[Bug c++/57734] New: Returning template alias to enum class fails with "invalid declarator"

[rschumacher at tamu dot edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57734

            Bug ID: 57734
           Summary: Returning template alias to enum class fails with
                    "invalid declarator"
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rschumacher at tamu dot edu

Created attachment 30390
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30390&action=edit
Test file exhibiting the bug (test.ii).

When attempting to return a template alias to an enum class, g++ emits the
error "invalid declarator before 'foo'".

Code:

enum class eclass { zero };

template<typename a>
using eclass_alias = eclass;

template<typename T0>
eclass_alias<T0> foo(T0 f) { return eclass_alias<T0>::zero; }

int main() {}

Command Line:

g++-4.9 -v -save-temps -std=c++11 test.cpp

Compiler Output:

test.cpp:7:18: error: invalid declarator before ‘foo’
 eclass_alias<T0> foo(T0 f) { return eclass_alias<T0>::zero; }
                  ^

Compiler Specs:

Using built-in specs.
COLLECT_GCC=g++-4.9
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /home/ras0219/abs/gcc-git/src/gcc/configure --prefix=/usr
--libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --datadir=/usr/share/gcc-4.9
--with-bugurl='http://aur.archlinux.org/packages.php?ID=16045'
--enable-languages=c,c++,lto --enable-shared --enable-threads=posix
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-clocale=gnu --disable-libstdcxx-pch --enable-gnu-unique-object
--enable-linker-build-id --enable-cloog-backend=isl
--disable-cloog-version-check --enable-lto --enable-gold --enable-ld=default
--enable-plugin --with-plugin-ld=ld.gold --with-linker-hash-style=gnu
--disable-install-libiberty --disable-multilib --disable-libssp
--disable-werror --enable-checking=release --program-suffix=-4.9
--enable-version-specific-runtime-libs : (reconfigured)
/home/ras0219/abs/gcc-git/src/gcc/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--datadir=/usr/share/gcc-4.9
--with-bugurl='http://aur.archlinux.org/packages.php?ID=16045'
--enable-languages=c,c++,lto --enable-shared --enable-threads=posix
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-clocale=gnu --disable-libstdcxx-pch --enable-gnu-unique-object
--enable-linker-build-id --enable-cloog-backend=isl
--disable-cloog-version-check --enable-lto --enable-gold --enable-ld=default
--enable-plugin --with-plugin-ld=ld.gold --with-linker-hash-style=gnu
--disable-install-libiberty --disable-multilib --disable-libssp
--disable-werror --enable-checking=release --program-suffix=-4.9
--enable-version-specific-runtime-libs
Thread model: posix
gcc version 4.9.0 20130627 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/cc1plus -E -quiet -v -D_GNU_SOURCE
test.cpp -mtune=generic -march=x86-64 -std=c++11 -fpch-preprocess -o test.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include/c++

/usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include/c++/x86_64-unknown-linux-gnu
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include/c++/backward
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include
 /usr/local/include
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/cc1plus -fpreprocessed test.ii
-quiet -dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase test -std=c++11
-version -o test.s
GNU C++ (GCC) version 4.9.0 20130627 (experimental) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.9.0 20130627 (experimental), GMP version
5.1.2, MPFR version 3.1.2, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.9.0 20130627 (experimental) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.9.0 20130627 (experimental), GMP version
5.1.2, MPFR version 3.1.2, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 527d08db754c44431edf3997957f9281

System Info:

Linux phylactery 3.9.6-1-ARCH #1 SMP PREEMPT Fri Jun 14 08:12:55 CEST 2013
x86_64 GNU/Linux