In the case of is_unsigned() and is_signed(), the natural thing would be
to compare to 0:
#define is_unsigned(x) (((typeof(x)) -1) > 0)
#define is_signed(x) (((typeof(x)) -1) < 0)
However, that would trigger -Wtype-limits, so we compare against 1,
which silences that, and does the same job.
Signed-off-by: Alejandro Colomar <alx@kernel.org>