(defconst 24870-syntax-table
  (let ((table (make-syntax-table)))
    (modify-syntax-entry ?\{  "(}1nb" table)
    (modify-syntax-entry ?\}  "){4nb" table)
    (modify-syntax-entry ?-  ". 123" table)
    table))

(defun 24870-test ()
  (interactive)
  (with-current-buffer (get-buffer-create "*24870 test*")
    (set-syntax-table 24870-syntax-table)
    (insert "{-C-}\nX")
    (message "pps nesting: %d" (nth 0 (parse-partial-sexp (point-min) (point-max))))
    (display-buffer (current-buffer))))