BUG #4200: Regexp character classes not UTF8-compliant

The following bug has been logged online:

Bug reference: 4200
Logged by: Jean-Baptiste Quenot
Email address: jbq(at)caraldi(dot)com
PostgreSQL version: 8.3.1
Operating system: Linux Ubuntu Hardy
Description: Regexp character classes not UTF8-compliant
Details:

PostgreSQL documentation at
http://www.postgresql.org/docs/8.3/static/functions-matching.html describes
the various character classes, and they can be used to match or replace
strings with regexp support. However, the [:alnum:] and [:alpha:] character
classes are not UTF8-compliant, like shown in the examples below:

dockee=# show client_encoding;
client_encoding
-----------------
UTF8
(1 row)

dockee=# show lc_ctype;
lc_ctype
-------------
en_US.UTF-8
(1 row)

dockee=# select regexp_replace('bbu', '[[:alnum:]]', '', 'g');
regexp_replace
----------------

(1 row)

ovhdev=# select regexp_replace('bbu', '[[:alpha:]]', '', 'g');
regexp_replace
----------------

(1 row)

dockee=# select regexp_replace('bbu', $$\w$$, '', 'g');
regexp_replace
----------------

(1 row)

Only characters in the ASCII range were correctly detected to belong to the
[:alnum:] character class, whereas other characters are valid too.