From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
X-Received: by 10.13.223.84 with SMTP id i81mr13326725ywe.9.1472744630610;
        Thu, 01 Sep 2016 08:43:50 -0700 (PDT)
X-Received: by 10.157.51.45 with SMTP id f42mr1621838otc.12.1472744630563;
 Thu, 01 Sep 2016 08:43:50 -0700 (PDT)
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!border2.nntp.dca1.giganews.com!nntp.giganews.com!j37no12185399qta.0!news-out.google.com!w143ni787itb.0!nntp.google.com!i184no358813itf.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Thu, 1 Sep 2016 08:43:50 -0700 (PDT)
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=2001:8a0:6a4f:fe01:bc32:3b9e:20d2:48bc;
 posting-account=nd46uAkAAAB2IU3eJoKQE6q_ACEyvPP_
NNTP-Posting-Host: 2001:8a0:6a4f:fe01:bc32:3b9e:20d2:48bc
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <6e4d6fc1-dcb9-454a-8c1e-df090224438e@googlegroups.com>
Subject: Rendezvous with select ... else and "or terminate" not possible - but
 how do I quit this task?
From: Some Dude <john@peppermind.com>
Injection-Date: Thu, 01 Sep 2016 15:43:50 +0000
Content-Type: text/plain; charset=UTF-8
Xref: news.eternal-september.org comp.lang.ada:31676
Date: 2016-09-01T08:43:50-07:00
List-Id: <comp.lang.ada>

I have a task with entries Start, Stop, Send, Close and an else clause that does some main processing when none of the entries are processed. So the structure is (very simplified):

task body Connection_Handler is
      Done : Boolean := False;
   begin
      accept Start (Socket : Socket_Type) do
        -- do this first 
      end Start;
      loop
         select when not Done =>
            accept Stop do
               Done := True;
            end Stop;
         or when not Done =>
            accept Send (Socket : Socket_Type; Command : Command_Type) do
               -- do something
            end Send;
         or when not Done =>
            accept Close (Socket : Socket_Type) do
               -- do something
               end Close;
         else
            if not Done then
               -- receive data if necessary using GNAT.sockets.Check_Selector
               -- while no data is sent
            end if;
         end select;
         exit when Done;
      end loop;
   end Connection_Handler;

However, when Stop is called and Done set to True, I get 

  raised TASKING_ERROR : s-tasren.adb:445

as an exception in my AUnit test harness and the test ends prematurely with an error code. This occurs in the main program task, or at least if I add a catch-all exception handler in the above task body, it is *not* triggered there.

I thought this occurs perhaps because there is no terminate alternative, but if I add:
 
   or terminate;

before the else part, I get the error message "else part not allowed with other alternatives". So this is not possible.

Is there a way to stop the task gracefully (without abort) but also do some continuous processing like in the else part? Does anybody have an idea what might cause this error?