在std :: reference_wrapper中的Visual C++ 10.0錯誤？

Question

代碼：

#include <functional> 

struct Foo 
{ 
    virtual void mf() = 0; 
}; 

struct Bar: Foo 
{ 
    virtual void mf() {} 
}; 

int main() 
{ 
    Bar o; 
    std::reference_wrapper<Foo const> wrapper(o); 
} 

結果使用MinGW克++ 4.6.1：

 
[d:\dev\test] 
>g++ foo.cpp -std=c++0x 

[d:\dev\test] 
> _ 

結果用Visual C++ 10.0：

 
[d:\dev\test] 
>cl foo.cpp 
foo.cpp 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
     C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xrefwrap(371) : see reference to class template instantiation 'std::tr1::_Call_wrapper' being compiled 
     with 
     [ 
      _Callable=std::tr1::_Callable_obj 
     ] 
     C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xrefwrap(416) : see reference to class template instantiation 'std::tr1::_Refwrap_impl' being compiled 
     with 
     [ 
      _Ty=const Foo 
     ] 
     foo.cpp(16) : see reference to class template instantiation 'std::tr1::reference_wrapper' being compiled 
     with 
     [ 
      _Ty=const Foo 
     ] 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2027: use of undefined type 'std:: 
tr1::_Result_of' 
     with 
     [ 
      _Ty=const Foo (void) 
     ] 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(9) : error C2143: syntax error : missing ';' before '(' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(9) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(10) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class 
     due to following members: 
     'void Foo::mf(void)' : is abstract 
     foo.cpp(5) : see declaration of 'Foo::mf' 

[d:\dev\test] 
> _ 

我喜歡的方式，所述的視覺C++編譯器11次告訴用戶抽象類不能被實例化，只是爲了錘鍊e點家，如果用戶不知道這一點。但std::reference_wrapper真的應該實例化類？是不是很多的（通過）參考而不是要求實例化？

也就是說，我強烈懷疑這是Visual C++標準庫實現中的一個錯誤嗎？

Answer 1

按問題作者解決。在Visual C++ 10.0中，這是一個bug，據推測，它在VC的下一個主要版本中得到修復。