Re: [ooc-compiler] Unsafe pointers on the stack

[Stewart G. <sgr...@ii...>]

Hi August,

> If I compile and run the following program I get a segmentation fault 
> rather that a run time exception.
>
>    MODULE Test;
>       PROCEDURE P;
>          VAR p: POINTER TO ARRAY OF LONGINT;
>       BEGIN
>          p[0] := 1
>       END P;
>    BEGIN
>       P
>    END Test.
>
> So in this regard the above program compiled with OOC is just as 
> unsafe as a C program. Wasn't the elimination of wild pointers one of 
> the design criteria of Oberon?

OOC generates the following warning for this code.

In file src/Test.Mod:
       PROCEDURE P;
          VAR p: POINTER TO ARRAY OF LONGINT;
       BEGIN
          p[0] := 1
#--------^
# 5:  Warning: Undefined variable
       END P;
    BEGIN
       P

OOC V1 used to support the optional initialisation of stack-based 
variables (obviously, with a performance cost) via the "Initialize := 
TRUE" pragma. I'm not sure if this feature made it into the V2 
compiler. Generally, if you check the compiler warnings it will pick up 
most of these cases.

Cheers,
   Stewart