Re: String Pointer Bug

["Christoph Karl Walter Grein" <AdaMagica@web.de>]

A long time ago, I made an exegesis of this problem. You may find it below
(sorry if the indentation should be lost, it's my mailer that swallows it, I do not know
to avoid this):

procedure Try is

  type D is array (Integer range <>) of Boolean;
  type A is access all D;

  X: aliased D (1..3);
  AX: A           := X'Access;  -- not OK
  BX: A (X'Range) := X'Access;  -- not OK

  Y: aliased D := X;
  AY: A           := Y'Access;  --   OK
  BY: A (Y'Range) := Y'Access;  -- OK

begin

  null;

end Try;
----------------------------------------------------
-- My exegesis:
--
-- RM 3.3.1(8,9)
--
--          Nominal     Actual
--                subtype
--    X     D (1..3)    D (1..3)
--    Y     D           D (1..3)
--
-- So the actual subtypes are constrained.
-- X is a constrained object because its nominal subtype is constrained
-- and Y is an object constrained by its initial value.
--
-- RM 3.10(10)
--
--    Designated subtype of A and A (X'Range) and A (Y'Range) is D.
--
-- RM 3.10.2(27/1)
--
--    A's designated subtype shall statically match the nominal subtype
--    of the view.
--
-- RM 4.9.1 (2)
--
--    Statically matching subtypes have statically matching constraints.
--
-- AX: Expected type of X'Access is A.
--     A's designated subtype D does not statically match X's nominal
--     subtype D(1..3).
--
-- BX: Expected type of X'Access is A(X'Range).
--     A(X'Range)'s designated subtype D does not statically match X's
--     nominal subtype D(1..3).
--
-- AY: Expected type of Y'Access is A.
--     A's designated subtype D does statically match Y's nominal subtype D.
--
-- BY: Expected type of Y'Access is A(Y'Range).
--     A(Y'Range)'s designated subtype D does statically match Y's nominal
--     subtype D.
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