Subject: bug#22729: 25.0.50; cl-union ignores :test when lists are equal

From: Nicolas Richard <[email-masked]>
Date: Wed, 17 Feb 2016 09:50:17 +0100

Evaluating
    (cl-union (list "foo") (list "foo") :test 'eql)
returns ("foo") but should return ("foo" "foo") instead.

I suggest the following patch.

>From bece6982ebb9cfc145d45d1c11379133717c947b Mon Sep 17 00:00:00 2001
From: Nicolas Richard <[email-masked]>
Date: Wed, 17 Feb 2016 09:08:03 +0100
Subject: [PATCH] cl-union should not ignore :test argument when lists are
 equal

* cl-seq.el (cl-union): Do not ignore :test argument when lists are equal.

* test/automated/cl-seq-tests.el: New file.
---
 lisp/emacs-lisp/cl-seq.el      |  2 +-
 test/automated/cl-seq-tests.el | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 test/automated/cl-seq-tests.el

diff --git a/lisp/emacs-lisp/cl-seq.el b/lisp/emacs-lisp/cl-seq.el
index 61ee569..21aec6c 100644
--- a/lisp/emacs-lisp/cl-seq.el
+++ b/lisp/emacs-lisp/cl-seq.el
@@ -774,7 +774,7 @@ cl-union
 \nKeywords supported:  :test :test-not :key
 \n(fn LIST1 LIST2 [KEYWORD VALUE]...)"
   (cond ((null cl-list1) cl-list2) ((null cl-list2) cl-list1)
-	((equal cl-list1 cl-list2) cl-list1)
+	((and (not cl-keys) (equal cl-list1 cl-list2)) cl-list1)
 	(t
 	 (or (>= (length cl-list1) (length cl-list2))
 	     (setq cl-list1 (prog1 cl-list2 (setq cl-list2 cl-list1))))
diff --git a/test/automated/cl-seq-tests.el b/test/automated/cl-seq-tests.el
new file mode 100644
index 0000000..f8c8a43
--- /dev/null
+++ b/test/automated/cl-seq-tests.el
@@ -0,0 +1,38 @@
+;;; cl-seq-tests.el --- Tests for cl-seq.el functionality  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2015-2016 Free Software Foundation, Inc.
+
+;; Author: Nicolas Richard <[email-masked]>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-seq)
+
+(ert-deftest cl-union-test-00 ()
+  (let ((str1 "foo")
+        (str2 "foo"))
+    (should (equal (cl-union (list str1) (list str2))
+                   (list str2)))
+    (should (equal (cl-union (list str1) (list str2) :test 'eql)
+                   (list str1 str2)))))
+
+(provide 'cl-seq-tests)
+;;; cl-seq-tests.el ends here
-- 
2.4.5

If ok to apply, on which branch ?

In GNU Emacs 25.0.50.2 (i686-pc-linux-gnu, X toolkit, Xaw scroll bars)
 of 2016-01-17 built on Aurora
Repository revision: a0d5b7ae3bb014bb0b1c205d123c597df0e76411
Windowing system distributor 'The X.Org Foundation', version 11.0.11702000
System Description:	Ubuntu 15.10

Configured using:
 'configure --with-x-toolkit=lucid --enable-checking --with-wide-int
 --cache-file=/tmp/emacs.config.cache 'CFLAGS= -O0 -g3''