[libsigcplusplus/variadic_mem_fun3: 135/148] mem_functor_base: Remove T_return template parameter.

[Murray Cumming <murrayc src gnome org>]

commit a12fd0b8ad4517a958160eeedf75113bbdf2fc24
Author: Murray Cumming <murrayc murrayc com>
Date:   Sat Mar 5 12:29:43 2016 +0100

    mem_functor_base: Remove T_return template parameter.
    
    Instead using std::result_of<> to discover it from the T_func.

 sigc++/adaptors/retype.h            |    6 +++---
 sigc++/functors/macros/mem_fun.h.m4 |   12 ++++++------
 2 files changed, 9 insertions(+), 9 deletions(-)
---
diff --git a/sigc++/adaptors/retype.h b/sigc++/adaptors/retype.h
index e333d7c..4984765 100644
--- a/sigc++/adaptors/retype.h
+++ b/sigc++/adaptors/retype.h
@@ -137,10 +137,10 @@ retype(const pointer_functor<T_return, T_arg...>& _A_functor)
  *
  * @ingroup retype
  */
-template <class T_func, class T_return, class T_obj, class... T_arg>
+template <class T_func, class T_obj, class... T_arg>
 inline decltype(auto)
-retype(const mem_functor_base<T_func, T_return, T_obj, T_arg...>& _A_functor)
-{ return retype_functor<mem_functor_base<T_func, T_return, T_obj, T_arg...>, T_arg...>
+retype(const mem_functor_base<T_func, T_obj, T_arg...>& _A_functor)
+{ return retype_functor<mem_functor_base<T_func, T_obj, T_arg...>, T_arg...>
     (_A_functor);
 }
 
diff --git a/sigc++/functors/macros/mem_fun.h.m4 b/sigc++/functors/macros/mem_fun.h.m4
index cb0a803..8d6ba35 100644
--- a/sigc++/functors/macros/mem_fun.h.m4
+++ b/sigc++/functors/macros/mem_fun.h.m4
@@ -33,7 +33,7 @@ template<class T_return, class T_obj, class... T_arg>
 using [$1]mem_functor =
   mem_functor_base<
     T_return (T_obj::*)(T_arg...) $2,
-    T_return, T_obj, T_arg...>;
+    T_obj, T_arg...>;
 ])
 
 define([BOUND_MEMBER_FUNCTOR],[dnl
@@ -67,7 +67,7 @@ inline decltype(auto)
 mem_fun(T_return (T_obj::*_A_func)(T_arg...) $3)
 { return mem_functor_base<
     T_return (T_obj::*)(T_arg...) $3,
-    T_return, T_obj, T_arg...>(_A_func); }
+    T_obj, T_arg...>(_A_func); }
 
 ])
 define([BOUND_MEM_FUN],[dnl
@@ -172,12 +172,12 @@ namespace sigc {
  * @ingroup sigcfunctors
  */
 
-template <class T_func, class T_return, class T_obj, class... T_arg>
+template <class T_func, class T_obj, class... T_arg>
 class mem_functor_base : public functor_base
 {
 public:
   using function_type = T_func;
-  using result_type = T_return;
+  using result_type = std::result_of_t<T_func(T_obj*, T_arg...)>;
 
   using obj_type_with_modifier = typename std::conditional_t<
     member_method_is_const<T_func>::value, const T_obj, T_obj>;
@@ -221,9 +221,9 @@ MEMBER_FUNCTOR([const_],[const])
 template <class T_func,
   class T_return, class T_obj, class... T_arg>
 class bound_mem_functor_base
-: mem_functor_base<T_func, T_return, T_obj, T_arg...>
+: mem_functor_base<T_func, T_obj, T_arg...>
 {
-  using base_type = mem_functor_base<T_func, T_return, T_obj, T_arg...>;
+  using base_type = mem_functor_base<T_func, T_obj, T_arg...>;
 public:
   using function_type = typename base_type::function_type;
   using result_type = typename base_type::result_type;