quirk of array type processing

I'm not sure if this should be considered a bug or not. At least in my case it
doesn't cause a problem. I think it could always be worked around with
explicit casts in any case, it just seems... wrong:

db=> create or replace function array_length(integer[]) returns integer   as 'SELECT array_upper($1)-array_lower($1)+1'
 language sql   strict immutable;
 

ERROR:  function array_upper(integer[]) does not exist
HINT:  No function matches the given name and argument types. You may need to add explicit typecasts.

db=> create or replace function array_length(anyarray) returns integer    as 'SELECT array_upper($1)-array_lower($1)+1'
  language sql    strict immutable;
 

CREATE FUNCTION


-- 
greg