Re: Generic instantiation in client vs child package

Re: Generic instantiation in client vs child package

[Tucker Taft]

Marc A. Criley (marc.a.criley@lmco.com) wrote:

: The following behavior is seen with GNAT 3.11b-beta on
: Linux 2.0.33 (COL 1.2).

: When instantiating a particular generic from Corey Minyard's "Ada
: Structured Library" (http://www.concentric.net/~Minyard) I get a
: clean compile in one situation and an error in another, and I'm
: not sure why.  I expect it's something I'm overlooking in Ada 95.
: ...

This sounds like a compiler bug.  Because of the generic contract model,
errors that occur during instantiation should always be suspect...

: Given a simple package spec:

: -- plain.ads
: package Plain is

:    type P is private;

: private
:    type P is new Integer;

: end Plain;

: ...

: -- plain-list.ads
: with ASGC.List.Dynamic;

: package Plain.List is

:    package P_Container is new ASGC(Contained_Type => P,
:                                    "="            => "=");
:    package P_List is new P_Container.List;
:    package P_List_Dyn is new P_List.Dynamic;

: end Plain.List;

: I get this error:

: plain-list.ads:9:04: instantiation error at asgc-list-dynamic.ads:26
: plain-list.ads:9:04: "Object" not declared in "List"
: plain-list.ads:9:04: instantiation error at asgc-list-dynamic.ads:27
: plain-list.ads:9:04: tagged type required, found type "Object" defined at
: asgc-list-dynamic.ads:26, instance at line 9
: <Two more similar error blocks are also produced>

: Marc A. Criley
: Chief Software Architect
: Lockheed Martin ATWCS
: marc.a.criley@lmco.com
: Phone: (610) 354-7861
: Fax  : (610) 354-7308

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA
An AverStar Company

Generic instantiation in client vs child package

[Marc A. Criley]

The following behavior is seen with GNAT 3.11b-beta on
Linux 2.0.33 (COL 1.2).

When instantiating a particular generic from Corey Minyard's "Ada
Structured Library" (http://www.concentric.net/~Minyard) I get a
clean compile in one situation and an error in another, and I'm
not sure why.  I expect it's something I'm overlooking in Ada 95.

Given a simple package spec:

-- plain.ads
package Plain is

   type P is private;

private
   type P is new Integer;

end Plain;

The following instantiation of a dynamic list in a client package
compiles cleanly:

-- plain_list.ads
with ASGC.List.Dynamic;  -- from ASL 1.0
with Plain;

package Plain_List is

   package P_Container is new ASGC(Contained_Type => Plain.P,
                                   "="            => Plain."=");
   package P_List is new P_Container.List;
   package P_List_Dyn is new P_List.Dynamic;

end Plain_List;

However, if I instantiate within a child, rather than client,
package:

-- plain-list.ads
with ASGC.List.Dynamic;

package Plain.List is

   package P_Container is new ASGC(Contained_Type => P,
                                   "="            => "=");
   package P_List is new P_Container.List;
   package P_List_Dyn is new P_List.Dynamic;

end Plain.List;

I get this error:

plain-list.ads:9:04: instantiation error at asgc-list-dynamic.ads:26
plain-list.ads:9:04: "Object" not declared in "List"
plain-list.ads:9:04: instantiation error at asgc-list-dynamic.ads:27
plain-list.ads:9:04: tagged type required, found type "Object" defined at
asgc-list-dynamic.ads:26, instance at line 9
<Two more similar error blocks are also produced>


Why is this instantiation acceptable in a client package, but not
in a child package?

-- 
Marc A. Criley
Chief Software Architect
Lockheed Martin ATWCS
marc.a.criley@lmco.com
Phone: (610) 354-7861
Fax  : (610) 354-7308