From 52cb8610cc4805be89ecf77285d9e6d1efaf9364 Mon Sep 17 00:00:00 2001
From: Stefan Kangas <stefan@marxist.se>
Date: Wed, 20 Oct 2021 14:16:07 +0200
Subject: [PATCH] Fix bug with string values in equal-including-properties

* src/intervals.c (intervals_equal_1): Factor out from
intervals_equal.  Use Fequal for comparison if third argument
use_equal is true.  This fixes a bug with string values in property
lists compared with 'equal-including-properties'.  (Bug#6581)
(intervals_equal): Update for the above.
(compare_string_intervals): Call intervals_equal1 with third
argument as true.
* src/intervals.h (intervals_equal_1): Declare.
* test/src/fns-tests.el (fns-tests-equal-including-properties)
(fns-tests-equal-including-properties/string-prop-vals): New tests.
---
 src/intervals.c       | 18 ++++++++++++++----
 src/intervals.h       |  1 +
 test/src/fns-tests.el | 19 +++++++++++++++++++
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/intervals.c b/src/intervals.c
index f88a41f254..cef5d9a4d7 100644
--- a/src/intervals.c
+++ b/src/intervals.c
@@ -166,10 +166,11 @@ merge_properties (register INTERVAL source, register INTERVAL target)
     }
 }
 
-/* Return true if the two intervals have the same properties.  */
+/* Return true if the two intervals have the same properties.
+   If use_equal is true, use Fequal for comparisons instead of EQ.  */
 
 bool
-intervals_equal (INTERVAL i0, INTERVAL i1)
+intervals_equal_1 (INTERVAL i0, INTERVAL i1, bool use_equal)
 {
   Lisp_Object i0_cdr, i0_sym;
   Lisp_Object i1_cdr, i1_val;
@@ -204,7 +205,8 @@ intervals_equal (INTERVAL i0, INTERVAL i1)
       /* i0 and i1 both have sym, but it has different values in each.  */
       if (!CONSP (i1_val)
 	  || (i1_val = XCDR (i1_val), !CONSP (i1_val))
-	  || !EQ (XCAR (i1_val), XCAR (i0_cdr)))
+	  || (!use_equal && !EQ (XCAR (i1_val), XCAR (i0_cdr)))
+	  || (use_equal && NILP (Fequal (XCAR (i1_val), XCAR (i0_cdr)))))
 	return false;
 
       i0_cdr = XCDR (i0_cdr);
@@ -218,6 +220,14 @@ intervals_equal (INTERVAL i0, INTERVAL i1)
   /* Lengths of the two plists were equal.  */
   return (NILP (i0_cdr) && NILP (i1_cdr));
 }
+
+/* Return true if the two intervals have the same properties.  */
+
+bool
+intervals_equal (INTERVAL i0, INTERVAL i1)
+{
+  return intervals_equal_1 (i0, i1, false);
+}
 
 
 /* Traverse an interval tree TREE, performing FUNCTION on each node.
@@ -2291,7 +2301,7 @@ compare_string_intervals (Lisp_Object s1, Lisp_Object s2)
 
       /* If we ever find a mismatch between the strings,
 	 they differ.  */
-      if (! intervals_equal (i1, i2))
+      if (! intervals_equal_1 (i1, i2, true))
 	return 0;
 
       /* Advance POS till the end of the shorter interval,
diff --git a/src/intervals.h b/src/intervals.h
index c1b19345d2..4096dc02fd 100644
--- a/src/intervals.h
+++ b/src/intervals.h
@@ -243,6 +243,7 @@ #define TEXT_PROP_MEANS_INVISIBLE(prop)					\
 
 extern INTERVAL create_root_interval (Lisp_Object);
 extern void copy_properties (INTERVAL, INTERVAL);
+bool intervals_equal_1 (INTERVAL, INTERVAL, bool);
 extern bool intervals_equal (INTERVAL, INTERVAL);
 extern void traverse_intervals (INTERVAL, ptrdiff_t,
                                 void (*) (INTERVAL, Lisp_Object),
diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index 3dc2e7b3ec..b4cb3c131a 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -57,6 +57,25 @@ fns-tests-equality-nan
       (puthash nan t h)
       (should (eq (funcall test nan -nan) (gethash -nan h))))))
 
+(ert-deftest fns-tests-equal-including-properties ()
+  (should (equal-including-properties "" ""))
+  (should (equal-including-properties "foobar" "foobar"))
+  (should (equal-including-properties #("a" 0 1 (k v))
+                                      #("a" 0 1 (k v))))
+  (should-not (equal-including-properties #("a" 0 1 (k v))
+                                          #("a" 0 1 (k x))))
+  (should-not (equal-including-properties #("a" 0 1 (k v))
+                                          #("b" 0 1 (k v)))))
+
+(ert-deftest fns-tests-equal-including-properties/string-prop-vals ()
+  "Handle string property values.  (Bug#6581)"
+  (should (equal-including-properties #("a" 0 1 (k "v"))
+                                      #("a" 0 1 (k "v"))))
+  (should-not (equal-including-properties #("a" 0 1 (k "v"))
+                                          #("a" 0 1 (k "x"))))
+  (should-not (equal-including-properties #("a" 0 1 (k "v"))
+                                          #("b" 0 1 (k "v")))))
+
 (ert-deftest fns-tests-reverse ()
   (should-error (reverse))
   (should-error (reverse 1))
-- 
2.30.2