From 70d98770ce6c1795ab172adf10bda87dafa310e3 Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Tue, 14 Mar 2023 09:58:29 -0700
Subject: [PATCH v5 1/5] Support language tags in older ICU versions (53 and
 earlier).

By calling uloc_canonicalize() before parsing the attributes, the
existing locale attribute parsing logic works on language tags as
well.

Fix a small memory leak, too.

Discussion: http://postgr.es/m/60da0cecfb512a78b8666b31631a636215d8ce73.camel@j-davis.com
---
 src/backend/commands/collationcmds.c          |  8 +++---
 src/backend/utils/adt/pg_locale.c             | 26 ++++++++++++++++---
 .../regress/expected/collate.icu.utf8.out     |  8 ++++++
 src/test/regress/sql/collate.icu.utf8.sql     |  4 +++
 4 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 8949684afe..b8f2e7059f 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -950,7 +950,6 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			const char *name;
 			char	   *langtag;
 			char	   *icucomment;
-			const char *iculocstr;
 			Oid			collid;
 
 			if (i == -1)
@@ -959,20 +958,19 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 				name = uloc_getAvailable(i);
 
 			langtag = get_icu_language_tag(name);
-			iculocstr = U_ICU_VERSION_MAJOR_NUM >= 54 ? langtag : name;
 
 			/*
 			 * Be paranoid about not allowing any non-ASCII strings into
 			 * pg_collation
 			 */
-			if (!pg_is_ascii(langtag) || !pg_is_ascii(iculocstr))
+			if (!pg_is_ascii(langtag) || !pg_is_ascii(langtag))
 				continue;
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
 									 COLLPROVIDER_ICU, true, -1,
-									 NULL, NULL, iculocstr, NULL,
-									 get_collation_actual_version(COLLPROVIDER_ICU, iculocstr),
+									 NULL, NULL, langtag, NULL,
+									 get_collation_actual_version(COLLPROVIDER_ICU, langtag),
 									 true, true);
 			if (OidIsValid(collid))
 			{
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 1d3d4d86d3..b9c7fbd511 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -2643,9 +2643,28 @@ pg_attribute_unused()
 static void
 icu_set_collation_attributes(UCollator *collator, const char *loc)
 {
-	char	   *str = asc_tolower(loc, strlen(loc));
+	UErrorCode	status;
+	int32_t		len;
+	char	   *icu_locale_id;
+	char	   *lower_str;
+	char	   *str;
 
-	str = strchr(str, '@');
+	/* first, make sure the string is an ICU format locale ID */
+	status = U_ZERO_ERROR;
+	len = uloc_canonicalize(loc, NULL, 0, &status);
+	icu_locale_id = palloc(len + 1);
+	status = U_ZERO_ERROR;
+	len = uloc_canonicalize(loc, icu_locale_id, len + 1, &status);
+	if (U_FAILURE(status))
+		ereport(ERROR,
+				(errmsg("canonicalization failed for locale string \"%s\": %s",
+						loc, u_errorName(status))));
+
+	lower_str = asc_tolower(icu_locale_id, strlen(icu_locale_id));
+
+	pfree(icu_locale_id);
+
+	str = strchr(lower_str, '@');
 	if (!str)
 		return;
 	str++;
@@ -2660,7 +2679,6 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 			char	   *value;
 			UColAttribute uattr;
 			UColAttributeValue uvalue;
-			UErrorCode	status;
 
 			status = U_ZERO_ERROR;
 
@@ -2727,6 +2745,8 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 								loc, u_errorName(status))));
 		}
 	}
+
+	pfree(lower_str);
 }
 
 #endif							/* USE_ICU */
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 9a3e12e42d..6225b575ce 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1304,6 +1304,14 @@ SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_inse
  t        | t
 (1 row)
 
+-- test language tags
+CREATE COLLATION lt_insensitive (provider = icu, locale = 'en-u-ks-level1', deterministic = false);
+SELECT 'aBcD' COLLATE lt_insensitive = 'AbCd' COLLATE lt_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
 CREATE TABLE test1cs (x text COLLATE case_sensitive);
 CREATE TABLE test2cs (x text COLLATE case_sensitive);
 CREATE TABLE test3cs (x text COLLATE case_sensitive);
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0790068f31..64cbfd0a5b 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -518,6 +518,10 @@ CREATE COLLATION case_insensitive (provider = icu, locale = '@colStrength=second
 SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
 SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
 
+-- test language tags
+CREATE COLLATION lt_insensitive (provider = icu, locale = 'en-u-ks-level1', deterministic = false);
+SELECT 'aBcD' COLLATE lt_insensitive = 'AbCd' COLLATE lt_insensitive;
+
 CREATE TABLE test1cs (x text COLLATE case_sensitive);
 CREATE TABLE test2cs (x text COLLATE case_sensitive);
 CREATE TABLE test3cs (x text COLLATE case_sensitive);
-- 
2.34.1