[sv-bc] Query related to tagged union variable initializations

Hi,

I have few queries regarding a packed tagged union variable initialization.

1. Can a packed tagged union variable be initialized without any tagged 
union expression(i.e. with any other expression)?

Consider the case :
typedef union tagged packed {
    bit [1:0] b1;
    bit [1:0] b2;
} U_T;

U_T  x = 4'b1010 ;   // Is it valid ?

Few standard tools considers it as valid (not giving any error).

2. If the above case is valid, then what should be the bit 
representation of the tagged union variable i.e.
    which tagged union member should have the assigned value?

Few standard tools are assigning the value to 'b2' for the above example.

3. If the case is invalid, then how a parameter with a tagged union 
datatype should be initialized?

Is following initialization is legal ?
parameter U_T p = tagged b2 2'b01;

I did not get any specific answer from LRM (IEEE 1800-2009 draft 7a).
Please someone assist me ragarding the above queries.

Thanks and Regards
Alok







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