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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Private extension of a synchronized interface
Date: Tue, 19 Feb 2019 11:29:20 +0000
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Date: 2019-02-19T11:29:20+00:00
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Egil H H <ehh.public@gmail.com> writes:

> On Monday, February 18, 2019 at 11:35:15 PM UTC+1, Randy Brukardt wrote:
>> 
>> This appears to be a GNAT bug, although I'm not 100% certain.
>
> There's definitely at least one GNAT bug here.
> Forcing a dispatching call on the interface (as suggested by Simon) works,
>   Example.An_Interface'Class(v).p1; 
>
> but forcing a dispatching call on the private extension, does not
>   Example.Instance'Class(v).p1; 
>
> It compiles and runs, but seems to call a null body...

Worse than that: it leaves the PO mangled! GCC 9.0.0 (which is built
with internal checks enabled: released versions aren't) raises an ICE
(internal compiler error),

+===========================GNAT BUG DETECTED==============================+
| 9.0.0 20190115 (experimental) (x86_64-apple-darwin15) Assert_Failure sem_disp.adb:491|

so the released version (CE, 8) rambles past this error, resulting in
the next call saying

raised PROGRAM_ERROR :
System.Tasking.Protected_Objects.Entries.Lock_Entries_With_Status:
protected object is finalized

Will report.