gistfile1.el

;; An attempt at this Emacs SX question:
;; https://emacs.stackexchange.com/questions/10359/delete-portion-of-isearch-string-that-does-not-match-or-last-char-if-complete-m

(defun isearch-delete-something ()
  "Delete non-matching text or the last character."
  ;; Mostly copied from `isearch-del-char' and Drew's answer on the page above
  (interactive)
  (if (= 0 (length isearch-string))
      (ding)
    (setq isearch-string
          (substring isearch-string
                     0
                     (or (isearch-fail-pos) (1- (length isearch-string)))))
    (setq isearch-message
          (mapconcat #'isearch-text-char-description isearch-string "")))
  (if isearch-other-end (goto-char isearch-other-end))
  (isearch-search)
  (isearch-push-state)
  (isearch-update))