Manual merge of patch for bug#11060 "Server crashes on calling stored

procedure with INSERT SELECT UNION SELECT" aka "Server crashes on
re-execution of prepared INSERT ... SELECT with UNION" into 5.0 tree.

mysql-test/r/ps.result

@@ -675,3 +675,9 @@ a
 10
 drop table t1;
 deallocate prepare stmt;
+create table t1 (id int);
+prepare stmt from "insert into t1 (id) select id from t1 union select id from t1";
+execute stmt;
+execute stmt;
+deallocate prepare stmt;
+drop table t1;

mysql-test/t/ps.test

@@ -693,3 +693,15 @@ execute stmt using @offset, @limit, @offset, @limit, @limit;
 
 drop table t1;
 deallocate prepare stmt;
+
+#
+# Bug#11060 "Server crashes on calling stored procedure with INSERT SELECT
+# UNION SELECT" aka "Server crashes on re-execution of prepared INSERT ...
+# SELECT with UNION".
+#
+create table t1 (id int);
+prepare stmt from "insert into t1 (id) select id from t1 union select id from t1";
+execute stmt;
+execute stmt;
+deallocate prepare stmt;
+drop table t1;

sql/sql_insert.cc

@@ -1988,10 +1988,22 @@ select_insert::select_insert(TABLE_LIST *table_list_par, TABLE *table_par,
 int
 select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 {
+  int res;
+  LEX *lex= thd->lex;
+  SELECT_LEX *lex_current_select_save= lex->current_select;
   DBUG_ENTER("select_insert::prepare");
 
   unit= u;
-  if (check_insert_fields(thd, table_list, *fields, values, !insert_into_view))
+  /*
+    Since table in which we are going to insert is added to the first
+    select, LEX::current_select should point to the first select while
+    we are fixing fields from insert list.
+  */
+  lex->current_select= &lex->select_lex;
+  res= check_insert_fields(thd, table_list, *fields, values,
+                           !insert_into_view);
+  lex->current_select= lex_current_select_save;
+  if (res)
     DBUG_RETURN(1);
   /*
     if it is INSERT into join view then check_insert_fields already found
@@ -2003,12 +2015,12 @@ select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
     Is table which we are changing used somewhere in other parts of
     query
   */
-  if (!(thd->lex->current_select->options & OPTION_BUFFER_RESULT) &&
+  if (!(lex->current_select->options & OPTION_BUFFER_RESULT) &&
       unique_table(table_list, table_list->next_global))
   {
     /* Using same table for INSERT and SELECT */
-    thd->lex->current_select->options|= OPTION_BUFFER_RESULT;
-    thd->lex->current_select->join->select_options|= OPTION_BUFFER_RESULT;
+    lex->current_select->options|= OPTION_BUFFER_RESULT;
+    lex->current_select->join->select_options|= OPTION_BUFFER_RESULT;
   }
   else
   {