Re: data structure overlay question.

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Hello Richard,

I think you have found a bug in the compiler.  I created a test program
using your supplied code and used EVAL %ADDR() to check the addresses of
the fields in the underlying data structure and the addresses of the
fields in the overlay and you are correct in your assertion that only the
first field is correctly overlayed.

I believe this is a bug because the following clumsy work-around causes
the overlays to be built correctly.

DDSINPUT        E DS                  EXTNAME(DSUPDPAG)

D DSDATA                       159                  overlay(DSINPUT)
D $fill1                              like(QZSESS ) overlay(DSdata)
D $fill2                              like(QZBTCH ) overlay(DSdata:*next)
D $fill3                              like(QZREF  ) overlay(DSdata:*next)
D $QzAmt                              like(QZAMT1 ) overlay(DSdata:*next)
D                                      dim(12) inz(0)
D $QzChk                              like(QZCHK1 ) overlay(DSdata:*next)
D                                      dim(12)

Notice that I have inserted a field which overlays the entire DS and the
other fields overlay that.  I didn't bother to pore over the RPG
Reference but I can see no difference between overlaying the DS name and
a subfield.  You should open an APAR with IBM support to get this fixed.
(It may be Working As Designed but it sure ain't correct.)

However, I think a better approach would be something like the following:

DDSINPUT        E DS                  EXTNAME(DSUPDPAG) INZ

D @QzAmt          S               *   INZ(%addr(qzamt1))
D @QzChk          S               *   INZ(%addr(qzchk1))

D $QzAmt          S                   like(QZAMT1 ) based(@qzamt)
D                                      dim(12)
D $QzChk          S                   like(QZCHK1 ) based(@qzchk)
D                                      dim(12)

then simply ignore the pointers and just use the arrays as you would
normally.

And why can't I code:

D $QzAmt          S                   like(QZAMT1 ) based(%addr(qzamt1))
D                                      dim(12)

and let the compiler worry about the pointer?

Regards,
Simon Coulter.

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