为什么clang会为具有异常虚拟方法的类提供弱vtable警告？

Question

Object.hpp：

class Object
{  
public:
    virtual ~Object();
};

Object.cpp：

#include "Object.hpp"

Object::~Object()
{
}

让我们编译它：

>clang++ -v
clang version 3.9.0 (branches/release_39)
Target: x86_64-pc-windows-msvc
Thread model: posix

>clang++ -Weverything -c Object.cpp
In file included from Object.cpp:1:
./Object.hpp:1:7: warning: 'Object' has no out-of-line virtual method definitions;
its vtable will be emitted in every translation unit [-Wweak-vtables]
class Object
      ^
1 warning generated.

但是Object确实有一个外联的虚拟方法，为什么Clang会产生这个警告呢？