GNU bug report logs - #19434
24.4; cl-subseq bounding issues

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Leo Liu <sdl.web <at> gmail.com>
Subject: bug#19434: closed (Re: bug#19434: 24.4; cl-subseq bounding issues)
Date: Sun, 18 Jan 2015 06:22:02 +0000

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Your bug report

#19434: 24.4; cl-subseq bounding issues

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 19434 <at> debbugs.gnu.org.

-- 
19434: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19434
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Leo Liu <sdl.web <at> gmail.com>
To: 19434-done <at> debbugs.gnu.org
Cc: Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#19434: 24.4; cl-subseq bounding issues
Date: Sun, 18 Jan 2015 14:21:08 +0800

Version: 25.1

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From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.4; cl-subseq bounding issues
Date: Wed, 24 Dec 2014 12:14:22 +0800

At the moment (cl-subseq '(1 2 3) 0 5) => (1 2 3 nil nil)

I propose the following fix:

diff --git a/lisp/emacs-lisp/cl-extra.el b/lisp/emacs-lisp/cl-extra.el
index a94dcd33..b50c1e6a 100644
--- a/lisp/emacs-lisp/cl-extra.el
+++ b/lisp/emacs-lisp/cl-extra.el
@@ -524,15 +524,21 @@ (defun cl-subseq (seq start &optional end)
               `(progn (cl-replace ,seq ,new :start1 ,start :end1 ,end)
                       ,new))))
   (if (stringp seq) (substring seq start end)
-    (let (len)
+    (let ((orig-start start) (orig-end end) len)
       (and end (< end 0) (setq end (+ end (setq len (length seq)))))
       (if (< start 0) (setq start (+ start (or len (setq len (length seq))))))
       (cond ((listp seq)
-	     (if (> start 0) (setq seq (nthcdr start seq)))
+	     (when (> start 0)
+	       (setq seq (nthcdr (1- start) seq))
+	       (or seq
+		   (error "Bad bounding indices: %s, %s" orig-start orig-end))
+	       (setq seq (cdr seq)))
 	     (if end
 		 (let ((res nil))
-		   (while (>= (setq end (1- end)) start)
+		   (while (and seq (>= (setq end (1- end)) start))
 		     (push (pop seq) res))
+		   (or (= start end)
+		       (error "Bad bounding indices: %s, %s" orig-start orig-end))
 		   (nreverse res))
 	       (copy-sequence seq)))
 	    (t
diff --git a/test/automated/cl-lib-tests.el b/test/automated/cl-lib-tests.el
index e4c6e914..162f7aeb 100644
--- a/test/automated/cl-lib-tests.el
+++ b/test/automated/cl-lib-tests.el
@@ -245,4 +245,10 @@ (ert-deftest cl-parse-integer ()
 (ert-deftest cl-loop-destructuring-with ()
   (should (equal (cl-loop with (a b c) = '(1 2 3) return (+ a b c)) 6)))
 
+(ert-deftest cl-subseq ()
+  (should-error (cl-subseq '(1 2 3) 4))
+  (should-not   (cl-subseq '(1 2 3) 3))
+  (should       (cl-subseq '(1 2 3) -3))
+  (should-error (cl-subseq '(1 2 3) 1 4)))
+
 ;;; cl-lib.el ends here

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