Re: [sv-ac] automatic variiables in clock expr // virtual interface

Sorry to push this issue, but it seems that 2 vendors implement this
differently + if the virtual interface signals cannot be referenced in an
expect, the expect is almost useless. Specifically:
class test_class;
virtual test_if tf;
task run_c();
 expect ( @(posedge clk) tf.a |-> ##2 !tf.a); // <-- ******
endtask

I understand that this is illegal. I don't understand why.
Also, from
http://verificationguild.com/modules.php?name=Forums&file=viewtopic&p=18171#18171
class ---

---
task run_c();
expect ( @(posedge tf.clk) tf.a |-> ##2 !tf.a);
endtask
----
endclass
That run OK on one simulator.
So what's the story and the rational for either answer, legal or illegal?
Ben
On Mon, Jun 14, 2010 at 11:34 PM, Rich, Dave <Dave_Rich@mentor.com> wrote:
> Daniel,
>
> I believe the intent of the rule was: These components *shall* only be
> used in procedural statements. period.
>
> A continuous assignment is not a procedural statement; the statements
> within an always block are procedural.
>
> The rule was mainly to avoid null virtual interface references at
> start-up time, as well as performance penalties for having dynamic
> sensitivity lists.
>
> Dave
>
>
> > -----Original Message-----
> > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
> Neil
> > Korpusik
> > Sent: Monday, June 14, 2010 5:30 PM
> > To: sv-ac@server.eda.org
> > Cc: danielm
> > Subject: RE: [sv-ac] automatic variiables in clock expr // virtual
> > interface
> >
> > <forwarding email from Daniel Mlynek>
> >
> > -------- Original Message --------
> > From: "Daniel Mlynek" <danielm@aldec.com>
> > To: "'Bresticker, Shalom'" <shalom.bresticker@intel.com>,
> >          <ben@systemverilog.us>, <sv-ac@eda.org>
> > Subject: RE: [sv-ac] automatic variiables in clock expr // virtual
> > interface
> > Date: Mon, 14 Jun 2010 15:42:05 +0200
> >
> >
> > Sensitivity list is also illegal. Could someone give an example for
> > illegal
> > usage of virtual interface on sensitivity list, I see nothing wrong in
> > example:
> >
> > interface ifc;
> > logic [7:0] data;
> > bit clk;
> > initial $monitor (data);
> > initial forever #5 clk =~ clk;
> > endinterface
> >
> > module test;
> >   ifc Rx();
> >   virtual ifc vi=Rx ;
> >   byte data1;
> >   initial forever #5 data1++;
> >   //assign vi.data=data1;  //illegal - ok
> >   always @vi.clk $display("event" ,$time); //legal???
> >   initial #101 $finish;
> > endmodule
> >
> >
> > DANiel
> >
> >    _____
> >
> > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
> > Bresticker, Shalom
> > Sent: Monday, June 14, 2010 3:25 PM
> > To: ben@systemverilog.us; sv-ac@eda.org
> > Subject: RE: [sv-ac] automatic variiables in clock expr // virtual
> > interface
> >
> >
> > Maybe the following (25.9):
> >
> > Once a virtual interface has been initialized, all the components of
> the
> > underlying interface instance are directly available to the virtual
> > interface via the dot notation. These components can only be used in
> > procedural statements; they cannot be used in continuous assignments
> or
> > sensitivity lists.
> >
> > Shalom
> >
> >
> >
> >    _____
> >
> > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
> ben
> > cohen
> > Sent: Monday, June 14, 2010 4:17 PM
> > To: sv-ac@eda.org
> > Subject: [sv-ac] automatic variiables in clock expr // virtual
> interface
> >
> >
> > See http://verificationguild.com/modules.php?name=Forums
> >
> <http://verificationguild.com/modules.php?name=Forums&file=viewtopic&p=1
> 8
> > 142
> > #18142> &file=viewtopic&p=18142#18142
> > Lrm reference ?
> > Question is somewhat related to our upcoming discussion in interfaces
> and
> > checkers.
> > Ben
> >
> > --
> > This message has been scanned for viruses and
> > dangerous content by  <http://www.mailscanner.info/> MailScanner, and
> is
> > believed to be clean.
> >
> > ---------------------------------------------------------------------
> >
> > Intel Israel (74) Limited
> >
> >
> >
> > This e-mail and any attachments may contain confidential material for
> >
> > the sole use of the intended recipient(s). Any review or distribution
> >
> > by others is strictly prohibited. If you are not the intended
> >
> > recipient, please contact the sender and delete all copies.
> >
> > --
> > This message has been scanned for viruses and
> > dangerous content by  <http://www.mailscanner.info/> MailScanner, and
> is
> > believed to be clean.
> >
> > --
> > This message has been scanned for viruses and
> > dangerous content by MailScanner, and is
> > believed to be clean.
> >
> >
> >
> >
> > --
> > This message has been scanned for viruses and
> > dangerous content by MailScanner, and is
> > believed to be clean.
> >
> >
> > --
> > This message has been scanned for viruses and
> > dangerous content by MailScanner, and is
> > believed to be clean.
>
>
> --
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
>
>
>
-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.