[Bug c++/47475] New: Static member function template of class variadic template can't be called from the inside

[Bug c++/47475] New: Static member function template of class variadic template can't be called from the inside

[flo.goujeon at orange dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47475

           Summary: Static member function template of class variadic
                    template can't be called from the inside
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: flo.goujeon@orange.fr


GCC 4.5 and 4.6 can't compile the following piece of code, which seems valid:
****************************************
template<typename... Ts>
struct test;

template<>
struct test<>
{
    template<typename>
    static void f()
    {
    }
};

template<typename T, typename... Ts>
struct test<T, Ts...>
{
    template<typename U>
    static void f()
    {
        test<Ts...>::f<U>(); //compiler error here
    }
};
****************************************

Here is the compiler error message:
****************************************
|| /usr/local/bin/g++ -c main.cpp -W -Wall -pedantic -std=c++0x
|| main.cpp: In static member function ‘static void test<T, Ts ...>::f()’:
main.cpp|19 col 19| error: expected primary-expression before ‘>’ token
main.cpp|19 col 21| error: expected primary-expression before ‘)’ token
|| make: *** [main.o] Error 1
****************************************

However, GCC doesn't complain with this:
****************************************
int main()
{
    test<int, double>::f<int>();
}
****************************************

[Bug c++/47475] [C++0x] Static member function template of class variadic template can't be called from the inside

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47475

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-01-26 16:41:26 UTC ---
The diagnostic isn't very good, but the code is invalid, it should be:

        test<Ts...>::template f<U>();

[Bug c++/47475] [C++0x] Static member function template of class variadic template can't be called from the inside

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47475

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-01-26 16:47:53 UTC ---
Note that this is not related to variadic templates, this gives the same error
using no C++0x features:

template<typename T, typename Ts>
struct test;

template<>
struct test<void, void>
{
    template<typename>
    static void f()
    {
    }
};

template<typename T, typename Ts>
struct test
{
    template<typename U>
    static void f()
    {
        test<void, Ts>::f<U>(); //compiler error here
    }
};

[Bug c++/47475] [C++0x] Static member function template of class variadic template can't be called from the inside

[flo.goujeon at orange dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47475

--- Comment #3 from flo.goujeon at orange dot fr 2011-01-26 16:54:18 UTC ---
Oh, so that is the purpose of the 'template' keyword in nested-name-specifier.
That's tricky.
Thank you Jonathan, and sorry about this invalid report.