小编sul*_*uke的帖子

我刚刚在clang和gcc之间遇到了一个奇怪的区别,我想编译看起来类似于以下内容的代码:

namespace n1 {
  template <class T1, class T2>
  struct MyTemplate {
    struct Inner {};
  };
}

using namespace n1;
namespace n2 {
  using MyClass = MyTemplate<int, int>;
}

namespace n1 {
  using n2::MyClass;
  template<> struct MyClass::Inner {
    int member;
  };

  MyClass::Inner inner{0};
}

Clang愉快地编写了这个:

$ clang++ -std=c++11 -c -o alias_specialization.o alias_specialization.cc

但是gcc会抛出以下错误:

$ g++ -std=c++11 -c -o alias_specialization.o alias_specialization.cc

alias_specialization:15:30: error: declaration of ‘struct n1::MyTemplate<int, int>::Inner’ in namespace ‘n1’ which does not enclose ‘using MyClass = struct n1::MyTemplate<int, int>’ …