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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,29fe9a340e0d180d,start
X-Google-Attributes: gid103376,public
From: Andre Spiegel <spiegel@inf.fu-berlin.de>
Subject: Depending on passing mechanism
Date: 1997/10/13
Message-ID: <x2hgal3jxa.fsf@moon.inf.fu-berlin.de>#1/1
X-Deja-AN: 280090106
Sender: spiegel@moon.inf.fu-berlin.de
Organization: Freie Universitaet Berlin
X-Access: 16 17 19
Newsgroups: comp.lang.ada
Date: 1997-10-13T00:00:00+00:00
List-Id: <comp.lang.ada>


This has been discussed before, but I couldn't find the information I
need on DejaNews...

In Ada, compilers may choose to pass certain types either by reference
or by copy (see RM95 6.2).  This allows for greater efficiency (bit
arrays may be passed in registers, etc.), but under some
circumstances, this can change program semantics (RM95 6.2(12)).

I know that it is not possible to forbid these problematic cases
altogether, because detecting them would be equivalent to solving the
halting problem.

Question: Could anyone give me references to papers, books, or web
pages where this is discussed?  Particularly, I'm looking for

  * the proof that it's equivalent to the halting problem.  (I could
    do it myself, but I'd like to reference it in a paper.)

  * a discussion as to how far compilers can reasonably go, i.e. which
    cases can in fact be detected, and under what cost.

Please reply by e-mail, I'll summarize.  
Thanks,

Andre Spiegel
Free University of Berlin