types: Fix potential timezone related bugs caused by gotime.Local (p…

…ingcap#13752)

types/time.go

@@ -430,7 +430,7 @@ func (t Time) RoundFrac(sc *stmtctx.StatementContext, fsp int8) (Time, error) {
 	} else {
 		// Take the hh:mm:ss part out to avoid handle month or day = 0.
 		hour, minute, second, microsecond := t.Time.Hour(), t.Time.Minute(), t.Time.Second(), t.Time.Microsecond()
-		t1 := gotime.Date(1, 1, 1, hour, minute, second, microsecond*1000, gotime.Local)
+		t1 := gotime.Date(1, 1, 1, hour, minute, second, microsecond*1000, sc.TimeZone)
 		t2 := roundTime(t1, fsp)
 		hour, minute, second = t2.Clock()
 		microsecond = t2.Nanosecond() / 1000

types/time_test.go

@@ -733,6 +733,30 @@ func (s *testTimeSuite) TestRoundFrac(c *C) {
 		// {"2012-01-00 23:59:59.999999", 3, "2012-01-01 00:00:00.000"},
 	}
 
+	for _, t := range tbl {
+		v, err := types.ParseTime(sc, t.Input, mysql.TypeDatetime, types.MaxFsp)
+		c.Assert(err, IsNil)
+		nv, err := v.RoundFrac(sc, t.Fsp)
+		c.Assert(err, IsNil)
+		c.Assert(nv.String(), Equals, t.Except)
+	}
+	// test different time zone
+	losAngelesTz, _ := time.LoadLocation("America/Los_Angeles")
+	sc.TimeZone = losAngelesTz
+	tbl = []struct {
+		Input  string
+		Fsp    int8
+		Except string
+	}{
+		{"2019-11-25 07:25:45.123456", 4, "2019-11-25 07:25:45.1235"},
+		{"2019-11-25 07:25:45.123456", 5, "2019-11-25 07:25:45.12346"},
+		{"2019-11-25 07:25:45.123456", 0, "2019-11-25 07:25:45"},
+		{"2019-11-25 07:25:45.123456", 2, "2019-11-25 07:25:45.12"},
+		{"2019-11-26 11:30:45.999999", 4, "2019-11-26 11:30:46.0000"},
+		{"2019-11-26 11:30:45.999999", 0, "2019-11-26 11:30:46"},
+		{"2019-11-26 11:30:45.999999", 3, "2019-11-26 11:30:46.000"},
+	}
+
 	for _, t := range tbl {
 		v, err := types.ParseTime(sc, t.Input, mysql.TypeDatetime, types.MaxFsp)
 		c.Assert(err, IsNil)