[libsigc++2/variadic] fix

[Murray Cumming <murrayc src gnome org>]

commit 784c51656e736cdeee53dfc08d8e4c44e0330656
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Jan 14 10:45:12 2016 +0100

    fix

 sigc++/functors/macros/slot.h.m4 |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/sigc++/functors/macros/slot.h.m4 b/sigc++/functors/macros/slot.h.m4
index bce6cfc..b8fe21a 100644
--- a/sigc++/functors/macros/slot.h.m4
+++ b/sigc++/functors/macros/slot.h.m4
@@ -329,6 +329,9 @@ FOR(1, $1,[
     {
       typedef typed_slot_rep<T_functor> typed_slot;
       typed_slot *typed_rep = static_cast<typed_slot*>(rep);dnl
+      //TODO_variadic: Avoid the specific call to the () overload when
+      //bind_functor::operator() is variadic. Then we can make this whole class
+      //variadic, and others that use it.
 ifelse($1,0,[
       return (typed_rep->functor_)();
 ],[