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From: stan@csam.lbl.gov (See-Mong Tan)
Newsgroups: comp.lang.c++
Subject: Bug in 2.0 with Pass by Reference?
Keywords: bug, cfront 2.0, pass by reference
Message-ID: <4577@helios.ee.lbl.gov>
Date: 7 Jan 90 02:35:49 GMT
Sender: usenet@helios.ee.lbl.gov
Reply-To: stan@brutus.cs.uiuc.edu (See-Mong Tan)
Followup-To: comp.lang.c++
Organization: Lawrence Berkeley Laboratory, University of Illinois
Lines: 48
X-Local-Date: 6 Jan 90 18:35:49 PST


I seem to have stumbled upon a bug with cfront 2.0.
It has to do with passing a variable by reference.  It failed
in this code here:

There are two functions, the first is:

> int FSI::pathOpen( char *, StoredObject * &, Class *);

Note that it expects the second argument to be a variable that's
passed by reference.

The next function calls the first:

> int FSI::keys(char *dirname, char *buf, int size, int &count)
> {
> 	ObjectDictionary * od = 0;
>       // call pathOpen, pass variable od by reference
> 	int status = pathOpen( dirname, od, ObjectDictionaryClass );
> 	....
> }

The generated code for the second function however, looks like:

> int keys__ [... declarations ..]
> {
> 
> struct ObjectDictionary *__1od;
> int __1status;
> 
> {
> struct StoredObject *__0__I36;             // A temporary variable?
> 
> __1status = pathOpen__3FSIFPcRP12StoredObjectP5Class ( __0this, __0dirname, (struct StoredObject **) ( (__0__I36 = (struct StoredObject *) __1od ), (& __0__I36 )) , ObjectDictionaryClass);
> 
> ...
> }
> 
> }

Notice that the call to pathOpen does not correctly pass by reference
the second argument... why does this happen?

It happened on a Cray first, with the cfront I ported, 
so I thought I broke something, but then cfront 2.0 for the
Suns here gave the same output.  Is there a fix for this?

stan