[sv-bc] FW: [sv-ec] Conflict in Tagged Union expression

 

-----Original Message-----
From: Sarmistha Bhattacharya [mailto:sarmisth@cal.interrasystems.com] 
Sent: Thursday, September 22, 2005 12:42 PM
To: Kausik Datta
Subject: Re: [sv-ec] Conflict in Tagged Union expression

Hi,
Thanks for the reply, but i am not clear why tagged union expression should
be made part of 'expression' ( SV-3.1a LRM, Page 495) .
Please consider  the following situation :

////////////////////////////////////////////
int a=0, b;
union tagged {
      int y;
       .. } x;

initial
 begin
    b = (tagged y a ) + 1; // -> syntactically correct by LRM, but makes no
sense end ///////////////////////////////////////////

I think from syntax this should not be supported, instead of making it a
semantic error.
Thanks,
-sarmistha.


Brad Pierce wrote:

>Sarmistha,
>
>I agree that the intent was probably
>
>     tagged_union_expression ::= tagged member_identifier [ primary ]
>
>This is really an SV-BC issue, not an SV-EC issue, so I'm adding its
>reflector  to the distribution.
>
>-- Brad
>
>-----Original Message-----
>From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
>Sarmistha Bhattacharya
>Sent: Tuesday, September 20, 2005 10:39 PM
>To: sv-ec@eda.org
>Subject: [sv-ec] Conflict in Tagged Union expression 
>
>Hi,
>The LRM says tagged union expressions are part of expression :
>(Ref :  SV-3.1a   LRM,  Page  495)
>
>expression ::=
>| tagged_union_expression
>
>And, tagged union expressions are defined as :
>(Ref :  SV-3.1a   LRM,  Page  495)
>
>tagged_union_expression ::= tagged member_identifier [ expression ]
>
>Consider the following situation :
>////////////////////////////////////////////
>int a=0, b=1;
>union tagged {
>      int y;
>       .. } x;
>
>initial
> begin
>    x = tagged y a + b;   //  -> parser conflict
>    ..
> end
>///////////////////////////////////////////
>
>The conflict arises because according rule, 'tagged y a' itself can be a
>tagged union expression, and since there is no delimiter, the parser
>does not understand whether to reduce it here, or shift further to get
>'tagged y a + b' as the whole tagged union expression .
>
>In the LRM, in all the examples, a bracket has been used for the
>expression part.
>( Ref :  SV-3.1a   LRM,  Page 85 )
>
>vi1 = tagged Valid (23+34);
>
>Could someone please tell me if the bracket has been missed out , or i
>am missing something here.
>Thanks,
>-sarmistha.
>
>
>
>
>  
>