[bugfix](concat) be crash caused by function concat(ifnull) (#13693)

be/src/vec/functions/function_ifnull.h

@@ -62,7 +62,7 @@ public:
     // ifnull(col_left, col_right) == if(isnull(col_left), col_right, col_left)
     Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                         size_t result, size_t input_rows_count) override {
-        const ColumnWithTypeAndName& col_left = block.get_by_position(arguments[0]);
+        ColumnWithTypeAndName& col_left = block.get_by_position(arguments[0]);
         if (col_left.column->only_null()) {
             block.get_by_position(result).column = block.get_by_position(arguments[1]).column;
             return Status::OK();
@@ -71,6 +71,8 @@ public:
         ColumnWithTypeAndName null_column_arg0 {nullptr, std::make_shared<DataTypeUInt8>(), ""};
         ColumnWithTypeAndName nested_column_arg0 {nullptr, col_left.type, ""};
 
+        col_left.column = col_left.column->convert_to_full_column_if_const();
+
         /// implement isnull(col_left) logic
         if (auto* nullable = check_and_get_column<ColumnNullable>(*col_left.column)) {
             null_column_arg0.column = nullable->get_null_map_column_ptr();

regression-test/data/query_p0/sql_functions/conditional_functions/test_nullif.out

@@ -1,4 +1,10 @@
 -- This file is automatically generated. You should know what you did if you want to edit this
+-- !ifnull_const1 --
+aA
+
+-- !ifnull_const2 --
+aA
+
 -- !select --
 true
 \N

regression-test/suites/query_p0/sql_functions/conditional_functions/test_nullif.groovy

@@ -16,6 +16,9 @@
 // under the License.
 
 suite("test_nullif") {
+    qt_ifnull_const1 """select CONCAT('a', ifnull(split_part('A.B','.',1), 'x'));"""
+    qt_ifnull_const2 """select CONCAT('a', ifnull(split_part('A.B','.',1), null));"""
+
     def tableName = "datetype"
 
     sql """ DROP TABLE IF EXISTS ${tableName} """