strange error in tiny ada 2012 program

strange error in tiny ada 2012 program

[Charly]

Hi all

I installed the new GNAT GPL 2012 and started playing with the new Synchronized_Queue Containers.
Unfortunately I got serverall problems, which can be shown in the following tiny test program


 1  with Ada.Containers.Synchronized_Queue_Interfaces;
 2  with Ada.Containers.Bounded_Synchronized_Queues;
 3  with Ada.Text_IO;
 4  
 5  procedure Ctest is
 6  
 7  
 8     package Integer_Queue_Interfaces is
 9           new Ada.Containers.Synchronized_Queue_Interfaces (Integer);
10  
11     package Integer_Queues is
12       new Ada.Containers.Bounded_Synchronized_Queues (Integer_Queue_Interfaces, 10);
13  
14     subtype Integer_Queue_Type is Integer_Queues.Queue;
15  
16     -- type New_Integer_Queue_Type is new Integer_Queue_Type with null record;
17  
18     type Integer_Queue_Record is tagged limited record
19        Queue : Integer_Queue_Type;
20     end record;
21  
22     --Integer_Queue1 : Integer_Queue_Type;
23     Integer_Queue2 : Integer_Queue_Record;
24  
25  begin
26  
27     Ada.Text_IO.Put_Line ("Hello Ada");
28  
29  end Ctest;


First problem occured in line 16 where I want to extend the Integer_Queue_Type
but I got an error message:

ctest.adb:16:04: parent type of a record extension cannot be a synchronized tagged type (RM 3.9.1 (3/1))

So I removed the statement and defined a new tagged type with the Integer_Queue_Type as record element
in lines 18 - 20. This variant compiles without messages but now I get an exception STORAGE_ERROR.
addr2line locates the error in line 5 what isn't very usefull. By trial and error I found, that the
error comes from line 23, when I replace it with line 22 the program 'works'.

So my questions are:
Did I make any mistake in this tiny program or is it a bug in the new GNAT version?
How can a extend a proteced type (line 16).


Thanks

Re: strange error in tiny ada 2012 program

[Adam Beneschan]

On Friday, July 6, 2012 2:55:53 PM UTC-7, Charly wrote:
 
> So my questions are:
> Did I make any mistake in this tiny program or is it a bug in the new GNAT version?
> How can a extend a proteced type (line 16).

I have no idea about the STORAGE_ERROR issue, but the answer to the second one is simple: you can't.  The following paragraph from AI95-345 appears to be the main reason:

An important advantage of eliminating inheritance of any code or data
for tasks and protected types is that the "monitor"-like benefits of
these constructs are preserved. All of the synchronizing operations are
implemented in a single module, simplifying analysis and avoiding any
inheritance "anomalies" that have been associated in the literature with
combining inheritance with synchronization.

                               -- Adam

Re: strange error in tiny ada 2012 program

[Georg Bauhaus]

On 06.07.12 23:55, Charly wrote:
> How can a extend a proteced type

Make another protected type that implements the
same interface. Use the original behind the scene.