* Defect with formal package parameters
@ 2008-06-19 15:14 Eric Hughes
2008-06-19 19:49 ` Simon Wright
2008-06-19 22:48 ` Georg Bauhaus
0 siblings, 2 replies; 5+ messages in thread
From: Eric Hughes @ 2008-06-19 15:14 UTC (permalink / raw)
GNAT 2008 (just installed) fails to compile the following example,
which was cut down from existing code to isolate the problem. This is
the error message.
> foo.ada-spec:16:34: actual for "Operation" in actual instance does not match formal
Changing the syntax to eliminate "others =>", which is what the
commented-out line does, allows the example to compile without error.
Unfortunately, that's not a viable workaround, because the real code
requires named parameters.
At present I am assuming this is a defect with GNAT 2008 rather than
with the Ada 2005 language definition. I had the identical problem
with GNAT 2007. I had stopped development back then, a few months
ago, in the apparently-misplaced hope that a new compiler version
would fix this.
I should point out, for those without significant experience in
generic programming, that this defect completely blocks a huge class
of generic layering techniques that are primarily of interest to
library authors. Code that does not admit significant reconfiguration
does not require this technique.
Eric
=======================================================
package Foo is
pragma Elaborate_Body( Foo ) ;
generic
with procedure Operation is <> ;
package Signature is end ;
procedure Operation_Actual is null ;
package Impl is new Signature( Operation => Operation_Actual ) ;
generic
with package S is new Signature( others => <> ) ;
-- with package S is new Signature( <> ) ;
package Module is end ;
package M is new Module( S => Impl ) ;
end ;
=======================================================
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Defect with formal package parameters
2008-06-19 15:14 Defect with formal package parameters Eric Hughes
@ 2008-06-19 19:49 ` Simon Wright
2008-06-21 18:42 ` Eric Hughes
2008-06-19 22:48 ` Georg Bauhaus
1 sibling, 1 reply; 5+ messages in thread
From: Simon Wright @ 2008-06-19 19:49 UTC (permalink / raw)
Eric Hughes <eric.eh9@gmail.com> writes:
> At present I am assuming this is a defect with GNAT 2008 rather than
> with the Ada 2005 language definition. I had the identical problem
> with GNAT 2007.
You don't mention the Bugzilla (or other) reference you reported this
under?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Defect with formal package parameters
2008-06-19 15:14 Defect with formal package parameters Eric Hughes
2008-06-19 19:49 ` Simon Wright
@ 2008-06-19 22:48 ` Georg Bauhaus
2008-06-20 17:25 ` Eric Hughes
1 sibling, 1 reply; 5+ messages in thread
From: Georg Bauhaus @ 2008-06-19 22:48 UTC (permalink / raw)
Eric Hughes wrote:
> GNAT 2008 (just installed) fails to compile the following example,
...
> =======================================================
> package Foo is
> pragma Elaborate_Body( Foo ) ;
>
> generic
> with procedure Operation is <> ;
> package Signature is end ;
>
> procedure Operation_Actual is null ;
> package Impl is new Signature( Operation => Operation_Actual ) ;
>
> generic
> with package S is new Signature( others => <> ) ;
> -- with package S is new Signature( <> ) ;
> package Module is end ;
>
> package M is new Module( S => Impl ) ;
> end ;
> =======================================================
Another workaround:
package Foo is
pragma Elaborate_Body( Foo ) ;
generic
with procedure Operation is <> ;
package Signature is end ;
procedure Operation is null ;
package Impl is new Signature ;
generic
with package S is new Signature( others => <> ) ;
package Module is end ;
package M is new Module( S => Impl ) ;
end ;
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Defect with formal package parameters
2008-06-19 22:48 ` Georg Bauhaus
@ 2008-06-20 17:25 ` Eric Hughes
0 siblings, 0 replies; 5+ messages in thread
From: Eric Hughes @ 2008-06-20 17:25 UTC (permalink / raw)
Eric Hughes wrote:
> procedure Operation_Actual is null ;
> package Impl is new Signature( Operation => Operation_Actual ) ;
On Jun 19, 4:48 pm, Georg Bauhaus <rm.tsoh.plus-
bug.bauh...@maps.futureapps.de> wrote:
> Another workaround:
>
> procedure Operation is null ;
> package Impl is new Signature ;
The whole point is that I was stacking these package instantiations
two layers deep, and this would cut out the second layer.
Eric
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2008-06-21 18:42 UTC | newest]
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2008-06-19 15:14 Defect with formal package parameters Eric Hughes
2008-06-19 19:49 ` Simon Wright
2008-06-21 18:42 ` Eric Hughes
2008-06-19 22:48 ` Georg Bauhaus
2008-06-20 17:25 ` Eric Hughes
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