implicit array type conversion

Why is it that implicit array type conversion does not apply to the
following situation?  I can't find anything in the RM that disallows
this situation for implicit conversion.

The compiler (Verdix Sun 4 Self, version 6.0.2(g)) gives the following
warning for the assignment to B:

warning: RM 3.6.1: bounds check will raise CONSTRAINT_ERROR at runtime

It does raise the exception on execution.

I sorta wanted to get some other views before I flag this to Verdix as a
bug.  Minor flame: Its real easy to miss some statement buried in the RM
which clarifies these kinds of language lawyer issues.

------------------------ cut here ----------------------------------
procedure Strings is

   type STRING (Len : NATURAL) is
      record
         S : Standard.STRING(1..Len);
      end record;

   A : Standard.STRING(7..7);
   B : STRING(1);

begin -- Strings

   A := "X";
   B := (A'length, A);

end Strings;

Terry J. Westley
Arvin/Calspan Advanced Technology Center
P.O. Box 400, Buffalo, NY 14225
acsu.buffalo.edu!planck!hercules!westley