Help with VAX/VMS Ada

["James Burnell, WVU Comp/Ele Engr" <UN025523@WVNVAXA.WVNET.EDU>]

Dear fellow Ada users,

I am taking a summer course in Ada (CompSci 2 at West Virginia 
University).  My teacher gave us an assignment to implement a Vector as 
a discriminated record in a generic package as follows (an excerpt from 
the specification she gave us):

generic
    type Vector_Element is private;
    Zero, One : Vector_Element;
    with function "+" (Left, Right : Vector_Element) return Vector_Element
       is <>;
    with function "-" (Left, Right : Vector_Element) return Vector_Element
       is <>;
    with function "*" (Left, Right : Vector_Element) return Vector_Element
       is <>;
package Vector_Package is
    type Vector (Lower_Bound, Upper_Bound : Integer := 0) is limited private;

-- Appropriate operations deleted....

private
    type Vector_Array is array (Integer range <>) of Vector_Element;
    type Vector (Lower_Bound, Upper_Bound : Integer := 0) is
       record
          The_Vector  : Vector_Array (Lower_Bound .. Upper_Bound)
	     := (others => Zero);
       end record;
end Vector_Package;

The package compiles without error.  But an instantiation, for example,

with Vector_Package;
package Int_Vect_Pack is new Vector_Package (Integer, 0, 1);

produces the following compiler warning:

    2 	package Int_Vect_Pack is new Vector_Package (Integer, 0, 1);
........1
%ADAC-I-CONS_OR_NUM_ERR, (1) (For Vector from Vector_Package at line 33) 
        CONSTRAINT_ERROR or NUMERIC_ERROR will be raised here [LRM 11.1(5-6), 
        F.9.5]
        during evaluation related to record type Vector at line 2 (from 
            Vector_Package at line 33)
%ADAC-I-ENDDIAGS, Ada compilation completed with 1 diagnostic


LRM 11.1(5-6) is simply an explanation of Constraint_Error and 
Numeric_Error; F.9.5 I have included below (used without permission):


F.9.5 Implementation Limits

 Limits       Description
-------------------------------------------------------------------------------
 32           Maximum number of formal parameters in a subprogram or entry
              declaration that are of an unconstrained type.
 120          Maximum identifier length (number of characters).
 120          Maximum number of characters in a source line.
 245          Maximum number of discriminants for a record type.
 246          Maximum number of formal parameters in an entry or subprogram
              declarations.
 255          Maximum number of dimensions in an array type.
 1000         Maximum number of library units and subunits in a program library
              or executable program.
 32757        Maximum number of objects declared with PSECT_OBJECT pragmas.
 65535        Maximum number of enumeration literals in an enumeration type
              definition.
 65535        Maximum number of characters in a value of the predefined type
              STRING.
 65535        Maximum number of frames that an exception can propagate.
 65535        Maximum number of lines in a source file.
 2^31 - 1     Maximum number of buts in any object.

As you can see, none of these is an _obvious_ reason for Constraint_Error to be
 
raised.  Furthermore, Constraint_Error is NOT raised if the default values for 
type Vector are removed.

My teacher is researching this also, but I (and she) would appreciate your 
input.  Why is Constraint_Error raised in this situation?

Please send responses to me.  Thanks for your time.

Sincerely,

Jim Burnell  

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