[sv-bc] [Fwd: Re: [sv-ec] query regarding pattern matching]

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Hello,

Let me be clear about my actual question-

In LRM pattern rule is  -

pattern ::= . variable_identifier
| .*
| constant_expression
| tagged member_identifier [ pattern ]

that is  pattern can be  "tagged member_identifier  constant_expression "
But LRM also says that -
"A tagged union pattern succeeds if the value has the same tag and, 
recursively, if the nested pattern matches the member value of the 
tagged union."
My understanding is  there is no place to keep  constant_expression or 
.* or structure_pattern
 with  tagged_expression.
tagged_expression  will have either .variable_identifier or  nothing 
which will be suceeded
when the member_identifier is tagged by some other process.

testcase:
-------
module top;
typedef union tagged{
      bit[7:0] t1;
      logic[2:0]t2[5];
}T12;

      T12 t12;

initial
t12  = tagged t1  (23+34);

initial
begin
  if (t12 matches (tagged t1 {8'b11001101, 8'b00110011, 8'b00110010})) 
//this is error
     begin
    end
  if (t12 matches (tagged t1 .n))  //valid
  begin
  end
end
endmodule

Thanks,

Moumita

Steven Sharp wrote:

>>Also, immediately before the "Pattern syntax" box the text says that
>>"For tagged union patterns, the identifier following the tagged keyword
>>is a union member name."  But 't1' is not a union member name.
>>    
>>
>
>Isn't it?  It is obscured by the unpacked dimension range after it,
>but it sure looks like the name of a member to me.
>
>Steven Sharp
>sharp@cadence.com
>
>
>  
>




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