PostgreSQL fails on empty constructor arrays - postgresql

Question

I have encountered a strange situation with arrays, which looks like a bug in PostgreSQL, unless I'm missing something...
According to PostgreSQL documentation, constructor and string presentations of arrays are interchangeable, i.e. we can either write ARRAY[1,2,3] or '{1,2,3}', which is the same.
However, I have found one case when they are not treated the same.
I am using an automatic SQL generator for multi-row updates that spits out the following:
UPDATE "myTable" AS t SET "data"=v."data"::int[] FROM (VALUES(1, array[]))
AS v("id", "data") WHERE t.id=v.id
The table is as follows:
CREATE TABLE myTable(
id serial PRIMARY KEY,
data int[] NULL
);
Executing that query produces error - cannot determine type of empty array, even though we are clearly casting the column type.
And if I replace array[] with the equivalent '{}', then it suddenly works.
I've never seen this happen before, this is first time, perhaps a unique situation, but from what I see, it goes against PostgreSQL documentation for interchangeable array presentation.
More examples, to explain the issue:
These work:
UPDATE "myTable" AS t SET "data"=v."data"::int[] FROM (VALUES(1, array[1,2,3]))
AS v("id", "data") WHERE t.id=v.id
UPDATE "myTable" AS t SET "data"=v."data"::int[] FROM (VALUES(1, '{1,2,3}'))
AS v("id", "data") WHERE t.id=v.id
UPDATE "myTable" AS t SET "data"=v."data"::int[] FROM (VALUES(1, '{}'))
AS v("id", "data") WHERE t.id=v.id
This one doesn't work:
UPDATE "myTable" AS t SET "data"=v."data"::int[] FROM (VALUES(1, array[]))
AS v("id", "data") WHERE t.id=v.id
So the type casting for array constructor works, for as long as the array isn't empty, just as it is empty, then the type casting stops working.

Answer 1

It is supported with type info:
pokus1=# select array[];
ERROR: cannot determine type of empty array
LINE 1: select array[];
^
HINT: Explicitly cast to the desired type, for example ARRAY[]::integer[].
pokus1=# select array[]::integer[];
array
-------
{}
(1 row)