std :: set中的unique_ptr找不到运算符<eventhough它在那里[重复]

可能重复：Clang，std :: shared_ptr和std :: less / operator <

所以，是的， Headers 几乎是整个问题 . 正如你从下面的片段中看到的那样，我确实实现了 operator< 所以我不知道发生了什么 .

这是代码：

namespace {

struct Transition {
    string name;
    StatePtr toState;

    Transition(string s = string(), StatePtr state = nullptr)
      : name(move(s))
      , toState(move(state))
    {}

    friend bool operator==(Transition const& lhs, Transition const & rhs) {
      return lhs.name == rhs.name && lhs.toState == rhs.toState;
    }

    friend bool operator<(Transition const & lhs, Transition const & rhs);
  };

  struct State {
    string name;
    set<TransitionPtr> transitions;

    explicit State(string s = string())
      : name(move(s))
    {}

    void addTransition(string s, StatePtr sp = nullptr){
      TransitionPtr new_t = make_transition(s, sp);
      for(auto& t : transitions){
        if(t == new_t){
          return;
        }
      }

      transitions.insert(move(new_t)); // This is where the error happens.
    }

  };
}

bool operator<(StateMachine::Transition const & lhs, StateMachine::Transition const & rhs) {
 return lhs.toState.get() < rhs.toState.get();
}

并且错误消息是：

在../llvm_opt_pass/cgd.cpp:3中包含的文件中：/srv/scratch/sigubufo/clang/stable/3.1_src/llvm/include/llvm/Instructions.h:23中包含的文件：包含在文件中/srv/scratch/sigubufo/clang/stable/3.1_src/llvm/include/llvm/ADT/ArrayRef.h:13：包含在/srv/scratch/sigubufo/clang/stable/3.1_src/llvm/include/中的文件中llvm / ADT / SmallVector.h:24：包含在/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c /4.7/memory:85的文件中：/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c /4.7/bits/unique_ptr.h:486:14：错误：没有匹配功能调用'std :: less <CT>'类型的对象返回std :: less <CT>（）（ x.get（），__ y.get（））; ^ ~~~~~~~~~~~~~~~ / usr / lib / gcc / x86_64-linux-nuu / 4.7 / ... / .. / .. / .. / include / c /4.7/bits /stl_function.h:237:20：注意：在实例化函数模板特化'std :: operator << :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition>，:: StateMachine :: Transition ，std :: default_delete <:: StateMachine :: Transition >>>'request here {return __x <__y; } ^ /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c /4.7/bits/stl_tree.h:1285:13：注意：在实例化中成员函数'std :: less :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >> >> :: operator（）'此处请求__comp = M_impl.M_key_compare（KeyOfValue（）（ v）， S_key （X））; ^ /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c /4.7/bits/stl_set.h:424:9：注意：>实例化函数模板特化'std :: _ Rb_tree :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>，std :: unique_ptr <:: StateMachine :: Transition，std :: default_delete <:: StateMachine： ：Transition >>，std :: _ Identity :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>>，std :: less :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >> >>，std :: allocator :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>> :: _ M_insert_unique :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >> >>'在这里请求_M_t.M_insert_unique（std :: move（ x））; ^ ../llvm_opt_pass/cgd.cpp:72:17：注意：在成员函数'std :: set :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>>的实例化中，std :: less :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>>，std :: allocator :: StateMachine :: Transition，std :: default_delete <:: StateMachine :: Transition >>>>： ：插入'在这里请求transitions.insert（move（new_t））; ^ /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c /4.7/bits/stl_function.h:236:7：注意：候选功能不可行：对于第一个参数，没有已知的从'指针'（又名':: StateMachine :: Transition *'）到':: StateMachine :: Transition * &&&'>的转换; operator（）（const Tp＆ x，const _Tp＆__y）const