prepared statements

Using GROUP_CONCAT() together with the WITH ROLLUP modifier
could crash the server.

The reason was a combination of several facts:

1. The Item_func_group_concat class stores pointers to ORDER
objects representing the columns in the ORDER BY clause of
GROUP_CONCAT().

2. find_order_in_list() called from
Item_func_group_concat::setup() modifies the ORDER objects so
that their 'item' member points to the arguments list
allocated in the Item_func_group_concat constructor.

3. In some cases (e.g. in JOIN::rollup_make_fields) a copy of
the original Item_func_group_concat object could be created by
using the Item_func_group_concat::Item_func_group_concat(THD
*thd, Item_func_group_concat *item) copy constructor. The
latter essentially creates a shallow copy of the source
object. Memory for the arguments array is allocated on
thd->mem_root, but the pointers for arguments and ORDER are
copied verbatim.

What happens in the test case is that when executing the query
for the first time, after a copy of the original
Item_func_group_concat object has been created by
JOIN::rollup_make_fields(), find_order_in_list() is called for
this new object. It then resolves ORDER BY by modifying the
ORDER objects so that they point to elements of the arguments
array which is local to the cloned object. When thd->mem_root
is freed upon completing the execution, pointers in the ORDER
objects become invalid. Those ORDER objects, however, are also
shared with the original Item_func_group_concat object which is
preserved between executions of a prepared statement. So the
first call to find_order_in_list() for the original object on
the second execution tries to dereference an invalid pointer.

The solution is to create copies of the ORDER objects when
copying Item_func_group_concat to not leave any stale pointers
in other instances with different lifecycles.



mysql-test/r/func_gconcat.result:
  Test case for bug #54476.
mysql-test/t/func_gconcat.test:
  Test case for bug #54476.
sql/item_sum.cc:
  Copy the ORDER objects pointed to by the elements of the 
  'order' array in the copy constructor of 
  Item_func_group_concat.
sql/table.h:
  Removed the unused 'item_copy' member of the ORDER class.

SHOW DATABASES LIKE ... was not converting to lowercase on comparison as the
documentation is suggesting. 
Fixed it to behave similarly to SHOW TABLES LIKE ... and updated the failing
on MacOSX lowercase_table2 test case.

           due to GCC preprocessor change
      
Addendum for trunk: add -DMYSQL_ABI_CHECK to the cmake ABI check.

           due to GCC preprocessor change

Addendum for trunk: do not include system header when checking
the ABI.

Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.

client/mysql.cc:
  Meaningless pointer dereferences.
client/mysql_upgrade.c:
  Check whether reading from the file succeeded.
extra/comp_err.c:
  Unused.
extra/yassl/src/yassl_imp.cpp:
  Skip instead of reading data that is discarded.
include/my_pthread.h:
  Variable is only used in debug builds.
include/mysys_err.h:
  Add new error messages.
mysys/errors.c:
  Add new error message for permission related functions.
mysys/mf_iocache.c:
  Variable is only checked under THREAD.
mysys/my_copy.c:
  Raise a error if chmod or chown fails.
mysys/my_redel.c:
  Raise a error if chmod or chown fails.
regex/engine.c:
  Use a equivalent variable for the assert.
server-tools/instance-manager/instance_options.cc:
  Unused.
sql/field.cc:
  Unused.
sql/item.cc:
  Unused.
sql/log.cc:
  Do not ignore the return value of freopen: only set buffer if
  reopening succeeds.
  
  Adjust doxygen comment to the right function.
  
  Pass message lenght to log function.
sql/mysqld.cc:
  Do not ignore the return value of freopen: only set buffer if
  reopening succeeds.
sql/partition_info.cc:
  Unused.
sql/slave.cc:
  No need to set pointer to the address of '\0'.
sql/spatial.cc:
  Unused. Left for historical purposes.
sql/sql_acl.cc:
  Unused.
sql/sql_base.cc:
  Pointers are always set to the same variables.
sql/sql_parse.cc:
  End statement if reading fails.
  
  Store the buffer after it has actually been updated.
sql/sql_repl.cc:
  No need to set pointer to the address of '\0'.
sql/sql_show.cc:
  Put variable under the same ifdef block.
sql/udf_example.c:
  Set null pointer flag appropriately.
storage/csv/ha_tina.cc:
  Meaningless dereferences.
storage/example/ha_example.cc:
  Return the error since it's available.
storage/myisam/mi_locking.c:
  Remove unused and dead code.

           due to GCC preprocessor change
      
The problem is that newer GCC versions treats missing headers
as fatal errors. The solution is to use a guard macro to prevent
the inclusion of system headers when checking the ABI with the
C Preprocessor.

Reference: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15638
           http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44836

Makefile.am:
  Define guard macro.
configure.in:
  Remove workaround.
include/mysql.h:
  Guard the header inclusion.
include/mysql.h.pp:
  Header is not included anymore.

           table with active trx

Essentially, the problem is that InnoDB does a implicit commit
when a cursor (table handler) is unlocked/closed, creating
a dissonance between the transaction state within the server
layer and the storage engine layer. Theoretically, a statement
transaction can encompass several table instances in a similar
manner to a multiple statement transaction, hence it does not
make sense to limit a statement transaction to the lifetime of
the table instances (cursors) used within it.

Since this particular instance of the problem is only triggerable
on 5.1 and is masked on 5.5 due 2PC being skipped (assertion is in
the prepare phase of a 2PC), the solution (which is less risky) is
to explicitly end the transaction before the cached table is unlock
on rename table.

The patch is to be null merged into trunk.

mysql-test/include/commit.inc:
  Fix counters, the binlog engine does not get involved anymore.
mysql-test/suite/innodb_plugin/r/innodb_bug54453.result:
  Add test case result for Bug#54453
mysql-test/suite/innodb_plugin/t/innodb_bug54453.test:
  Add test case for Bug#54453
sql/sql_table.cc:
  End transaction as otherwise InnoDB will end it behind our backs.

This bug is a design flaw of the fix for the bug#33546. It assumed that an
item can be used only in one comparison context, but actually it isn't the
case. Item_cache_datetime is used to store result for MIX/MAX aggregate
functions. Because Arg_comparator always compares datetime values as INTs when
possible the Item_cache_datetime most time caches only INT value. But
since all datetime values has STRING result type MIN/MAX functions are asked
for a STRING value when the result is being sent to a client. The
Item_cache_datetime was designed to avoid conversions and get INT/STRING
values from an underlying item, but at the moment the values is asked
underlying item doesn't hold it anymore thus wrong result is returned.
Beside that MIN/MAX aggregate functions was wrongly initializing cached result
and this led to a wrong result.

The Item::has_compatible_context helper function is added. It checks whether
this and given items has the same comparison context or can be compared as
DATETIME values by Arg_comparator. The equality propagation optimization is
adjusted to take into account that items which being compared as DATETIME
can have different comparison contexts.
The Item_cache_datetime now converts cached INT value to a correct STRING
DATETIME value by means of number_to_datetime & my_TIME_to_str functions.
The Arg_comparator::set_cmp_context_for_datetime helper function is added. 
It sets comparison context of items being compared as DATETIMEs to INT if
items will be compared as longlong.
The Item_sum_hybrid::setup function now correctly initializes its result
value.
In order to avoid unnecessary conversions Item_sum_hybrid now states that it
can provide correct longlong value if the item being aggregated can do it
too.

mysql-test/r/group_by.result:
  Added a test case for the bug#49771.
sql/item.cc:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  The equality propagation mechanism is adjusted to take into account that
  items which being compared as DATETIME can have different comparison
  contexts.
  The Item_cache_datetime now converts cached INT value to a correct STRING
  DATETIME/TIME value.
sql/item.h:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  The Item::has_compatible_context helper function is added. It checks whether
  this and given items has the same comparison context or can be compared as
  DATETIME values by Arg_comparator.
  Added Item_cache::clear helper function.
sql/item_cmpfunc.cc:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  The Arg_comparator::set_cmp_func now sets the correct comparison context
  for items being compared as DATETIME values.
sql/item_cmpfunc.h:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  The Arg_comparator::set_cmp_context_for_datetime helper function is added. 
  It sets comparison context of items being compared as DATETIMEs to INT if
  items will be compared as longlong.
sql/item_sum.cc:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  The Item_sum_hybrid::setup function now correctly initializes its result
  value.
sql/item_sum.h:
  Bug#49771: Incorrect MIN/MAX for date/time values.
  In order to avoid unnecessary conversions Item_sum_hybrid now states that it
  can provide correct longlong value if the item being aggregated can do it
  too.

Put '-features=no%except' back into Solaris/x86 CXXFLAGS.