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From: Georg Bauhaus on 16 Dec 2009 10:54
Andrea Taverna schrieb:
> On 16 Dic, 14:14, Georg Bauhaus <rm.dash-bauh...(a)futureapps.de> wrote:
>> Andrea Taverna schrieb:
>>
>>> and the compiler replied
>>> -----%<-----%<-----%<-----%<-----%<
>>> ]# gnatmake main.adb
>>> gcc -c main.adb
>>> main.adb:9:05: instantiation error at parent-child.adb:6
>>> main.adb:9:05: "F" is not visible (more references follow)
>>> main.adb:9:05: instantiation error at parent-child.adb:6
>>> main.adb:9:05: non-visible declaration at q.ads:3
>>> gnatmake: "main.adb" compilation error
>>> -----%<-----%<-----%<-----%<-----%<
>>> Am I missing something?
>> It's not a "use" issue I think. P.F is marked invisible,
>> too.
> I'm not sure I understand you correctly here, however P.F *is*
> visible, in fact the compiler stops complaining after prefixig P's
> name to F.

My mistake, sorry. (I had forgotton to prefix the other F.)

Is the question then whether or not "use" of a generic
formal package extends to the formal parameters of the
generic formal package (a formal package with a (<>))?

My best guess would be to start from Ada 95 12.7(10),
if that still applies, but I simply don't know, and I
don't have my other compiler handy which might give a more
detailed error message.
From: Andrea Taverna on 16 Dec 2009 11:54
On 16 Dic, 16:54, Georg Bauhaus <rm.dash-bauh...(a)futureapps.de> wrote:
> Andrea Taverna schrieb:
>
>
>
> > On 16 Dic, 14:14, Georg Bauhaus <rm.dash-bauh...(a)futureapps.de> wrote:
> >> Andrea Taverna schrieb:
>
> >>> and the compiler replied
> >>> -----%<-----%<-----%<-----%<-----%<
> >>> ]# gnatmake main.adb
> >>> gcc -c main.adb
> >>> main.adb:9:05: instantiation error at parent-child.adb:6
> >>> main.adb:9:05: "F" is not visible (more references follow)
> >>> main.adb:9:05: instantiation error at parent-child.adb:6
> >>> main.adb:9:05: non-visible declaration at q.ads:3
> >>> gnatmake: "main.adb" compilation error
> >>> -----%<-----%<-----%<-----%<-----%<
> >>> Am I missing something?
> >> It's not a "use" issue I think.  P.F is marked invisible,
> >> too.
> > I'm not sure I understand you correctly here, however P.F *is*
> > visible, in fact the compiler stops complaining after prefixig P's
> > name to F.
>
> My mistake, sorry. (I had forgotton to prefix the other F.)
>
> Is the question then whether or not "use" of a generic
> formal package extends to the formal parameters of the
> generic formal package (a formal package with a (<>))?

Hmm... I know that they are already visible in Parent as soon as I add
the use-clause. The problem is whether I can "use" the generic formal
package in a child of the generic package of which is a parameter.The
fact the package itself is visible in every children of such package
would suggest that I could.

> My best guess would be to start from Ada 95 12.7(10),
> if that still applies, but I simply don't know, and I
> don't have my other compiler handy which might give a more
> detailed error message.
Please bear some patience, I'ma self-thaught newbie.
http://www.adapower.com/adapower1/rm95/arm95_187.html
In Ada95 12.7 there seems not to be anything relevant about such
problem. What does the "(10)" mean?

thanks

Andrea
From: Georg Bauhaus on 16 Dec 2009 13:54
Andrea Taverna schrieb:
> On 16 Dic, 16:54, Georg Bauhaus <rm.dash-bauh...(a)futureapps.de> wrote:
>> Andrea Taverna schrieb:
>>
>>
>>
>>> On 16 Dic, 14:14, Georg Bauhaus <rm.dash-bauh...(a)futureapps.de> wrote:
>>>> Andrea Taverna schrieb:
>>>>> and the compiler replied
>>>>> -----%<-----%<-----%<-----%<-----%<
>>>>> ]# gnatmake main.adb
>>>>> gcc -c main.adb
>>>>> main.adb:9:05: instantiation error at parent-child.adb:6
>>>>> main.adb:9:05: "F" is not visible (more references follow)
>>>>> main.adb:9:05: instantiation error at parent-child.adb:6
>>>>> main.adb:9:05: non-visible declaration at q.ads:3
>>>>> gnatmake: "main.adb" compilation error
>>>>> -----%<-----%<-----%<-----%<-----%<
>>>>> Am I missing something?
>>>> It's not a "use" issue I think. P.F is marked invisible,
>>>> too.
>>> I'm not sure I understand you correctly here, however P.F *is*
>>> visible, in fact the compiler stops complaining after prefixig P's
>>> name to F.
>> My mistake, sorry. (I had forgotton to prefix the other F.)
>>
>> Is the question then whether or not "use" of a generic
>> formal package extends to the formal parameters of the
>> generic formal package (a formal package with a (<>))?
>
> Hmm... I know that they are already visible in Parent as soon as I add
> the use-clause. The problem is whether I can "use" the generic formal
> package in a child of the generic package of which is a parameter.The
> fact the package itself is visible in every children of such package
> would suggest that I could.

My idea, possibly confused, is that somehow the
formal parameter F of generic package Q is not made visible
in Parent.Child.

With LRM 95 12.7(10) in mind,

generic
with package P is new Q (<>);
...
package Parent...

means, I think, that the parameters for which (<>) stands
are included in visibility decisions.


> http://www.adapower.com/adapower1/rm95/arm95_187.html

(The paragraph numbering on that page is a bit different from
what is normally used in the RM. (10) means the tenth paragraph
which happens to be "Static Semantics, 2nd", on adapower.com)

"The visible part of a formal package includes the first
list of basic_declarative_items of the package_specification.
In addition, if the formal_package_actual_part is (<>),
it also includes the generic_formal_part of the template
for the formal package."

P is the formal package with formal_package_actual_part (<>).
Q is the template, F is in Qs generic_format_part.
So F should be as visible as anything specified in P.
But I'm a layman, hopefully some expert can explain all this.

From: sjw on 16 Dec 2009 16:26
On Dec 16, 4:54 pm, Andrea Taverna <a.t...(a)hotmail.it> wrote:

> Please bear some patience, I'ma self-thaught newbie.http://www.adapower.com/adapower1/rm95/arm95_187.html
> In Ada95 12.7 there seems not to be anything relevant about such
> problem. What does the "(10)" mean?

That's not a very good copy of the RM (I don't know where the pages
originated). A much better one is at http://www.adaic.com/standards/95lrm/html/RM-12-7.html
-- "(10)" means paragraph 10, preceded at the left with a small '10'.

I don't recall exactly why you want to 'use P;'? Personally I wouldn't
even be tempted to do so; many bad experiences with similar usages!
Even discounting compiler errors/bombs, consider:

- what happens if there's another F (with the same profile) visible?
- what happens if you change P so it no longer has an F (with a
matching profile)?
From: Adam Beneschan on 16 Dec 2009 16:27
On Dec 15, 11:28 am, Andrea Taverna <a.t...(a)hotmail.it> wrote:
> Hello everyone,
>
> I have the following packages:
>
> generic
>         with package P is new Q (<>);
>         use P;
> package Parent is
> ...
> end Parent;
>
> generic
> Parent.Child is
> ...
> end Parent.Child;
>
> I can see P declarations inside Parent, but in Child I need to prefix
> everything with 'P.', even if I add a use-clause.
> This happens with gnat-4.3.0 .
> Is it normal?

It's a bug. The scope of the "use P" is supposed to include
Parent.Child (8.1(9), 8.4(7)).

-- Adam
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