Re: [Gm2] VAR array parameter type compatibility

[Gaius Mulley]

Fischlin Andreas <address@hidden> writes:

> Hi all,
>
> I agree, this compatibility should actually work and the compiler
> should accept types which have been made equal. Other examples are:
>
> TYPE
>       MYSHORTREAL = REAL;
>
> TYPE
>       PROCA = PROCEDURE (VAR ARRAY OF REAL);
>       PROCB = PROCEDURE (VAR ARRAY OF MYSHORTREAL);
>
> VAR
>       pa: PROCA; pb: PROCB;
>         x: ARRAY [0..1] OF REAL;
>         y: ARRAY [0..1] OF MYSHORTREAL;
>
> PROCEDURE ProcA(VAR z: ARRAY OF REAL);
> PROCEDURE ProcB(VAR z: ARRAY OF MYSHORTREAL);
>
> then pa and pb should be type compatible and interchangeably usable,
> i.e. all following statements should all be legal:
>
>       x := y;
>       pa := ProcA; pb := ProcB;
>       pa(x); pa(y); pb(x); pb(y);
>       pa := ProcB; pb := ProcA;
>       pa(x); pa(y); pb(x); pb(y);
>
>       
> Regards,
> Andreas
>               
>
>
> On 01/Feb/2010, at 22:07 , SiTex Graphics wrote:
>
>> Hi Gaius,
>>
>> I have a case where GM2 appears to enforce different type
>> compatibility rules depending on whether a VAR array parameter is a
>> variable or the parameter in a procedure.
>>
>> With
>>
>> TYPE
>>  fooADDRESS = ADDRESS;
>>
>> VAR
>>  foo : ARRAY [0..9] OF fooADDRESS;
>>
>> GM2 accepts a call to
>>
>> PROCEDURE DoAddress(VAR a : ARRAY OF ADDRESS)
>>
>> passing foo.  However, the following call produces a compiler error:
>>
>> PROCEDURE DoFoo(VAR f : ARRAY OF fooADDRESS);
>> BEGIN
>>  DoAddress(f);
>> END DoFoo;
>>
>> "'f' cannot be passed to a VAR formal parameter"
>>
>> Test code attached.  Compile with
>>
>> gm2 -fiso -c arraytype.mod
>>
>> -Scott

Hi Scott and Andreas,

I agree a bug - it looks as if the type equivalence checking code has
a bug inside the parameter checking component.  Thanks for the test
code - it should make tracking this bug down easier

regards,
Gaius