[Bug c++/53837] New: Unpacking variadic template parameters in a method parameter default value gives parse error

[Bug c++/53837] New: Unpacking variadic template parameters in a method parameter default value gives parse error

[johannes at laire dot fi]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53837

             Bug #: 53837
           Summary: Unpacking variadic template parameters in a method
                    parameter default value gives parse error
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: johannes@laire.fi


-------- bug.cpp --------
template <typename... Args>
int f() { return 42; }

template <typename... Args>
struct B1 {
        B1(int i = f<Args...>()); // ERROR
        void m(int i = f<Args...>()); // ERROR
};

struct B2 {
        template <typename... Args>
        void m(int i = f<Args...>()); // ERROR
};

template <typename... Args>
struct B3 {
        B3(int i = call_f()); // OK
        void m(int i = call_f()); // OK
        static int call_f() { return f<Args...>(); }
};

template <typename... Args>
void g(int i = f<Args...>()); // OK

int main() {}
-------- bug.cpp --------

$ g++ -std=c++0x bug.cpp
bug.cpp:6:22: error: expected ‘)’ before ‘>’ token
bug.cpp:6:19: error: expected ‘;’ at end of member declaration
bug.cpp:6:22: error: expected unqualified-id before ‘>’ token
bug.cpp:7:26: error: expected ‘)’ before ‘>’ token
bug.cpp:7:23: error: expected ‘;’ at end of member declaration
bug.cpp:7:26: error: expected unqualified-id before ‘>’ token
bug.cpp:6:13: error: parse error in template argument list
bug.cpp:7:17: error: parse error in template argument list
bug.cpp:12:26: error: expected ‘)’ before ‘>’ token
bug.cpp:12:26: error: expected initializer before ‘>’ token
$ clang++ -std=c++0x bug.cpp
$


GCC versions 4.4.3, 4.6.2, and 4.7.1 give parse errors on the marked lines.
Clang 3.0 doesn't complain.

Note that g() parses fine.

[Bug c++/53837] Unpacking variadic template parameters in a method parameter default value gives parse error

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53837

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler at
                   |                            |googlemail dot com

--- Comment #1 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2012-07-03 17:38:56 UTC ---
The same problem exists for gcc 4.8.0 20120624 (experimental)

[Bug c++/53837] Unpacking variadic template parameters in a method parameter default value gives parse error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53837

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-10-10
     Ever Confirmed|0                           |1
           Severity|minor                       |normal

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-10 19:37:00 UTC ---
Confirming.

[Bug c++/53837] Unpacking variadic template parameters in a method parameter default value gives parse error

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53837

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
      Known to work|                            |4.9.0, 5.0
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.9.0

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed long time ago.