Fixes for bug#8115 "Server Crash with prepared statement"

 and bug#8849 "problem with insert statement with table alias's": 
make equality propagation work in stored procedures and prepared 
statements.
Equality propagation can change AND/OR structure of ON expressions,
so the fix is to provide each execution of PS/SP with it's own
copy of AND/OR tree. We have been doing that already for WHERE clauses,
now ON clauses are also copied.


mysql-test/r/ps.result:
  Bug#8115: test results fixed.
mysql-test/r/sp.result:
  Bug#8849: test results fixed.
mysql-test/t/ps.test:
  A test case for Bug#8115 "Server Crash with prepared statement".
mysql-test/t/sp.test:
  A test case for Bug#8849 "problem with insert statement with table 
  alias's".
sql/item_cmpfunc.cc:
  Comment a parse tree transformation.
sql/item_cmpfunc.h:
  Comment how Item_equal works with PS/SP.
sql/mysql_priv.h:
  Add declaration for init_stmt_after_parse.
sql/sp_head.cc:
  Call init_stmt_after_parse in restore_lex(), which is used to
  grab TABLE_LIST and SELECT_LEX list of a parsed substatement of
  stored procedure. This is a necessary post-init step which 
  must be done for any statement which can be executed many times.
sql/sql_prepare.cc:
  Implement init_stmt_after_parse() which prepares AND/OR
  structure of all ON expressions and WHERE clauses of a statement
  for copying.
sql/sql_select.cc:
  Implementation of equality propagation inspected with regard to 
  prepared statements and stored procedures. We now restore
  AND/OR structure of every ON expression in addition to AND/OR
  structure of WHERE clauses when reexecuting a PS/SP.
sql/table.h:
  Add declaration for TABLE::prep_on_expr.

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 212a3dd4501..5a87635a4dc 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -1095,6 +1095,12 @@ public:
   predicates that can not be used to access tables in the investigated
   plan for those, obtained by substitution of some fields for equal fields,
   that can be used.     
+
+  Prepared Statements/Stored Procedures note: instances of class
+  Item_equal are created only at the time a PS/SP is executed and
+  are deleted in the end of execution. All changes made to these
+  objects need not be registered in the list of changes of the parse
+  tree and do not harm PS/SP re-execution.
 */
 
 class Item_equal: public Item_bool_func