Fix tem object out of scope issue (#8767)

close #8674

dbms/src/Flash/Coprocessor/ArrowColCodec.cpp

@@ -347,9 +347,8 @@ void flashEnumColToArrowCol(
                 enum_value,
                 enum_value_size);
 
-        TiDBEnum ti_enum(
-            enum_value,
-            enum_type->getNameForValue(static_cast<const DataTypeEnum16::FieldType>(enum_value)));
+        const auto & enum_name = enum_type->getNameForValue(static_cast<const DataTypeEnum16::FieldType>(enum_value));
+        TiDBEnum ti_enum(enum_value, enum_name);
         dag_column.append(ti_enum);
     }
 }

dbms/src/Flash/Coprocessor/TiDBEnum.h

@@ -32,6 +32,6 @@ class TiDBEnum
         , name(name_)
     {}
     UInt64 value;
-    const StringRef & name;
+    const StringRef name;
 };
 } // namespace DB

tests/fullstack-test/issues/issue_8767.test

@@ -0,0 +1,28 @@
+# Copyright 2024 PingCAP, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+mysql> drop table if exists test.t1
+mysql> create table test.t1 (COL1 enum('^YSQT0]V@9TFN>^WB6G?NG@S8>VYOM;BSC@<BCQ6'), COL2 mediumint(41) DEFAULT NULL, COL3 year(4) DEFAULT NULL, KEY `U_M_COL4` (`COL1`,`COL2`), KEY U_M_COL5 (COL3, COL2));
+mysql> insert into test.t1 values ('^YSQT0]V@9TFN>^WB6G?NG@S8>VYOM;BSC@<BCQ6', -1881752, 1986);
+mysql> alter table test.t1 set tiflash replica 1
+func> wait_table test t1
+
+mysql> set session tidb_isolation_read_engines='tiflash'; set tidb_enforce_mpp=1; SELECT * FROM test.t1 where col2 = -1881752 and col2 * -1881752 != 8366212;
++------------------------------------------+----------+------+
+| COL1                                     | COL2     | COL3 |
++------------------------------------------+----------+------+
+| ^YSQT0]V@9TFN>^WB6G?NG@S8>VYOM;BSC@<BCQ6 | -1881752 | 1986 |
++------------------------------------------+----------+------+
+
+mysql> drop table if exists test.t1