From b9cf6379e2d86857efef85db00b01bfc66c9c4e2 Mon Sep 17 00:00:00 2001
From: "vitess-bot[bot]" <108069721+vitess-bot[bot]@users.noreply.github.com>
Date: Thu, 16 Jan 2025 07:15:34 +0100
Subject: [PATCH] Cherry-pick 5468f5db7db117f955aaf9c56182f05fc496c14b

Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
---
 go/vt/vtgate/engine/fake_vcursor_test.go |  2 +-
 go/vt/vtgate/evalengine/fn_time.go       |  4 ++--
 go/vt/vtgate/safe_session.go             | 11 ++++++-----
 go/vt/vtgate/safe_session_test.go        | 14 ++++++++++----
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/go/vt/vtgate/engine/fake_vcursor_test.go b/go/vt/vtgate/engine/fake_vcursor_test.go
index 9ba4fdc6a6b..4c7ed3b3689 100644
--- a/go/vt/vtgate/engine/fake_vcursor_test.go
+++ b/go/vt/vtgate/engine/fake_vcursor_test.go
@@ -164,7 +164,7 @@ func (t *noopVCursor) Environment() *vtenv.Environment {
 }
 
 func (t *noopVCursor) TimeZone() *time.Location {
-	return nil
+	return time.Local
 }
 
 func (t *noopVCursor) SQLMode() string {
diff --git a/go/vt/vtgate/evalengine/fn_time.go b/go/vt/vtgate/evalengine/fn_time.go
index 2d5e12f518d..322b89faafb 100644
--- a/go/vt/vtgate/evalengine/fn_time.go
+++ b/go/vt/vtgate/evalengine/fn_time.go
@@ -256,7 +256,7 @@ func (call *builtinNow) constant() bool {
 
 func (call *builtinSysdate) eval(env *ExpressionEnv) (eval, error) {
 	now := SystemTime()
-	if tz := env.currentTimezone(); tz != nil {
+	if tz := env.currentTimezone(); tz != time.Local {
 		now = now.In(tz)
 	}
 	return newEvalDateTime(datetime.NewDateTimeFromStd(now), int(call.prec), false), nil
@@ -701,7 +701,7 @@ func (b *builtinFromUnixtime) eval(env *ExpressionEnv) (eval, error) {
 	}
 
 	t := time.Unix(sec, frac)
-	if tz := env.currentTimezone(); tz != nil {
+	if tz := env.currentTimezone(); tz != time.Local {
 		t = t.In(tz)
 	}
 
diff --git a/go/vt/vtgate/safe_session.go b/go/vt/vtgate/safe_session.go
index 1d57c63ef35..dda4005774c 100644
--- a/go/vt/vtgate/safe_session.go
+++ b/go/vt/vtgate/safe_session.go
@@ -569,17 +569,18 @@ func (session *SafeSession) TimeZone() *time.Location {
 	session.mu.Unlock()
 
 	if !ok {
-		return nil
+		return time.Local
 	}
 
 	tz, err := sqltypes.DecodeStringSQL(zoneSQL)
 	if err != nil {
-		return nil
+		return time.Local
 	}
 
-	loc, _ := datetime.ParseTimeZone(tz)
-	// it's safe to ignore the error - if we get an error, loc will be nil,
-	// and this is exactly the behaviour we want anyway
+	loc, err := datetime.ParseTimeZone(tz)
+	if err != nil {
+		return time.Local
+	}
 	return loc
 }
 
diff --git a/go/vt/vtgate/safe_session_test.go b/go/vt/vtgate/safe_session_test.go
index ce681fe7fd3..f3a78d7f497 100644
--- a/go/vt/vtgate/safe_session_test.go
+++ b/go/vt/vtgate/safe_session_test.go
@@ -72,6 +72,10 @@ func TestTimeZone(t *testing.T) {
 		tz   string
 		want string
 	}{
+		{
+			tz:   "",
+			want: time.Local.String(),
+		},
 		{
 			tz:   "'Europe/Amsterdam'",
 			want: "Europe/Amsterdam",
@@ -82,16 +86,18 @@ func TestTimeZone(t *testing.T) {
 		},
 		{
 			tz:   "foo",
-			want: (*time.Location)(nil).String(),
+			want: time.Local.String(),
 		},
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.tz, func(t *testing.T) {
+			sysvars := map[string]string{}
+			if tc.tz != "" {
+				sysvars["time_zone"] = tc.tz
+			}
 			session := NewSafeSession(&vtgatepb.Session{
-				SystemVariables: map[string]string{
-					"time_zone": tc.tz,
-				},
+				SystemVariables: sysvars,
 			})
 
 			assert.Equal(t, tc.want, session.TimeZone().String())