Bug #851: cast() no longer works in array inserts

Malcolm Tredinnick (malcolm(at)commsecure(dot)com(dot)au) reports a bug with a severity of 2
The lower the number the more severe it is.

Short Description
cast() no longer works in array inserts

Long Description
If I have a table containing an array (e.g. a bigint[] field), then it does not appear to be possible to insert values using the cast() function. This used to work in PostgreSQL 7.1, but no longer works in 7.2 or 7.3. I cannot see anything in the release notes saying the previous behaviour was considered incorrect and the documentation seems to indicate it should be possible.

If this is not meant to work, then this is a documentation bug, because it is unclear how to insert a constant like 0 into a bigint field in an array.

The example code below works in 7.1, but not in later versions. The error message given is

ERROR: Bad int8 external representation "{0::bigint, 0::bigint}"

for the first example and similarly for the second (with the appropriate cast statements substituted).

Sample Code
create table foo (bar bigint[]);

insert into foo values ('{"0"::bigint, "0"::bigint}');

insert into foo values ('{cast("0" as decimal(12)), cast("0" as decimal(12))}');

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