Re: Simple 4 lines hang code using Ravenscar. Its this a Gnat bug?

[Daniel <danielnorberto@gmail.com>]

El viernes, 22 de febrero de 2019, 11:01:51 (UTC+1), Niklas Holsti  escribió:
> On 19-02-22 10:56 , Daniel wrote:
> >
> > Hello,
> > I found something strange using Ravenscar with Gnat. The code hangs without any explanation when i try to declare a task type...¡even if i dont use any variable of this type!!. If i quit the Ravenscar pragma it works well. This is the code:
> >
> > --MAIN PROCEDURE
> > with tmr;
> > with ada.Text_IO; use ada.Text_IO;
> > procedure main is
> > begin
> >    put_line("Let's hang..");
> > end main;
> >
> > --- TMR.ADS FILE
> > pragma Profile (Ravenscar);
> > package Tmr is
> >    task type K_Timer is
> >    end K_Timer;
> > end Tmr;
> >
> > -- TMR.ADB FILE
> > package body Tmr is
> >    task body K_Timer  is
> >    begin
> >      null;
> >    end K_Timer;
> > end Tmr;
> >
> >
> > Im using GNAT GPL 2017 for windows.
> > Thank you and best regards.
> >
> 
> In a Ravenscar program, no task should terminate, and this includes the 
> environment task. However, your "main" subprogram, which is where the 
> environment task ends up after elaboration, does terminate. Therefore no 
> Ravenscar program is expected to terminate at all!
> 
> My guess is that without the task-type declaration, the tasking part of 
> the Ravenscar run-time is omitted from the program, and the environment 
> task can terminate and this terminates the program. With the task-type 
> declaration, the Ravenscar tasking run-time is included, and termination 
> of the environment task becomes a no-no. Or at least it no longer 
> terminates the program, which therefore seems to "hang".
> 
> This is just a guess, of course.
> 
> You could try to put an eternal loop in the "main", say
> 
>     loop
>        Put_Line ("Idling...");
>        delay until Ada.Real_Time.Clock + Ada.Real_Time.Seconds (1);
>     end loop;
> 
> HTH
> 
> -- 
> Niklas Holsti
> Tidorum Ltd
> niklas holsti tidorum fi
>        .      @       .

It really make sense. Thank you.