Don't allow creation of database with ICU locale with unsupported encoding

Check in CREATE DATABASE and initdb that the selected encoding is
supported by ICU.  Before, they would pass but users would later get
an error from the server when they tried to use the database.

Also document that initdb sets the encoding to UTF8 by default if the
ICU locale provider is chosen.

Author: Marina Polyakova <m.polyakova@postgrespro.ru>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://www.postgresql.org/message-id/6dd6db0984d86a51b7255ba79f111971@postgrespro.ru

4 files changed, 54 insertions, 2 deletions

diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 59e217b9f9d..cba929b7f99 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1033,6 +1033,12 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 
 	if (dblocprovider == COLLPROVIDER_ICU)
 	{
+		if (!(is_encoding_supported_by_icu(encoding)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("encoding \"%s\" is not supported with ICU provider",
+							pg_encoding_to_char(encoding))));
+
 		/*
 		 * This would happen if template0 uses the libc provider but the new
 		 * database uses icu.
@@ -1041,10 +1047,9 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("ICU locale must be specified")));
-	}
 
-	if (dblocprovider == COLLPROVIDER_ICU)
 		check_icu_locale(dbiculocale);
+	}
 
 	/*
 	 * Check that the new encoding and locale settings match the source
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 89b888eaa5a..429844fdd35 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2092,6 +2092,27 @@ check_locale_encoding(const char *locale, int user_enc)
 }
 
 /*
+ * check if the chosen encoding matches is supported by ICU
+ *
+ * this should match the similar check in the backend createdb() function
+ */
+static bool
+check_icu_locale_encoding(int user_enc)
+{
+	if (!(is_encoding_supported_by_icu(user_enc)))
+	{
+		pg_log_error("encoding mismatch");
+		pg_log_error_detail("The encoding you selected (%s) is not supported with the ICU provider.",
+							pg_encoding_to_char(user_enc));
+		pg_log_error_hint("Rerun %s and either do not specify an encoding explicitly, "
+						  "or choose a matching combination.",
+						  progname);
+		return false;
+	}
+	return true;
+}
+
+/*
  * set up the locale variables
  *
  * assumes we have called setlocale(LC_ALL, "") -- see set_pglocale_pgservice
@@ -2359,7 +2380,11 @@ setup_locale_encoding(void)
 	}
 
 	if (!encoding && locale_provider == COLLPROVIDER_ICU)
+	{
 		encodingid = PG_UTF8;
+		printf(_("The default database encoding has been set to \"%s\".\n"),
+			   pg_encoding_to_char(encodingid));
+	}
 	else if (!encoding)
 	{
 		int			ctype_enc;
@@ -2411,6 +2436,10 @@ setup_locale_encoding(void)
 	if (!check_locale_encoding(lc_ctype, encodingid) ||
 		!check_locale_encoding(lc_collate, encodingid))
 		exit(1);				/* check_locale_encoding printed the error */
+
+	if (locale_provider == COLLPROVIDER_ICU &&
+		!check_icu_locale_encoding(encodingid))
+		exit(1);
 }
 
 
diff --git a/src/bin/initdb/t/001_initdb.pl b/src/bin/initdb/t/001_initdb.pl
index a37f6dd9b33..164fc11cbff 100644
--- a/src/bin/initdb/t/001_initdb.pl
+++ b/src/bin/initdb/t/001_initdb.pl
@@ -118,6 +118,15 @@ if ($ENV{with_icu} eq 'yes')
 		],
 		qr/FATAL:  could not open collator for locale/,
 		'fails for invalid ICU locale');
+
+	command_fails_like(
+		[
+			'initdb',                '--no-sync',
+			'--locale-provider=icu', '--encoding=SQL_ASCII',
+			'--icu-locale=en', "$tempdir/dataX"
+		],
+		qr/error: encoding mismatch/,
+		'fails for encoding not supported by ICU');
 }
 else
 {
diff --git a/src/bin/scripts/t/020_createdb.pl b/src/bin/scripts/t/020_createdb.pl
index e91c1d013d0..e95f200d0b9 100644
--- a/src/bin/scripts/t/020_createdb.pl
+++ b/src/bin/scripts/t/020_createdb.pl
@@ -50,6 +50,15 @@ if ($ENV{with_icu} eq 'yes')
 		],
 		'fails for invalid ICU locale');
 
+	$node->command_fails_like(
+		[
+			'createdb',             '-T',
+			'template0',            '--locale-provider=icu',
+			'--encoding=SQL_ASCII', 'foobarX'
+		],
+		qr/ERROR:  encoding "SQL_ASCII" is not supported with ICU provider/,
+		'fails for encoding not supported by ICU');
+
 	# additional node, which uses the icu provider
 	my $node2 = PostgreSQL::Test::Cluster->new('icu');
 	$node2->init(extra => ['--locale-provider=icu', '--icu-locale=en']);