少于模板参数的比较

Question

I have a templated class implementing red black tree that would behave kind of like a (pseudo)map. Pseudo-map because it would not store keys, only values, with keys being embedded in the values. It would require operator== and operator< overloads to test stored values against an arbitrary key and againts each other (using embedded key). Eg

struct Val
{
    //some actual data
    std::string key;

    bool operator==(const Val &val) { return this->key == val.key; }
    bool opeartor==(const std::string &str) { return this->key == str; }
    bool opeartor<(const Val &val) { return this->key < val.key; }
    bool opeartor<(const std::string &str) { return this->key < str; }
};

This kind of "value" would go into this templated class:

template<typename T>
class Map
{
    struct Node
    {
        //...
        T data;
    };
    public:
        //..
        template<typename K> T value(const K &key) const
        {
            Node *it;
            //...
            if(it->data == key)
            //...

            int dir = (it->data < key);
            //...
        }
};

However while the line if(it->data == key) checks out fine (I am not using the class yet) the second one int dir = (it->data < key); does not with error "parse error in template argument list". Strangely if I change the comparison to <= it compiles fine. However at that point I already know it is not equal (the first check so < would do.

How do I fix it and why is it complaining about one operator and not the others?

Answer 1

TC has posted the answer in the comments so I will just repeat it as an answer. The behaviour is due to long-standing bug in GCC https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10200 that manifests itself when one is not very creative with naming and has bunch of the same names in the class (in this case member variable named data in the nested class and the member method called data in the super-class).