Class not_char_pointer

test/doctest.h:1317–1317

    template<class T>               struct decay_array<T[]>  { using type = T*; };

    template<class T>   struct not_char_pointer              { static DOCTEST_CONSTEXPR int value = 1; };
    template<>          struct not_char_pointer<char*>       { static DOCTEST_CONSTEXPR int value = 0; };
    template<>          struct not_char_pointer<const char*> { static DOCTEST_CONSTEXPR int value = 0; };