Re: BUG #16547: ECPG can't CALL the procedure which has INOUT parameter

On Tue, Jul 21, 2020 at 07:44:54AM +0000, PG Bug reporting form wrote:
> The following bug has been logged on the website:
> 
> Bug reference:      16547
> Logged by:          yusuke egashira
> Email address:      egashira.yusuke@jp.fujitsu.com
> PostgreSQL version: 11.8
> Operating system:   Red Hat Enterprise Linux Server release 6.10
> Description:        
> 
> I created the procedure with INOUT parameter as :
>   CREATE OR REPLACE PROCEDURE inout_proc(a in int, b inout int) 
>   LANGUAGE plpgsql AS $$
>   BEGIN
>       b = a + b;
>       RETURN;
>   END;
>   $$;
> 
> If I called it in ECPG by "EXEC SQL CALL inout_proc(1,2);", "SQL error: too
> few arguments on line xx" is caused.
> 
> On the other hand, if the procedure don't have INOUT parameter (IN only),
> "EXEC SQL CALL inout_proc(1,2);" statement succeeded.
> 
> This error seems to occur because ECPG doesn't expect the value to be
> returned by CALL statement.
> Is this a bug?
> Or, is the current version limited to calling procedures with INOUT
> parameters from ECPG?
> 
> I found this behavior in PostgreSQL 11.8 and 12.3.
> 
> 
> Also, I found the patch[1] introducing "INTO" clause in CALL of ECPG.
> However, the patch changes the EXC SQL CALL statement to always require INTO
> clause.
> 
> [1]
> https://www.postgresql.org/message-id/CAE9k0P%3DGQFjfy9jHCPDw4Eh_xE%3DNw%3D9y4f-CuTZp1L%2B6vEHwFg%40mail.gmail.com

This looks like something we should either fix or document.  Michael
Meskes, do you have an opinion?

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee