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From: Reto Buerki <reet@codelabs.ch>
Newsgroups: comp.lang.ada
Subject: Re: Barrier re-evaluation issue with GNAT 4.3.2
Date: Tue, 29 Sep 2009 10:30:44 +0200
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Date: 2009-09-29T10:30:44+02:00
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Jeffrey R. Carter wrote:
> Reto Buerki wrote:
>>
>> Update: we just noticed that the warning actually *does* show up but we
>> missed it in the previous build.
>>
>> I also think the warning is irrelevant. It seems that the compiler is
>> not smart enough to figure out that the Signal() entry is always open.
> 
> An entry call is always potentially blocking, regardless of its barrier;
> see ARM 9.5.1. Technically, this code contains a bounded error. Since
> the potentially blocking operation was detected, your program should
> raise Program_Error; GNAT pretends that it hasn't detected that the
> operation is potentially blocking and lets you get away with only a
> warning. Other compilers (and even other versions of GNAT) may actually
> raise Program_Error.

Thanks for the clarification and the pointer to the ARM. This basically
means that our workaround is not legal Ada code ...