VASG Issue Number:      0222
Comment Author:         Paul Menchini
Comment Number:         01
Comment Date:           1991/03/22

The prefix of 'LENGTH must be "appropriate for an array object, or an alias
thereof, or [it must denote] a constrained array subtype."  (LRM Section 14.1,
the prefix description for the 'LENGTH attribute, on page 14-5.)

The value returned by a function call is just that: a value.  (Paragraph 2 of
Section 6.1 states: "If the prefix of a name is a function call, then the name
denotes an element, a slice, or an attribute, either of the result of the
function call, or (if the result is an access value) of the object returned by
the result."

Therefore, the example is defective.  The function F returns a Bit_Vector
value, not a Bit_Vector object.  Therefore, "F'Length" cannot be interpreted as
applying the suffix to the result of the function call.

A more appropriate example for this issue is:

        package P
          type T is access Bit_Vector;
          function F return T;
          attribute length: Integer;
          attribute length of F: function is 5;
        end P;