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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Why is the destructor called multiple times after I declare an
 object?
Date: Mon, 11 Jan 2016 17:43:36 -0700
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Date: 2016-01-11T17:43:36-07:00
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On 01/11/2016 09:29 AM, Brian Drummond wrote:
> 
> Somehow I expected "extended return" to allocate space and "build in 
> place" during the execution of the return statement. 

Extended return is required for a limited type other than returning a function
call or aggregate. Limited types are build in place. But using an extended
return for a non-build-in-place type makes no difference.

> Is this something legal that Gnat doesn't take advantage of? Or is there 
> a Gnat option I'm not aware of?

A compiler can eliminate the anonymous object if it can be sure the result is
always the same as using it. It can build in place when not so required if it
can be sure the result is always the same as not building in place.

-- 
Jeff Carter
"C's solution to this [variable-sized array parameters] has real
problems, and people who are complaining about safety definitely
have a point."
Dennis Ritchie
25