Re: [sv-bc] Resolving a forward typedef via a package import

So, without 'export', I have to redeclare the type, even when I don't
wish to alias it?

     package pkg1;
       typedef struct {logic a, b;} ab;
     endpackage

     package pkg2;
       import pkg1::*;
       typedef ab ab;  //<-----
     endpackage

     module test(input a1, b1, output a2, b2);
       import pkg2::*;
       assign '{a2, b2} = ab'{a1, b1};
     endmodule

-- Brad

-----Original Message-----
From: Greg Jaxon [mailto:Jaxon@synopsys.COM] 
Sent: Thursday, September 28, 2006 5:43 PM
To: Gordon Vreugdenhil
Cc: Brad Pierce; sv-bc@eda.org
Subject: Re: [sv-bc] Resolving a forward typedef via a package import

This also makes me uneasy.

Consider the problem of establishing the unique identity
of this type in the instantiation hierarchy.   I assume
that a typedef forward can only be completed by a full typedef /in the
same scope/, so that both have the same
full hierarchical name.   If it helps to consider an
implementation, imagine that the forward typedef actually produces the
basic type identity sans structural info.
References to the incomplete type may refer to this record location, and
the completion simply fills in the details under the previously reserved
identity.

An import affects the receiving scope like a declaration.
But so does the forward typedef.  I say they collide and do not form a
completed pair.

Greg

Gordon Vreugdenhil wrote:
> 
> I'm not quite sure that I buy your example.
> 
> If you have:
>    typedef ab;
> ....
>    import pkg1::ab;
> 
> I can buy that as a completion of the forward, but what you are 
> asserting is that the forward typedef is completed *upon its 
> declaration* if the type is is a candidate from some package.
> 
> That isn't an obvious conclusion from the text and is one that I am 
> not sure I agree with.
> 
> An implication of such a statement is that if ANY package has a 
> visible type "T" then you can't forward declare "T"  even if your 
> intent was to have the declaration complete locally.
> 
> I would contend that the forward declaration does NOT count as a 
> reference and the the completion must either be via an explicitly 
> named import or by a subsequent typedef.
> 
> So
>    typedef ab;
> ...
>    typedef pkg1::ab ab;
> would be fine as would my earlier example, but your example would not.
> 
> Gord.
> 
> 
> Brad Pierce wrote:
> 
>> According to the final sentence of 4.9,
>>
>>    "Importing a typedef from a package into a local scope can also
>>     resolve a type definition."
>>
>> It would be helpful to add an example of that, such as,
>>
>>     package pkg1;
>>       typedef struct {logic a, b;} ab;
>>     endpackage
>>
>>     package pkg2;
>>       import pkg1::*;
>>       typedef ab;
>>     endpackage
>>
>>     module test(input a1, b1, output a2, b2);
>>       import pkg2::*;
>>       assign '{a2, b2} = ab'{a1, b1};
>>     endmodule
>>
>> -- Brad
>>
>>
>