From: "Alex Mentis" <foo@invalid.invalid>
Subject: Unconstrained base subtype questions
Date: Thu, 31 Mar 2011 20:25:13 +0000 (UTC)
Date: 2011-03-31T20:25:13+00:00 [thread overview]
Message-ID: <in2nv8$v3e$1@dont-email.me> (raw)
The following does not cause a constraint error in my version of GNAT
on my system:
...
Integer_Result := (Integer'Last + Integer'Last) / 2;
...
If I understand correctly, this is because the Integer operators are
defined for operands of type Integer'Base, which is an unconstrained
subtype and allows the operands to be stored in extended-length
registers so that intermediate values in calculations do not overflow.
My questions are:
1) Do I understand correctly what's going on?
2) Does the language make any guarantees about preventing spurious
overflow, or am I just getting lucky with my compiler/architecture? If
guarantees are made by the language, what are they?
Thanks,
Alex
next reply other threads:[~2011-03-31 20:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-31 20:25 Alex Mentis [this message]
2011-03-31 21:09 ` Unconstrained base subtype questions Ludovic Brenta
2011-03-31 21:26 ` Alex Mentis
2011-03-31 21:36 ` Ludovic Brenta
2011-03-31 22:18 ` Adam Beneschan
2011-03-31 21:10 ` Adam Beneschan
2011-03-31 21:18 ` Simon Wright
2011-03-31 21:24 ` Randy Brukardt
2011-03-31 21:51 ` Alex Mentis
2011-04-01 8:20 ` Dmitry A. Kazakov
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