Move reset of insert_values to ensure it's done also during error conditions

This fixed a failure of insert_update.test on some platforms


mysys/thr_alarm.c:
  Fixed problem noticed by valgrind
sql/opt_range.cc:
  Simple optimization for common case
sql/sql_base.cc:
  Safety assert
sql/sql_insert.cc:
  Added comment

mysys/thr_alarm.c

@@ -86,6 +86,7 @@ void init_thr_alarm(uint max_alarms)
   {
     struct sigaction sact;
     sact.sa_flags = 0;
+    bzero((char*) &sact, sizeof(sact));
     sact.sa_handler = thread_alarm;
     sigaction(THR_CLIENT_ALARM, &sact, (struct sigaction*) 0);
   }

sql/opt_range.cc

@@ -981,8 +981,7 @@ get_mm_parts(PARAM *param, COND *cond_func, Field *field,
     SEL_TREE *tree2= get_mm_parts(param, cond_func,
 				  field, Item_func::GT_FUNC,
                                   value, cmp_type);
-    if (!tree2)
-      DBUG_RETURN(0);
+    /* tree_or() will return 0 if tree2 is 0 */
     tree= tree_or(param,tree,tree2);
   }
   DBUG_RETURN(tree);

sql/sql_base.cc

@@ -979,6 +979,7 @@ TABLE *open_table(THD *thd,const char *db,const char *table_name,
   if (table->timestamp_field)
     table->timestamp_field_type= table->timestamp_field->get_auto_set_type();
   DBUG_ASSERT(table->key_read == 0);
+  DBUG_ASSERT(table->insert_values == 0);
   DBUG_RETURN(table);
 }
 

sql/sql_insert.cc

@@ -516,6 +516,10 @@ int mysql_insert(THD *thd,TABLE_LIST *table_list,
     ON DUPLICATE KEY ...
     we should be able to refer to sum1 in the ON DUPLICATE KEY part
 
+  WARNING
+    You MUST set table->insert_values to 0 after calling this function
+    before releasing the table object.
+
   RETURN VALUE
     0   OK
     -1  error (message is not sent to user)

sql/sql_parse.cc

@@ -2891,12 +2891,12 @@ mysql_execute_command(THD *thd)
       /* revert changes for SP */
       lex->select_lex.resolve_mode= SELECT_LEX::INSERT_MODE;
       delete result;
-      insert_table->insert_values= 0;
       if (thd->net.report_error)
         res= -1;
     }
     else
       res= -1;
+    insert_table->insert_values= 0;        // Set by mysql_prepare_insert()
     first_local_table->next= tables;
     lex->select_lex.table_list.first= (byte*) first_local_table;
     break;