🚀 go-pugleaf

In article <1992Nov21.095307.19198@neptune.inf.ethz.ch> templ@inf.ethz.ch (Josef Templ) writes:
>
>A. Borchert writes:
>> Here an example, following program is perfectly legal Oberon text
>> but rejected by the Sparc Oberon System from ETH Zurich:
>> 
>> (* CLASS=CONFORMANCE *)
>> MODULE t03;
>>    TYPE c = RECORD a, b: INTEGER END;
>>    PROCEDURE e;
>>       TYPE b = POINTER TO c;
>>          c = ARRAY 3 OF CHAR;
>>       VAR p: b;
>>    BEGIN (* e *)
>>       p^[1] := "x";
>>    END e;
>> END t03.
>> The compiler complains at the designator >>p^[1]<< that
>> "indexed variable is not an array".
>
>I think this is an ambiguity in the language definition.
>The forward declaration rule should be explicitely restricted to
>the cases where T1 is not visible at the point of the forward declaration.
>Anyway, the intention is that the above program is neither legal
>Oberon nor legal Oberon-2.
>

Of course, it's legal. It's just not what the programmer intended :-)
The "c" referred to in "b = POINTER TO c" is the record structure declared in
the outer scope. So obviously, using indexing on a record generates an error
in >>p[1]<<. 

-- 
Cheryl Lins  Oberon Paladin  lins@apple.com
"Beware the following code - I've only proven it correct, not tested it" Knuth