character type value is not padded with spaces

Character type value including multibyte characters is not padded
with spaces. It reproduces at 7.3.x, 7.4.x and 8.0.x.

create table t (a char(10));
insert into t values ('XXXXX'); -- X is 2byte character.

I expect that 'XXXXX ' is inserted. But 'XXXXX' is inserted.

select a, octed_length(a) from t;

a | octet_length
-------+--------------
XXXXX | 10

If padded with spaces, octet_length(a) is 15. This problem is caused
that string length is calculated by byte length(VARSIZE) in
exprTypmod().

I attache the patch for this problem.

Regards,

--
Yoshiyuki Asaba
y-asaba(at)sra(dot)co(dot)jp