weird compiler behaviour with procedures

[James Rich <james@xxxxxxxxxxx>]

Hey guys, I've come across something that I can't explain.  I'm working 
on updating an old RPG/36 program to more modern techniques.  The first 
thing I did was to change the screen to be externally defined.  Among 
the many fields on this screen is one called WOSTAT which is defined 
thus (this is from the compile listing so that I would be sure that I 
wasn't getting confused):

WOSTAT         2A  O  4 47

This same field is in the program in the I specs of one the program 
described files.  The I specs from the program look like this:

I                                  2    3 0WOSTAT            25

Notice that the data types don't match.  The weird part is that this 
compile of the program completed successfully!!  A look at the compile 
listing for the program shows this:

WOSTAT            P(2,0)                814D   2821    2850    3592

A little more investigation shows that the record format of the screen 
file that contains the WOSTAT definition above isn't included in the 
output specs of the compile listing.  So that explains why the compile 
succeeded.  I don't reference that record format anywhere in the 
program.  That is probably why it is missing from the compile listing of 
the program (though it seems odd to me to omit it).

But then it gets weird.  I added a little procedure at the bottom of 
this program (after all the O specs, which is where procedures should 
go, right?  I've done this before, so that's one reason I'm surprised at 
what happened next).  The procedure I added appears before the 
compile-time arrays (remember, this is old-school code here).  The 
procedure I added does not reference the record format in question, nor 
does it reference the field WOSTAT.  But now the compile fails!  Now the 
record format is copied into the program (even though it still isn't 
referenced).  Does putting a procedure body at the bottom of a program 
change the way the compiler includes/ignores externally defined 
fields/formats?  I admit that I need to change the screen specs, but why 
did the behaviour of the compiler change when I coded the procedure?

James Rich

"As for security, being lectured by Microsoft is like receiving wise 
words on the subject of compassion from Stalin."
      -- mormop on lwn.net