From abdb802483042ca6c913cc2b5cddfff79082b08f Mon Sep 17 00:00:00 2001
From: =?utf8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Sun, 28 Apr 2024 23:17:48 +0200
Subject: [PATCH] Fix value< string comparison ungoodthink

* src/fns.c (string_cmp): Fix bad comparisons for certain strings.
This only affected `value<` for aggregates, not `string<`.
* test/src/fns-tests.el (fns-value<-ordered): Add test cases.

(cherry picked from commit 9b1e44c7fb5281688488ec077c048e268b716ad2)
---
 src/fns.c             | 8 ++++----
 test/src/fns-tests.el | 6 ++++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/fns.c b/src/fns.c
index 5cdd7e67f31..d4ba0601889 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -481,7 +481,7 @@ string_cmp (Lisp_Object string1, Lisp_Object string2)
       int d = memcmp (SSDATA (string1), SSDATA (string2), n);
       if (d)
 	return d;
-      return n < SCHARS (string2) ? -1 : n > SCHARS (string2);
+      return n < SCHARS (string2) ? -1 : n < SCHARS (string1);
     }
   else if (STRING_MULTIBYTE (string1) && STRING_MULTIBYTE (string2))
     {
@@ -515,7 +515,7 @@ string_cmp (Lisp_Object string1, Lisp_Object string2)
 
       if (b >= nb)
 	/* One string is a prefix of the other.  */
-	return b < nb2 ? -1 : b > nb2;
+	return b < nb2 ? -1 : b < nb1;
 
       /* Now back up to the start of the differing characters:
 	 it's the last byte not having the bit pattern 10xxxxxx.  */
@@ -540,7 +540,7 @@ string_cmp (Lisp_Object string1, Lisp_Object string2)
 	  if (c1 != c2)
 	    return c1 < c2 ? -1 : 1;
 	}
-      return i1 < SCHARS (string2) ? -1 : i1 > SCHARS (string2);
+      return i1 < SCHARS (string2) ? -1 : i1 < SCHARS (string1);
     }
   else
     {
@@ -553,7 +553,7 @@ string_cmp (Lisp_Object string1, Lisp_Object string2)
 	  if (c1 != c2)
 	    return c1 < c2 ? -1 : 1;
 	}
-      return i1 < SCHARS (string2) ? -1 : i1 > SCHARS (string2);
+      return i1 < SCHARS (string2) ? -1 : i1 < SCHARS (string1);
     }
 }
 
diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index 068daf893f1..a73a7a42f26 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -1614,6 +1614,12 @@
                    ;; strings
                    ("" . "a") ("a" . "b") ("A" . "a") ("abc" . "abd")
                    ("b" . "ba")
+                   ;; strings again, but in a context where 3-way comparison
+                   ;; matters
+                   (("" . 2) . ("a" . 1))
+                   (("å" . 2) . ("åü" . 1))
+                   (("a" . 2) . ("aå" . 1))
+                   (("\x80" . 2) . ("\x80Ã¥" . 1))
 
                    ;; lists
                    ((1 2 3) . (2 3 4)) ((2) . (2 1)) (() . (0))
-- 
2.39.5