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Path: utzoo!utgpu!water!watnot!watmath!clyde!burl!codas!peora!petsd!joe
From: joe@petsd.UUCP
Newsgroups: comp.lang.ada
Subject: Re: language problem
Message-ID: <997@petsd.UUCP>
Date: Wed, 1-Apr-87 10:05:16 EST
Article-I.D.: petsd.997
Posted: Wed Apr  1 10:05:16 1987
Date-Received: Sat, 4-Apr-87 07:03:15 EST
References: <8703261730.AA28726@taurus>
Reply-To: joe@petsd.UUCP (Joseph M. Orost)
Distribution: world
Organization: Concurrent Computer Corporation, Tinton Falls, NJ
List-Id: <comp.lang.ada>

In article <8703261730.AA28726@taurus> amiram@TAURUS.BITNET.UUCP writes:
>A colleague of mine, Yossi Veler of AITECH has come up with the following
>program in Ada, which seems to create a serious problem.
>
>procedure boolsub is
>   subtype bool is boolean range true..true;
>   type arr is array(1..10) of bool;
>   a : arr := (1..10 => true); -- this seems like the only legal value
>begin
>   a := not a;
>-- Here a(1)=a(2)=...=a(10)= FALSE !!!! No exception occurs etc.
>   a := (1..10 => false);
>-- This does cause an exception
>end boolsub;
>
>The program seems legal : we inspected the LRM and also the implementers
>guide, and we ran it on both the DDC and VERDIX compilers. It seems that
>a combination of innocent features in Ada produces a result that seems to
>contradict with the basic philosophy of the language, that is an object
>posseses a value which is not in the appropriate type.

Our compiler (C3Ada R00-01.02/Beta) correctly raises CONSTRAINT_ERROR on the
statement "a := not a;".

				regards,
				joe

--

 Full-Name:  Joseph M. Orost
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