An issue about index ranges

Gentlemen,

How do we determine the index range of a function that returns an
unconstrained array? I could not find anything in the LRM for this.

The context is the following. We have these functions declarations.

     function int2slv ( integer ) return std_logic_vector;

     function slv2int ( a : std_logic_vector; b : integer ) return
integer;

If we now have an expression
 
            slv2int ( int2slv ( 15 ), 8 )

then how is the index range of the formal obtained within the body
of slv2int?

Would appreciate any pointers you could give.

Regards,

-ajay

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