Обсуждение: pgsql: Add some sanity checks to CREATE CAST ...

Log Message:
-----------
Add some sanity checks to CREATE CAST ... WITHOUT FUNCTION. Disallow
composite, enum and array types, as those are surely not binary-compatible
with anything else because of the embedded OIDs.

Inspired by bug report by Oleg Serov.

Modified Files:
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    pgsql/src/backend/commands:
        functioncmds.c (r1.108 -> r1.109)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/functioncmds.c?r1=1.108&r2=1.109)