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

[August K. <fus...@co...>]

Stewart Greenhill wrote:
> 
> 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
> 
> 

OK, thanks. Maybe a warning is enough.

-- 
august