Re: [Q] non-limited record and "self-pointer"

[Stephen Leake <stephen_leake@acm.org>]

Georg Bauhaus <sb463ba@uni-duisburg.de> writes:

> Is there any circumstance which might allow the following type
> (Read_Only_Set) to be o.K.? The record isn't limited, the compiler
> does not complain unless I remove the "container" component. It says
> then that for correct instantiation the current instance must be a
> limited type. Which has some words that I had thought it could say.

I'm not clear what you are asking. 

The prefix of 'Access or 'Unchecked_Access must be aliased. ARM 3.10
(9) says the current instance of a limited type is aliased. Sor for
'Unchecked_Access to be legal, Read_Only_Set must be limited.

Apparently the compiler thinks including teh Container component makes
Read_Only_Set limited. But in the version of Charles I have,
Charles.Sets.Sorted.Unbounded.Container_Type is not limited. So that's
a puzzle. What does your version of Charles say?

>    package Implementation is
>       new Charles.Sets.Sorted.Unbounded(Element);
>         -- (Element is generic formal private)
> 
>    type Read_Only_Set is tagged    <-- not limited
>       record
>          container: Implementation.Container_Type;
> 
>         -- line 102:
>          self: Set_Ptr := Read_Only_Set'unchecked_access;  <-- no complaints
>          --  used in value_in_place


-- 
-- Stephe