[Bug c++/55710] New: [C++11] Linkage errors with lambdas

["daniel.kruegler at googlemail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55710

             Bug #: 55710
           Summary: [C++11] Linkage errors with lambdas
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: daniel.kruegler@googlemail.com


The following program compiled with gcc 4.8.0 20121209 (experimental) and
compiled with flags

-Wall -std=c++11 -pedantic

//----------------
template <class T>
struct X {
  static void (*code) ();
};

template <class T>
void (*X<T>::code) () = []{};  // Line 7

struct Y {
  void (*code) () = []{} ; // Line 10
  void operator()() { code(); }
};

int main () {
  X<int>::code();
  Y()();
}
//----------------

gives two linkage errors:

"|In function `Y::code::{lambda()#1}::operator void (*)()() const':|
10|undefined reference to `Y::code::{lambda()#1}::_FUN()'|
|In function `X<int>::code::{lambda()#1}::operator void (*)()() const':|
7|undefined reference to `X<int>::code::{lambda()#1}::_FUN()'|
"

for the functions that should be defined for the corresponding uncaptured
lambda expressions.

It should be noted, that

struct Z {
  static void (*code) ();
};

void (*Z::code) () = []{};

int main () {
  Z::code();
}

doesn't cause a similar linkage error, though.