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* Re: c++/6507: auto type promotion of referee in reference member variable initialization
@ 2002-06-05 8:26 lerdsuwa
0 siblings, 0 replies; 6+ messages in thread
From: lerdsuwa @ 2002-06-05 8:26 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, stephen.hill
Synopsis: auto type promotion of referee in reference member variable initialization
State-Changed-From-To: open->feedback
State-Changed-By: lerdsuwa
State-Changed-When: Wed Jun 5 08:26:53 2002
State-Changed-Why:
The testcase is missing from the bug report. Could you
please submit it again?
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6507
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/6507: auto type promotion of referee in reference member variable initialization
@ 2003-01-23 1:45 bangerth
0 siblings, 0 replies; 6+ messages in thread
From: bangerth @ 2003-01-23 1:45 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, stephen.hill
Synopsis: auto type promotion of referee in reference member variable initialization
State-Changed-From-To: open->closed
State-Changed-By: bangerth
State-Changed-When: Thu Jan 23 01:45:36 2003
State-Changed-Why:
Duplicate of PR 986.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6507
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/6507: auto type promotion of referee in reference member variable initialization
@ 2003-01-17 14:47 paolo
0 siblings, 0 replies; 6+ messages in thread
From: paolo @ 2003-01-17 14:47 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, stephen.hill
Synopsis: auto type promotion of referee in reference member variable initialization
State-Changed-From-To: closed->open
State-Changed-By: paolo
State-Changed-When: Fri Jan 17 06:47:39 2003
State-Changed-Why:
At last, testcase received.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6507
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/6507: auto type promotion of referee in reference member variable initialization
@ 2003-01-17 14:46 Hill Stephen-STEHILL1
0 siblings, 0 replies; 6+ messages in thread
From: Hill Stephen-STEHILL1 @ 2003-01-17 14:46 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c++/6507; it has been noted by GNATS.
From: Hill Stephen-STEHILL1 <Stephen.Hill@motorola.com>
To: Hill Stephen-STEHILL1 <Stephen.Hill@motorola.com>,
"'gcc-gnats@gcc.gnu.org'" <gcc-gnats@gcc.gnu.org>,
"'gcc-prs@gcc.gnu.org'" <gcc-prs@gcc.gnu.org>,
"'gcc-bugs@gcc.gnu.org'"
<gcc-bugs@gcc.gnu.org>,
"'nobody@gcc.gnu.org'" <nobody@gcc.gnu.org>
Cc:
Subject: Re: c++/6507: auto type promotion of referee in reference member
variable initialization
Date: Fri, 17 Jan 2003 14:41:56 -0000
This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
------_=_NextPart_000_01C2BE36.95877D52
Content-Type: text/plain;
charset="iso-8859-1"
Apologies,
I had some email issues which led to my mail of the testcase (attached)
being bounced. This got missed in the email deluge on my return from a
holiday. So here is the testcase again.
Thanks
Steve
<<bug_test.cc>>
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&p
r=6507
------_=_NextPart_000_01C2BE36.95877D52
Content-Type: application/octet-stream;
name="bug_test.cc"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: attachment;
filename="bug_test.cc"
/* gcc version 3.1 configured with configure --enable-threads =
--with-cpu=3Di686
first discovered on g++ version 2.95.2 19991024 (release)=20
=09
bug_test - steve hill 29/04/02. email: stephen.hill@motorola.com
=09
a,b are constant references to private member variables p_a,p_b. If we =
get the class wrong on p_b (line 52), then b and p_b are of different =
classes
but the compiler does not issue a warning or error, and makes p_b =
refer to a different address than the one we intend - probably because =
the automatic=20
type promotion is invoked. No warning is issued that auto type =
promotion (or whatever) has changed the address of the referee. */
#include <iostream>
using namespace std;
typedef unsigned short int ID;
class Foo
{
int i;
=09
public:
Foo(int j) //no bug if this is declared as explicit
:i(j)
{};
=09
/* //Issues a compile error if this is included because auto type =
promotion is not now possible
Foo()
:i(0)
{};=20
*/
~Foo()
{};
};
class bug_test
{
public:
const ID &a;
const Foo &b; =20
=09
bug_test()
:a(p_a),b(p_b),p_a(1),p_b(2)
{
cerr<<"Reference addresses:\t" << &a << " " << &b << "\n";
cerr<<"Referee addresses:\t"<<&p_a << " " << &p_b << "\n";
};
~bug_test()
{};
=09
private:
ID p_a;
ID p_b; // !! should be declared as a Foo !! =09
};
int main()
{
bug_test b;
return 0;
}
------_=_NextPart_000_01C2BE36.95877D52--
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/6507: auto type promotion of referee in reference member variable initialization
@ 2003-01-14 22:58 bangerth
0 siblings, 0 replies; 6+ messages in thread
From: bangerth @ 2003-01-14 22:58 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, stephen.hill
Synopsis: auto type promotion of referee in reference member variable initialization
State-Changed-From-To: feedback->closed
State-Changed-By: bangerth
State-Changed-When: Tue Jan 14 14:58:05 2003
State-Changed-Why:
No feedback.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6507
^ permalink raw reply [flat|nested] 6+ messages in thread
* c++/6507: auto type promotion of referee in reference member variable initialization
@ 2002-04-29 8:16 stephen.hill
0 siblings, 0 replies; 6+ messages in thread
From: stephen.hill @ 2002-04-29 8:16 UTC (permalink / raw)
To: gcc-gnats
>Number: 6507
>Category: c++
>Synopsis: auto type promotion of referee in reference member variable initialization
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: unassigned
>State: open
>Class: accepts-illegal
>Submitter-Id: net
>Arrival-Date: Mon Apr 29 08:16:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: stephen.hill@motorola.com
>Release: gcc 2.95.2 19991024 (release)
>Organization:
>Environment:
Linux x86 (suse 7.0 default install)
>Description:
Note: I'm not sure if this really is a bug (or just a feature), but it strikes me that the code is doing something so different from a reasonable expectation that a closer examination of the reasoning might be desirable.
When initializing a reference member variable of a class, it appears that gcc attempts do do a type promotion of the referee into the reference class, then references the promoted variable.
In the attached code, note the difference between reference and referee addresses.If the constructor (lines 19-22) is replaced by a constructor which does not take an argument of the reference type (lines 24-27) an error is generated. This makes me believe that automatic type promotion is involved.
Note that if b (line 38) is declared as
const explicit Foo &b;
rather than
const Foo &b
then no problem results.
Thanks,
steve
>How-To-Repeat:
compile attached file (gcc -o bug_test bug_test.cc)
run (./bug_test)
>Fix:
Assume that member references to member variables are explicit or warn?
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2003-01-23 1:45 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2002-06-05 8:26 c++/6507: auto type promotion of referee in reference member variable initialization lerdsuwa
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2003-01-23 1:45 bangerth
2003-01-17 14:47 paolo
2003-01-17 14:46 Hill Stephen-STEHILL1
2003-01-14 22:58 bangerth
2002-04-29 8:16 stephen.hill
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