*: panic guard for warnings (#54043) (#54369)

close #48756

pkg/executor/show.go

@@ -1909,7 +1909,11 @@ func (e *ShowExec) fetchShowWarnings(errOnly bool) error {
 			sqlErr := terror.ToSQLError(x)
 			e.appendRow([]interface{}{w.Level, int64(sqlErr.Code), sqlErr.Message})
 		default:
-			e.appendRow([]interface{}{w.Level, int64(mysql.ErrUnknown), warn.Error()})
+			var err string
+			if warn != nil {
+				err = warn.Error()
+			}
+			e.appendRow([]any{w.Level, int64(mysql.ErrUnknown), err})
 		}
 	}
 	return nil

pkg/executor/test/executor/executor_test.go

@@ -4453,3 +4453,22 @@ func TestIssue51324(t *testing.T) {
 	tk.MustQuery("show warnings").Check(testkit.Rows("Warning 1364 Field 'a' doesn't have a default value", "Warning 1364 Field 'b' doesn't have a default value", "Warning 1364 Field 'c' doesn't have a default value", "Warning 1364 Field 'd' doesn't have a default value"))
 	tk.MustQuery("select * from t order by id").Check(testkit.Rows("13 <nil> <nil> 0 0", "21 1 <nil> 0 1", "22 1 <nil> 0 1"))
 }
+
+func TestIssue48756(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE t (id INT, a VARBINARY(20), b BIGINT)")
+	tk.MustExec(`INSERT INTO t VALUES(1, _binary '2012-05-19 09:06:07', 20120519090607),
+(1, _binary '2012-05-19 09:06:07', 20120519090607),
+(2, _binary '12012-05-19 09:06:07', 120120519090607),
+(2, _binary '12012-05-19 09:06:07', 120120519090607)`)
+	tk.MustQuery("SELECT SUBTIME(BIT_OR(b), '1 1:1:1.000002') FROM t GROUP BY id").Sort().Check(testkit.Rows(
+		"2012-05-18 08:05:05.999998",
+		"<nil>",
+	))
+	tk.MustQuery("show warnings").Check(testkit.Rows(
+		"Warning 1292 Incorrect time value: '120120519090607'",
+		"Warning 1105 ",
+	))
+}