Add a std::make_unique implementation

Some compilers we care about (mostly g++) do not support std::make_unique yet,
but we still want to use it in our codebase to make unique_ptr code more
readable. This commit introduces an implementation derivated from the libc++
code in the Dolphin codebase so we can use it right now everywhere.

Adapted from delroth's pull request.

Source/Core/Common/Common.vcxproj

@@ -72,6 +72,7 @@
     <ClInclude Include="LinearDiskCache.h" />
     <ClInclude Include="Log.h" />
     <ClInclude Include="LogManager.h" />
+    <ClInclude Include="MakeUnique.h" />
     <ClInclude Include="MathUtil.h" />
     <ClInclude Include="MemArena.h" />
     <ClInclude Include="MemoryUtil.h" />

Source/Core/Common/Common.vcxproj.filters

@@ -33,6 +33,7 @@
     <ClInclude Include="Hash.h" />
     <ClInclude Include="IniFile.h" />
     <ClInclude Include="LinearDiskCache.h" />
+    <ClInclude Include="MakeUnique.h" />
     <ClInclude Include="MathUtil.h" />
     <ClInclude Include="MemArena.h" />
     <ClInclude Include="MemoryUtil.h" />

Source/Core/Common/StdMakeUnique.h

@@ -0,0 +1,82 @@
+// Copyright 2013 Dolphin Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#pragma once
+
+// VS 2013 defines __cplusplus as 199711L but has std::make_unique.
+#if __cplusplus > 201103L || _MSC_VER >= 1800
+#include <memory>
+#else
+
+// Implementation of C++14 std::make_unique, which is not supported by all the
+// compilers we care about yet.
+//
+// NOTE: This code is based on the libc++ implementation of std::make_unique.
+//
+// Copyright (c) 2009-2014 by the libc++ contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+
+namespace std
+{
+
+struct unspecified {};
+
+template<class T>
+struct unique_if
+{
+	typedef std::unique_ptr<T> unique_single;
+};
+
+template<class T>
+struct unique_if<T[]>
+{
+	typedef std::unique_ptr<T[]> unique_array_unknown_bound;
+};
+
+template<class T, size_t N>
+struct unique_if<T[N]>
+{
+	typedef void unique_array_known_bound;
+};
+
+template<class T, class... Args>
+inline typename unique_if<T>::unique_single make_unique(Args&&... args)
+{
+	return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+}
+
+template<class T>
+inline typename unique_if<T>::unique_array_unknown_bound make_unique(size_t n)
+{
+	typedef typename std::remove_extent<T>::type U;
+	return std::unique_ptr<T>(new U[n]());
+}
+
+template<class T, class... Args>
+typename unique_if<T>::unique_array_known_bound make_unique(Args&&...) = delete;
+
+}  // namespace std
+
+#endif // __cplusplus