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From: Christoph Grein <christoph.grein@eurocopter.de>
Subject: Re: Access to strings and string subtypes?
Date: 2000/03/17
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package Test is

   type Ref is access all String;     <-- unconstrained

   subtype Name is String(1..10);     <-- constrained
   type Name_Ref is access all Name;

   A : aliased Name;                  <-- constrained
   C : aliased String (1..10);        <-- constrained

   D : Name_Ref := A'Access; -- OK
   E : Ref := A'Access; -- Does not statically match designated subtype ???
   F : Ref := C'Access; -- Does not statically match designated subtype ???

   G : Ref := new String'("THIS WORKS"); -- OK!

end Test;

The compiler message ("Does not statically match designated subtype") says
exactly what is wrong:

A pointer to an unconstrained string has to take care of the actual object's 
ranges, a pointer to a constrained string need not.

Thus A'Access and C'Access do not provide range information whereas
   new String'("THIS WORKS")
does.