported C++ dialects.  */
enum cxx_dialect {
  cxx_unset,
  /* C++98 with TC1  */
  cxx98,
  cxx03 = cxx98,
  /* C++11  */
  cxx0x,
  cxx11 = cxx0x,
  /* C++14 */
  cxx14,
  /* C++1z (C++17?) */
  cxx1z
};