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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Pointer to instance of indefinite array?
Date: Wed, 13 Aug 2014 21:17:08 +0300
Organization: Tidorum Ltd
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Date: 2014-08-13T21:17:08+03:00
List-Id: <comp.lang.ada>

On 14-08-13 07:31 , Per Sandberg wrote:
> Well,
> The compiler uses the most appropriate method of passing parameters (by
> value or by reference) depending on the kind of object, this usually
> means that composite types is passed by reference and scalars is passed
> by value.

Anecdote: Long ago, there was an (in)famous version of GNAT (something
like 2.95p, perhaps?) for which AdaCore had decided to be "more
compatible with C" and therefore to pass record types by copy.

I was developing an application that heavily relied on passing large
records around. We ended up delivering the application with advice to
use a 10 MB stack limit... a large amount, at the time. Luckily the
application was not time-critical.

However, this compiler "feature" also revealed an aliasing bug in the
application, where one of my procedures was reading a record object
passed as a parameter, while modifying it as a global (IIRC). Perhaps
GNAT should have an option to use pass-by-copy wherever it can, to smoke
out such bugs :-).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .