The problem is that MySQL use of pthread_setschedprio is not
supported by i5/OS and the default system behavior for unsupported
calls is to emit a SIGILL signal which causes the server to
abort.

The solution is to treat the pthread_setschedprio as inexistent
when compiling binaries for i5/OS. This also does not invalidate
the fix for bug 38477 as the only supported dispatch class is
SCHED_OTHER (which is passed to pthread_setschedparam).

configure.in:
  Skip pthread_setschedprio check on i5/OS.

+ minor improvements

Documented behaviour was broken by the patch for bug 33699
that actually is not a bug.

This fix reverts patch for bug 33699 and reverts the
UPDATE of NOT NULL field with NULL query to old
behavior.


mysql-test/extra/rpl_tests/rpl_extraMaster_Col.test:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/include/ps_modify.inc:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/auto_increment.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/csv_not_null.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/null.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/ps_2myisam.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/ps_3innodb.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/ps_4heap.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/ps_5merge.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/r/warnings.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/suite/ndb/r/ps_7ndb.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/suite/rpl/r/rpl_extraColmaster_innodb.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/suite/rpl/r/rpl_extraColmaster_myisam.result:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/suite/rpl/t/rpl_err_ignoredtable.test:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/t/auto_increment.test:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/t/csv_not_null.test:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/t/null.test:
  Bug #39265: fix for the bug 33699 should be reverted
mysql-test/t/warnings.test:
  Bug #39265: fix for the bug 33699 should be reverted
sql/sql_update.cc:
  Bug #39265: fix for the bug 33699 should be reverted

            ORDER BY could cause a server crash

Dependent subqueries like

  SELECT COUNT(*) FROM t1, t2 WHERE t2.b
   IN (SELECT DISTINCT t2.b FROM t2 WHERE t2.b = t1.a)

caused a memory leak proportional to the
number of outer rows.


The make_simple_join() function has been modified to
JOIN class method to store join_tab_reexec and
table_reexec values in the parent join only
(make_simple_join of tmp_join may access these values
via 'this' pointer of the parent JOIN).

NOTE: this patch doesn't include standard test case (this is
"out of memory" bug). See bug #42037 page for test cases.


sql/sql_select.cc:
  Bug #42037: Queries containing a subquery with DISTINCT and
              ORDER BY could cause a server crash
  
  The make_simple_join() function has been modified to
  JOIN class method to store join_tab_reexec and
  table_reexec values in the parent join only.
sql/sql_select.h:
  Bug #42037: Queries containing a subquery with DISTINCT and
              ORDER BY could cause a server crash
  
  1. The make_simple_join() function has been modified to
     JOIN class method.
  
  2. Type of JOIN::table_reexec field has been changed from
     TABLE** to TABLE *table_reexec[1]: this field always was
     NULL or a pointer to one-element array of pointers, so
     a pointer to a pointer has been replaced with one pointer
     and unnecessary memory allocation has been eliminated.

Problem: some queries using NAME_CONST(.. COLLATE ...)
lead to server crash due to failed type cast.

Fix: return the underlying item's type in case of
NAME_CONST(.. COLLATE ...) to avoid wrong casting.


mysql-test/r/func_misc.result:
  Fix for bug#42014: Crash, name_const with coll
    - test result.
mysql-test/t/func_misc.test:
  Fix for bug#42014: Crash, name_const with coll
    - test case.
sql/item.cc:
  Fix for bug#42014: Crash, name_const with coll
    - in case of NAME_CONST('name', 'value' COLLATE collation)
  Item_name_const::type() returns type of 'value' argument 
  to awoid wrong type casting of the Item_name_const items.

   code backported from 6.0


per-file messages:
  include/my_global.h
    Remove SC_MAXWIDTH. This is unused and irrelevant nowadays.
  include/my_sys.h
    Remove errbuf declaration and unused definitions.
  mysys/my_error.c
    Remove errbuf definition and move and adjust ERRMSGSIZE.
  mysys/my_init.c
    Declare buffer on the stack and use my_snprintf.
  mysys/safemalloc.c
    Use size explicitly. It's more than enough for the message at hand.
  sql/sql_error.cc
    Use size explicitly. It's more than enough for the message at hand.
  sql/sql_parse.cc
    Declare buffer on the stack. Use my_snprintf as it will result in
    less stack space being used than by a system provided sprintf --
    this allows us to put the buffer on the stack without causing much
    trouble. Also, the use of errbuff here was not thread-safe as the
    function can be entered concurrently from multiple threads.
  sql/sql_table.cc
    Use MYSQL_ERRMSG_SIZE. Extra space is not needed as my_snprintf will
    nul terminate strings.
  storage/myisam/ha_myisam.cc
Use MYSQL_ERRMSG_SIZE.
  sql/share/errmsg.txt
    Error message truncation in test "innodb" in embedded mode
    filename in the error message can safely take up to 210 symbols.

Accessing well defined MERGE table may return an error
stating that the merge table is incorrectly defined. This
happens if MERGE child tables were accessed before and we
failed to open another incorrectly defined MERGE table in
this connection.

myrg_open() internally used my_errno as a variable for determining
failure, and thus could be tricked into a wrong decision by other
uses of my_errno.

With this fix we use function local boolean flag instead of my_errno
to determine failure.

myisammrg/myrg_open.c:
  There are two requirement for accessing/setting my_errno variable,
  which were not followed by myrg_open():
  - it must be checked immediately after a function returned an error. There
    must be no calls to other functions that may change it's value between.
  - my_errno value must be set right before a function is going to return an
    error. There must be no calls to other functions that may change it's
    value between (that's why we have these tricks with save_errno at the
    bottom of myrg_open()).
  
  myrg_open() internally used my_errno as a variable for determining
  failure, and thus could be tricked into a wrong decision by other
  uses of my_errno.
mysql-test/r/merge.result:
  A test case for BUG#32047.
mysql-test/t/merge.test:
  A test case for BUG#32047.

Problem:
   RelativeLocationPath can appear only after a node-set expression
   in the third and the fourth branches of this rule:
     PathExpr :: =  LocationPath
                    | FilterExpr
                    | FilterExpr '/' RelativeLocationPath
                    | FilterExpr '//' RelativeLocationPath
   XPatch code didn't check the type of FilterExpr and crashed.
Fix:
   If FilterExpr is a scalar expression
   (variable reference, literal, number, scalar function call)
   return error.


mysql-test/r/xml.result:
  test result
mysql-test/t/xml.test:
  test case
sql/item_xmlfunc.cc:
  Problem:
     RelativeLocationPath can appear only after a node-set expression
     in the third and the fourth branches of this rule:
       PathExpr :: =  LocationPath
                      | FilterExpr
                      | FilterExpr '/' RelativeLocationPath
                      | FilterExpr '//' RelativeLocationPath
     XPatch code didn't check the type of FilterExpr and crashed.
  Fix:
     If FilterExpr is a scalar expression
     (variable reference, literal, number, scalar function call)
     return error.

fixing build issue, caused by the previous push.

sql/log_event.cc:
  moving a new declaration out of mysqlbinlog compilation scope.

            
The bug happened because filtering-out a STMT_END_F-flagged event so that
the transaction COMMIT finds traces of incomplete statement commit.
Such situation is only possible with ndb circular replication. The filtered-out
rows event is one that immediately preceeds the COMMIT query event.
      
Fixed with deploying an the rows-log-event statement commit at executing
of the transaction COMMIT event. 
Resources that were allocated by other than STMT_END_F-flagged event of
the last statement are clean up prior execution of the commit logics.


mysql-test/suite/rpl_ndb/t/disabled.def:
  re-enabling two tests.
sql/log_event.cc:
  Adding the statement cleanup to execute at the transaction commit time.
  The statement might not be ended with execution of STMT_END_F-flagged event because of
  the event was filtered out by SERVER_ID rules.
  Small refactoring for Rows_log_event::do_update_pos() to be split on two parts:
  the statement commit that releases its execution time allocated resources, and
  the relay log update.

 - Properly set --bindir=$path_client_bindir and --basedir=$basedir by adding %s format specifier

                    functions
      
String::realloc() did not check whether the existing string data fits in the newly
allocated buffer for cases when reallocating a String object with external buffer
(i.e.alloced == FALSE).  This could lead to memory overruns in some cases.


mysql-test/r/func_str.result:
  Added a test case for bug #41868.
mysql-test/t/func_str.test:
  Added a test case for bug #41868.
sql/sql_class.cc:
  After each call to Item::send() in select_send::send_data() reset buffer to its
  original state to reduce unnecessary malloc() calls. See comments for bug #41868
  for detailed analysis.
sql/sql_string.cc:
  Fixed String::realloc() to check whether the existing string data fits in the newly allocated buffer for cases when reallocating a String object with external buffer.

           upgrading lock, even with low_priority_updates

The problem is that there is no mechanism to control whether a
delayed insert takes a high or low priority lock on a table.

The solution is to modify the delayed insert thread ("handler")
to take into account the global value of low_priority_updates
when taking table locks. The value of low_priority_updates is
retrieved when the insert delayed thread is created and will
remain the same for the duration of the thread.


include/thr_lock.h:
  Update prototype.
mysql-test/r/delayed.result:
  Add test case result for Bug#40536
mysql-test/t/delayed.test:
  Add test case for Bug#40536
mysys/thr_lock.c:
  Add function parameter which specifies the write lock type.
sql/sql_insert.cc:
  Take a low priority write lock if global value of low_priority_updates
  was ON when the thread was created.

+ fix wrong resultfile have_outfile.require

Option opt_threads is deprecated in 5.1, and a warning is
printed when used. Will remove in 6.0.

      
There was a type casting problem in the storage/innobase/handler/ha_innodb.cc,
(int ha_innobase::write_row(...)). Innobase uses has an internal error variable
of type 'ulint' while mysql uses an 'int'. 
      
To fix the problem the function manipulates an error variable of
type 'ulint' and only casts it into 'int' when needs to return the value.