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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ichbiah's Letter
Date: Sun, 26 Oct 2014 00:33:31 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2014-10-26T00:33:31-05:00
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"Simon Wright" <simon@pushface.org> wrote in message 
news:lyppdg8k7q.fsf@pushface.org...
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>
>> Presently approximately 50-80% of all run-time faults are due to
>> false-positive dynamic checks.
>
> This is certainly not true in the code I have been involved with. In
> fact I don't recall ever having seen such a fault (assuming, that is,
> that 'false-positive' means that it's some non-obvious consequence of
> Ada's rules).

If you use anonymous access types unsafely (that is, to convert them to 
other types), it will happen a lot. If you use anonymous access types 
sparingly (mostly as a stand-in for out parameters in functions, a 
work-around you don't need in Ada 2012), you won't run into *dynamic* 
accessibility checks. (Dynamic checks are only possible in generic bodies 
and with anonymous access types.)

Similarly for the checks associated with class-wide types. If you don't 
derive tagged types in subprograms, you'll never see one of those checks (if 
everything is library-level, no check is possible). And again, almost all of 
those checks are static.

                         Randy.