From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,4fe0da28a190b761,start
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!inka.de!rz.uni-karlsruhe.de!news.belwue.de!LF.net!news.enyo.de!not-for-mail
From: Florian Weimer <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
Subject: Storage management
Date: Sat, 01 Nov 2008 12:13:01 +0100
Message-ID: <87fxmbog1u.fsf@mid.deneb.enyo.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: idssi.enyo.de 1225537981 23233 212.9.189.177 (1 Nov 2008 11:13:01
 GMT)
X-Complaints-To: 
Cancel-Lock: sha1:zCxHg9LW/c4pS0vJhgVe38r6cpQ=
Xref: g2news1.google.com comp.lang.ada:2544
Date: 2008-11-01T12:13:01+01:00
List-Id: <comp.lang.ada>

What is the current state of the art with regard to programmer support
for storage management?

With GNAT, Ada.Finalization adds tons of run-time calls to deal with
abort deferral (even with pragma Restrictions (No_Abort_Statements)),
puts the object on some sort of list, and does some secondary stack
allocations which I don't understand.  Clearly, this is not supposed
to be used in performance-critical code, so I doubt it can be used for
a generic smart pointer implementation.  (Object allocation in inner
loops is generally a bad idea, but this overhead is also incurred when
copying smart pointers around.)

Is there some other approach?  Can limited types be used to enforce
linearity (in the sense of linear types, cf.
<http://home.pipeline.com/~hbaker1/Use1Var.html> and
<http://iml.univ-mrs.fr/~girard/linear.pdf>)?

If it's about pure storage management, GC support would be an option,
too, but AFAIK, you need one of the managed code implementations for
that, or somewhat unsafe libraries (in the sense that you need to
specify which objects are leaf objects, and only store access values
in locations where they are visible to the collector).