Subject: Re: bug#6106: 24.0.50; info.el adds 'search-failed to debug-ignored-errors

From: [email-masked]
Date: Sat, 01 Apr 2017 17:08:42 -0400

Eli Zaretskii <[email-masked]> writes:
>
> Thanks.  I think the symbol you are introducing and its plist should
> be documented in the ELisp manual and mentioned in NEWS.

I added it to `(elisp) Standard Errors' after `user-error'.  Or should
it go next to `search-failed'?  It says the list is "grouped by concept"
though it seems to be alphabetical.

Mark Oteiza <[email-masked]> writes:

> On 01/04/17 at 09:43am, [email-masked] wrote:
>> [email-masked] writes:
>> 
>> > (Info-select-node, Info-search): Replace (signal 'search-failed ...)
>> > with (user-error "Search failed: "...).
>> 
>> Turns out this breaks isearch over multiple nodes, as noted by Mark
>> Oteiza in [1].  I believe this is fixed by the patch below.
>> 
>> [1]: http://lists.gnu.org/archive/html/emacs-devel/2017-03/msg00869.html
>
> Thanks for addressing.  I get the following with your patch:
>
>   peculiar error: "cats", "(end of node)"

Sorry, I messed up.  I did an initial implementation using
`define-error' in lisp, and I didn't retest after moving that part to
C.  Here's a corrected patch.

>From bc0b21552dd782190662fe1fcbf7cd8197a7822e Mon Sep 17 00:00:00 2001
From: Noam Postavsky <[email-masked]>
Date: Sat, 1 Apr 2017 09:34:04 -0400
Subject: [PATCH v2] Throw a `search-failed' derived error in Info search

The original fix for Bug#6106 switched from signalling `search-failed'
to `user-error'.  However, this breaks incremental searching over
multiple nodes because the isearch code doesn't expect a `user-error'.

* src/search.c (syms_of_search): New error, `user-search-failed',
with `user-error' and `search-failed' as parents.
* doc/lispref/errors.texi (Standard Errors): Document it.
* etc/NEWS: Announce it.
* lisp/info.el (Info-search): Use it instead of `user-error' so that
isearch will handle failed searches correctly.
---
 doc/lispref/errors.texi |  6 ++++++
 etc/NEWS                |  4 ++++
 lisp/info.el            | 12 ++++++------
 src/search.c            | 10 ++++++++++
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/doc/lispref/errors.texi b/doc/lispref/errors.texi
index 2ec1a108ea..1f67819c34 100644
--- a/doc/lispref/errors.texi
+++ b/doc/lispref/errors.texi
@@ -186,6 +186,12 @@ Standard Errors
 @item user-error
 The message is the empty string.  @xref{Signaling Errors}.
 
+@item user-search-failed
+This is like @samp{search-failed}, but doesn't trigger the debugger,
+like @samp{user-error}.  @xref{Signaling Errors}, and @xref{Searching
+and Matching}.  This is used for searching in Info files, @xref{Search
+Text,,,info,Info}.
+
 @item void-function
 The message is @samp{Symbol's function definition is void}.
 @xref{Function Cells}.
diff --git a/etc/NEWS b/etc/NEWS
index c09cc390bb..f4627ac3a6 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1067,6 +1067,10 @@ its window gets deleted by 'delete-other-windows'.
 *** New command 'window-swap-states' swaps the states of two live
 windows.
 
++++
+*** New error type 'user-search-failed' like 'search-failed' but
+avoids debugger like 'user-error'.
+
 
 * Changes in Emacs 26.1 on Non-Free Operating Systems
 
diff --git a/lisp/info.el b/lisp/info.el
index a06c868fb3..28534f13e6 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -1998,20 +1998,20 @@ Info-search
                   Info-isearch-initial-node
                   bound
                   (and found (> found opoint-min) (< found opoint-max)))
-	(user-error "Search failed: `%s' (end of node)" regexp))
+	(signal 'user-search-failed (list regexp "(end of node)")))
 
       ;; If no subfiles, give error now.
       (unless (or found Info-current-subfile)
         (if isearch-mode
-            (user-error "Search failed: `%s' (end of manual)" regexp)
+            (signal 'user-search-failed (list regexp "end of manual"))
           (let ((search-spaces-regexp Info-search-whitespace-regexp))
             (unless (if backward
                         (re-search-backward regexp nil t)
                       (re-search-forward regexp nil t))
-              (user-error "Search failed: `%s'" regexp)))))
+              (signal 'user-seach-failed (list regexp))))))
 
       (if (and bound (not found))
-          (user-error "Search failed: `%s'" regexp))
+          (signal 'user-search-failed (list regexp)))
 
       (unless (or found bound)
 	(unwind-protect
@@ -2055,8 +2055,8 @@ Info-search
 		    (setq list nil)))
 	      (if found
 		  (message "")
-                (user-error "Search failed: `%s'%s"
-                            regexp (if isearch-mode " (end of manual)" ""))))
+                (signal 'user-search-failed
+                        `(,regexp ,@(if isearch-mode '("end of manual"))))))
 	  (if (not found)
 	      (progn (Info-read-subfile osubfile)
 		     (goto-char opoint)
diff --git a/src/search.c b/src/search.c
index 33cb02aa7a..c0deb57213 100644
--- a/src/search.c
+++ b/src/search.c
@@ -3389,6 +3389,10 @@ syms_of_search (void)
   /* Error condition used for failing searches.  */
   DEFSYM (Qsearch_failed, "search-failed");
 
+  /* Error condition used for failing searches started by user, i.e.,
+     where failure should not invoke the debugger.  */
+  DEFSYM (Quser_search_failed, "user-search-failed");
+
   /* Error condition signaled when regexp compile_pattern fails.  */
   DEFSYM (Qinvalid_regexp, "invalid-regexp");
 
@@ -3397,6 +3401,12 @@ syms_of_search (void)
   Fput (Qsearch_failed, Qerror_message,
 	build_pure_c_string ("Search failed"));
 
+  Fput (Quser_search_failed, Qerror_conditions,
+        listn (CONSTYPE_PURE, 4,
+               Quser_search_failed, Quser_error, Qsearch_failed, Qerror));
+  Fput (Quser_search_failed, Qerror_message,
+        build_pure_c_string ("Search failed"));
+
   Fput (Qinvalid_regexp, Qerror_conditions,
 	listn (CONSTYPE_PURE, 2, Qinvalid_regexp, Qerror));
   Fput (Qinvalid_regexp, Qerror_message,
-- 
2.11.1