MDEV-316 lp:1009085 Assertion failed: warn_item, file item_cmpfunc.cc, line 3613

make sure that find_date_time_item() is called before agg_arg_charsets_for_comparison().
optimize Item_func_conv_charset to avoid conversion if no string result is needed

mysql-test/r/mdev316.result

+set names swe7;
+select '' in ('',convert(0,time));
+'' in ('',convert(0,time))
+1
+select case '' when '' then 1 when convert(0,time) then 2 end;
+case '' when '' then 1 when convert(0,time) then 2 end
+1

mysql-test/t/mdev316.test

+#
+# MDEV-316 lp:1009085 Assertion failed: warn_item, file item_cmpfunc.cc, line 3613
+#
+set names swe7;
+select '' in ('',convert(0,time));
+select case '' when '' then 1 when convert(0,time) then 2 end;

sql/item_cmpfunc.cc

@@ -3032,6 +3032,11 @@ void Item_func_case::fix_length_and_dec()
     nagg++;
     if (!(found_types= collect_cmp_types(agg, nagg)))
       return;
+
+    Item *date_arg= 0;
+    if (found_types & (1 << TIME_RESULT))
+      date_arg= find_date_time_item(args, arg_count, 0);
+
     if (found_types & (1 << STRING_RESULT))
     {
       /*
@@ -3071,16 +3076,12 @@ void Item_func_case::fix_length_and_dec()
         change_item_tree_if_needed(thd, &args[nagg * 2], agg[nagg + 1]);
     }
 
-    Item *date_arg= 0;
     for (i= 0; i <= (uint)TIME_RESULT; i++)
     {
       if (found_types & (1 << i) && !cmp_items[i])
       {
         DBUG_ASSERT((Item_result)i != ROW_RESULT);
 
-        if ((Item_result)i == TIME_RESULT)
-          date_arg= find_date_time_item(args, arg_count, 0);
-
         if (!(cmp_items[i]=
             cmp_item::get_comparator((Item_result)i, date_arg,
                                      cmp_collation.collation)))
@@ -4051,15 +4052,15 @@ void Item_func_in::fix_length_and_dec()
   }
   else
   {
+    if (found_types & (1 << TIME_RESULT))
+      date_arg= find_date_time_item(args, arg_count, 0);
+    if (found_types & (1 << STRING_RESULT) &&
+        agg_arg_charsets_for_comparison(cmp_collation, args, arg_count))
+      return;
     for (i= 0; i <= (uint) TIME_RESULT; i++)
     {
       if (found_types & (1 << i) && !cmp_items[i])
       {
-        if ((Item_result)i == STRING_RESULT &&
-            agg_arg_charsets_for_comparison(cmp_collation, args, arg_count))
-          return;
-        if ((Item_result)i == TIME_RESULT)
-          date_arg= find_date_time_item(args, arg_count, 0);
         if (!cmp_items[i] && !(cmp_items[i]=
             cmp_item::get_comparator((Item_result)i, date_arg,
                                      cmp_collation.collation)))

sql/item_strfunc.h

@@ -854,6 +854,14 @@ public:
     }
   }
   String *val_str(String *);
+  longlong val_int()
+  { return args[0]->val_int(); }
+  double val_real()
+  { return args[0]->val_real(); }
+  my_decimal *val_decimal(my_decimal *d)
+  { return args[0]->val_decimal(d); }
+  bool get_date(MYSQL_TIME *ltime, ulonglong fuzzydate)
+  { return args[0]->get_date(ltime, fuzzydate); }
   void fix_length_and_dec();
   const char *func_name() const { return "convert"; }
   virtual void print(String *str, enum_query_type query_type);