From 2a22494c9938b2baf499f06e4ea8ed23b5468792 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 27 Oct 2026 20:08:45 +0100
Subject: [PATCH] Add test for ICU digit reorder bug

---
 .../regress/expected/collate.icu.utf8.out     | 36 +++++++++++++++++++
 src/test/regress/sql/collate.icu.utf8.sql     | 18 ++++++++++
 2 files changed, 54 insertions(+)

diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 69b2f5109ad..91bd5718a45 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1265,6 +1265,42 @@ SELECT 'Goldmann' < 'Götz' COLLATE "de-x-icu", 'Goldmann' > 'Götz' COLLATE tes
  t        | t
 (1 row)
 
+-- Test that reordering the "digit" reordering group is applied consistently
+-- by comparisons and by sorting (which may use sort keys).  In some ICU
+-- versions, comparisons ignored the reordering while sort keys honored it
+-- (ICU-23016).
+CREATE COLLATION testcoll_digitslast (provider = icu, locale = 'und-u-kr-latn-digit');
+CREATE TABLE test_digitslast (a text COLLATE testcoll_digitslast);
+INSERT INTO test_digitslast VALUES ('1'), ('2'), ('a'), ('b'), ('A'), ('B');
+-- The sorted position of each value must agree with direct comparisons.
+SELECT bool_and(consistent) FROM
+  (SELECT row_number() OVER (ORDER BY a) =
+          1 + (SELECT count(*) FROM test_digitslast u WHERE u.a < x.a)
+          AS consistent
+   FROM test_digitslast x) s;
+ bool_and 
+----------
+ t
+(1 row)
+
+SELECT a FROM test_digitslast ORDER BY a;  -- letters sort before digits
+ a 
+---
+ a
+ A
+ b
+ B
+ 1
+ 2
+(6 rows)
+
+SELECT 'a' < '1' COLLATE testcoll_digitslast;  -- true
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_digitslast;
 -- rules
 CREATE COLLATION testcoll_rules1 (provider = icu, locale = '', rules = '&a < g');
 NOTICE:  using standard form "und" for ICU locale ""
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 87cea263780..8e1495a9011 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -501,6 +501,24 @@ CREATE COLLATION testcoll_de_phonebook (provider = icu, locale = 'de@collation=p
 SELECT 'Goldmann' < 'Götz' COLLATE "de-x-icu", 'Goldmann' > 'Götz' COLLATE testcoll_de_phonebook;
 
 
+-- Test that reordering the "digit" reordering group is applied consistently
+-- by comparisons and by sorting (which may use sort keys).  In some ICU
+-- versions, comparisons ignored the reordering while sort keys honored it
+-- (ICU-23016).
+CREATE COLLATION testcoll_digitslast (provider = icu, locale = 'und-u-kr-latn-digit');
+CREATE TABLE test_digitslast (a text COLLATE testcoll_digitslast);
+INSERT INTO test_digitslast VALUES ('1'), ('2'), ('a'), ('b'), ('A'), ('B');
+-- The sorted position of each value must agree with direct comparisons.
+SELECT bool_and(consistent) FROM
+  (SELECT row_number() OVER (ORDER BY a) =
+          1 + (SELECT count(*) FROM test_digitslast u WHERE u.a < x.a)
+          AS consistent
+   FROM test_digitslast x) s;
+SELECT a FROM test_digitslast ORDER BY a;  -- letters sort before digits
+SELECT 'a' < '1' COLLATE testcoll_digitslast;  -- true
+DROP TABLE test_digitslast;
+
+
 -- rules
 
 CREATE COLLATION testcoll_rules1 (provider = icu, locale = '', rules = '&a < g');
-- 
2.56.0