"STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

"STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

[jocpaine]

Hi. I've defined a queue type by instantiating Ada.Containers.Bounded_Synchronized_Queues . When I define a record with a field of that type, and then declare a variable of the record type, I get the storage error mentioned in the email subject line. That happens even if I never use the variable. However, if my variable is the queue type, I don't get the error. I'm surprised at that, because I'd expect a one-field record to have exactly the same storage layout as its field, so if one provokes the error, so should the other. That aside though, can anyone suggest a fix? 

Google shows me that similar errors have been reported before (not with the queue types): for example https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42816 , "Bug 42816 - Crash in Ada.Containers.Vectors.Update_Element".

I'm using Gnat Ada 2014: specifically, gnatmake GPL 2014 (20140331) on Ubuntu 14.10 on version 3.16.0-30-generic of the Linux kernel. My program is below. I compiled it by doing
  gnatmake q11
from the file q11.adb . Running it by doing
  ./q11
gives the error.

Here's the program:

with Ada.Containers.Synchronized_Queue_Interfaces;
with Ada.Containers.Bounded_Synchronized_Queues;

procedure Q11 is

 package Job_Queues_Interface is
    new Ada.Containers.Synchronized_Queue_Interfaces
      ( Element_Type => Integer );

  package Job_Queues_Package is
    new Ada.Containers.Bounded_Synchronized_Queues
      ( Queue_Interfaces => Job_Queues_Interface
      , Default_Capacity => 100 
      );

  subtype My_Queue_Type is Job_Queues_Package.Queue; 
      
  type Job_Queue is record
                      Queue: My_Queue_Type;
                    end record;  

  q : Job_Queue;
  -- This is the line causing the error. If I give q
  -- My_Queue_Type instead, the error doesn't happen.
	
begin
  NULL;
end;

Thanks
Jocelyn Ireson-Paine
www.j-paine.org
www.jocelyns-cartoons.uk

Re: "STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

[Simon Wright]

GCC 4.9.1 gives a similar error (here, Mac OS X, it's Constraint_Error):
GCC 5.0.0 doesn't.

Re: "STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

[Stephen Leake]

jocpaine@googlemail.com writes:

> with Ada.Containers.Synchronized_Queue_Interfaces;
> with Ada.Containers.Bounded_Synchronized_Queues;
>
> procedure Q11 is
>
>  package Job_Queues_Interface is
>     new Ada.Containers.Synchronized_Queue_Interfaces
>       ( Element_Type => Integer );
>
>   package Job_Queues_Package is
>     new Ada.Containers.Bounded_Synchronized_Queues
>       ( Queue_Interfaces => Job_Queues_Interface
>       , Default_Capacity => 100 
>       );
>
>   subtype My_Queue_Type is Job_Queues_Package.Queue; 
>       
>   type Job_Queue is record
>                       Queue: My_Queue_Type;
>                     end record;  
>
>   q : Job_Queue;
>   -- This is the line causing the error. If I give q
>   -- My_Queue_Type instead, the error doesn't happen.

The declaration of Queue in Ada.Containers.Bounded_Synchronized_Queues
includes:

   protected type Queue
     (Capacity : Count_Type := Default_Capacity;
      Ceiling  : System.Any_Priority := Default_Ceiling)
   with
     Priority => Ceiling
   is new Queue_Interfaces.Queue with
   ...
   private
      List : Implementation.List_Type (Capacity);
   end Queue;

List_Type is:

      type List_Type (Capacity : Count_Type) is tagged limited record
         First, Last : Count_Type := 0;
         Length      : Count_Type := 0;
         Max_Length  : Count_Type := 0;
         Elements    : Element_Array (1 .. Capacity) := (others => <>);
      end record;

So if Capacity is large enough, you'll get Storage_Error.

In type Queue, the discriminant Capacity has a default value, which
means it is allowed to be changed, in particular to Count_Type'last,
which is large enough to cause Storage_Error. 

If you change Default_Capacity to 2**31-1, you get Storage_Error for
either case.

So apparently GNAT allocates the largest allowed space when you use type
Job_Queue, but when you use the type My_Queu_Type, it allocates the
space needed for the current discriminant.

-- 
-- Stephe

Re: "STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

[AdaMagica]

Am Samstag, 28. Februar 2015 22:59:47 UTC+1 schrieb Stephen Leake:
> In type Queue, the discriminant Capacity has a default value, which
> means it is allowed to be changed,

No, I think Queue is limited, so the discriminant cannot be changed.

> in particular to Count_Type'last,
> which is large enough to cause Storage_Error.

Re: "STORAGE_ERROR : s-intman.adb:139 explicit raise" from record containing a queue from Ada.Containers.Bounded_Synchronized_Queues in Gnat Ada 2014

[Egil H H]

For what it's worth: On a 32-bit platform I get
- warning: "STORAGE_ERROR" will be raised at run time