未评估的上下文中的“无法调用成员函数…没有对象”-GCC错误？

Question

The following program compiles fine with Clang:

template< typename > struct X
{
  void foo() {}

  auto bar() -> decltype( X::foo() )
  {
    return foo();
  }
};

int main()
{
  X<int>().bar();
}

But GCC 4.8.1 gives:

main.cpp: In instantiation of 'struct X<int>':
main.cpp:13:10:   required from here
main.cpp:5:34: error: cannot call member function 'void X< <template-parameter-1-1> >::foo() [with <template-parameter-1-1> = int]' without object
   auto bar() -> decltype( X::foo() )
                                  ^
main.cpp: In function 'int main()':
main.cpp:13:12: error: 'struct X<int>' has no member named 'bar'
   X<int>().bar();
            ^

Live example

When I change the code to decltype( std::declval<X>().foo() ) GCC compiles it.

Is this a bug in GCC (and is there an existing bug report for it or should report it?) or is there anything wrong with my code?

Answer 1

Possibly this bug? decltype needs explicit 'this' pointer in member function declaration of template class with trailing return type – dyp

Fixed.