What is 'required from here' error

问题:

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

I don't like to have errors or warnings. Does anybody know what that is?

回答1:

This behavior is a bug of eclipse CDT Error Parser: https://bugs.eclipse.org/bugs/show_bug.cgi?id=108720 Actually this error is a warning and boost is responsible for it. You can disable this special kind of warnings to omit them.

回答2:

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;