From e5468b7d7df1daf4a37082b3faefa8d7d79f89e1 Mon Sep 17 00:00:00 2001
From: djshow832 <873581766@qq.com>
Date: Thu, 29 Sep 2022 16:45:57 +0800
Subject: [PATCH] revert lc_messages

---
 sessionctx/variable/noop.go        |  3 ++-
 sessionctx/variable/sysvar_test.go | 11 ++++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/sessionctx/variable/noop.go b/sessionctx/variable/noop.go
index b720490d03423..398ea09f3ec92 100644
--- a/sessionctx/variable/noop.go
+++ b/sessionctx/variable/noop.go
@@ -295,7 +295,8 @@ var noopSysVars = []*SysVar{
 	{Scope: ScopeGlobal, Name: SlowQueryLog, Value: "0"},
 	{Scope: ScopeSession, Name: "debug_sync", Value: ""},
 	{Scope: ScopeGlobal, Name: InnodbStatsAutoRecalc, Value: "1"},
-	{Scope: ScopeGlobal | ScopeSession, Name: "lc_messages", Value: "en_US", ReadOnly: true},
+	// lc_messages cannot be read_only, see https://github.com/pingcap/tidb/issues/38231.
+	{Scope: ScopeGlobal | ScopeSession, Name: "lc_messages", Value: "en_US"},
 	{Scope: ScopeGlobal | ScopeSession, Name: "bulk_insert_buffer_size", Value: "8388608", IsHintUpdatable: true},
 	{Scope: ScopeGlobal | ScopeSession, Name: BinlogDirectNonTransactionalUpdates, Value: Off, Type: TypeBool},
 	{Scope: ScopeGlobal, Name: "innodb_change_buffering", Value: "all"},
diff --git a/sessionctx/variable/sysvar_test.go b/sessionctx/variable/sysvar_test.go
index a3aadde315370..a9e97ec5338ca 100644
--- a/sessionctx/variable/sysvar_test.go
+++ b/sessionctx/variable/sysvar_test.go
@@ -468,12 +468,17 @@ func TestLcTimeNamesReadOnly(t *testing.T) {
 	require.Error(t, err)
 }
 
-func TestLcMessagesReadOnly(t *testing.T) {
+func TestLcMessages(t *testing.T) {
 	sv := GetSysVar("lc_messages")
 	vars := NewSessionVars()
 	vars.GlobalVarsAccessor = NewMockGlobalAccessor4Tests()
-	_, err := sv.Validate(vars, "newvalue", ScopeGlobal)
-	require.Error(t, err)
+	_, err := sv.Validate(vars, "zh_CN", ScopeGlobal)
+	require.NoError(t, err)
+	err = sv.SetSessionFromHook(vars, "zh_CN")
+	require.NoError(t, err)
+	val, err := vars.GetSessionOrGlobalSystemVar("lc_messages")
+	require.NoError(t, err)
+	require.Equal(t, val, "zh_CN")
 }
 
 func TestDDLWorkers(t *testing.T) {