Any extended integer types that exist in the implementation (6.2.5).
Whether signed integer types are represented using sign and magnitude,
two's complement, or one's complement, and whether the extraordinary value
is a trap representation or an ordinary value (220.127.116.11).
GCC supports only two's complement integer types, and all bit patterns
are ordinary values.
The rank of any extended integer type relative to another extended
integer type with the same precision (18.104.22.168).
The result of, or the signal raised by, converting an integer to a
signed integer type when the value cannot be represented in an object of
that type (22.214.171.124).
The results of some bitwise operations on signed integers (6.5).