From b926f52688603fbcfb1df082b2711850b3127007 Mon Sep 17 00:00:00 2001
From: Frank Tang <ftang@chromium.org>
Date: Mon, 29 Mar 2021 20:35:43 +0000
Subject: [PATCH] ICU-21550 Add zzzz to subdivision if len==2

See #1662
---
 icu4c/source/common/locid.cpp                     |  7 +++++--
 icu4c/source/test/intltest/loctest.cpp            | 15 +++++++++++++++
 .../core/src/com/ibm/icu/util/ULocale.java        | 11 ++++++-----
 .../com/ibm/icu/dev/test/util/ULocaleTest.java    | 14 ++++++++++++++
 4 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/icu4c/source/common/locid.cpp b/icu4c/source/common/locid.cpp
index b79ba40ae7c..0d506293a99 100644
--- a/icu4c/source/common/locid.cpp
+++ b/icu4c/source/common/locid.cpp
@@ -1519,9 +1519,12 @@ AliasReplacer::replaceSubdivision(
         // Found replacement data for this subdivision.
         size_t len = (firstSpace != nullptr) ?
             (firstSpace - replacement) : uprv_strlen(replacement);
-        // Ignore len == 2, see CLDR-14312
-        if (3 <= len && len <= 8) {
+        if (2 <= len && len <= 8) {
             output.append(replacement, (int32_t)len, status);
+            if (2 == len) {
+                // Add 'zzzz' based on changes to UTS #35 for CLDR-14312.
+                output.append("zzzz", 4, status);
+            }
         }
         return true;
     }
diff --git a/icu4c/source/test/intltest/loctest.cpp b/icu4c/source/test/intltest/loctest.cpp
index f113eba6933..53d5721a98f 100644
--- a/icu4c/source/test/intltest/loctest.cpp
+++ b/icu4c/source/test/intltest/loctest.cpp
@@ -4938,6 +4938,21 @@ void LocaleTest::TestCanonicalize(void)
         { "und-FR-u-sd-frg", "und-FR-u-sd-frges"},
         { "und-LU-u-sd-lud", "und-LU-u-sd-lucl"},
 
+        // ICU-21550
+        { "und-u-rg-fi01", "und-u-rg-axzzzz"},
+        { "und-u-rg-frcp", "und-u-rg-cpzzzz"},
+        { "und-u-rg-frpm", "und-u-rg-pmzzzz"},
+        { "und-u-rg-usvi", "und-u-rg-vizzzz"},
+        { "und-u-rg-cn91", "und-u-rg-hkzzzz"},
+        { "und-u-rg-nlaw", "und-u-rg-awzzzz"},
+
+        { "und-NO-u-sd-frre", "und-NO-u-sd-rezzzz"},
+        { "und-CN-u-sd-nlcw", "und-CN-u-sd-cwzzzz"},
+        { "und-CZ-u-sd-usgu", "und-CZ-u-sd-guzzzz"},
+        { "und-FR-u-sd-shta", "und-FR-u-sd-tazzzz"},
+        { "und-FR-u-sd-cn71", "und-FR-u-sd-twzzzz"},
+
+
         // ICU-21401
         { "cel-gaulish", "xtg"},
 
diff --git a/icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java b/icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java
index 6e0009e881f..84472f5b301 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java
@@ -1402,11 +1402,12 @@ public final class ULocale implements Serializable, Comparable<ULocale> {
                     throw new IllegalArgumentException(
                         "Incorrect key [" + aliasFrom + "] in alias:territory.");
                 }
-                if (aliasTo.length() < 3 || aliasTo.length() > 8) {
-                    // Ignore replacement < 3 for now. see CLDR-14312
-                    // throw new IllegalArgumentException(
-                    //    "Incorrect value [" + aliasTo + "] in alias:subdivision.");
-                    continue;
+                if (aliasTo.length() == 2) {
+                    // Add 'zzzz' based on changes to UTS #35 for CLDR-14312.
+                    aliasTo += "zzzz";
+                } else if (aliasTo.length() < 2 || aliasTo.length() > 8) {
+                    throw new IllegalArgumentException(
+                        "Incorrect value [" + aliasTo + "] in alias:territory.");
                 }
                 subdivisionAliasMap.put(aliasFrom, aliasTo);
             }
diff --git a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/ULocaleTest.java b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/ULocaleTest.java
index c2d8c0739c2..cbd7a4fcbb0 100644
--- a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/ULocaleTest.java
+++ b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/ULocaleTest.java
@@ -5250,6 +5250,20 @@ public class ULocaleTest extends TestFmwk {
         Assert.assertEquals("und-FR-u-sd-frges", canonicalTag("und-FR-u-sd-frg"));
         Assert.assertEquals("und-LU-u-sd-lucl", canonicalTag("und-LU-u-sd-lud"));
 
+        // ICU-21550
+        Assert.assertEquals("und-u-rg-axzzzz", canonicalTag("und-u-rg-fi01"));
+        Assert.assertEquals("und-u-rg-cpzzzz", canonicalTag("und-u-rg-frcp"));
+        Assert.assertEquals("und-u-rg-pmzzzz", canonicalTag("und-u-rg-frpm"));
+        Assert.assertEquals("und-u-rg-vizzzz", canonicalTag("und-u-rg-usvi"));
+        Assert.assertEquals("und-u-rg-hkzzzz", canonicalTag("und-u-rg-cn91"));
+        Assert.assertEquals("und-u-rg-awzzzz", canonicalTag("und-u-rg-nlaw"));
+
+        Assert.assertEquals("und-NO-u-sd-rezzzz", canonicalTag("und-NO-u-sd-frre"));
+        Assert.assertEquals("und-CN-u-sd-cwzzzz", canonicalTag("und-CN-u-sd-nlcw"));
+        Assert.assertEquals("und-CZ-u-sd-guzzzz", canonicalTag("und-CZ-u-sd-usgu"));
+        Assert.assertEquals("und-FR-u-sd-tazzzz", canonicalTag("und-FR-u-sd-shta"));
+        Assert.assertEquals("und-FR-u-sd-twzzzz", canonicalTag("und-FR-u-sd-cn71"));
+
         // ICU-21401
         Assert.assertEquals("xtg", canonicalTag("cel-gaulish"));