Bug: compiler hangs on circular type dependency

Bug: compiler hangs on circular type dependency

[Victor Porton]

This is sent to report@gnat.com and duplicated in comp.lang.ada

Gnat (both 3.14 and 3.15) hangs on compiling the following
(erraneous) stuff:

package P is
    type A is tagged null record;
    type B is new A with private;
    type C is new A with private;
private
    type B is new C with null record;
    type C is new B with null record;
end P;

BTW, comp.lang.ada, what in Ada Standard deprecated such circularity?
Isn't it forgotten in the Standard itself?

Re: compiler hangs on circular type dependency

[James S. Rogers]

"Victor Porton" <porton@ex-code.com> wrote in message
news:3e2cb563$0$33929$bed64819@news.gradwell.net...
> This is sent to report@gnat.com and duplicated in comp.lang.ada
>
> Gnat (both 3.14 and 3.15) hangs on compiling the following
> (erraneous) stuff:
>
> package P is
>     type A is tagged null record;
>     type B is new A with private;
>     type C is new A with private;
> private
>     type B is new C with null record;
>     type C is new B with null record;
> end P;
>
> BTW, comp.lang.ada, what in Ada Standard deprecated such circularity?
> Isn't it forgotten in the Standard itself?

No, this is clearly covered in the standard:

Section 3.4 paragraph 4 states:

A type shall be completely defined (see 3.11.1) prior to being specified
as the parent type in a derived_type_definition - the
full_type_declarations for the parent type and any of its
subcomponents have to precede the derived_type_definition.

Your private definitions violate this rule.

Jim Rogers

Re: compiler hangs on circular type dependency

[tmoran]

> >     type B is new A with private;
> > private
> >     type B is new C with null record;
>...
> A type shall be completely defined (see 3.11.1) prior to being specified
>...
> Your private definitions violate this rule.
  The private definition of B also contradicts the public one.

Re: compiler hangs on circular type dependency

[Victor Porton]

In article <OI5X9.76286$1q3.11915@sccrnsc01>,
	tmoran@acm.org writes:
>> >     type B is new A with private;
>> > private
>> >     type B is new C with null record;
>>...
>> A type shall be completely defined (see 3.11.1) prior to being specified
>>...
>> Your private definitions violate this rule.
>   The private definition of B also contradicts the public one.

No, in private a base type can be replaced to its derivative.

Re: compiler hangs on circular type dependency

[Wes Groleau]

>>private
>>    type B is new C with null record;
>>    type C is new B with null record;
 >
> Section 3.4 paragraph 4 states:
> 
> A type shall be completely defined (see 3.11.1) prior to being specified
> as the parent type in a derived_type_definition - the
> full_type_declarations for the parent type and any of its
> subcomponents have to precede the derived_type_definition.
> 
> Your private definitions violate this rule.

But it is a GNAT bug to hang.  Please send a NON-crossposted
note to report@gnat.com

Re: compiler hangs on circular type dependency

[Victor Porton]

In article <nqcX9.2478$c6.2673@bos-service2.ext.raytheon.com>,
	Wes Groleau <wesgroleau@despammed.com> writes:
> 
>>>private
>>>    type B is new C with null record;
>>>    type C is new B with null record;
> >
> But it is a GNAT bug to hang.  Please send a NON-crossposted
> note to report@gnat.com

I've already sent there. Well, cross-posted :-)

Re: compiler hangs on circular type dependency

[Stephen Leake]

porton@ex-code.com (Victor Porton) writes:

> In article <nqcX9.2478$c6.2673@bos-service2.ext.raytheon.com>,
> 	Wes Groleau <wesgroleau@despammed.com> writes:
> > 
> >>>private
> >>>    type B is new C with null record;
> >>>    type C is new B with null record;
> > >
> > But it is a GNAT bug to hang.  Please send a NON-crossposted
> > note to report@gnat.com
> 
> I've already sent there. Well, cross-posted :-)

The point is that report@gnat.com has a filter that rejects
cross-posted emails. Or something like that; they won't see it if it
is crosss-posted.

-- 
-- Stephe