Legality: formal packages with controlled types

Legality: formal packages with controlled types

[Simon Wright]

The code below fails on OA 7.2 with

bug.ada: Error: line 21 col 42 LRM:3.9.1(3), The accessibility level
       of a record extension shall not exceed that of its parent; this
       also applies in a generic instantiation (In instance of generic
       base at bug.ada: line 7 col 7)

and similar code fails similarly on OA 7.2.1 and AdaMULTI v3.1 I'm
told.  Presumably they all share a front end.

The code compiles OK if Base.Container isn't derived from Controlled.

Is it really the case that it's legal to instantiate a generic package
with a package that contains a controlled type but illegal to
instantiate a generic subprogram?

========================================================
with ada.finalization;
generic
	type item is private;
package base is
	type container is tagged private;
private
	type container is new ada.finalization.controlled with record
		the_item : item;
	end record;
end base;

with base;
generic
	type item is private;
	with package New_Base is new base (item);  -- <==== ok
package Generic_package is end Generic_package;

with base;
generic
	type item is private;
	with package new_base is new base (item);  -- <==== failure
procedure Generic_Procedure;

procedure generic_procedure is
begin
	null;
end generic_procedure;

Re: Legality: formal packages with controlled types

[Jeffrey Carter]

The code compiles without error with GNAT 3.13p/Win98.

-- 
Jeff Carter
"Perfidious English mouse-dropping hoarders."
Monty Python & the Holy Grail

Re: Legality: formal packages with controlled types

[Simon Wright]

Jeffrey Carter <jrcarter@acm.org> writes:

> The code compiles without error with GNAT 3.13p/Win98.

Yes, I know, but I have found that sometimes OA is right under these
circumstances!

Re: Legality: formal packages with controlled types

[Simon Wright]

Simon Wright <simon@pushface.org> writes:

> The code below fails on OA 7.2 with
> 
> bug.ada: Error: line 21 col 42 LRM:3.9.1(3), The accessibility level
>        of a record extension shall not exceed that of its parent; this
>        also applies in a generic instantiation (In instance of generic
>        base at bug.ada: line 7 col 7)
> 
> and similar code fails similarly on OA 7.2.1 and AdaMULTI v3.1 I'm
> told.  Presumably they all share a front end.
> 
> The code compiles OK if Base.Container isn't derived from Controlled.
> 
> Is it really the case that it's legal to instantiate a generic package
> with a package that contains a controlled type but illegal to
> instantiate a generic subprogram?
> 
> ========================================================
> with ada.finalization;
> generic
> 	type item is private;
> package base is
> 	type container is tagged private;
> private
> 	type container is new ada.finalization.controlled with record
> 		the_item : item;
> 	end record;
> end base;
> 
> with base;
> generic
> 	type item is private;
> 	with package New_Base is new base (item);  -- <==== ok
> package Generic_package is end Generic_package;
> 
> with base;
> generic
> 	type item is private;
> 	with package new_base is new base (item);  -- <==== failure
> procedure Generic_Procedure;
> 
> procedure generic_procedure is
> begin
> 	null;
> end generic_procedure;

I'm informed by ACT that this code is legal and that the compilers
that reject it (which, BTW, include Apex) are wrong to do so.