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From: levi@localhost.nc3a.nato.int
Subject: forward pointers
Date: 22 Jun 2001, 15:36:16

On Fri, 22 Jun 2001, Christopher Ferrall wrote:

> 
> This is listed in "Other known bugs"
> >     forward referencing pointers generate debug info that appears as generic pointers; no information of `with'
> >     statements is currently given to the debugger; error in debug entries generated for objects
> 
> Is this the same as this problem:
> 
> type
>    xptr = ^x_type;
>    x_type = record
> 	     stuff ...
>              next : xptr;
>             end;
> var 
>    xlist,
>    x     : xptr;
> begin
>    new(xlist); xlist.next:=nil;

This line should read:
     new(xlist); xlist^.next:=nil;

>    ...
>    x := xlist;
>    repeat with x^ do begin

Since there is no code here to end the loop replaced it with a for-loop.
Also the begin does not have a matching end.
 
>      new(next);
>      x := next;
>    until no_more_to_create;
> 
> At runtime:
>   Program received signal SIGSEGV, Segmentation fault.
> Inside gdb:
>  (gdb) print x[0]
>   Attempt to dereference a generic pointer.
>
While I have not used gbd, with the changes above the program works.
Increasing the size of the for-loop to force it to run out of heap
and the program exits with a "out of heap" message.
Conclusion: you are dereferencing a pointer but the dereference is
in code you didn't supply.

Hope this helps
  Russ

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