"Limited with" usage

"Limited with" usage

[Damien Carbonne]

Hi,

I am doing tests related to "limited with" using GNAT GPL2005 and GPS on 
a Linux box.

This very simple test fails:

----------------------------------------
limited with B;
package A is
end A;

with A;
package B is
end B;
----------------------------------------

with this message:
gnatmake -u -c -u -P/home/damien/dev/tests05/tests05.gpr a.ads -d
gcc -c -gnat05 -I- -gnatA /home/damien/dev/tests05/src/a.ads
a.ads:1:14: circular unit dependency
a.ads:1:14: "A (spec)" depends on "B (spec)"
a.ads:1:14: "B (spec)" depends on "A (spec)"
a.ads:1:14: "A (spec)" depends on "A (spec)"
gnatmake: "/home/damien/dev/tests05/src/a.ads" compilation error


If I replace "with A;" by "limited with A;" in package B, then it 
compiles fine.

Reading this paper 
(http://www.adacore.com/multimedia/pdfs/Ada05_rational_03.pdf, page 5):
-------------------------------------------------------------------------
It is important to understand that a limited with clause does not impose 
a dependence. Thus if a package A has a limited with clause for B, then 
A does not depend on B as it would with a normal with clause, and so B 
does not have to be compiled before A or placed into the library before A.
If we have a cycle of packages we only have to put limited with on one 
package since that is sufficient to break the cycle of dependences. 
However, for symmetry, in this example we have made them both have a 
limited view of each other.
-------------------------------------------------------------------------

I would think that there is a GNAT bug.
Am I right or did I miss something ?

Thanks for any answer.

Damien

Re: "Limited with" usage

[Georg Bauhaus]

Damien Carbonne wrote:

> ----------------------------------------
> limited with B;
> package A is
> end A;
> 
> with A;
> package B is
> end B;
> ----------------------------------------
> 
> gcc -c -gnat05 -I- -gnatA /home/damien/dev/tests05/src/a.ads
> a.ads:1:14: circular unit dependency

> I would think that there is a GNAT bug.
> Am I right or did I miss something ?

The GNAT in GCC 4.1 (FSF GNAT) compiles this without complaint.

Re: "Limited with" usage

[Alex R. Mosteo]

Georg Bauhaus wrote:
> Damien Carbonne wrote:
> 
>> ----------------------------------------
>> limited with B;
>> package A is
>> end A;
>>
>> with A;
>> package B is
>> end B;
>> ----------------------------------------
>>
>> gcc -c -gnat05 -I- -gnatA /home/damien/dev/tests05/src/a.ads
>> a.ads:1:14: circular unit dependency
> 
> 
>> I would think that there is a GNAT bug.
>> Am I right or did I miss something ?
> 
> 
> The GNAT in GCC 4.1 (FSF GNAT) compiles this without complaint.

I'm glad to hear this. I had tested too the limited with feature with 
similar results in the past, making it almost unusable, but was doubtful 
about who was wrong, me or gnat.

Thanks for the info.