[Bug c++/64514] New: Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[Bug c++/64514] New: Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[freddie_chopin at op dot pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

            Bug ID: 64514
           Summary: Error in template instantiation in GCC 4.9, works fine
                    in GCC 4.8
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: freddie_chopin at op dot pl

The test code below works perfectly fine with GCC 4.8 (and 4.7):

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

#include <type_traits>

template<typename T, T &object, typename... Args>
struct Functor
{
    template<float (T::*function)(Args...), Args... args>
    struct Inner
    {
        float operator()() const
        {
            return (object.*function)(args...);
        }
    };
};

class Object
{
public:

    float someFunction()
    {
        return {};
    }

    float someFunctionWithArgument(int)
    {
        return {};
    }
};

Object object;

Functor<Object, object>::Inner<&Object::someFunction> functor1;
Functor<Object, object, int>::Inner<&Object::someFunctionWithArgument, 1>
functor2;

int main()
{

}

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

However with GCC 4.9 it fails with a rather unhelpful message at the point of
instantiation of functor1:

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

$ g++ -std=c++11 test.cpp 
test.cpp: In instantiation of ‘struct Functor<Object, (* & object)>’:
test.cpp:33:24:   required from here
test.cpp:7:9: error: wrong number of template arguments (2, should be 1)
  struct Inner
         ^
test.cpp:7:9: error: provided for ‘template<class T, T& object, class ... Args>
template<float (T::* function)(Args ...), Args ...args> struct Functor<T,
object, Args>::Inner’
test.cpp:7:9: error: wrong number of template arguments (2, should be 1)
test.cpp:7:9: error: provided for ‘template<class T, T& object, class ... Args>
template<float (T::* function)(Args ...), Args ...args> struct Functor<T,
object, Args>::Inner’
test.cpp:33:26: error: ‘Inner’ in ‘struct Functor<Object, (* & object)>’ does
not name a template type
 Functor<Object, object>::Inner<&Object::someFunction> functor1;
                          ^

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

If I comment the line with functor1 instantiation, everything else (functor2)
works fine.

At the stackoverflow question I asked (
http://stackoverflow.com/questions/27802404/error-in-template-instantiation-in-gcc-4-9-works-fine-in-gcc-4-8?noredirect=1#comment44015634_27802404
) it was reported that clang 3.5 and Visual Studio 2015 Preview accept this
code, while intel 14 errors out (with an unreported message) and solaris studio
12.4 crashes.

Is there something wrong with this code (which was working for me for over 2
years with older versions) or maybe this is a regression?
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Subject: [Bug c++/64489] A simple struct wrapping a const int is not trivially copyable
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd489

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Tue Jan  6 20:44:32 2015
New Revision: 219265

URL: https://gcc.gnu.org/viewcvs?rev!9265&root=gcc&view=rev
Log:
    PR c++/64489
    * class.c (check_field_decls): Make copy assignment operators
    complex only in c++98 mode.

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/class.c
    trunk/gcc/testsuite/g++.dg/ext/is_trivially_constructible1.C

[Bug c++/64514] Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-12
                 CC|                            |ville.voutilainen at gmail dot com
     Ever confirmed|0                           |1
      Known to fail|                            |4.9.1, 5.0

[Bug c++/64514] [4.9/5 Regression] Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[freddie_chopin at op dot pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

--- Comment #1 from Freddie Chopin <freddie_chopin at op dot pl> ---
The question at stackoverflow has an answer with much simpler test-case which
also shows the problem. http://stackoverflow.com/a/27810002/157344

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

template<typename... T>
struct Functor
{
    template <T...>
    struct Inner
    {};
};

template struct Functor<>::Inner<>;

int main()
{

}

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

Compiled with GCC 4.9.2:

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

$ g++ -std=c++11 test.cpp 
test.cpp: In instantiation of ‘struct Functor<>’:
test.cpp:9:26:   required from here
test.cpp:5:12: error: wrong number of template arguments (1, should be 0)
     struct Inner
            ^
test.cpp:5:12: error: provided for ‘template<class ... T> template<T
...<anonymous> > struct Functor<T>::Inner’
test.cpp:5:12: error: wrong number of template arguments (1, should be 0)
test.cpp:5:12: error: provided for ‘template<class ... T> template<T
...<anonymous> > struct Functor<T>::Inner’
test.cpp:9:28: error: ‘Inner’ is not a class template
 template struct Functor<>::Inner<>;
                            ^
test.cpp:9:28: error: ‘Inner’ in ‘struct Functor<>’ does not name a type

--- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 --- >8 ---

Works fine with GCC 4.8.

The answer also suggests there might be another similar bug, possibly related
to the first one.
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Subject: [Bug tree-optimization/64454] optimize (x%5)%5
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd454

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #5)
> The reason for tree_int_cst_sgn (vr->min) >= 0 was that I don't want to let
> 0 through and for negative values, handling those would require computing
> absolute value, but as match.pd already folds x % -5 already into x % 5,
> there is no need to bother with it, so I'm just trying to play safe.

I don't think we are talking about the same thing. Restricting to positive op1
is good. What I find a little strange is:

+      if (TYPE_UNSIGNED (TREE_TYPE (op0))
+      || tree_int_cst_sgn (vr->min) >= 0
+      || tree_int_cst_lt (fold_unary (NEGATE_EXPR, TREE_TYPE (op1), op1),
+                  vr->min))

where condition 2: min>=0 is more restrictive than condition 3: min>-op1 (since
op1 is known to be positive) so we could skip condition 2.

[Bug c++/64514] [4.9/5 Regression] Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Tue Jan 13 21:04:35 2015
New Revision: 219558

URL: https://gcc.gnu.org/viewcvs?rev=219558&root=gcc&view=rev
Log:
    PR c++/64514
    * pt.c (coerce_template_parameter_pack): Return NULL for a
    zero-length fixed parameter pack with a pack expansion arg.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/variadic165.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c

[Bug c++/64514] [4.9/5 Regression] Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Wed Jan 28 17:21:06 2015
New Revision: 220210

URL: https://gcc.gnu.org/viewcvs?rev=220210&root=gcc&view=rev
Log:
    PR c++/64514
    * pt.c (coerce_template_parameter_pack): Return NULL for a
    zero-length fixed parameter pack with a pack expansion arg.

Added:
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/cpp0x/variadic165.C
Modified:
    branches/gcc-4_9-branch/gcc/cp/ChangeLog
    branches/gcc-4_9-branch/gcc/cp/pt.c

[Bug c++/64514] [4.9/5 Regression] Error in template instantiation in GCC 4.9, works fine in GCC 4.8

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64514

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jason at gcc dot gnu.org
         Resolution|---                         |FIXED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
   Target Milestone|---                         |4.9.3

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 4.9.3/5