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From: "andreas.milton.m at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/46061] New: Variadic Template Templates: not expandable into fixed-size argument list, Implementation Gap.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D46061

           Summary: Variadic Template Templates: not expandable into
                    fixed-size argument list, Implementation Gap.
           Product: gcc
           Version: 4.5.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: andreas.milton.m@gmail.com


Created attachment 22073
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=3D22073
full demo for bug ( .ii-file <14 lines)

The following struct "type_list" marks a list of types, which is constructe=
d as
a template template class with a variadic type list of template arguments:

template <typename H, template <typename> class T, template <typename> clas=
s...
R>=20
struct type_list=20
{=20
   typedef type_list< T<H>, R... > tail;=20
};=20

template<typename H, template<typename> class T>=20
struct type_list<H,T> {};


The code (attached as variadic_templ_templ.ii) produces the following
error-message (identical for gcc 4.4 and 4.5.1):

"sorry, unimplemented: cannot expand =E2=80=98template<class> class ... R .=
..=E2=80=99 into a
fixed-length argument list"

No other flags than -v -save-temps -Wall -std=3Dc++0x were used.