refactored insert overloads

include/boost/unordered/detail/foa.hpp

@@ -1084,43 +1084,6 @@ private:
   static constexpr bool has_mutable_iterator=
     !std::is_same<key_type,value_type>::value;
 
-  template<
-    typename T,
-    typename RawT=typename std::remove_cv<
-      typename std::remove_reference<T>::type>::type
-  >
-  using value_from_return_type=typename std::conditional<
-    std::is_same<RawT,init_type>::value||std::is_same<RawT,value_type>::value,
-    T,
-    typename std::conditional<
-      std::is_convertible<T,init_type&&>::value,
-      init_type,
-      typename std::conditional<
-        std::is_convertible<T,value_type&&>::value,
-        value_type,
-        typename std::conditional<
-          std::is_convertible<T,const init_type&>::value,
-          const init_type&,
-          typename std::conditional<
-            std::is_convertible<T,const value_type&>::value,
-            const value_type&,
-            void
-          >::type
-        >::type
-      >::type
-    >::type
-  >::type;
-
-  template<
-    typename T,
-    typename std::enable_if<
-      !std::is_void<value_from_return_type<T&&>>::value>::type* =nullptr
-  >
-  static inline value_from_return_type<T&&> value_from(T&& x)
-  {
-    return std::forward<T>(x);
-  }
-
 public:
   using hasher=Hash;
   using key_equal=Pred;
@@ -1306,17 +1269,21 @@ public:
       std::forward_as_tuple(std::forward<Args>(args)...));
   }
 
-  template<typename T>
+  BOOST_FORCEINLINE std::pair<iterator,bool>
-  BOOST_FORCEINLINE auto insert(T&& x)
+  insert(const init_type& x){return emplace_impl(x);}
-    ->decltype(value_from(std::forward<T>(x)),std::pair<iterator,bool>())
-  {
-    return emplace_impl(value_from(std::forward<T>(x)));
-  }
 
-  BOOST_FORCEINLINE std::pair<iterator,bool> insert(init_type&& x)
+  BOOST_FORCEINLINE std::pair<iterator,bool>
-  {
+  insert(init_type&& x){return emplace_impl(std::move(x));}
-    return emplace_impl(std::move(x));
+
-  }
+  /* template<typename=void> tilts call ambiguities in favor of init_type */
+
+  template<typename=void>
+  BOOST_FORCEINLINE std::pair<iterator,bool>
+  insert(const value_type& x){return emplace_impl(x);}
+
+  template<typename=void>
+  BOOST_FORCEINLINE std::pair<iterator,bool>
+  insert(value_type&& x){return emplace_impl(std::move(x));}
 
   template<
     bool dependent_value=false,