Allowing same cursor name in nested levels

Hi Tom,

While going through few test-cases, I found that we cannot have two opened
cursors with same name even though they are in two different functions. Here
is what I mean:

1. I have two functions func1 and func2.
2. func1 calls func2
3. Both has cursor with same name, say mycursor
4. Somehow I forgot closing it
5. executing func1 throws an error 'cursor "mycursor" already in use'

Is this expected behavior???

I just mingled around the code and later appended a cursor count to the
cursor name to allow same cursor name in nested levels. I have run make
check and didn't find any side-effect other than one expected output change.

PFA, patch for the same.

Please let me know your views / suggestions.

Thanks

Test-case:
===

CREATE OR REPLACE FUNCTION func1() RETURNS void AS $$
DECLARE
res int;
mycursor CURSOR FOR SELECT 'foo';
BEGIN
OPEN mycursor;
SELECT func2() INTO res;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION func2() RETURNS int AS $$
DECLARE
mycursor CURSOR FOR SELECT 'bar';
BEGIN
OPEN mycursor;
return 1;
END;
$$ LANGUAGE plpgsql;

SELECT func1();
ERROR: cursor "mycursor" already in use
CONTEXT: PL/pgSQL function "func2" line 5 at OPEN
SQL statement "SELECT func2()"
PL/pgSQL function "func1" line 7 at SQL statement

--
Jeevan B Chalke
Senior Software Engineer, R&D
EnterpriseDB Corporation
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