[Gm2] INTEGER CARDINAL compatibility

[Gaius Mulley]

Hi,

I'm in the middle of correcting the compatibility between INTEGERs
and CARDINALs during assignment, expression, parameter passing
and INC and DEC.  (With appropriate runtime range checking).

I see from PIM4 and ISO that mixed expressions using an INTEGER
and CARDINAL variable are disallowed.  But I couldn't find whether
this also includes:

MODULE foo ;
VAR
   i: INTEGER ;
   c: CARDINAL ;
BEGIN
   IF i>c
   THEN

   END
END foo.

from my reading is that this is illegal according to ISO and PIM, but
this does seem restrictive..  I was just wondering whether I'd missed
something, or misinterpreted something?

Conversely its my understanding that:

DEC(c, i)    (* legal providing 0 <= i <= MAX(CARDINAL)
                (* the later always true for i *) *)

and 

DEC(i, c)    (* legal providing 0 <= c <= MAX(INTEGER) *)


regards,
Gaius