diff --git a/configure.in b/configure.in
index ae26a0c44df..58682063593 100644
--- a/configure.in
+++ b/configure.in
@@ -342,7 +342,7 @@ AC_SUBST(CXXFLAGS)
 AC_SUBST(LD)
 AC_SUBST(INSTALL_SCRIPT)
 
-export CC CXX CFLAGS LD LDFLAGS AR
+export CC CXX CFLAGS LD LDFLAGS AR ARFLAGS
 
 if test "$GCC" = "yes"
 then
diff --git a/innobase/configure.in b/innobase/configure.in
index baf11272ab9..c56bd8274c4 100644
--- a/innobase/configure.in
+++ b/innobase/configure.in
@@ -117,6 +117,13 @@ case "$target" in
 	 CFLAGS="$CFLAGS -DUNIV_MUST_NOT_INLINE";;
 esac
 
+# must go in pair with AR as set by MYSQL_CHECK_AR
+if test -z "$ARFLAGS"
+then
+  ARFLAGS="cru"
+fi
+AC_SUBST(ARFLAGS)
+
 AC_OUTPUT(Makefile os/Makefile ut/Makefile btr/Makefile dnl
 		buf/Makefile data/Makefile dnl
 		dict/Makefile dyn/Makefile dnl
diff --git a/mysql-test/mysql-test-run.pl b/mysql-test/mysql-test-run.pl
index 6e2fb50d988..2051afc7745 100755
--- a/mysql-test/mysql-test-run.pl
+++ b/mysql-test/mysql-test-run.pl
@@ -303,7 +303,7 @@ sub mysqld_arguments ($$$$$);
 sub stop_masters_slaves ();
 sub stop_masters ();
 sub stop_slaves ();
-sub run_mysqltest ($$);
+sub run_mysqltest ($);
 sub usage ($);
 
 ######################################################################
@@ -1342,10 +1342,11 @@ sub run_testcase ($) {
 
   if ( ! $glob_use_running_server and ! $glob_use_embedded_server )
   {
-    if ( $tinfo->{'master_restart'} or $master->[0]->{'uses_special_flags'} )
+    if ( $tinfo->{'master_restart'} or
+         $master->[0]->{'running_master_is_special'} )
     {
       stop_masters();
-      $master->[0]->{'uses_special_flags'}= 0; # Forget about why we stopped
+      $master->[0]->{'running_master_is_special'}= 0; # Forget why we stopped
     }
 
     # ----------------------------------------------------------------------
@@ -1423,9 +1424,9 @@ sub run_testcase ($) {
         }
       }
 
-      if ( @{$tinfo->{'master_opt'}} )
+      if ( $tinfo->{'master_restart'} )
       {
-        $master->[0]->{'uses_special_flags'}= 1;
+        $master->[0]->{'running_master_is_special'}= 1;
       }
     }
 
@@ -1472,7 +1473,7 @@ sub run_testcase ($) {
     }
     unlink($path_timefile);
 
-    my $res= run_mysqltest($tinfo, $tinfo->{'master_opt'});
+    my $res= run_mysqltest($tinfo);
 
     if ( $res == 0 )
     {
@@ -1973,9 +1974,8 @@ sub stop_slaves () {
 }
 
 
-sub run_mysqltest ($$) {
+sub run_mysqltest ($) {
   my $tinfo=       shift;
-  my $master_opts= shift;
 
   my $cmdline_mysqldump= "$exe_mysqldump --no-defaults -uroot " .
                          "--socket=$master->[0]->{'path_mysock'} --password=";
diff --git a/mysql-test/r/case.result b/mysql-test/r/case.result
index a854cf4c7b0..b02f85132aa 100644
--- a/mysql-test/r/case.result
+++ b/mysql-test/r/case.result
@@ -160,6 +160,21 @@ t1	CREATE TABLE `t1` (
   `COALESCE('a' COLLATE latin1_bin,'b')` varchar(1) character set latin1 collate latin1_bin NOT NULL default ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
+SELECT 'case+union+test'
+UNION 
+SELECT CASE LOWER('1') WHEN LOWER('2') THEN 'BUG' ELSE 'nobug' END;
+case+union+test
+case+union+test
+nobug
+SELECT CASE LOWER('1') WHEN LOWER('2') THEN 'BUG' ELSE 'nobug' END;
+CASE LOWER('1') WHEN LOWER('2') THEN 'BUG' ELSE 'nobug' END
+nobug
+SELECT 'case+union+test'
+UNION 
+SELECT CASE '1' WHEN '2' THEN 'BUG' ELSE 'nobug' END;
+case+union+test
+case+union+test
+nobug
 CREATE TABLE t1 (EMPNUM INT);
 INSERT INTO t1 VALUES (0), (2);
 CREATE TABLE t2 (EMPNUM DECIMAL (4, 2));
diff --git a/mysql-test/t/case.test b/mysql-test/t/case.test
index f2cfce9085d..e942333d5fe 100644
--- a/mysql-test/t/case.test
+++ b/mysql-test/t/case.test
@@ -111,6 +111,17 @@ explain extended SELECT
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+# Test for BUG#10151
+SELECT 'case+union+test'
+UNION 
+SELECT CASE LOWER('1') WHEN LOWER('2') THEN 'BUG' ELSE 'nobug' END;
+
+SELECT CASE LOWER('1') WHEN LOWER('2') THEN 'BUG' ELSE 'nobug' END;
+
+SELECT 'case+union+test'
+UNION 
+SELECT CASE '1' WHEN '2' THEN 'BUG' ELSE 'nobug' END;
+
 #
 # Tests for bug #9939: conversion of the arguments for COALESCE and IFNULL
 #
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 5a2e14eef2e..0442865b7f9 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1420,6 +1420,8 @@ Item *Item_func_case::find_item(String *str)
   my_decimal *first_expr_dec, first_expr_dec_val;
   longlong first_expr_int;
   double   first_expr_real;
+  char buff[MAX_FIELD_WIDTH];
+  String buff_str(buff,sizeof(buff),default_charset());
 
   /* These will be initialized later */
   LINT_INIT(first_expr_str);
@@ -1433,7 +1435,7 @@ Item *Item_func_case::find_item(String *str)
     {
       case STRING_RESULT:
       	// We can't use 'str' here as this may be overwritten
-	if (!(first_expr_str= args[first_expr_num]->val_str(&str_value)))
+	if (!(first_expr_str= args[first_expr_num]->val_str(&buff_str)))
 	  return else_expr_num != -1 ? args[else_expr_num] : 0;	// Impossible
         break;
       case INT_RESULT:
diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index 29cee6da4d3..825ec34e410 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -509,7 +509,7 @@ sp_head::destroy()
     delete i;
   delete_dynamic(&m_instr);
   m_pcont->destroy();
-  free_items(free_list);
+  free_items();
 
   /*
     If we have non-empty LEX stack then we just came out of parser with
@@ -596,7 +596,6 @@ sp_head::execute(THD *thd)
     ctx->clear_handler();
   thd->query_error= 0;
   old_arena= thd->current_arena;
-  thd->current_arena= this;
 
   /*
     We have to save/restore this info when we are changing call level to
@@ -636,23 +635,18 @@ sp_head::execute(THD *thd)
       break;
     DBUG_PRINT("execute", ("Instruction %u", ip));
     thd->set_time();		// Make current_time() et al work
-    {
-      /*
-        We have to substitute free_list of executing statement to
-        current_arena to store there all new items created during execution
-        (for example '*' expanding, or items made during permanent subquery
-        transformation)
-        Note: Every statement have to have all its items listed in free_list
-        for correct cleaning them up
-      */
-      Item *save_free_list= thd->current_arena->free_list;
-      thd->current_arena->free_list= i->free_list;
-      ret= i->execute(thd, &ip);
-      i->free_list= thd->current_arena->free_list;
-      thd->current_arena->free_list= save_free_list;
-    }
+    /*
+      We have to set thd->current_arena before executing the instruction
+      to store in the instruction free_list all new items, created
+      during the first execution (for example expanding of '*' or the
+      items made during other permanent subquery transformations).
+    */
+    thd->current_arena= i;
+    ret= i->execute(thd, &ip);
     if (i->free_list)
       cleanup_items(i->free_list);
+    i->state= Query_arena::EXECUTED;
+
     // Check if an exception has occurred and a handler has been found
     // Note: We havo to check even if ret==0, since warnings (and some
     //       errors don't return a non-zero value.
@@ -694,7 +688,6 @@ sp_head::execute(THD *thd)
   DBUG_ASSERT(!thd->derived_tables);
   thd->derived_tables= old_derived_tables;
 
-  cleanup_items(thd->current_arena->free_list);
   thd->current_arena= old_arena;
   state= EXECUTED;
 
@@ -728,8 +721,8 @@ sp_head::execute_function(THD *thd, Item **argp, uint argcount, Item **resp)
   sp_rcontext *nctx = NULL;
   uint i;
   int ret;
-  MEM_ROOT *old_mem_root, call_mem_root;
-  Item *old_free_list, *call_free_list;
+  MEM_ROOT call_mem_root;
+  Query_arena call_arena(&call_mem_root, INITIALIZED_FOR_SP), backup_arena;
 
   if (argcount != params)
   {
@@ -741,14 +734,12 @@ sp_head::execute_function(THD *thd, Item **argp, uint argcount, Item **resp)
   }
 
   init_alloc_root(&call_mem_root, MEM_ROOT_BLOCK_SIZE, 0);
-  old_mem_root= thd->mem_root;
-  thd->mem_root= &call_mem_root;
-  old_free_list= thd->free_list; // Keep the old list
-  thd->free_list= NULL;	// Start a new one
+
+  thd->set_n_backup_item_arena(&call_arena, &backup_arena);
 
   // QQ Should have some error checking here? (types, etc...)
   nctx= new sp_rcontext(csize, hmax, cmax);
-  nctx->callers_mem_root= old_mem_root;
+  nctx->callers_mem_root= backup_arena.mem_root;
   for (i= 0 ; i < argcount ; i++)
   {
     sp_pvar_t *pvar = m_pcont->find_pvar(i);
@@ -780,9 +771,7 @@ sp_head::execute_function(THD *thd, Item **argp, uint argcount, Item **resp)
   // Partially restore context now.
   // We still need the call mem root and free list for processing
   // of the result.
-  call_free_list= thd->free_list;
-  thd->free_list= old_free_list;
-  thd->mem_root= old_mem_root;
+  thd->restore_backup_item_arena(&call_arena, &backup_arena);
 
   if (m_type == TYPE_ENUM_FUNCTION && ret == 0)
   {
@@ -802,8 +791,7 @@ sp_head::execute_function(THD *thd, Item **argp, uint argcount, Item **resp)
   thd->spcont= octx;
 
   // Now get rid of the rest of the callee context
-  cleanup_items(call_free_list);
-  free_items(call_free_list);
+  call_arena.free_items();
   free_root(&call_mem_root, MYF(0));
 
   DBUG_RETURN(ret);
@@ -835,8 +823,8 @@ sp_head::execute_procedure(THD *thd, List<Item> *args)
   sp_rcontext *octx = thd->spcont;
   sp_rcontext *nctx = NULL;
   my_bool tmp_octx = FALSE;	// True if we have allocated a temporary octx
-  MEM_ROOT *old_mem_root, call_mem_root;
-  Item *old_free_list, *call_free_list;
+  MEM_ROOT call_mem_root;
+  Query_arena call_arena(&call_mem_root, INITIALIZED_FOR_SP), backup_arena;
 
   if (args->elements != params)
   {
@@ -846,10 +834,7 @@ sp_head::execute_procedure(THD *thd, List<Item> *args)
   }
 
   init_alloc_root(&call_mem_root, MEM_ROOT_BLOCK_SIZE, 0);
-  old_mem_root= thd->mem_root;
-  thd->mem_root= &call_mem_root;
-  old_free_list= thd->free_list; // Keep the old list
-  thd->free_list= NULL;	// Start a new one
+  thd->set_n_backup_item_arena(&call_arena, &backup_arena);
 
   if (csize > 0 || hmax > 0 || cmax > 0)
   {
@@ -919,9 +904,7 @@ sp_head::execute_procedure(THD *thd, List<Item> *args)
   // Partially restore context now.
   // We still need the call mem root and free list for processing
   // of out parameters.
-  call_free_list= thd->free_list;
-  thd->free_list= old_free_list;
-  thd->mem_root= old_mem_root;
+  thd->restore_backup_item_arena(&call_arena, &backup_arena);
 
   if (!ret && csize > 0)
   {
@@ -996,8 +979,7 @@ sp_head::execute_procedure(THD *thd, List<Item> *args)
   thd->spcont= octx;
 
   // Now get rid of the rest of the callee context
-  cleanup_items(call_free_list);
-  free_items(call_free_list);
+  call_arena.free_items();
   thd->lex->unit.cleanup();
   free_root(&call_mem_root, MYF(0));
 
@@ -1291,6 +1273,13 @@ void sp_head::add_instr(sp_instr *instr)
 {
   instr->free_list= m_thd->free_list;
   m_thd->free_list= 0;
+  /*
+    Memory root of every instruction is designated for permanent
+    transformations (optimizations) made on the parsed tree during
+    the first execution. It points to the memory root of the
+    entire stored procedure, as their life span is equal.
+  */
+  instr->mem_root= &main_mem_root;
   insert_dynamic(&m_instr, (gptr)&instr);
 }
 
diff --git a/sql/sp_head.h b/sql/sp_head.h
index 2c75a320f30..aaef5a3d50e 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -274,7 +274,7 @@ private:
 // "Instructions"...
 //
 
-class sp_instr : public Sql_alloc
+class sp_instr :public Query_arena, public Sql_alloc
 {
   sp_instr(const sp_instr &);	/* Prevent use of these */
   void operator=(sp_instr &);
@@ -282,17 +282,16 @@ class sp_instr : public Sql_alloc
 public:
 
   uint marked;
-  Item *free_list;              // My Items
   uint m_ip;			// My index
   sp_pcontext *m_ctx;		// My parse context
 
   // Should give each a name or type code for debugging purposes?
   sp_instr(uint ip, sp_pcontext *ctx)
-    :Sql_alloc(), marked(0), free_list(0), m_ip(ip), m_ctx(ctx)
+    :Query_arena(0, INITIALIZED_FOR_SP), marked(0), m_ip(ip), m_ctx(ctx)
   {}
 
   virtual ~sp_instr()
-  { free_items(free_list); }
+  { free_items(); }
 
   // Execute this instrution. '*nextp' will be set to the index of the next
   // instruction to execute. (For most instruction this will be the
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 8abd7cbbe7d..20f48da9283 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -171,9 +171,6 @@ THD::THD()
    spcont(NULL)
 {
   current_arena= this;
-#ifndef DBUG_OFF
-  backup_arena= 0;
-#endif
   host= user= priv_user= db= ip= 0;
   catalog= (char*)"std"; // the only catalog we have for now
   host_or_ip= "connecting host";
@@ -528,7 +525,7 @@ void THD::cleanup_after_query()
     next_insert_id= 0;
   }
   /* Free Items that were created during this execution */
-  free_items(free_list);
+  free_items();
   /*
     In the rest of code we assume that free_list never points to garbage:
     Keep this predicate true.
@@ -1485,6 +1482,21 @@ Query_arena::Type Query_arena::type() const
 }
 
 
+void Query_arena::free_items()
+{
+  Item *next;
+  DBUG_ENTER("Query_arena::free_items");
+  /* This works because items are allocated with sql_alloc() */
+  for (; free_list; free_list= next)
+  {
+    next= free_list->next;
+    free_list->delete_self();
+  }
+  /* Postcondition: free_list is 0 */
+  DBUG_VOID_RETURN;
+}
+
+
 /*
   Statement functions 
 */
@@ -1556,11 +1568,11 @@ void THD::end_statement()
 void Query_arena::set_n_backup_item_arena(Query_arena *set, Query_arena *backup)
 {
   DBUG_ENTER("Query_arena::set_n_backup_item_arena");
-  DBUG_ASSERT(backup_arena == 0);
+  DBUG_ASSERT(backup->is_backup_arena == FALSE);
   backup->set_item_arena(this);
   set_item_arena(set);
 #ifndef DBUG_OFF
-  backup_arena= 1;
+  backup->is_backup_arena= TRUE;
 #endif
   DBUG_VOID_RETURN;
 }
@@ -1569,10 +1581,11 @@ void Query_arena::set_n_backup_item_arena(Query_arena *set, Query_arena *backup)
 void Query_arena::restore_backup_item_arena(Query_arena *set, Query_arena *backup)
 {
   DBUG_ENTER("Query_arena::restore_backup_item_arena");
+  DBUG_ASSERT(backup->is_backup_arena);
   set->set_item_arena(this);
   set_item_arena(backup);
 #ifndef DBUG_OFF
-  backup_arena= 0;
+  backup->is_backup_arena= FALSE;
 #endif
   DBUG_VOID_RETURN;
 }
diff --git a/sql/sql_class.h b/sql/sql_class.h
index a635a126f84..adc164085f9 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -663,7 +663,10 @@ public:
   Item *free_list;
   MEM_ROOT *mem_root;                   // Pointer to current memroot
 #ifndef DBUG_OFF
-  bool backup_arena;
+  bool is_backup_arena; /* True if this arena is used for backup. */
+#define INIT_ARENA_DBUG_INFO is_backup_arena= 0
+#else 
+#define INIT_ARENA_DBUG_INFO  
 #endif
   enum enum_state
   {
@@ -681,12 +684,14 @@ public:
 
   Query_arena(MEM_ROOT *mem_root_arg, enum enum_state state_arg) :
     free_list(0), mem_root(mem_root_arg), state(state_arg)
-  {}
+  { INIT_ARENA_DBUG_INFO; }
   /*
     This constructor is used only when Query_arena is created as
     backup storage for another instance of Query_arena.
   */
-  Query_arena() {};
+  Query_arena() { INIT_ARENA_DBUG_INFO; }
+
+#undef INIT_ARENA_DBUG_INFO
   virtual Type type() const;
   virtual ~Query_arena() {};
 
@@ -726,6 +731,8 @@ public:
   void set_n_backup_item_arena(Query_arena *set, Query_arena *backup);
   void restore_backup_item_arena(Query_arena *set, Query_arena *backup);
   void set_item_arena(Query_arena *set);
+
+  void free_items();
 };
 
 
diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index eeea493d868..c97cb037f15 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -2429,7 +2429,7 @@ Prepared_statement::~Prepared_statement()
 {
   if (cursor)
     cursor->Cursor::~Cursor();
-  free_items(free_list);
+  free_items();
   delete lex->result;
 }
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 1487dfbb436..96a25c7919b 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1914,8 +1914,7 @@ Cursor::close()
   }
   join= 0;
   unit= 0;
-  free_items(free_list);
-  free_list= 0;
+  free_items();
   /*
     Must be last, as some memory might be allocated for free purposes,
     like in free_tmp_table() (TODO: fix this issue)