Enable debug in flycheck-error-with-buffer macro

When I investigated flycheck behavior with edebug, especially for `flycheck-create-overlay`. I was confused about  edebug finished at the `flycheck-error-with-buffer` macro entry.
How about declare debug spec?
http://www.gnu.org/software/emacs/manual/html_node/elisp/Declare-Form.html#Declare-Form