Fixed many compiler warnings

Fixed bugs in group_concat with ORDER BY and DISTINCT (Bugs #2695, #3381 and #3319)
Fixed crash when doing rollback in slave and the io thread catched up with the sql thread
Set locked_in_memory properly


include/mysql_com.h:
  Fixed compiler warning
libmysqld/emb_qcache.cc:
  Removed not used variable
libmysqld/lib_sql.cc:
  Removed not used variable
myisam/mi_locking.c:
  Added comment
myisam/mi_rnext.c:
  Fixed bug in concurrent insert
myisam/mi_rprev.c:
  Simple optimization
mysql-test/r/func_gconcat.result:
  New tests
mysql-test/t/func_gconcat.test:
  New tests
mysql-test/t/func_group.test:
  Cleanup
sql-common/client.c:
  Removed compiler warning
sql/derror.cc:
  Better comments
sql/field.cc:
  Removed not used function/variable
sql/field.h:
  Removed not needed variable
sql/ha_innodb.cc:
  Removed not used function
sql/item.cc:
  Fixed compiler warning
sql/item_cmpfunc.cc:
  Fixed compiler warning
sql/item_func.cc:
  Fixed compiler warning
sql/item_geofunc.cc:
  Fixed compiler warning
sql/item_sum.cc:
  Fixed bugs in group_concat and added more comments
  (Bugs #2695, #3381 and #3319)
  - field->abs_offset was not needed
  - Wrong assumption of field order in temporary table
  - Some not used variables removed
  - Added ORDER BY fields after argument fields so that code in sql_select.cc can move all fields to point to temporary tables, if needed.
  - Optimized loops
sql/item_sum.h:
  Bug fixing and cleanup of group_concat()
sql/log.cc:
  Removed wrong comment
sql/log_event.cc:
  Removed compiler warning
sql/mysqld.cc:
  Set locked_in_memory properly
sql/protocol.cc:
  Removed compiler warning
sql/set_var.cc:
  Code cleanup
sql/slave.cc:
  Fixed crash when doing rollback in slave and the io thread catched up with the sql thread
sql/sql_cache.cc:
  Removed compiler warnings
sql/sql_derived.cc:
  Removed not used variable
sql/sql_insert.cc:
  Removed compiler warnings
sql/sql_lex.cc:
  Removed not used lable
sql/sql_lex.h:
  Removed compiler warnings
sql/sql_parse.cc:
  Removed compiler warnings
sql/sql_prepare.cc:
  Removed compiler warnings
sql/sql_select.cc:
  Removed not used variables
  Added function comments
sql/sql_show.cc:
  Removed compiler warnings
sql/sql_yacc.yy:
  Fix for ORDER BY handling in GROUP_CONCAT()

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/set_var.cc b/sql/set_var.cc
index 5d2a6c1d39e..b99816eaccd 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -838,7 +838,8 @@ bool update_sys_var_str(sys_var_str *var_str, rw_lock_t *var_mutex,
 {
   char *res= 0, *old_value=(char *)(var ? var->value->str_value.ptr() : 0);
   uint new_length= (var ? var->value->str_value.length() : 0);
-  if (!old_value) old_value="";
+  if (!old_value)
+    old_value= (char*) "";
   if (!(res= my_strdup_with_length(old_value, new_length, MYF(0))))
     return 1;
   /*