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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Uninitialized "out" parameters
Date: 1996/07/24
Message-ID: <Dv2Cq5.HFp@world.std.com>#1/1
X-Deja-AN: 169950749
references: <4smh9i$gp5@krusty.irvine.com> <4ste71$hg8@felix.seas.gwu.edu>
 <4svba5$j2i@mulga.cs.mu.OZ.AU> <4t3o3s$kt9@felix.seas.gwu.edu>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-07-24T00:00:00+00:00
List-Id: <comp.lang.ada>


There's a lot of stuff about warnings in this thread.

With regard to uninit vars, the compiler can categorize each variable
reference as one of (1) correct, (2) wrong, or (3) don't know.  A goal,
of course, is to make the compiler as smart as possible, so the
likelihood of category (3) is as small as possible.  The halting theorem
tells we can't shrink (3) to zero (given the rules of Ada).

Clearly, the compiler should warn for (2), not warn for (1).  But what
should it do for (3)?  False warnings can be such a big pain as to make
all the warnings useless.  I don't want to clutter my code with useless
initializations, in cases where I'm smart enough to prove it, but the
compiler isn't.  My experience is that most compilers leave a *lot* of
cases in category (3).  Opinions?

- Bob