integer input functions : interesting limit behaviour

I was looking in the int*in() functions and found some interesting limit
behaviours :

* Here, the most negative value is sometimes accepted, sometimes not :

test=> SELECT -2147483648::INTEGER;
ERREUR: entier en dehors des limites

test=> SELECT '-2147483648'::INTEGER;
int4
-------------
-2147483648

* Same for smallint :

test=> SELECT -32768::SMALLINT;
ERREUR: smallint en dehors des limites

test=> SELECT '-32768'::SMALLINT;
int2
--------
-32768
(1 ligne)

* For BIGINT :

test=> SELECT -9223372036854775808::BIGINT;
ERREUR: bigint en dehors des limites

test=> SELECT '-9223372036854775808'::BIGINT;
int8
----------------------
-9223372036854775808
(1 ligne)

Temps : 0,185 ms
test=> SELECT '-000000009223372036854775808'::BIGINT;
ERREUR: la valeur « -000000009223372036854775808 » est en dehors des
limites du type bigint

Interesting, isn't it ?

I guess it's good to reject -2147483648::INTEGER because this is ugly :

test=> CREATE TABLE foo AS (SELECT '-2147483648'::INTEGER AS x);
test=> SELECT -x FROM foo;
ERREUR: entier en dehors des limites

I can make a fix...