[Bug c++/21514] New: operator<< and anonymous enum

[Bug c++/21514] New: operator<< and anonymous enum

[papadopo at shfj dot cea dot fr]

Hi,

The attached code emits a mysterious error:

$ g++ -c foo.cc
foo.cc: In function 'int main()':
foo.cc:13: error: '<anonymous enum>' is/uses anonymous type
foo.cc:13: error:   trying to instantiate 'template<class T> void
operator<<(MyClass&, const T&)'
$ 

The compiler apparently fails to see that the anonymous enum can be cast to an
integer.

-- 
           Summary: operator<< and anonymous enum
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: papadopo at shfj dot cea dot fr
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: sparc-sun-solaris2.8
  GCC host triplet: sparc-sun-solaris2.8
GCC target triplet: sparc-sun-solaris2.8


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] operator<< and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-11 14:14 -------
There is some discussion on the list about this.  Right now there is a DR report about this and about is 
this really invalid code or not.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-05-11 14:14:28
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] operator<< and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-11 14:15 -------
Suspending as there is still questions is this really invalid code or not.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] templates and anonymous enum

[papadopo at shfj dot cea dot fr]

------- Additional Comments From papadopo at shfj dot cea dot fr  2005-05-11 14:21 -------
Whether the code is valid or not, please improve the error message :-)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] templates and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-11 14:25 -------
I don't see any how to improve the error message really since it says what the problem is.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] templates and anonymous enum

[papadopo at shfj dot cea dot fr]

------- Additional Comments From papadopo at shfj dot cea dot fr  2005-05-11 14:38 -------
I think the first line could be made clearer:
'<anonymous enum>' is/uses anonymous type
I'm reading it again and again, and it doesn't make sense to me.

Then the second line refers to an operator<< most probably defined in some
remote header file. This is distracting. I would suggest not printing this
second line at all.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] templates and anonymous enum

[papadopo at shfj dot cea dot fr]

------- Additional Comments From papadopo at shfj dot cea dot fr  2005-05-18 09:33 -------
I'm not sure what a DR is, probably a C++ standard defect report. After asking
on fr.comp.lang.c++ I was referred to Core Issue 278:
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#278

Whether the compiler should compile the code or not, the error message really
needs to be improved. My understanding of the situation is that :

1.a) The compiler first attempts to apply the shift operator to integer "i".
However the right-side argument is an anonymous enum. The compiler will not
implictly cast the anonymous enum to a size_t to be used as the right-hand
argument for operator<<.

1.b) Note that an *explicit* cast does work, so I'm not sure how this whole
issue is related to Core Issue 278 and external linkage. Just change from:
    i<<HSize;
to:
    i<<int(HSize);
and the program while compile and link.

2) The compiler then attemps to use operator<<(MyClass& b, const T& t). Instead
of reporting an error on the first argument (type 'MyClass' expected, type 'int'
actually used), it reports an obscure error on the second argument. This is
totally non-intuitive for humans.

Therefore:

* Concerning 1.a) and 1.b) I'm not convinced this is related to Core Issue 278
and external linkage since the explicit cast works. Anyway, if you feel Core
Issue 278 or some paragraph of the standard forbid the implicit cast, I agree
this bug report should be kept open until the comitee resolves the problem.

* In the meanwhile, the error message really needs to be improved, taking into
account point 2).


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED
            Summary|templates and anonymous enum|[DR 278] templates and
                   |                            |anonymous enum


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2005-05-18 14:04 -------
Subject: Re:  templates and anonymous enum

"papadopo at shfj dot cea dot fr" <gcc-bugzilla@gcc.gnu.org> writes:

[...]

| Therefore:
| 
| * Concerning 1.a) and 1.b) I'm not convinced this is related to Core Issue 278
| and external linkage since the explicit cast works. Anyway, if you feel Core
| Issue 278 or some paragraph of the standard forbid the implicit cast, I agree
| this bug report should be kept open until the comitee resolves the problem.

The way it is related is that the CWG has introduced the concent of
linkage for type -- which did not exist in ARM and existed only for
function type in C++98/03 and the unnamed enum no longer has an
external linkage.  As I said on fr.comp.lang.c++, I brought the issue
to the C++ committee and I think the issue should not be closed.

The answer I gave you was much more detailed and accurate that what
you report here :-) -- in particular, the ocmpiler is attempting to do
overload resolution and it is in the phase of constructing the
overload set that the error appears.  But, the whole thing is confused
:-)

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[papadopo at shfj dot cea dot fr]

------- Additional Comments From papadopo at shfj dot cea dot fr  2005-05-18 14:56 -------
I guess what I meant is: whatever the reason for this error message and whatever
the eventual decision taken about it, it would be nice to have an error message
that really means something to end-users.

For example, as an end-user, I still can't understand the difference between the
explicit cast and the implicit (non-)cast, why it works in the first case and
not in the latter. The error message shoudl really point at what's wrong in the
source code, not at what's wrong in the C++ standard.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[pcarlini at suse dot de]

------- Additional Comments From pcarlini at suse dot de  2005-05-18 15:00 -------
> .......... The error message shoudl really point at what's wrong in the
> source code, not at what's wrong in the C++ standard.

But unfortunately if the compiler is conforming, and the latter is wrong,
the former is "correct" as-is and the error message too ;)

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2005-05-18 15:07 -------
Subject: Re:  [DR 278] templates and anonymous enum

"papadopo at shfj dot cea dot fr" <gcc-bugzilla@gcc.gnu.org> writes:

| I guess what I meant is: whatever the reason for this error message
| and whatever the eventual decision taken about it, it would be nice
| to have an error message that really means something to end-users.

100% agreed.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[papadopo at shfj dot cea dot fr]

------- Additional Comments From papadopo at shfj dot cea dot fr  2005-05-18 15:13 -------
OK, then what I really meant is that error message doesn't mean anything in
plain English, thus it doesn't mean anything to end-users. So it needs to be
improved. I understand it's not easy - after all no one here is able to explain
what really is behind this bug. I'm not a native speaker, I'm just a rather
skilled end-user; I can nevertheless guarantee that end-users don't understand
this error message. We spent a few hours trying and finding what needs to be
changed in some 3rd party library we're using, because the compiler was pointing
to a totally unrelated template definition of operator<< in our own sources.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2005-05-18 17:08 -------
Subject: Re:  [DR 278] templates and anonymous enum

"pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

| > .......... The error message shoudl really point at what's wrong in the
| > source code, not at what's wrong in the C++ standard.
| 
| But unfortunately if the compiler is conforming, and the latter is wrong,
| the former is "correct" as-is and the error message too ;)

I think his point is that the diagnostic message is not helpful.  And
I agree with him.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-21 18:01 -------
*** Bug 21701 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mmarcus at emarcus dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[ebotcazou at gcc dot gnu dot org]

------- Additional Comments From ebotcazou at gcc dot gnu dot org  2005-05-31 16:55 -------
Not specific to sparc-sun-solaris2.8.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  GCC build triplet|sparc-sun-solaris2.8        |
   GCC host triplet|sparc-sun-solaris2.8        |
 GCC target triplet|sparc-sun-solaris2.8        |s


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-15 19:48 -------
*** Bug 22505 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |snoonan at nvidia dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 278] templates and anonymous enum

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2005-09-15 21:31 -------
Why is this marked as DR 278?  I think it's DR 488.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 488] templates and anonymous enum

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-09-16 15:42 -------
Subject: Bug 21514

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	mmitchel@gcc.gnu.org	2005-09-16 15:41:45

Modified files:
	gcc/cp         : ChangeLog pt.c 
	gcc/testsuite  : ChangeLog 
	gcc/testsuite/g++.dg/template: crash19.C local4.C 

Log message:
	PR c++/21514
	* pt.c (check_instantiated_args): Treat uses of anonymous types as
	causing type-deduction failure.
	
	PR c++/21514
	* g++.dg/template/crash19.C: Remove dg-error marker.
	* g++.dg/template/local4.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4895&r2=1.4896
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/pt.c.diff?cvsroot=gcc&r1=1.1037&r2=1.1038
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.6070&r2=1.6071
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/crash19.C.diff?cvsroot=gcc&r1=1.3&r2=1.4
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/local4.C.diff?cvsroot=gcc&r1=1.3&r2=1.4



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 488] templates and anonymous enum

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-09-16 15:43 -------
Subject: Bug 21514

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-4_0-branch
Changes by:	mmitchel@gcc.gnu.org	2005-09-16 15:43:14

Modified files:
	gcc/cp         : ChangeLog pt.c 
	gcc/testsuite  : ChangeLog 
	gcc/testsuite/g++.dg/template: crash19.C local4.C 

Log message:
	PR c++/21514
	* pt.c (check_instantiated_args): Treat uses of anonymous types as
	causing type-deduction failure.
	
	PR c++/21514
	* g++.dg/template/crash19.C: Remove dg-error marker.
	* g++.dg/template/local4.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.4648.2.105&r2=1.4648.2.106
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/pt.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.978.2.26&r2=1.978.2.27
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.5084.2.407&r2=1.5084.2.408
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/crash19.C.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.3&r2=1.3.12.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/local4.C.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.2.6.1&r2=1.2.6.2



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 488] templates and anonymous enum

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2005-09-16 15:47 -------
Fixed in 4.0.2.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.0.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514

[Bug c++/21514] [DR 488] templates and anonymous enum

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-16 16:01 -------
*** Bug 21701 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21514