[Bug c++/34052] New: [4.3 regression] Trouble with variadic templates as template-template parameter

[Bug c++/34052] New: [4.3 regression] Trouble with variadic templates as template-template parameter

[reichelt at gcc dot gnu dot org]

The following code snippet is IMHO wrongly accepted on mainline:

=====================================================================
template<template<typename... T, typename = T> class U> struct A {};
=====================================================================

A slightly modified example ICE's:

=====================================================================
template<template<typename... T, typename = T> class U> struct A
{
  template<int> U<int> foo();
};
=====================================================================

bug.cc:3: internal compiler error: in tsubst, at cp/pt.c:8466
Please submit a full bug report, [etc.]


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           Summary: [4.3 regression] Trouble with variadic templates as
                    template-template parameter
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: ice-on-invalid-code, accepts-invalid, monitored
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[reichelt at gcc dot gnu dot org]

-- 

reichelt at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-11-19 04:17 -------
Confirmed, the regression part is an error-recovery issue.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |error-recovery
   Last reconfirmed|0000-00-00 00:00:00         |2007-11-19 04:17:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2007-12-02 20:58 -------
 Mark, this is really only an error recovery regression. Can you relook at the
current priority?

Thanks,
Andrew Pinski

t1.cc:2: error: ISO C++ does not include variadic templates
t1.cc:4: internal compiler error: tree check: accessed elt 3 of tree_vec with 2
elts in coerce_template_parms, at cp/pt.c:5225
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mmitchel at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[dgregor at gcc dot gnu dot org]

-- 

dgregor at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |dgregor at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-11-19 04:17:13         |2007-12-20 21:00:48
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-01-03 16:01 -------
I agree, these sort of bugs should be P4 as a user will only see

t.C:1: error: ISO C++ does not include variadic templates
t.C:3: confused by earlier errors, bailing out


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[mmitchel at gcc dot gnu dot org]

------- Comment #4 from mmitchel at gcc dot gnu dot org  2008-01-03 17:02 -------
A user that has turned on C++0x will of course not see the message that ISO C++
doesn't allow variadic templates.  Our NEWS file is going to say that we have a
great new feature: variadic templates.  Given that, it's a feature just like
any other.  I'd like to see new features held to a high quality standard.

I see the argument that this isn't a regression, but if I'm a user, and I read
about the new feature, and I try it out, and things break, that seems bad.  So,
I'd prefer to leave it P2, but I agree that it's sort of a "low P2".


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[dgregor at gcc dot gnu dot org]

------- Comment #5 from dgregor at gcc dot gnu dot org  2008-01-11 15:24 -------
Amusingly enough (since this is the second time this has happened today), this
problem occurs both with and without variadic templates. The following code is
ill-formed according to C++98, but GCC accepts it:

  template<template<typename T = int, typename U> class C> struct X;

I'm working on a fix for both issues.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[andreasmeier80 at gmx dot de]

------- Comment #6 from andreasmeier80 at gmx dot de  2008-01-12 19:08 -------
Patch at http://gcc.gnu.org/ml/gcc-patches/2008-01/msg00491.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[dgregor at gcc dot gnu dot org]

------- Comment #7 from dgregor at gcc dot gnu dot org  2008-01-15 00:12 -------
Patch here: http://gcc.gnu.org/ml/gcc-patches/2008-01/msg00491.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[dgregor at gcc dot gnu dot org]

------- Comment #8 from dgregor at gcc dot gnu dot org  2008-01-15 16:07 -------
Subject: Bug 34052

Author: dgregor
Date: Tue Jan 15 16:06:48 2008
New Revision: 131543

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=131543
Log:
2008-01-15  Douglas Gregor  <doug.gregor@gmail.com>

       PR c++/34052
       * pt.c (check_default_tmpl_args): Check for parameter packs that
       aren't at the end of a primary template.
       (push_template_decl_real): Remove check for parameter packs that
       aren't at the end of a primary template; that now happens in
       check_default_tmpl_args.
       * semantics.c (finish_template_template_parm): Use
       check_default_tmpl_args to check for errors in the template
       parameter list.

2008-01-15  Douglas Gregor  <doug.gregor@gmail.com>

       PR c++/34052
       * g++.dg/cpp0x/vt-34052.C: New.
       * g++.dg/template/ttp26.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/vt-34052.C
    trunk/gcc/testsuite/g++.dg/template/ttp26.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052

[Bug c++/34052] [4.3 regression] Trouble with variadic templates as template-template parameter

[dgregor at gcc dot gnu dot org]

------- Comment #9 from dgregor at gcc dot gnu dot org  2008-01-15 16:07 -------
Fixed in mainline


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dgregor at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34052