MDEV-38391 Memory leak in innodb.import_hidden_fts_debug

update_vcol_pos(): Move DBUG_EXECUTE_IF before pars_info_create()
to prevent memory leak and fix test to properly
save/restore debug_dbug variable.

Author: Thirunarayanan

mysql-test/suite/innodb/r/import_hidden_fts_debug.result

@@ -26,19 +26,22 @@ f2 CHAR(2) NOT NULL,
 f3 INT as (f1) VIRTUAL, INDEX(f3))ENGINE=InnoDB;
 ALTER TABLE t1 DISCARD TABLESPACE;
 restore: t1 .ibd and .cfg files
+SET @save_debug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_set_index_root_failure";
 ALTER TABLE t1 IMPORT TABLESPACE;
 ERROR HY000: Too many active concurrent transactions
-SET DEBUG_DBUG="-d,ib_import_set_index_root_failure";
+set DEBUG_DBUG=@save_dbug;
+SET @save_debug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_vcol_update_fail";
 ALTER TABLE t1 IMPORT TABLESPACE;
 ERROR 23000: Can't write; duplicate key in table 't1'
-SET DEBUG_DBUG="-d,ib_import_vcol_update_fail";
+set DEBUG_DBUG=@save_dbug;
 restore: t1 .ibd and .cfg files
+SET @save_dbug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_fts_error";
 ALTER TABLE t1 IMPORT TABLESPACE;
 ERROR 23000: Can't write; duplicate key in table 't1'
-SET DEBUG_DBUG="-d,ib_import_fts_error";
+SET DEBUG_DBUG=@save_dbug;
 unlink: t1.ibd
 unlink: t1.cfg
 SELECT NAME FROM INFORMATION_SCHEMA.INNODB_SYS_COLUMNS

mysql-test/suite/innodb/t/import_hidden_fts_debug.test

@@ -39,26 +39,29 @@ ib_restore_tablespaces("test", "t1");
 EOF
 
 --disable_warnings
+SET @save_debug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_set_index_root_failure";
 --error ER_TOO_MANY_CONCURRENT_TRXS
 ALTER TABLE t1 IMPORT TABLESPACE;
-SET DEBUG_DBUG="-d,ib_import_set_index_root_failure";
+set DEBUG_DBUG=@save_dbug;
 
+SET @save_debug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_vcol_update_fail";
 --error ER_DUP_KEY
 ALTER TABLE t1 IMPORT TABLESPACE;
-SET DEBUG_DBUG="-d,ib_import_vcol_update_fail";
+set DEBUG_DBUG=@save_dbug;
 
 perl;
 do "$ENV{MTR_SUITE_DIR}/include/innodb-util.pl";
 ib_discard_tablespaces("test", "t1");
 ib_restore_tablespaces("test", "t1");
 EOF
 
+SET @save_dbug=@@debug_dbug;
 SET DEBUG_DBUG="+d,ib_import_fts_error";
 --error ER_DUP_KEY
 ALTER TABLE t1 IMPORT TABLESPACE;
-SET DEBUG_DBUG="-d,ib_import_fts_error";
+SET DEBUG_DBUG=@save_dbug;
 --enable_warnings
 
 perl;

storage/innobase/row/row0import.cc

@@ -4558,11 +4558,11 @@ static void row_import_autoinc(dict_table_t *table, row_prebuilt_t *prebuilt,
 @return DB_SUCCESS or error code */
 dberr_t update_vcol_pos(table_id_t table_id, ulint new_pos, trx_t *trx)
 {
+  DBUG_EXECUTE_IF("ib_import_vcol_update_fail",
+                  return DB_DUPLICATE_KEY;);
   pars_info_t *info= pars_info_create();
   pars_info_add_ull_literal(info, "id", table_id);
   pars_info_add_int4_literal(info, "old_pos", new_pos - 1);
-  DBUG_EXECUTE_IF("ib_import_vcol_update_fail",
-                  return DB_DUPLICATE_KEY;);
   return que_eval_sql(info,
                       "PROCEDURE UPDATE_VCOL () IS\n"
                       "BEGIN\n"