Improving flat containers interface.

base/bind_internal.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_BIND_INTERNAL_H_
 #define BASE_BIND_INTERNAL_H_
 
 #include <stddef.h>
 
 #include <tuple>
@@ skipping 28 matching lines @@
 //                     invocation manner for a Functor.  This is where function
 //                     signature adapters are applied.
 //  InvokeHelper<> -- Take a Functor + arguments and actully invokes it.
 //                    Handle the differing syntaxes needed for WeakPtr<>
 //                    support.  This is separate from Invoker to avoid creating
 //                    multiple version of Invoker<>.
 //  Invoker<> -- Unwraps the curried parameters and executes the Functor.
 //  BindState<> -- Stores the curried parameters, and is the main entry point
 //                 into the Bind() system.
 
-template <typename...>
-struct make_void {
-  using type = void;
-};
-
-// A clone of C++17 std::void_t.
-// Unlike the original version, we need |make_void| as a helper struct to avoid
-// a C++14 defect.
-// ref: http://en.cppreference.com/w/cpp/types/void_t
-// ref: http://open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#1558
-template <typename... Ts>
-using void_t = typename make_void<Ts...>::type;
-
 template <typename Callable,
           typename Signature = decltype(&Callable::operator())>
 struct ExtractCallableRunTypeImpl;
 
 template <typename Callable, typename R, typename... Args>
 struct ExtractCallableRunTypeImpl<Callable, R(Callable::*)(Args...) const> {
   using Type = R(Args...);
 };
 
 // Evaluated to RunType of the given callable type.
@@ skipping 454 matching lines @@
 
 // Returns a RunType of bound functor.
 // E.g. MakeUnboundRunType<R(A, B, C), A, B> is evaluated to R(C).
 template <typename Functor, typename... BoundArgs>
 using MakeUnboundRunType =
     typename internal::MakeUnboundRunTypeImpl<Functor, BoundArgs...>::Type;
 
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_