BUG #2917: spi_prepare doesn't accept typename aliases such as 'integer'

The author of this bug was good enough to send me a copy, since I don't 
normally read the -bugs list. It can now be found at 
http://archives.postgresql.org/pgsql-bugs/2007-01/msg00111.php .

I dug into it a bit and found that pltcl and plpython appear to use 
almost identical code, but only pltcl has this limitation documented. 
I'm inclined to say we should document this for plperl and plpython for 
stable releases and remove the limitation for all three for 8.3. I see 
that SQL level prepare calls regprocin() to resolve type names, so maybe 
we should that for the PLs when calling SPI_prepare as well. 
Alternatively, should we adjust things lower down (e.g. in 
typenameType() or LookupTypeName() ) ?

Comments?

cheers

andrew