Merged fix for the bug#37870.

sql/item_cmpfunc.cc

@@ -413,11 +413,11 @@ static bool convert_constant_item(THD *thd, Item_field *field_item,
     thd->count_cuted_fields= CHECK_FIELD_IGNORE;
 
     /*
-      Store the value of the field if it references an outer field because
+      Store the value of the field/constant if it references an outer field because
       the call to save_in_field below overrides that value.
-      Don't store it for EXPLAIN since it's not initialized.
+      Don't save value of the field for EXPLAIN since it's not initialized.
     */
-    if (field_item->depended_from && !thd->lex->describe)
+    if (field_item->depended_from && (!thd->lex->describe || field_item->const_item()))
       orig_field_val= field->val_int();
     if (!(*item)->is_null() && !(*item)->save_in_field(field, 1))
     {
@@ -428,7 +428,7 @@ static bool convert_constant_item(THD *thd, Item_field *field_item,
       result= 1;					// Item was replaced
     }
     /* Restore the original field value. */
-    if (field_item->depended_from && !thd->lex->describe)
+    if (field_item->depended_from && (!thd->lex->describe || field_item->const_item()))
     {
       result= field->store(orig_field_val, TRUE);
       /* orig_field_val must be a valid value that can be restored back. */