4 ms·

I don't get what you mean. I thought they specify how the type can be used?

• secondcoming 2y ago
  Technically, you're not supposed to add your own specialisations to the `std` namespace
  • pmalynin 2y ago
    In general this isn’t true (i guess it is in this specific context). For example I believe it’s totally expected to specialize std hash
    • tyleo 2y ago
      I’ve also done this with hash… though given the footguns scattered about, I wouldn’t be surprised if it broke the spec.
      • Conscat 2y ago
        That is a completely intended way to use std::hash, along with a few other functions like std::tuple_size and std::tuple_element.
• badmintonbaseba 2y ago
  The cppreference page says: > If the program adds specializations for std::is_fundamental or std::is_fundamental_v, the behavior is undefined. This is an oversimplification. The actual rule is https://eel.is/c++draft/library#namespace.std-2 https://eel.is/c++draft/library#namespace.std-2 . > the specialization meets the standard library requirements for the original template. For is_fundamental<YourClassType> it means that is_fundamental<YourClassType>::value must be false, as YourClassType is not a fundamental type, as defined in https://eel.is/c++draft/basic.fundamental#17 https://eel.is/c++draft/basic.fundamental#17 . Some traits are just not designed to be customization points.