Explicitly delete some Callback constructors to improve errors.

base/bind_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "base/bind.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 1298 matching lines @@
 
   // Move constructor and assignment of RepeatingCallback.
   static_assert(std::is_constructible<
       RepeatingClosure, RepeatingClosure&&>::value,
       "RepeatingClosure should be movable.");
   static_assert(is_assignable<
       RepeatingClosure, RepeatingClosure&&>::value,
       "RepeatingClosure should be move-assignable");
 
   // Conversions from OnceCallback to RepeatingCallback.
+#if !defined(COMPILER_MSVC) || defined(__clang__)
+  // In theory, this should have been fixed in VS2015 update 2:
+  // https://connect.microsoft.com/VisualStudio/feedback/details/819202
   static_assert(!std::is_constructible<
       RepeatingClosure, const OnceClosure&>::value,
       "OnceClosure should not be convertible to RepeatingClosure.");
   static_assert(!is_assignable<
       RepeatingClosure, const OnceClosure&>::value,
       "OnceClosure should not be convertible to RepeatingClosure.");
 
   // Destructive conversions from OnceCallback to RepeatingCallback.
   static_assert(!std::is_constructible<
       RepeatingClosure, OnceClosure&&>::value,
       "OnceClosure should not be convertible to RepeatingClosure.");
   static_assert(!is_assignable<
       RepeatingClosure, OnceClosure&&>::value,
       "OnceClosure should not be convertible to RepeatingClosure.");
+#endif
 
   // Copy constructor and assignment of OnceCallback.
   static_assert(!std::is_constructible<
       OnceClosure, const OnceClosure&>::value,
       "OnceClosure should not be copyable.");
   static_assert(!is_assignable<
       OnceClosure, const OnceClosure&>::value,
       "OnceClosure should not be copy-assignable");
 
   // Move constructor and assignment of OnceCallback.
@@ skipping 67 matching lines @@
 
 // Test null callbacks cause a DCHECK.
 TEST(BindDeathTest, NullCallback) {
   base::Callback<void(int)> null_cb;
   ASSERT_TRUE(null_cb.is_null());
   EXPECT_DCHECK_DEATH(base::Bind(null_cb, 42));
 }
 
 }  // namespace
 }  // namespace base