14

Código:Error de Visual C++ 10.0 en std :: reference_wrapper?

#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); 
} 

resultado con MinGW g ++ 4.6.1:

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

[d:\dev\test] 
> _ 

Resultado con 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] 
> _ 

me gusta la forma en que el Visual El compilador de C++ le dice al usuario 11 veces que la clase abstracta no puede ser instanciada, solo para martillar e punto de inicio, como, en caso de que el usuario no lo supiera. ¿Pero debería std::reference_wrapper realmente instanciar la clase? No es gran cosa el punto de (pasar) referencia a no requiere instanciación?

Es decir, ¿es esto, como sospecho firmemente, un error en la implementación de la biblioteca estándar de Visual C++?

+4

Envié un [informe de error] (https://connect.microsoft.com/VisualStudio/feedback/details/727368/std-reference-wrapper-fails-to-wrap-reference-to-object-of-abstract -clase) a Microsoft. –

+0

¿No debería estar creando la referencia_capería con la función ref helper? –

+0

@jamesj: no. eso es solo una función auxiliar, para evitar especificar el tipo explícitamente. para investigar un error, es mejor tener cosas explícitas que implícitas. –

Respuesta

4

Resuelto por el autor de la pregunta. Es un bug en Visual C++ 10.0 supuestamente corregido en la próxima versión principal de VC.

+0

¿Quizás crees que esta Wiki de la comunidad? – Bart

+0

Buena idea. Hecho. –

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