Add new error and function `user-error'.

* lisp/subr.el (user-error): New function.
* lisp/window.el (switch-to-buffer):
* lisp/vc/smerge-mode.el (smerge-resolve-function, smerge-resolve)
(smerge-match-conflict):
* lisp/simple.el (previous-matching-history-element)
(next-matching-history-element, goto-history-element, undo-more)
(undo-start):
* lisp/progmodes/etags.el (visit-tags-table-buffer, find-tag-tag)
(find-tag-noselect, find-tag-in-order, etags-goto-tag-location)
(next-file, tags-loop-scan, list-tags, complete-tag):
* lisp/progmodes/compile.el (compilation-loop):
* lisp/mouse.el (mouse-minibuffer-check):
* lisp/man.el (Man-bgproc-sentinel, Man-goto-page):
* lisp/info.el (Info-find-node-2, Info-extract-pointer, Info-history-back)
(Info-history-forward, Info-follow-reference, Info-menu)
(Info-extract-menu-item, Info-extract-menu-counting)
(Info-forward-node, Info-backward-node, Info-next-menu-item)
(Info-last-menu-item, Info-next-preorder, Info-last-preorder)
(Info-next-reference, Info-prev-reference, Info-index)
(Info-index-next, Info-follow-nearest-node)
(Info-copy-current-node-name):
* lisp/imenu.el (imenu--make-index-alist)
(imenu-default-create-index-function, imenu-add-to-menubar):
* lisp/files.el (basic-save-buffer, recover-file):
* lisp/emacs-lisp/easy-mmode.el (easy-mmode-define-navigation):
* lisp/emacs-lisp/checkdoc.el (checkdoc-continue, checkdoc-comments)
(checkdoc-message-text, checkdoc-defun):
* lisp/dabbrev.el (dabbrev-completion, dabbrev--abbrev-at-point):
* lisp/cus-edit.el (customize-changed-options, customize-rogue)
(customize-saved, custom-variable-set, custom-variable-mark-to-save)
(custom-variable-mark-to-reset-standard)
(custom-variable-reset-backup, custom-face-mark-to-reset-standard)
(custom-file):
* lisp/completion.el (check-completion-length):
* lisp/comint.el (comint-search-arg)
(comint-previous-matching-input-string-position)
(comint-previous-matching-input)
(comint-replace-by-expanded-history-before-point, comint-send-input)
(comint-copy-old-input, comint-backward-matching-input)
(comint-goto-process-mark, comint-set-process-mark):
* lisp/calendar/calendar.el (calendar-cursor-to-date): Use it.
* lisp/bindings.el (debug-ignored-errors): Remove regexps, add `user-error'.
* src/data.c (PUT_ERROR): New macro.
(syms_of_data): Use it.  Add new error type `user-error'.
* src/undo.c (user_error): New function.
(Fprimitive_undo): Use it.
* src/print.c (print_error_message): Adjust print style for `user-error'.
* src/keyboard.c (user_error): New function.
(Fexit_recursive_edit, Fabort_recursive_edit): Use it.

1 files changed, 11 insertions, 0 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index 1f9f3aee9fa..8cfb1eeea16 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -274,6 +274,17 @@ for the sake of consistency."
     (signal 'error (list (apply 'format args)))))
 (set-advertised-calling-convention 'error '(string &rest args) "23.1")
 
+(defun user-error (format &rest args)
+  "Signal a pilot error, making error message by passing all args to `format'.
+In Emacs, the convention is that error messages start with a capital
+letter but *do not* end with a period.  Please follow this convention
+for the sake of consistency.
+This is just like `error' except that `user-error's are expected to be the
+result of an incorrect manipulation on the part of the user, rather than the
+result of an actual problem."
+  (while t
+    (signal 'user-error (list (apply #'format format args)))))
+
 ;; We put this here instead of in frame.el so that it's defined even on
 ;; systems where frame.el isn't loaded.
 (defun frame-configuration-p (object)