[Bug c++/56611] New: [C++11] Template instanciation failure with variadic arguments and template aliases

["antoinep92 at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56611

             Bug #: 56611
           Summary: [C++11] Template instanciation failure with variadic
                    arguments and template aliases
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: antoinep92@gmail.com


The attached code fails to compile because of failed template instanciation /
type matching, but seems correct, compiles with clang, and can be made to
compile with gcc with minor modifications (see code comments).

Problem statement:
R<Func(int, int)> need result2<int, int> but the compiler does not seem able to
instanciate result2<int, int>. If result2<int, int> is explicitly instanciated,
the code compiles. Also if template alias result2 is replaced with a typedef in
a class (result1) the code compiles.
______________________

gcc 4.7.2 configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.7.2-2ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object
--enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu