Merge magare.gmz:/home/kgeorge/mysql/autopush/B31440-5.0-opt

into  magare.gmz:/home/kgeorge/mysql/work/B31440-5.1-opt

mysql-test/r/func_regexp.result

@@ -98,3 +98,8 @@ R2
 R3
 deallocate prepare stmt1;
 drop table t1;
+End of 4.1 tests
+SELECT 1 REGEXP NULL;
+1 REGEXP NULL
+NULL
+End of 5.0 tests

mysql-test/t/func_regexp.test

@@ -74,4 +74,13 @@ execute stmt1 using @a;
 deallocate prepare stmt1;
 drop table t1;
 
-# End of 4.1 tests
+--echo End of 4.1 tests
+
+
+#
+# Bug #31440: 'select 1 regex null' asserts debug server
+#
+
+SELECT 1 REGEXP NULL;
+
+--echo End of 5.0 tests

sql/item_cmpfunc.cc

@@ -4398,6 +4398,7 @@ Item_func_regex::fix_fields(THD *thd, Item **ref)
     if (args[1]->null_value)
     {						// Will always return NULL
       maybe_null=1;
+      fixed= 1;
       return FALSE;
     }
     int error;