What is 'required from here' error

Question

It is in my Eclipse Problems view. The code compiles fine but there is an error saying \"required from here\", pointing to some boost header file and to the lin

Answer 1

Did you actually returned? and check the types &state new_state and old_state. if you used: int new_state; and in the function compare_exchange(size_t &state, size_t new_state, size_t old_state) You get this error, well i did :)

          state_data const current_state = interlocked_compare_exchange(&state,new_state,old_state);

add:

      return new_state;