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From: "W. Wesley Groleau (Wes)" <wwgrol@PSESERV3.FW.HAC.COM>
Subject: Re: Integer'Size < 32 ?
Date: 1996/08/08
Message-ID: <9608081258.AA02749@most>#1/1
X-Deja-AN: 173071677
sender: Ada programming language <INFO-ADA@LISTSERV.NODAK.EDU>
comments: To: info-ada%listserv.nodak.edu@emcee.com
mailer: Elm [revision: 70.85]
newsgroups: comp.lang.ada
Date: 1996-08-08T00:00:00+00:00
List-Id: <comp.lang.ada>


There have been many good answers to the two questions about 16 bit
integers (IMHO Dewar's was the clearest) but none of them mentioned
one detail:

One of the queries suggested that constraint_error would be raised
if the compiler did not have a big enough predefined integer type.

The truth is, if such a type is not supported, the compiler is supposed
to refuse to compile the program.

But I have a related question: many of the posts on the topic repeated
the definition

   .... range -(2**31) .. ((2**31)-1)

I once used a compiler for which Integer'Size = 32 and which had an
interesting "feature."  It recognized that the above would fit in 32 bits,
so it compiled for that size.  Then at run-time, it would (obeying
the precedence rules) try to compute 2**31 and raise constraint_error.
(I didn't use the parentheses, but that doesn't change the semantics.)
The ugly work-around was

   .... range  -2**31 .. 2**30 + (2**30 - 1);

My question is, "Is this a common 'feature'?"  (Since so many people have
quoted the same example, I presume the answer is 'no')

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