Merge 10.1 into 10.2

For MDEV-15955, the fix in create_tmp_field_from_item() would cause a
compilation error. After a discussion with Alexander Barkov, the fix
was omitted and only the test case was kept.

In 10.3 and later, MDEV-15955 is fixed properly by overriding
create_tmp_field() in Item_func_user_var.

1 files changed, 11 insertions, 9 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index bdab9cf76cf..1b82b11fce6 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -7961,6 +7961,7 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
     KEYUSE *keyuse= pos->key;
     KEYUSE *prev_ref_keyuse= keyuse;
     uint key= keyuse->key;
+    bool used_range_selectivity= false;
     
     /*
       Check if we have a prefix of key=const that matches a quick select.
@@ -7986,6 +7987,7 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
           keyparts++;
         }
         sel /= (double)table->quick_rows[key] / (double) table->stat_records();
+        used_range_selectivity= true;
       }
     }
     
@@ -8021,13 +8023,14 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
           if (keyparts > keyuse->keypart)
 	  {
             /* Ok this is the keyuse that will be used for ref access */
-            uint fldno;
-            if (is_hash_join_key_no(key))
-	      fldno= keyuse->keypart;
-            else
-              fldno= table->key_info[key].key_part[keyparts-1].fieldnr - 1;
-            if (keyuse->val->const_item())
+            if (!used_range_selectivity && keyuse->val->const_item())
             { 
+              uint fldno;
+              if (is_hash_join_key_no(key))
+                fldno= keyuse->keypart;
+              else
+                fldno= table->key_info[key].key_part[keyparts-1].fieldnr - 1;
+
               if (table->field[fldno]->cond_selectivity > 0)
 	      {            
                 sel /= table->field[fldno]->cond_selectivity;
@@ -16344,10 +16347,9 @@ Field *Item::create_tmp_field(bool group, TABLE *table, uint convert_int_length)
 static Field *create_tmp_field_from_item(THD *thd, Item *item, TABLE *table,
                                          Item ***copy_func, bool modify_item)
 {
-  Field *UNINIT_VAR(new_field);
   DBUG_ASSERT(thd == table->in_use);
-  new_field= item->Item::create_tmp_field(false, table);
-    
+  Field *new_field= item->Item::create_tmp_field(false, table);
+
   if (copy_func &&
       (item->is_result_field() || 
        (item->real_item()->is_result_field())))