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From: "G.B." <bauhaus@futureapps.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Is this a bug in my code or the compiler?
Date: Fri, 12 Jun 2015 19:25:00 +0200
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Date: 2015-06-12T19:25:00+02:00
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On 12.06.15 18:15, Dmitry A. Kazakov wrote:
> Foo (A) and Foo (A) -- Illegal
> Foo (A) and then Foo (A) -- Legal

C has similar features...

> P.P.S. It would become even worse with fine-grained parallelism, as Georg
> keep on suggesting.

Not sure to what this is referring (or how concatenation
"&" necessitates the apparent omission of a call, if not
a gotcha?).

Query-command separation (on objects) seems far better than
functions that make their side effects explicit.
IIUC, SofCheck has brought tons of aliasing analysis and
more to the AdaCore offerings, plus Parasail's automatically
parallel loops...

So, in Ada 83, when A is of an access type,

    Foo (A) and Foo (A)  -- Legal

Moreover, if B and A become pointing to the same object,

    Foo (A) and Foo (B)  -- Legal, same effects

Can a compiler detect this? --- So, you'd be asking for pure
functions? Or total referential transparency?