No_Implicit_Heap_Allocations

No_Implicit_Heap_Allocations

[Maciej Sobczak]

Consider this reduced test:

--  file p.ads:
package P is
   procedure Wait_Until_Something;
end P;

--  file p.adb:
package body P is

   protected Object is
      entry Wait_Until_Something;
   private
      Something : Boolean := False;
   end Object;

   protected body Object is
      entry Wait_Until_Something when Something is
      begin
         null;
      end Wait_Until_Something;
   end Object;

   procedure Wait_Until_Something is
   begin
      Object.Wait_Until_Something;
   end Wait_Until_Something;

end P;

--  file foo.adb:
pragma Restrictions (No_Implicit_Heap_Allocations);

with P;

procedure Foo is
begin
   null;
end Foo;

Now the interesting part:

$ gnatmake foo
gcc -c p.adb
gnatbind -x foo.ali
error: "foo.adb" has restriction No_Implicit_Heap_Allocations
error: but the following files violate this restriction:
error:   "p.adb"
gnatmake: *** bind failed.
$

What happens here? In what way p.adb violates the restriction on
implicit heap usage?
I don't see anything there that could possibly violate it and if it
does due to internals of this trivial protected object, then I think
Ravenscar programs are in trouble.

This is GNAT GPL 2009 on Linux-x86.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com

Re: No_Implicit_Heap_Allocations

[Maciej Sobczak]

On Jan 27, 11:38 am, Maciej Sobczak <see.my.homep...@gmail.com> wrote:

> This is GNAT GPL 2009 on Linux-x86.

Sorry, there was a typo.

This is GNAT GPL 2010 (20100603) on Linux-x86.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com

Re: No_Implicit_Heap_Allocations

[Mark Lorenzen]

On 27 Jan., 11:38, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
>
> What happens here? In what way p.adb violates the restriction on
> implicit heap usage?
> I don't see anything there that could possibly violate it and if it
> does due to internals of this trivial protected object, then I think
> Ravenscar programs are in trouble.
>
> This is GNAT GPL 2009 on Linux-x86.

Add pragma Restrictions (No_Implicit_Heap_Allocations) the
specification of P and it will build.

- Mark L

Re: No_Implicit_Heap_Allocations

[Maciej Sobczak]

On Jan 27, 12:06 pm, Mark Lorenzen <mark.loren...@gmail.com> wrote:

> Add pragma Restrictions (No_Implicit_Heap_Allocations) the
> specification of P and it will build.

That is true, but it still looks like a compiler bug to me.

I should not add all possible Restrictions to my library units just in
case any of them will be some day used in a program that imposes any
of these restrictions, right?.
This check should be done automagically and in fact different versions
of GNAT behave differently in this regard.

--
Maciej Sobczak * http://www.inspirel.com

Re: No_Implicit_Heap_Allocations

[Vinzent Hoefler]

Maciej Sobczak wrote:

> I should not add all possible Restrictions to my library units just in
> case any of them will be some day used in a program that imposes any
> of these restrictions, right?.

1) Why don't you use a separate file for the configuration pragmas and
    add this to the project instead?

2) If you do, does it make a difference?


Vinzent.

-- 
You know, we're sitting on four million pounds of fuel, one nuclear weapon,
and a thing that has 270,000 moving parts built by the lowest bidder.
Makes you feel good, doesn't it?
   --  Rockhound, "Armageddon"

Re: No_Implicit_Heap_Allocations

[Maciej Sobczak]

On Jan 27, 7:07 pm, "Vinzent Hoefler"
<0439279208b62c95f1880bf0f8776...@t-domaingrabbing.de> wrote:

> 1) Why don't you use a separate file for the configuration pragmas and
>     add this to the project instead?

I was not aware of this possibility. How should I do that, precisely?

--
Maciej Sobczak * http://www.inspirel.com

Re: No_Implicit_Heap_Allocations

[Yannick Duchêne (Hibou57)]

Le Thu, 27 Jan 2011 23:13:15 +0100, Maciej Sobczak  
<see.my.homepage@gmail.com> a écrit:

> On Jan 27, 7:07 pm, "Vinzent Hoefler"
> <0439279208b62c95f1880bf0f8776...@t-domaingrabbing.de> wrote:
>
>> 1) Why don't you use a separate file for the configuration pragmas and
>>     add this to the project instead?
>
> I was not aware of this possibility. How should I do that, precisely?
>
> --
> Maciej Sobczak * http://www.inspirel.com
>
Hi Maciej,

This file is commonly named “gnat.adc”, while this can be named any other  
way. You may find more about this Configuration Pragmas File here :  
http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/The-Configuration-Pragmas-Files.html

Now about where/how it takes place:  
http://www.cs.fsu.edu/~baker/ada/gnat/html/gnat_ugn_3.html

This file is useful in many case, like with GNATElim, which is (the  
latter) useful to remove unnecessary stuffs in a GNAT-compiled  
application. This use to be my main usage of “gnat.adc” ( about this  
particular usage, this old page,  
http://www.les-ziboux.rasama.org/reduire-taille-executable-gnat.html if  
ever you read french ).

-- 
Si les chats miaulent et font autant de vocalises bizarres, c’est pas pour  
les chiens.

“I am fluent in ASCII” [Warren 2010]

Re: No_Implicit_Heap_Allocations

[Maciej Sobczak]

On Jan 28, 6:15 am, Yannick Duchêne (Hibou57)
<yannick_duch...@yahoo.fr> wrote:

> This file is commonly named “gnat.adc”, while this can be named any other  
> way. You may find more about this Configuration Pragmas File here :  http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/The-Configuration-Pragmas-...

Thank you for explanations. Indeed, a separate file dedicated for
configuration pragmas can be very handy.

--
Maciej Sobczak * http://www.inspirel.com

Re: No_Implicit_Heap_Allocations

[Mark Lorenzen]

On 28 Jan., 16:19, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> On Jan 28, 6:15 am, Yannick Duchêne (Hibou57)
>
> <yannick_duch...@yahoo.fr> wrote:
> > This file is commonly named “gnat.adc”, while this can be named any other  
> > way. You may find more about this Configuration Pragmas File here :  http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/The-Configuration-Pragmas-...
>
> Thank you for explanations. Indeed, a separate file dedicated for
> configuration pragmas can be very handy.

Indeed. On the project I'm working on at the moment, we plan to place
all Restriction pragmas in a common file to ensure that all units are
compiled with the same set of restrictions. Maybe it isn't strictly
necessary, but better safe than sorry.

- Mark L