The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/static/datatype-character.html
Description:
removing trailing spaces on (implicit) cast from char to text can be
painful, and always surprising as shown in example with
SELECT 'a '::CHAR(2) collate "C" < E'a\n'::CHAR(2)
would it be worth mentioning a tip, that this behaviour can be monkey hacked
by concat(str "any" function that accepts char and returns text, thus
respecting the spaces, eg SELECT concat('a '::CHAR(2) collate "C") <
E'a\n'::CHAR(2) will return false as expected...