diff --git a/src/pl/parser/gen_parser.sh b/src/pl/parser/gen_parser.sh
index 62f08a997..a077e1097 100755
--- a/src/pl/parser/gen_parser.sh
+++ b/src/pl/parser/gen_parser.sh
@@ -18,18 +18,25 @@ if [ "$BISON_VERSION" != "$NEED_VERSION" ]; then
   exit 1
 fi
 
+bison_parser() {
+BISON_OUTPUT="$(bison -v -Werror -d $1 -o $2 2>&1)"
+BISON_RETURN="$?"
+echo $BISON_OUTPUT
+if [ $BISON_RETURN -ne 0 ]
+  then
+  >&2 echo "Compile error: $BISON_OUTPUT, abort."
+  exit 1
+fi
+if [[ $BISON_OUTPUT == *"conflict"* ]]
+then
+  >&2 echo "Compile conflict: $BISON_OUTPUT, abort."
+  exit 1
+fi
+}
+
 # generate pl_parser
-bison -v -Werror -d ../../../src/pl/parser/pl_parser_mysql_mode.y -o ../../../src/pl/parser/pl_parser_mysql_mode_tab.c
-if [ $? -ne 0 ]
-then
-    echo Compile error[$?], abort
-    exit 1
-fi
-if [ $? -ne 0 ]
-then
-    echo Compile error[$?], abort.
-    exit 1
-fi
+bison_parser ../../../src/pl/parser/pl_parser_mysql_mode.y ../../../src/pl/parser/pl_parser_mysql_mode_tab.c
+
 flex -o ../../../src/pl/parser/pl_parser_mysql_mode_lex.c ../../../src/pl/parser/pl_parser_mysql_mode.l ../../../src/pl/parser/pl_parser_mysql_mode_tab.h
 #./gen_type_name.sh ob_item_type.h >type_name.c
 
diff --git a/src/pl/parser/pl_parser_mysql_mode.y b/src/pl/parser/pl_parser_mysql_mode.y
index b2b47a0c4..e15e1cd8e 100644
--- a/src/pl/parser/pl_parser_mysql_mode.y
+++ b/src/pl/parser/pl_parser_mysql_mode.y
@@ -543,7 +543,7 @@ call_sp_stmt:
 
 opt_sp_cparam_list:
     /* Empty */ { $$ = NULL; }
-  | '(' ')' { $$ =NULL; }
+  | '(' ')' { $$ = NULL; }
   | '(' sp_cparams ')'
     {
       merge_nodes($$, parse_ctx->mem_pool_, T_SP_CPARAM_LIST, $2);
@@ -589,7 +589,7 @@ opt_sp_cparam_with_assign:
 ;
 
 cexpr:
-    {
+    %prec LOWER_PARENS {
       //same as expr in sql rule, and terminate when read ';'
       do_parse_sql_expr_rule($$, parse_ctx, 3, ',', ')', PARAM_ASSIGN_OPERATOR);
       if (NULL == $$) {