Remove unbound base::Bind overload

base/bind.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_H_
 #define BASE_BIND_H_
 
 #include "base/bind_internal.h"
 #include "base/callback_internal.h"
 
@@ skipping 29 matching lines @@
 // via an indirection like we do below.
 //
 // TODO(ajwong): We might be able to avoid this now, but need to test.
 //
 // It is possible to move most of the static_assert into BindState<>, but it
 // feels a little nicer to have the asserts here so people do not need to crack
 // open bind_internal.h.  On the other hand, it makes Bind() harder to read.
 
 namespace base {
 
-template <typename Functor>
-base::Callback<
-    typename internal::BindState<
-        typename internal::FunctorTraits<Functor>::RunnableType,
-        typename internal::FunctorTraits<Functor>::RunType>::UnboundRunType>
-Bind(Functor functor) {
-  // Typedefs for how to store and run the functor.
-  typedef typename internal::FunctorTraits<Functor>::RunnableType RunnableType;
-  typedef typename internal::FunctorTraits<Functor>::RunType RunType;
-
-  typedef internal::BindState<RunnableType, RunType> BindState;
-
-  return Callback<typename BindState::UnboundRunType>(
-      new BindState(internal::MakeRunnable(functor)));
-}
-
 template <typename Functor, typename... Args>
 base::Callback<
     typename internal::BindState<
         typename internal::FunctorTraits<Functor>::RunnableType,
         typename internal::FunctorTraits<Functor>::RunType,
         typename internal::CallbackParamTraits<Args>::StorageType...>
             ::UnboundRunType>
 Bind(Functor functor, const Args&... args) {
   // Typedefs for how to store and run the functor.
   typedef typename internal::FunctorTraits<Functor>::RunnableType RunnableType;
   typedef typename internal::FunctorTraits<Functor>::RunType RunType;
 
   // Use RunnableType::RunType instead of RunType above because our
   // checks should below for bound references need to know what the actual
   // functor is going to interpret the argument as.
   typedef typename RunnableType::RunType BoundRunType;
 
+  using BoundArgs =
+      internal::TakeTypeListItem<sizeof...(Args),
+                                 internal::ExtractArgs<BoundRunType>>;

[dcheng, 2015/12/15 19:42:54]

OK, I understand why this is necessary now.

Should we add another test case to bind_unittest.cc in
UnboundArgumentTypeSupport?

Given this:
void F1(int&);
void F2(int, int&);

This worked:
CallbacK<void(int&)> cv = base::Bind(&F1);

But this didn't:
Callback<void(int&)> cb = base::Bind(&F2, 0);

but with your patch, they both work now.

[tzik, 2015/12/16 08:02:47]

Added. Yes, we should.

+
   // Do not allow binding a non-const reference parameter. Non-const reference
   // parameters are disallowed by the Google style guide.  Also, binding a
   // non-const reference parameter can make for subtle bugs because the
   // invoked function will receive a reference to the stored copy of the
   // argument and not the original.
-  static_assert(!internal::HasNonConstReferenceParam<BoundRunType>::value,
+  static_assert(!internal::HasNonConstReferenceItem<BoundArgs>::value,
                 "do not bind functions with nonconst ref");
 
   const bool is_method = internal::HasIsMethodTag<RunnableType>::value;
 
   // For methods, we need to be careful for parameter 1.  We do not require
   // a scoped_refptr because BindState<> itself takes care of AddRef() for
   // methods. We also disallow binding of an array as the method's target
   // object.
   static_assert(!internal::BindsArrayToFirstArg<is_method, Args...>::value,
                 "first bound argument to method cannot be array");
   static_assert(
       !internal::HasRefCountedParamAsRawPtr<is_method, Args...>::value,
       "a parameter is a refcounted type and needs scoped_refptr");
 
   typedef internal::BindState<
       RunnableType, RunType,
       typename internal::CallbackParamTraits<Args>::StorageType...>
       BindState;
 
   return Callback<typename BindState::UnboundRunType>(
       new BindState(internal::MakeRunnable(functor), args...));
 }
 
 }  // namespace base
 
 #endif  // BASE_BIND_H_